liu.seSearch for publications in DiVA
Endre søk
Begrens søket
12345 101 - 150 of 207
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 101. Hannink, G
    et al.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Schreurs, BW
    Buma, P
    High doses of OP-1 inhibit fibrous tissue ingrowth in impaction grafting2006Inngår i: Clinical Orthopaedics and Related Research, ISSN 0009-921X, E-ISSN 1528-1132, nr 452, s. 250-259Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A major concern in using growth factors in impaction grafting is the potential stimulation of the osteoclastic lineage. A solution would be using an osteoconductive material resistant to resorption and providing initial stability after reconstruction. Growth factors may promote bone formation in combination with such graft materials. We determined whether OP-1 would promote the incorporation of impacted morselized allografts and tricalcium phosphate/hydroxyapatite (TCP/HA) into host bone, whether bone formation would be preceded by an initial process of accelerated resorption, and whether the response to OP-1 remodeling/incorporation would be dose-related. We performed two bone chamber studies in goats to ascertain the early effects of OP-1 dose on resorption and incorporation of impacted morselized allografts and TCP/HA. After 4 weeks, the incorporation process of impacted morselized allografts and TCP/HA was not promoted by OP-1. We observed no signs of accelerated resorption preceding bone formation. An increase in OP-1 dose resulted in an inhibition of fibrous tissue formation but OP-1 did not promote bone formation. Early failures in impaction grafting, using mixes with OP-1, might be explained by the lack of fibrous tissue ingrowth and not by increased resorption and remodeling. © 2006 Lippincott Williams & Wilkins, Inc.

  • 102. Hannink, Gerjon
    et al.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Schreurs, B Willem
    Buma, Pieter
    Development of a large titanium bone chamber to study in vivo bone ingrowth2006Inngår i: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 27, nr 9, s. 1810-1816Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the bone conduction chamber (BCC) various materials and factors have been tested for their effect on bone graft incorporation and bone healing. However, biomaterials often have to be crushed to fit in this small chamber. Since cellular responses to biomaterials are influenced by the size and shape of particles, research concerning the evaluation of biomaterials is limited by the dimensions of this bone chamber. We enlarged and modified the BCC in order to be able to investigate the in vivo influences of biomaterials, growth factors and bone graft processing on tissue and bone ingrowth. Seven goats received four bone chambers each, three modified models and a BCC. The first model (BCC+) had two ingrowth openings, similar to that of the BCC. The second model had two round ingrowth openings (ROU). The third model had a open bottom for bone ingrowth (BOT). After 12 weeks, bone ingrowth distances were measured on histological sections and using μCT. Bone ingrowth was significantly higher (p=0.009 and 0.008) in the ROU compared to the BCC+ and the BOT, respectively. Similar results were found using μCT. The ROU model performed most similar to the BCC (gold standard) and is considered to be a promising new tool in biomaterials research. © 2005 Elsevier Ltd. All rights reserved.

  • 103.
    Hansson, Ulrik
    et al.
    Lund University Hospital, Sweden.
    Toksvig-Larsen, Sören
    Lund University Hospital, Sweden.
    Ryd, Leif
    Karolinska University Hospital, Huddinge, Sweden.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Once-weekly oral medication with alendronate does not prevent migration of knee prostheses: A double-blind randomized RSA study2009Inngår i: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 80, nr 1, s. 41-45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background and purpose

    Early migration of joint replacements is an effect of poor fixation and can predict late loosening. By reducing the bone resorption after implantation of a joint replacement, it should be possible to enhance the initial fixation of the implant. We studied the effect of once-weekly treatment with alendronate after knee replacement.

    Patients and methods

    We recruited 60 patients (60 knees) with gonarthrosis who were scheduled for a total knee replacement. They were operated on with identical implants and uncemented fixation. 30 patients were treated with a bisphosphonate (alendronate) and 30 patients underwent placebo treatment. The treatment started postoperatively and continued on a weekly basis for 6 months. The fixation of the implants was measured with repeated radiostereometry for 2 years.

    Results

    There was no difference in migration of implants between the two groups.

    Conclusion

    With uncemented fixation of knee implants, no benefit of once-weekly treatment with alendronate, starting postoperatively, could be seen during a 2-year follow-up period.

  • 104.
    Harding, A.K.
    et al.
    Department of Orthopedics, Lund University Hospital, SE-221 85 Lund, Sweden.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Kataoka, M.
    Department of Orthopedics, Lund University Hospital, SE-221 85 Lund, Sweden, Department of Orthopaedic Surgery, Oita University, Oita, Japan.
    Bylski, D.
    Department of Orthopedics, Lund University Hospital, SE-221 85 Lund, Sweden.
    Tagil, M.
    Tägil, M., Department of Orthopedics, Lund University Hospital, SE-221 85 Lund, Sweden.
    Aharinejad, S.
    Aharinejad, S..
    Manipulating the anabolic and catabolic response in bone graft remodeling: Synergism by a combination of local BMP-7 and a single systemic dosis of zoledronate2008Inngår i: Journal of Orthopaedic Research, ISSN 0736-0266, E-ISSN 1554-527X, Vol. 26, nr 9, s. 1245-1249Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Remodeling of a bone graft can be influenced both by anabolic substances, such as a bone morphogenic protein (BMP) and by anticatabolic substances, such as the bisphosphonates. BMPs are potent bone anabolic substances, but also boost catabolism and cause resorption. Bisphosphonates inhibit osteoclast function and can be used to postpone resorption. In the present study a combination of both drugs was explored in a rat bone chamber model. Cancellous bone grafts were treated with either BMP-7 or saline and placed in a bone chamber implanted in the proximal tibia. After 2 weeks, an injection of either zoledronate 0.1 mg/kg or saline was given subcutaneously. The rats were killed after 6 weeks, and bone ingrowth distance into the graft and graft resorption were measured by histomorphometry. BMP-7 significantly (p = 0.007) increased new bone ingrowth distance into the graft from 2.0 mm (SD = 0.98 mm) in the controls to 3.1 mm (SD = 0.93 mm). If bisphosphonate was not given, most of the newly formed and old graft bone was resorbed. A single injection of zoledronate significantly (p< 0.001) increased the trabecular volume/total volume to 40% (SD = 9%) compared to 14% (SD = 10%) in the nonbisphosphonate treated. In total, the net amount of bone increased by 400% when BMP-7 and zoledronate combined was compared to saline. A bone graft can be treated with BMP-7 to increase new bone formation and at the same time be protected against premature catabolism by a single dose of a bisphosphonate. This combination might be useful in various conditions in orthopedic reconstruction. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  • 105. Hilding, M.
    et al.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Intraoperative Ibandronate Reduced Prosthesis Migration After Implantation of Total Knee Prosthesis2008Inngår i: Journal of Bone and Joint Surgery. American volume, ISSN 0021-9355, E-ISSN 1535-1386, Vol. 90A, nr 11, s. 2555-2555Annet (Annet vitenskapelig)
  • 106.
    Hilding, Maria
    et al.
    Vasteras Hosp, Dept Orthoped, Vasteras, Sweden.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Local peroperative treatment with a bisphosphonate improves the fixation of total knee prostheses - A randomized, double-blind radiostereometric study of 50 patients2007Inngår i: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 78, nr 6, s. 795-799Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background Postoperative migration of a joint prosthesis is related to the risk of late loosening. We have previously reported that oral treatment with clodronate reduced migration of the cemented NexGen total knee prosthesis during the first postoperative year, as measured by radiostereometry (RSA). Oral bisphosphonate treatment is sometimes unpleasant, and local treatment will enable higher local concentrations. We now report the results of local peroperative treatment with another bisphosphonate, ibandronate, with the same prosthesis. Methods This is a double-blind, randomized study of 50 patients using RSA with maximal total point motion (MTPM) as primary effect variable. 1 mg ibandronate (1 mL) or 1 mL saline was applied to the tibial bone surface 1 min before cementation. RSA examination was done on the first postoperative day, and at 6, 12, and 24 months. Results One ibandronate-treated patient died of unrelated causes, and I control patient refused to come for follow-up, leaving 24 patients in each group for analysis. There were no cases of aseptic loosening. By repeated measures ANOVA, migration (MTPM) was reduced by local application of ibandronate (p = 0.006). The effect was most pronounced at 6 months, with a reduction from 0.45 to 0.32 mm (95% CI for reduction: 0.04-0.21 mm). At 12 months, the migration from the postoperative examination was reduced from 0.47 to 0.36 mm (95 % CI for reduction: 0.02-0.20 mm). At 24 months, the reduction was from 0.47 to 0.40 mm (95% CI: -0.01-0.16 mm). Interpretation This is the first study to show improvement of prosthesis fixation by local pharmacological treatment in humans. The treatment appears to be safe, cheap, and easy to perform. However, the improvement in postoperative stability was not greater than with systemic clodronate treatment.

  • 107. Hilding, Maria
    et al.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Postoperative clodronate decreases prosthetic migration: 4-Year follow-up of a randomized radiostereometric study of 50 total knee patients2006Inngår i: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 77, nr 6, s. 912-916Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: We have previously reported that 6 months of oral treatment with clodronate reduced the migration of the NexGen total knee prosthesis during the first postoperative year, as measured by radiostereometry (RSA). We now report the 4-year results. Methods: This was a double-blind randomized study, using RSA with maximal total point motion (MTPM). Results: With analysis according to the "intention to treat" principle, the only remaining difference between the groups at 4 years was reduced rotation around the transverse axis (a secondary variable) in the clodronate group. However, 3 patients (all clodronate) did not take any tablet after surgery. If they are excluded, there was an almost statistically significant difference between the groups at 4 years regarding MTPM from baseline, with the clodronate group showing 25% less migration. From 1 to 4 years, there was no difference in migration rate by MTPM, but there was a continuous increase in rotation around the transverse axis in the controls, which differed from the clodronate group. There were no cases of aseptic loosening. 2 patients had migration of more than 1.3 mm from baseline to 4 years, neither of them had taken clodronate. The others had migration of less than 0.9 mm. Interpretation: Because migration was clearly reduced by clodronate during the first postoperative year, and there was still a difference at 4 years when analyzed per protocol, it appears likely that this treatment can diminish the risk of loosening. The difference in the number of outliers also points in this direction, and may be more relevant than mean migration values. Copyright© Taylor & Francis 2006.

  • 108.
    Hilding, MB
    et al.
    Cent Hosp Vasteras, Dept Orthopaed, S-72189 Vasteras, Sweden Linkoping Univ Hosp, Dept Orthopaed, Linkoping, Sweden.
    Ryd, Leif
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Clodronate inhibits prosthetic migration - A randomized double-blind placebo controlled radiostereometric (RSA) study of 50 total knee patients2002Inngår i: Bone, ISSN 8756-3282, E-ISSN 1873-2763, Vol. 30, nr 3, s. B48-Konferansepaper (Annet vitenskapelig)
  • 109.
    Jarvinen, T. L. N.
    et al.
    University of Helsinki, Finland; University of Helsinki, Finland.
    Michaelsson, K.
    Uppsala University, Sweden.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Sievanen, H.
    UKK Institute Health Promot Research, Finland.
    Osteoporosis: the emperor has no clothes2015Inngår i: Journal of Internal Medicine, ISSN 0954-6820, E-ISSN 1365-2796, Vol. 277, nr 6, s. 662-673Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Current prevention strategies for low-trauma fractures amongst older persons depend on the notions that fractures are mainly caused by osteoporosis (pathophysiology), that patients at high risk can be identified (screening) and that the risk is amenable to bone-targeted pharmacotherapy (treatment). However, all these three notions can be disputed. PathophysiologyMost fracture patients have fallen, but actually do not have osteoporosis. A high likelihood of falling, in turn, is attributable to an ageing-related decline in physical functioning and general frailty. ScreeningCurrently available fracture risk prediction strategies including bone densitometry and multifactorial prediction tools are unable to identify a large proportion of patients who will sustain a fracture, whereas many of those with a high fracture risk score will not sustain a fracture. TreatmentThe evidence for the viability of bone-targeted pharmacotherapy in preventing hip fracture and other clinical fragility fractures is mainly limited to women aged 65-80years with osteoporosis, whereas the proof of hip fracture-preventing efficacy in women over 80years of age and in men at all ages is meagre or absent. Further, the antihip fracture efficacy shown in clinical trials is absent in real-life studies. Many drugs for the treatment of osteoporosis have also been associated with increased risks of serious adverse events. There are also considerable uncertainties related to the efficacy of drug therapy in preventing clinical vertebral fractures, whereas the efficacy for preventing other fractures (relative risk reductions of 20-25%) remains moderate, particularly in terms of the low absolute risk reduction in fractures with this treatment.

  • 110.
    Jeppsson, Charlotte
    et al.
    Ortopeden Lund.
    Åstrand, Jörgen
    Ortopeden Lund.
    Tägil, Magnus
    Ortopeden Lund.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    A combination of bisphosphonate and BMP additives in impacted bone allografts2003Inngår i: Acta Orthopaedica Scandinavica, ISSN 0001-6470, Vol. 74, nr 4, s. 483-489Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    OP-1 increases bone ingrowth distance of new bone into allografts (TΣgil et al. 2000), but the bone density after incorporation may be reduced by an increase in resorption (H÷stner et al. 2000). Bisphosphonates inactivate osteoclasts and can be used to increase allograft bone density after incorporation (Aspenberg and ┼strand 2002). A combination of locally-applied bisphosphonate and OP-1 in the graft could therefore be expected to increase both new bone ingrowth and density. We tested this by using a rat bone chamber model. OP-1 alone increased the ingrowth distance of bone. Clodronate increased final bone density greatly, but reduced the ingrowth distance of new bone into grafts that were extremely impacted. This reduction was improved by adding OP-1. Regardless of graft density, combinations of OP-1 and clodronate included a high final bone density, but the ingrowth distances were shorter than with OP-1 alone. These data indicate that new bone and tissue ingrowth into a compacted graft depends on resorption and that resorption is a prerequisite for the stimulating effect of OP-1 in this experimental set-up. Although the problems associated with the use of OP-1 in impaction grafting may be solved by adding a bisphosphonate, some of the benefits of OP-1 can be lost.

  • 111. Johansson, H. R.
    et al.
    Skripit, R.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Bisphosphonates can block the deterioration in implant fixation after withdrawal of intermittent doses of parathyroid hormone2008Inngår i: Journal of Bone and Joint Surgery, ISSN 0301-620X, E-ISSN 2044-5377, Vol. 90, nr 3, s. 400-404Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have examined the deterioration of implant fixation after withdrawal of parathyroid hormone (PTH) in rats. First, the pull-out force for stainless-steel screws in the proximal tibia was measured at different times after withdrawal. The stimulatory effect of PTH on fixation was lost after 16 days. We then studied whether bisphosphonates could block this withdrawal effect. Mechanical and histomorphometric measurements were conducted for five weeks after implantation. Subcutaneous injections were given daily. Specimens treated with either PTH or saline during the first two weeks showed no difference in the mechanical or histological results (pull-out force 76 N vs 81 N, bone volume density 19% vs 20%). Treatment with PTH for two weeks followed by pamidronate almost doubled the pull-out force (152 N, p < 0.001) and the bone volume density (37%, ANOVA, p < 0.001). Pamidronate alone did not have this effect (89 N and 25%, respectively). Thus, the deterioration can be blocked by bisphosphonates. The clinical implications are discussed. ©2008 British Editorial Society of Bone and Joint Surgery.

  • 112.
    Johansson, Lars
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik. Linköpings universitet, Tekniska högskolan.
    Edlund, Ulf
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik. Linköpings universitet, Tekniska högskolan.
    Fahlgren, Anna
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    A model for bone resorption2006Inngår i: ESDA 2006, 8th Biennial ASME Conference on Engineering Systems Design and Analysis,2006, ASME Press, 2006, s. 487-495Konferansepaper (Fagfellevurdert)
  • 113.
    Johansson, Lars
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik. Linköpings universitet, Tekniska högskolan.
    Edlund, Ulf
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik. Linköpings universitet, Tekniska högskolan.
    Fahlgren, Anna
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Bone Resorption Induced by Fluid Flow2009Inngår i: Journal of Biomechanical Engineering, ISSN 0148-0731, E-ISSN 1528-8951, Vol. 131, nr 9, s. 094505-1-094505-5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A model where bone resorption is driven by stimulus from fluid flow is developed and used as a basis for computer simulations, which are compared with experiments. Models for bone remodeling are usually based on the state of stress, strain, or energy density of the bone tissue as the stimulus for remodeling. We believe that there is experimental support for an additional pathway, where an increase in the amount of osteoclasts, and thus osteolysis, is caused by the time history of fluid flow velocity, fluid pressure, or other parameters related to fluid flow at the bone/soft tissue interface of the porosities in the bone.

  • 114.
    Johansson, Lars
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik. Linköpings universitet, Tekniska högskolan.
    Edlund, Ulf
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik. Linköpings universitet, Tekniska högskolan.
    Fahlgren, Anna
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Fluid-induced osteolysis: modelling and experiments2011Inngår i: COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING, ISSN 1025-5842, Vol. 14, nr 4, s. 305-318Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A model to calculate bone resorption driven by fluid flow at the bone-soft tissue interface is developed and used as a basis for computer calculations, which are compared to experiments where bone is subjected to fluid flow in a rat model. Previous models for bone remodelling calculations have been based on the state of stress, strain or energy density of the bone tissue as the stimulus for remodelling. We believe that there is experimental support for an additional pathway where an increase in the amount of the cells directly involved in bone removal, the osteoclasts, is caused by fluid pressure, flow velocity or other parameters related to fluid flow at the bone-soft tissue interface, resulting in bone resorption.

  • 115.
    Johansson, Torsten
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Bachrach-Lindström, Margareta
    Linköpings universitet, Institutionen för medicin och hälsa, Omvårdnad. Linköpings universitet, Hälsouniversitetet.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Jonsson, Dick
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk teknologiutvärdering. Linköpings universitet, Hälsouniversitetet.
    Wahlström, Ola
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    The total costs of a displaced femoral neck fracture: comparison of internal fixation and total hip replacement. A randomised study of 146 hips2006Inngår i: International Orthopaedics, ISSN 0341-2695, Vol. 30, nr 1, s. 1-6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We randomised 143 patients –age 75 years or older–with displaced femoral neck fracture to either internal fixation or total hip replacement (THR) and compared the socio-economic consequences. In the internal fixation group, 34 of 78 hips underwent secondary surgery. In the THR group, 12 of 68 hips dislocated, the majority in mentally impaired patients. We calculated the total hospital costs for two years after operation. When secondary surgery was included, there was no difference in costs between the internal fixation and THR groups, or between the mentally impaired and lucid subgroups. The costs to the community were calculated comparing the baseline cost before surgery with the average cost per month during the first postoperative year. No difference was found between the treatment groups. The Harris hip scores were higher in the THR group, and pain was more common in the internal fixation group. In lucid patients, THR gives a better clinical result at the same cost.

  • 116. Johnsson, Ragnar
    et al.
    Strömqvist, Björn
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Randomized radiostereometric study comparing osteogenic protein-1 (BMP-7) and autograft bone in human noninstrumented posterolateral lumbar fusion: 2002 Volvo award in clinical studies2002Inngår i: Spine, ISSN 0362-2436, E-ISSN 1528-1159, Vol. 27, nr 23, s. 2654-2661Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Study Design. Randomized efficacy trial comparing two types of noninstrumented posterolateral fusion between L5 and S1 in patients with L5 spondylolysis and vertebral slip less than 50%, as evaluated by radiostereometric analysis. Objective. To determine whether osteogenic protein-1 (BMP-7) in the OP-1 Implant yields better stabilizing bony fusion than autograft bone. Summary of Background Data. Animal studies of osteoinductive proteins in noninstrumented posterolateral fusions have shown high fusion rates. No similar conclusive study on humans has been performed. Methods. For this study, 20 patients were randomized to fusion with either OP-1 Implant or autograft bone from the iliac crest, 10 in each group. The patients were instructed to keep the trunk straight for 5 months after surgery with the aid of a soft lumbar brace. At surgery 0.8-mm metallic markers were positioned in L5 and the sacrum, enabling radiostereometric follow-up analysis during 1 year. The three-dimensional vertebral movements, as measured by radiostereometric analysis induced by positional change from supine posture to standing and sitting, were calculated with an accuracy of 0.5 to 0.7 mm and 0.5░ to 2.0░. Conventional radiography was added. Results. No significant difference was noted between the radiostereometric and radiographic results of fusion with the OP-1 Implant and fusion with autograft bone. There was a significant relation between reduced vertebral movements and better bone formation. No adverse effects of the OP-1 Implant occurred. Persistent minor pain at the iliac crest was noticed in one patient. Conclusions. There was no significant difference between the two fusion versions. Thus, the OP-1 Implant did not yield better stabilizing bony fusion than autograft bone.

  • 117.
    Kesteris, U.
    et al.
    Department of Orthopedics, Lund University Hospital, SE-221 85 Lund, Sweden.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Rinsing morcellised bone grafts with bisphosphonate solution prevents their resorption. A prospective randomised double-blinded study2006Inngår i: Journal of Bone and Joint Surgery, ISSN 0301-620X, E-ISSN 2044-5377, Vol. 88, nr 8, s. 993-996Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During revision total hip replacement using morcellised compacted bone allograft, 16 patients were randomised to receive a graft which had been rinsed in either an ibandronate solution or in saline. Patients were assessed by dual energy x-ray absorptiometry after operation and at 3, 6, 12 and 24 months. A region of interest between the tip of the femoral stem and the distal plastic plug was chosen to measure the changes in bone density over time. The study was double-blinded. In all the control patients the bone density decreased during the first three months and then remained constant at this lower level. A large proportion of the mass of the bone graft was lost. In contrast, all patients with grafts treated with bisphosphonate showed a slight increase in bone density. The difference between the groups was highly significant at all points in time. We conclude that rinsing the graft in a bisphosphonate solution prevents its resorption and may therefore reduce the risk of mechanical failure. The treatment is simple, inexpensive, and appears virtually free of risk. ©2006 British Editorial Society of Bone and Joint Surgery.

  • 118.
    Kharazmi, Mohammad
    et al.
    Uppsala University, Sweden.
    Hallberg, Par
    Uppsala University, Sweden.
    Schilcher, Jörg
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping. Linköpings universitet, Medicinska fakulteten.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Michaelsson, Karl
    Uppsala University, Sweden.
    Mortality After Atypical Femoral Fractures: A Cohort Study2016Inngår i: Journal of Bone and Mineral Research, ISSN 0884-0431, E-ISSN 1523-4681, Vol. 31, nr 3, s. 491-497Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although osteoporotic fracture rates can be reduced by bisphosphonates, prolonged therapy is associated with higher risk of atypical femoral fractures. Ordinary fragility fractures are linked to high mortality rates. We aimed to determine whether atypical femoral fractures also confer excess mortality. Radiographs were reviewed for all patients aged 55 years who had experienced a subtrochanteric or femoral shaft fracture in Sweden in 2008 to 2010. The fractures were classified as either atypical or ordinary. Data on medication use, coexisting conditions, and date of death were obtained from national registers. We estimated multivariable-adjusted relative risks of death after atypical femoral fractures compared with ordinary subtrochanteric or femoral shaft fractures and calculated age- and sex-standardized mortality ratios (SMRs) for atypical and ordinary fractures compared with the population average. During a mean of 4 years of follow-up, 39 of 172 (23%) patients with an atypical fracture had died compared with 588 of 952 (62%) with an ordinary fracture, corresponding to a relative risk of 0.51 (95% confidence interval [CI] 0.38-0.68). The lower risk was evident in both users and nonusers of bisphosphonates. No patient with atypical fracture died in the first year after fracture. Individuals with an ordinary fracture had a higher mortality risk than the general population (SMR=1.82; 95% CI 1.69-1.99), but no excess risk was found in patients with atypical fracture (SMR=0.92; 95% CI 0.65-1.26). We conclude that in contrast to ordinary subtrochanteric and femoral shaft fractures, atypical femoral fractures are not associated with excess mortality. (c) 2015 American Society for Bone and Mineral Research.

  • 119.
    Khayyeri, Hanifeh
    et al.
    Trinity College, Dublin.
    Checa, Sara
    Trinity College, Dublin.
    Tagil, Magnus
    Lund University Hospital, Lund.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Prendergast, Patrick J
    Trinity College, Dublin.
    Variability observed in mechano-regulated in vivo tissue differentiation can be explained by variation in cell mechano-sensitivity2011Inngår i: JOURNAL OF BIOMECHANICS, ISSN 0021-9290, Vol. 44, nr 6, s. 1051-1058Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Computational simulations of tissue differentiation have been able to capture the main aspects of tissue formation/regeneration observed in animal experiments except for the considerable degree of variability reported. Understanding and modelling the source of this variability is crucial if computational tools are to be developed for clinical applications. The objective of this study was to test the hypothesis that differences in cell mechano-sensitivity between individuals can explain the variability of tissue differentiation patterns observed experimentally. Simulations of an experiment of tissue differentiation in a mechanically loaded bone chamber were performed. Finite element analysis was used to determine the biophysical environment, and a lattice-modelling approach was used to simulate cell activity. Differences in cell mechano-sensitivity among individuals were modelled as differences in cell activity rates, with the activation of cell activities regulated by the mechanical environment. Predictions of the tissue distribution in the chambers produced the two different classes of results found experimentally: (i) chambers with a layer of bone across the chamber covered by a layer of cartilage on top and (ii) chambers with almost no bone, mainly fibrous tissue and small islands of cartilage. This indicates that the differing cellular response to the mechanical environment (i.e., subject-specific mechano-sensitivity) could be a reason for the different outcomes found when implants (or tissue engineered constructs) are used in a population.

  • 120.
    Khayyeri, Hanifeh
    et al.
    Lund University, Sweden.
    Gustafsson, Anna
    Lund University, Sweden.
    Heuijerjans, Ashley
    Eindhoven University of Technology, Netherlands.
    Matikainen, Marko K.
    Lappeenranta University of Technology, Finland.
    Julkunen, Petro
    Kuopio University Hospital, Finland; University of Eastern Finland, Finland.
    Eliasson, Pernilla
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Isaksson, Hanna
    Lund University, Sweden.
    A Fibre-Reinforced Poroviscoelastic Model Accurately Describes the Biomechanical Behaviour of the Rat Achilles Tendon2015Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, nr 6, artikkel-id e0126869Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background Computational models of Achilles tendons can help understanding how healthy tendons are affected by repetitive loading and how the different tissue constituents contribute to the tendons biomechanical response. However, available models of Achilles tendon are limited in their description of the hierarchical multi-structural composition of the tissue. This study hypothesised that a poroviscoelastic fibre-reinforced model, previously successful in capturing cartilage biomechanical behaviour, can depict the biomechanical behaviour of the rat Achilles tendon found experimentally. Materials and Methods We developed a new material model of the Achilles tendon, which considers the tendons main constituents namely: water, proteoglycan matrix and collagen fibres. A hyperelastic formulation of the proteoglycan matrix enabled computations of large deformations of the tendon, and collagen fibres were modelled as viscoelastic. Specimen-specific finite element models were created of 9 rat Achilles tendons from an animal experiment and simulations were carried out following a repetitive tensile loading protocol. The material model parameters were calibrated against data from the rats by minimising the root mean squared error (RMS) between experimental force data and model output. Results and Conclusions All specimen models were successfully fitted to experimental data with high accuracy (RMS 0.42-1.02). Additional simulations predicted more compliant and soft tendon behaviour at reduced strain-rates compared to higher strain-rates that produce a stiff and brittle tendon response. Stress-relaxation simulations exhibited strain-dependent stress-relaxation behaviour where larger strains produced slower relaxation rates compared to smaller strain levels. Our simulations showed that the collagen fibres in the Achilles tendon are the main load-bearing component during tensile loading, where the orientation of the collagen fibres plays an important role for the tendons viscoelastic response. In conclusion, this model can capture the repetitive loading and unloading behaviour of intact and healthy Achilles tendons, which is a critical first step towards understanding tendon homeostasis and function as this biomechanical response changes in diseased tendons.

  • 121. Khoschnau, Shwan
    et al.
    Fahlgren, Anna
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Rahme, Hans
    Improved healing of ligament to bone with point fixation in rabbits2006Inngår i: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 77, nr 6, s. 967-972Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Secure healing of soft tissue to bone is a prerequisite for many orthopedic operations. This healing can be achieved either by pressing the tissue against the bone (press fixation) or by suturing the soft tissue to the bone (point fixation). Experiments and findings: We tested the hypothesis that point fixation of soft tissue to bone results in better mechanical properties than press fixation. 10 skeletally mature New Zealand White rabbits were operated on bilaterally at the knees. The medial collateral ligaments were fixated to the bone just above the original insertion on the tibia. Two types of plates were used for this purpose, one with flat undersurface (left knee) and the other one with a pegged undersurface (right knee). The pegged plate was thought to mimic fixation achieved with suture anchors. After 4 weeks, mechanical testing revealed an almost doubled force at failure, stiffness and energy uptake in the knees operated with the pegged plates. Interpretation: Suture anchors or devices with a pegged undersurface are better for soft tissue fixation to bone than devices with a flat surface, such as screws with washers or staples. Copyright© Taylor & Francis 2006.

  • 122. Kjaersgaard-Andersen , P
    et al.
    Jensen, K
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Correspondence - Cox inhibitors and bone healing 2003Inngår i: Acta Orthopaedica Scandinavica, ISSN 0001-6470, Vol. 74, nr 2, s. 230-231Artikkel i tidsskrift (Annet vitenskapelig)
  • 123.
    Koeppen, V A
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Schilcher, Jörg
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Atypical fractures do not have a thicker cortex2012Inngår i: Osteoporosis International, ISSN 0937-941X, E-ISSN 1433-2965, Vol. 23, nr 12, s. 2893-2896Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An association between atypical fractures and general cortical thickness of the femoral shaft is often suggested in the literature. Our radiographic measurements of 59 atypical and 218 ordinary fractures now exclude a difference larger than 10 % in mean femoral cortical thickness (sum of lateral and medial) with 95 % confidence. less thanbrgreater than less thanbrgreater thanAn increased general cortical thickness in patients with fatigue fracture of the femoral shaft (atypical fractures) is commonly suggested. However, there are scarce data to support this. less thanbrgreater than less thanbrgreater thanIn a published nationwide Swedish study, we identified by radiographic review 59 women with an atypical fracture during 2008. The femoral cortical thickness index (thickness/femoral diameter) of these women was now compared with the 218 ordinary fractures that occurred in the same region of the femur in a case-control design. The cortical thickness index 5 cm below the lesser trochanter was the primary variable. less thanbrgreater than less thanbrgreater thanPatients with atypical fractures were younger. Without correction for age, they had a thicker cortex (i.e., higher index). However, the difference in cortical thickness disappeared after age correction. The 95 % CI excludes a group mean difference exceeding 10 % of total mean thickness. Similarly, there was no significant difference in cortical thickness between patients with or without bisphosphonate treatment or between the ipsi- and contralateral femurs in patients with an atypical fracture. less thanbrgreater than less thanbrgreater thanThe concept of a generally increased cortical thickness in patients with atypical fractures should be reconsidered.

  • 124.
    Koeppen, Veronika A
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för inflammationsmedicin. Linköpings universitet, Hälsouniversitetet.
    Schilcher, Jörg
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för inflammationsmedicin. Linköpings universitet, Hälsouniversitetet.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för inflammationsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Dichotomous location of 160 atypical femoral fractures2013Inngår i: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 84, nr 6, s. 561-564Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background and purpose The risk of atypical fracture of the femur is associated with bisphosphonate use. While characterizing atypical fractures from a previous nationwide study in radiographic detail, we had the impression that the fractures were located either in the subtrochanteric region or in the shaft. We determined whether there is a dichotomy in this respect. less thanbrgreater than less thanbrgreater thanPatients and methods The distance between the atypical fractures and the lesser trochanter was measured on plain radiographs from 129 of 160 patients with atypical fractures, taken from 2008 through 2010. Analysis of the distances measured showed 2 clusters, which were then analyzed with regard to bisphosphonate use and age. less thanbrgreater than less thanbrgreater thanResults The distribution of the distances would be best described as 2 clusters, with a dichotomy at 8 cm. The proximal (subtrochanteric) cluster comprised 25 patients who were generally younger (median 71 years) than the 104 patients in the cluster with shaft fractures (median 80 years). The 95% CI for the difference between medians was 4-11 years. Of the patients with subtrochanteric fractures, 18 of 25 used bisphosphonates as compared to 89 of 104 with shaft fractures. less thanbrgreater than less thanbrgreater thanInterpretation The younger age and possibly smaller proportion of bisphosphonate users in the subtrochanteric cluster may be compatible with a greater influence of mechanical stress in the underlying pathophysiology of proximal fractures.

  • 125. Kopylov, P
    et al.
    Adalberth, K
    Jonsson, K
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Norian SRS versus functional treatment in redisplaced distal radial fractures: A randomized study in 20 patients2002Inngår i: Journal of Hand Surgery - British and European Volume, ISSN 0266-7681, E-ISSN 1532-2211, Vol. 27 B, nr 6, s. 538-541Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We compared the use of Norian SRS, an injectable calcium phosphate bone cement, with functional treatment of redisplaced distal radial fractures in a prospective randomized study of 20 patients. The redisplaced fractures were either rereduced and stabilized by Norian SRS, or the displaced position was accepted and was not rereduced. All wrists were immobilized in a short-arm dorsal splint for 1 week, followed by a removable splint for another 3 weeks. The chosen primary effect variable was grip strength at 7 weeks, and this did not differ between the two treatment groups. The clinical results at 6 months in both groups were similar. We conclude that aggressive treatment of redisplaced fractures of the distal radius may be unnecessary in most women aged 50 years or more.

  • 126. Lauge-Pedersen, H
    et al.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Ryd, Leif
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Tanner, K E
    Arch-shaped versus flat arthrodesis of the ankle joint: strength measurements using synthetic cancellous bone2002Inngår i: Proceedings of the Institution of mechanical engineers. Part H, journal of engineering in medicine, ISSN 0954-4119, E-ISSN 2041-3033, Vol. 216, s. 43-49Artikkel i tidsskrift (Fagfellevurdert)
  • 127. Lauge-Pedersen, Henrik
    et al.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Arthrodesis by percutaneous fixation2002Inngår i: Acta Orthopaedica Scandinavica, ISSN 0001-6470, Vol. 73, s. 186-189Artikkel i tidsskrift (Fagfellevurdert)
  • 128.
    Lauge-Pedersen, Henrik
    et al.
    Lund.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Synovial fluid depletion: Successful arthrodesis without operative cartilage removal2003Inngår i: Journal of Orthopaedic Science, ISSN 0949-2658, E-ISSN 1436-2023, Vol. 8, nr 4, s. 591-595Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Operative arthrodesis has been thought to require surgical removal of remaining joint cartilage, but we have found in rabbits that even a joint with intact cartilage can fuse if rigidly fixed. This may enable new percutaneous techniques for arthrodesis. Rigid adaptation of the joint surfaces deprives the cartilage of mechanical stimulation and depletes the cells of synovial fluid transport of oxygen and nutrition. To better understand the requirements for successful arthrodesis, we studied the histological consequences of the complete absence of mechanical stimulation alone or in combination with synovial depletion by placing a metal cap over part of the joint cartilage in rabbits. The cap was either closed or had an opening to permit synovial fluid to reach the cartilage. We also studied if penetration of the bone-cartilage junction by a drill hole would facilitate cartilage resorption. Synovial fluid depletion in combination with a drill hole through the bone-cartilage junction led to disappearance of all cartilage matrix after 7 weeks. Synovial fluid depletion with an intact bone-cartilage junction led to complete disappearance of the cartilage matrix in four of seven rabbits after 7 weeks. With a hole in the cap for synovial fluid, the cartilage matrix was still present to varying degrees after 7 weeks in all the rabbits. In conclusion, percutaneous arthrodesis by rigid adaptation may lead to cartilage disappearance due to synovial depletion rather than due to the absence of mechanical stimulation. A combination with perforation of the bone-cartilage junction appears to lead to reasonably quick removal of the cartilage matrix.

  • 129.
    Ledin, Hakan
    et al.
    Aleris Specialist Care, Sweden .
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Good, Lars
    Oskarshamn Hospital, Sweden .
    Tourniquet use in total knee replacement does not improve fixation, but appears to reduce final range of motion A randomized RSA study involving 50 patients2012Inngår i: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 83, nr 5, s. 499-503Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background and purpose Although a tourniquet may reduce bleeding during total knee replacement (TKA), and thereby possibly improve fixation, it might also cause complications. Migration as measured by radiostereometric analysis (RSA) can predict future loosening. We investigated whether the use of a tourniquet influences prosthesis fixation measured with RSA. This has not been investigated previously to our knowledge. less thanbrgreater than less thanbrgreater thanMethods 50 patients with osteoarthritis of the knee were randomized to cemented TKA with or without tourniquet. RSA was performed postoperatively and at 6 months, 1 year, and 2 years. Pain during hospital stay was registered with a visual analog scale (VAS) and morphine consumption was measured. Overt bleeding and blood transfusions were registered, and total bleeding was estimated by the hemoglobin dilution method. Range of motion was measured up to 2 years. less thanbrgreater than less thanbrgreater thanResults RSA maximal total point motion (MTPM) differed by 0.01 mm (95% CI-0.13 to 0.15). Patients in the tourniquet group had less overt bleeding (317 mL vs. 615 mL), but the total bleeding estimated by hemoglobin dilution at day 4 was only slightly less (1,184 mL vs. 1,236 mL) with a mean difference of -54 mL (95% CI-256 to 152). Pain VAS measurements were lower in the non-tourniquet group (p = 0.01). There was no significant difference in morphine consumption. Range of motion was 11 more in the non-tourniquet group (p = 0.001 at 2 years). less thanbrgreater than less thanbrgreater thanInterpretation Tourniquet use did not improve fixation but it may cause more postoperative pain and less range of motion.

  • 130. Lindau, T
    et al.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    The radioulnar joint in distal radial fractures2002Inngår i: Acta Orthopaedica Scandinavica, ISSN 0001-6470, Vol. 73, s. 579-588Artikkel i tidsskrift (Fagfellevurdert)
  • 131.
    Lindau, Tommy
    et al.
    Ängelholm.
    Adlercreutz, Catarina
    Lund.
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Cartilage injuries in distal radial fractures2003Inngår i: Acta Orthopaedica Scandinavica, ISSN 0001-6470, Vol. 74, nr 3, s. 327-331Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Subchondral hematomas have been found with arthroscopy in one third of patients with dislocated distal radial fractures. The aim of the present, prospective study was to determine whether these hematomas might cause radiographic osteoarthrosis. We studied 41 patients (age 20-57 years, 22 women) with a dislocated distal radial fracture. At the time of fracture, 12 patients had subchondral hematomas in a radiocarpal compartment without a fracture line, as defined by arthroscopy. The 1-year follow-up included clinical and radiographic examinations. At follow-up, radiographic subchondral bone plate changes occurred in unfractured compartments in 8 patients, of whom 7 had had a previous arthroscopically diagnosed subchondral hematoma (p = 0.02) in the same compartment. Of the 8 patients with radiographic changes, 4 had also developed joint space narrowing (osteoarthrosis (OA) grade 1) after 1 year and 6 after 3 years. All but 1 had had a hematoma in the same compartment. More importantly, 3 of the 16 patients with entirely extra-articular fractures had subchondral bone plate changes in a compartment corresponding to a previous subchondral hematoma (p = 0.02). One of these had also developed joint space narrowing. The patients with radiographic changes had a worse outcome, as measured with the Gartland and Werley wrist score (p = 0.06). In conclusion, subchondral hematomas in distal radial fractures can lead to early onset of mild OA and worse outcome after 1 year.

  • 132. Lindau, Tommy
    et al.
    Runnquist, Kerstin
    Aspenberg, Per
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Patients with laxity of the distal radioulnar joint after distal radial fractures have impaired function, but no loss of strength2002Inngår i: Acta Orthopaedica Scandinavica, ISSN 0001-6470, Vol. 73, s. 151-156Artikkel i tidsskrift (Fagfellevurdert)
  • 133.
    Linderbäck, Paula
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Agholme, Fredrik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Wermelin, Karin
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Närhi, Timo
    Turku Clinical Biomaterial Centre, The University of Turku, FI-20520 Turku, Finland.
    Tengvall, Pentti
    University of Gothenburg.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Weak effect of strontium on early implant fixation in rat tibia2012Inngår i: Bone, ISSN 8756-3282, E-ISSN 1873-2763, Vol. 50, nr 1, s. 350-356Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Strontium ranelate increases bone mass and is used in the treatment of osteoporosis. Its effects in metaphyseal bone repair are largely unknown. We inserted a stainless steel and a PMMA screw into each tibia of male Sprague-Dawley rats. The animals were fed with ordinary feed (n =40) or with addition of strontium ranelate (800mg/kg/day; n = 20). As a positive control, half of the animals on control feed received alendronate subcutaneously. The pullout force of the stainless steel screws was measured after 4 and 8 weeks, and μCT was used to assess bone formation around the PMMA screws. No significant effects of strontium treatment on pullout force were observed, but animals treated with bisphosphonate showed a doubled pullout force. Strontium improved the microarchitecture of the cancellous bone below the primary spongiosa at the growth plate, but no significant effects were found around the implants. Strontium is known to improve bone density, but it appears that this effect is weak in conjunction with metaphyseal bone repair and early implant fixation.

  • 134.
    Linderbäck, Paula
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Areva, Sami
    University of Turku.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Tengvall, Pentti
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Sol-gel derived titania coating with immobilized bisphosphonate enhances screw fixation in rat tibia2010Inngår i: JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A, ISSN 1549-3296, Vol. 94A, nr 2, s. 389-395Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A variety of surface modifications have been tested for the enhancement of screw fixation in bone, and locally delivered anti-osteoporosis drugs such as bisphosphonates (BP) are then of interest. In this in vivo study, the impact of surface immobilized BP was compared with systemic BP delivery and screws with no BP. After due in vitro characterization, differently treated stainless steel (SS) screws were divided into four groups with 10 rats each. Three of the groups received screws coated with sol gel derived TiO2 and calcium phosphate (SS+TiO2+CaP). One of these had no further treatment, one had alendronate (BP) adsorbed to calcium phosphate mineral, and one received systemic BP treatment. The fourth group received uncoated SS screws and no BP (control). The screw pullout force was measured after 4 weeks of implantation in rat tibiae. The immobilized amount and release rate of alendronate could be controlled by different immersion times. The SS+TiO2+CaP coating did not increase the pullout force compared to SS alone. Surface delivered alendronate enhanced the pullout force by 93% [p = 0.000; 95% Confidence Interval (CI): 67-118%] compared to SS, and by 39% (p = 0.044; 95% CI: 7-71%) compared to systemic alendronate delivery. Both surface immobilized and systemically delivered alendronate improved implant fixation. Also, locally delivered, that is, surface immobilized alendronate showed a better fixation than systemically delivered. Using sot gel derived TiO2 as a platform, it is possible to administer controllable amounts of a variety of BPs.

  • 135.
    Lundin, Anna-Carin
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Hälsouniversitetet.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för inflammationsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Eliasson, Pernilla T.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för inflammationsmedicin. Linköpings universitet, Hälsouniversitetet.
    Trigger finger, tendinosis, and intratendinous gene expression2014Inngår i: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 24, nr 2, s. 363-368Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The pathogenesis of trigger finger has generally been ascribed to primary changes in the first annular ligament. In contrast, we recently found histological changes in the tendons, similar to the findings in Achilles tendinosis or tendinopathy. We therefore hypothesized that trigger finger tendons would show differences in gene expression in comparison to normal tendons in a pattern similar to what is published for Achilles tendinosis. We performed quantitative real-time polymerase chain reaction on biopsies from finger flexor tendons, 13 trigger fingers and 13 apparently healthy control tendons, to assess the expression of 10 genes which have been described to be differently expressed in tendinosis (collagen type 1a1, collagen 3a1, MMP-2, MMP-3, ADAMTS-5, TIMP-3, aggrecan, biglycan, decorin, and versican). In trigger finger tendons, collagen types 1a1 and 3a1, aggrecan and biglycan were all up-regulated, and MMP-3and TIMP-3 were down-regulated. These changes were statistically significant and have been previously described for Achilles tendinosis. The remaining four genes were not significantly altered. The changes in gene expression support the hypothesis that trigger finger is a form of tendinosis. Because trigger finger is a common condition, often treated surgically, it could provide opportunities for clinical research on tendinosis.

  • 136.
    Lundin, Anna-Carin
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Hand och plastikkirurgi. Linköpings universitet, Hälsouniversitetet.
    Eliasson, Pernilla
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi. Linköpings universitet, Hälsouniversitetet.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Trigger finger and tendinosis2012Inngår i: Journal of Hand Surgery, European Volume, ISSN 1753-1934, E-ISSN 2043-6289, Vol. 37, nr 3, s. 233-236Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The pathogenesis of trigger finger has generally been ascribed to primary changes in the pulley. Histological examination of the affected tendons has rarely been done. We studied biopsies from tendons of trigger fingers from 29 patients and compared these to biopsies from six intact tendons. We used a modified Movin score, which describes the tendinosis of the Achilles tendon. Trigger finger tendons had a high score (14.2; SD, 2.2) consistent with tendinosis, while the controls were almost normal (2.5; SD, 1.9). This suggests that the tendon is also affected, and that trigger finger is a form of tendinosis.

  • 137.
    Macias, Brandon R.
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Agholme, Fredrik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Paradoxical Sost gene expression response to mechanical unloading in metaphyseal bone2013Inngår i: Bone, ISSN 8756-3282, E-ISSN 1873-2763, Vol. 53, nr 2, s. 515-519Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Sost gene encodes Sclerostin, an inhibitor of Wnt-signaling, generally considered a main response gene to mechanical loading in bone. Several papers describe that unloading leads to upregulation of Sost, which in turn may lead to loss of bone. These studies were based on whole bone homogenates or cortical bone. By serendipity, we noted an opposite response to unloading in the proximal rat tibia. Therefore, we hypothesized that Sost-expression in response to changes in mechanical load is bone site specific. less thanbrgreater than less thanbrgreater thanOne hind limb of male, 3 month old rats was unloaded by paralyzing the extensors with Botulinium toxin A (Botox) injections. A series of experiments compared the expression of Sost mRNA in the unloaded and contralateral, loaded limbs, after 3 or 10 days, in metaphyseal cancellous bone, metaphyseal cortical bone, and diaphyseal cortical bone. We also conducted mu CT to confirm changes in bone volume density related to unloading. Sost mRNA expression in the cancellous metaphyseal bone was downregulated almost 2-fold, both 3 days and 10 days after unloading (Pandlt;0.05). A similar tendency was seen in the metaphyseal cortical bone, in which Sost was 1.5-fold downregulated (Pandlt;0.05) after 10 days, but not significantly changed after 3 days. In contrast, diaphyseal cortical Sost expression was instead upregulated 1.4-fold (Pandlt;0.05) following 3-day unloading, while there was no significant change after 10 days. Cancellous bone volume density was 58% lower (Pandlt;0.001, compared to cage controls) in the unloaded limb but not significantly affected in the loaded limb. less thanbrgreater than less thanbrgreater thanThe results suggest that Sost mRNA expression in metaphyseal bone responds to mechanical unloading in an opposite direction to that observed in diaphyseal cortical bone. This proposes a more complex expression pattern for Sost in response to unloading. Therapeutics that target Sclerostin during altered loading conditions may result in local bone mass changes that are difficult to predict.

  • 138.
    Meunier, Andreas
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Parecoxib impairs early metaphyseal bone healing in rats2006Inngår i: Archives of Orthopaedic and Trauma Surgery, ISSN 0936-8051, E-ISSN 1434-3916, Vol. 126, nr 7, s. 433-436Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Introduction Cox2 inhibitors decrease prostaglandin production and therefore influence bone healing especially in unstable long bone models. It is unclear to what extent implant fixation in stable metaphyseal bone is impaired.

    Method Male rats numbering 30 and female rats numbering 40 received a stainless steel screw in the metaphyseal bone of the proximal tibia. Half of the rats were treated with 6.4 mg/kg BW parecoxib by continuous release from a subcutaneous mini pump during 7 or 14 days. After treatment, the pull out force, stiffness, and pull out energy of the screw were measured.

    Results No effect of parecoxib on the pull out force was found for male rats. In female rats the pull out force was decreased by 16% (P = 0.03) after 7 days treatment with parecoxib. This effect had disappeared after 14 days.

    Conclusion Adverse effects of parecoxib on the early phase healing of metaphyseal bone in female rats are small and were not detectable after 14 days. No effect was seen in male rats, possibly due to a faster metabolic elimination of the drug

  • 139.
    Meunier, Andreas
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Good, Lars
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Celecoxib does not appear to affect prosthesis fixation in total knee replacement2009Inngår i: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 80, nr 1, s. 46-50Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background and purpose: After joint replacement, a repair process starts at the interface between bone and cement. If this process is disturbed, the prosthesis may never become rigidly fixed to the bone, leading to migration and with time loosening. Cox-2 inhibitors are widely used as postoperative analgesics, and have adverse effects on bone healing. This could tamper prosthesis fixation. We investigated if celecoxib, a selective Cox-2 inhibitor, increases prosthesis migration in total knee replacement (TKR).

    Methods: 50 patients were randomized to either placebo or celecoxib 200mg twice daily during 3 weeks after TKR (NexGen®, Zimmer). Maximum total point motion (MTPM) of the tibial component was measured after 2 years using radiostereometric analysis (RSA). In addition, range of motion, pain, and, subjective outcome were evaluated.

    Results: No differences in prosthesis migration, pain scores, range of motion or subjective outcome were found after 2 years. Confidence intervals were narrow.

    Interpretation: Celecoxib is not likely to increase the risk of loosening and may be used safely in conjunction with TKR.

  • 140.
    Michaelsson, K
    et al.
    Uppsala University, Sweden .
    Schilcher, Jörg
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Letter: Comment on Compston: Pathophysiology of atypical femoral fractures and osteonecrosis of the jaw2012Inngår i: Osteoporosis International, ISSN 0937-941X, E-ISSN 1433-2965, Vol. 23, nr 12, s. 2901-2902Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    n/a

  • 141.
    Michaelsson, Karl
    et al.
    Uppsala University, Sweden.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Postmenopausal Osteoporosis2016Inngår i: New England Journal of Medicine, ISSN 0028-4793, E-ISSN 1533-4406, Vol. 374, nr 21, s. 2095-2097Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    n/a

  • 142.
    Movérare-Skrtic, Sofia
    et al.
    Sahlgrenska Academy at University of Gothenburg, Sweden.
    Henning, Petra
    Sahlgrenska Academy at University of Gothenburg, Sweden.
    Liu, Xianwen
    Harvard School of Dental Medicine, Boston, Massachusetts, USA; Sichuan University, China.
    Nagano, Kenichi
    Harvard School of Dental Medicine, Boston, Massachusetts, USA.
    Saito, Hiroaki
    Harvard School of Dental Medicine, Boston, Massachusetts, USA.
    Börjesson, Anna E
    Sahlgrenska Academy at University of Gothenburg, Sweden.
    Sjögren, Klara
    Sahlgrenska Academy at University of Gothenburg, Sweden.
    Windahl, Sara H
    Sahlgrenska Academy at University of Gothenburg, Sweden.
    Farman, Helen
    Sahlgrenska Academy at University of Gothenburg, Sweden.
    Kindlund, Bert
    Sahlgrenska Academy at University of Gothenburg, Sweden.
    Engdahl, Cecilia
    Sahlgrenska Academy at University of Gothenburg, Sweden.
    Koskela, Antti
    University of Oulu, Finland.
    Zhang, Fu-Ping
    University of Turku, Finland.
    Eriksson, Emma E
    Karolinska Institutet, Pediatric Endocrinology Unit, Stockholm, Sweden.
    Zaman, Farasat
    Karolinska Institutet, Pediatric Endocrinology Unit, Stockholm, Sweden.
    Hammarstedt, Ann
    Sahlgrenska Academy at University of Gothenburg, Sweden.
    Isaksson, Hanna
    Lund University, Sweden.
    Bally, Marta
    Chalmers University of Technology, Gothenburg, Sweden..
    Kassem, Ali
    Umeå University, Sweden.
    Lindholm, Catharina
    Sahlgrenska Academy at University of Gothenburg, Sweden.
    Sandberg, Olof
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Hälsouniversitetet.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Sävendahl, Lars
    Karolinska Institutet, Pediatric Endocrinology Unit, Stockholm, Sweden.
    Feng, Jian Q
    Texas A&M Health Science Center, Dallas, Texas, USA.
    Tuckermann, Jan
    University of Ulm, Germany.
    Tuukkanen, Juha
    University of Oulu, Finland.
    Poutanen, Matti
    Sahlgrenska Academy at University of Gothenburg, Sweden.
    Baron, Roland
    Harvard School of Dental Medicine, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA.
    Lerner, Ulf H
    Sahlgrenska Academy at University of Gothenburg, Sweden.
    Gori, Francesca
    Harvard School of Dental Medicine, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA.
    Ohlsson, Claes
    Sahlgrenska Academy at University of Gothenburg, Sweden.
    Osteoblast-derived WNT16 represses osteoclastogenesis and prevents cortical bone fragility fractures2014Inngår i: Nature Medicine, ISSN 1078-8956, E-ISSN 1546-170X, Vol. 20, nr 11, s. 1279-1288Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The WNT16 locus is a major determinant of cortical bone thickness and nonvertebral fracture risk in humans. The disability, mortality and costs caused by osteoporosis-induced nonvertebral fractures are enormous. We demonstrate here that Wnt16-deficient mice develop spontaneous fractures as a result of low cortical thickness and high cortical porosity. In contrast, trabecular bone volume is not altered in these mice. Mechanistic studies revealed that WNT16 is osteoblast derived and inhibits human and mouse osteoclastogenesis both directly by acting on osteoclast progenitors and indirectly by increasing expression of osteoprotegerin (Opg) in osteoblasts. The signaling pathway activated by WNT16 in osteoclast progenitors is noncanonical, whereas the pathway activated in osteoblasts is both canonical and noncanonical. Conditional Wnt16 inactivation revealed that osteoblast-lineage cells are the principal source of WNT16, and its targeted deletion in osteoblasts increases fracture susceptibility. Thus, osteoblast-derived WNT16 is a previously unreported key regulator of osteoclastogenesis and fracture susceptibility. These findings open new avenues for the specific prevention or treatment of nonvertebral fractures, a substantial unmet medical need.

  • 143.
    Obradovic Wagner, Darja
    et al.
    Free University of Berlin.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Where did bone come from? An overview of its evolution2011Inngår i: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 82, nr 4, s. 393-398Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bone is specific to vertebrates, and originated as mineralization around the basal membrane of the throat or skin, giving rise to tooth-like structures and protective shields in animals with a soft cartilage-like endoskeleton. A combination of fossil anatomy and genetic information from modern species has improved our understanding of the evolution of bone. Thus, even in man, there are still similarities in the molecular regulation of skin append-ages and bone. This article gives a brief overview of the major milestones in skeletal evolution. Some molecular machineries involving members of core genetic networks and their interactions are described in the context of both old theories and modern genetic approaches.

  • 144.
    Pasternak, Björn
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Malmö University Hospital, Malmö, Sweden.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Metalloproteinases and their inhibitors-diagnostic and therapeutic opportunities in orthopedics.2009Inngår i: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 80, nr 6, s. 693-703Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Matrix metalloproteinases (MMPs) and related enzymes (ADAMs, ADAMTS) and their inhibitors control matrix turnover and function. Recent advances in our understanding of musculoskeletal conditions such as tendinopathy, arthritis, Dupuytren's disease, degenerative disc disease, and bone and soft tissue healing suggest that MMPs have prominant roles. Importantly, MMPs are amenable to inhibition by cheap, safe, and widely available drugs such as the tetracycline antibiotics and the bisphosphonates. This indicates that these MMP inhibitors, if proven effective for any novel indication, may be quickly brought into clinical practice.

  • 145.
    Pasternak, Björn
    et al.
    Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Fellenius, Mårten
    Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Aspenberg, Per
    Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Ortopedi och Idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Doxycycline impairs tendon repair in rats2006Inngår i: Acta Orthopaedica Belgica, ISSN 0001-6462, Vol. 72, nr 6, s. 756-760Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Doxycycline exhibits various effects apart from its antimicrobial activity, such as inhibition of matrix metalloproteinases (MMPs). MMPs, mainly collagenases and gelatinases, are capable of degrading virtually all constituents of the extracellular matrix and are critical to connective tissue remodelling and healing. We therefore hypothesised that doxycycline would negatively influence the rat tendon healing process and impede tendon regeneration. The Achilles tendon of 60 Sprague Dawley rats was transected transversely. The animals were treated with doxycycline, 130 mg/kg body weight/day. The healing tendons were evaluated mechanically at 5, 8 and 14 days. Doxycycline significantly decreased force at failure (p < 0.005) and energy uptake (p < 0.001). Doxycycline serum concentration was 3.4 (SD 1.0) µg/ml. In conclusion, tendon healing can be affected by doxycycline at clinically relevant serum concentrations. This observation might be of relevance to further studies exploring effects of MMP-inhibitors on tendon tissue.

  • 146.
    Pasternak, Björn
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Matthiessen, Peter
    Department of Surgery, Örebro University Hospital, Örebro, Sweden.
    Jansson, Kjell
    Department of Surgery, Örebro University Hospital, Örebro, Sweden.
    Andersson, Magnus
    Department of Surgery, Örebro University Hospital, Örebro, Sweden.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Elevated intraperitoneal matrix metalloproteinases-8 and -9 in patients who develop anastomotic leakage after rectal cancer surgery: a pilot study2010Inngår i: Colorectal Disease, ISSN 1462-8910, E-ISSN 1463-1318, Vol. 12, nr 7, s. e93-e98Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective  Experimental studies suggest that matrix metalloproteinase (MMP) enzymes mediate the early tissue breakdown that leads to a decrease in intestinal anastomotic strength. Patients with upregulation of MMPs in intestinal biopsies have an increased rate of anastomotic leakage. We measured MMPs and their inhibitors [tissue inhibitors of metalloproteinases (TIMPs)] in postoperative intraperitoneal fluid after rectal cancer surgery, and hypothesized that they would be elevated in patients who later would develop anastomotic leakage.

    Method  Twenty-nine patients with rectal carcinoma underwent low anterior resection of the rectum for cancer. Intraperitoneal fluid was collected via a pelvic drain at a median of 4 h postoperatively. MMP-1, -2, -3, -7, -8, -9 and -13 were determined using particle-based multiplex flow-cytometry. TIMP-1 and -2 were measured by enzyme-linked immunosorbent assays. MMP-9 was considered the main outcome variable.

    Results  Ten patients developed anastomotic leakage. These patients had increased intraperitoneal MMP-9 [median difference (m.d.) 29%; P = 0.03] and MMP-8 (m.d. 58%; P = 0.02), compared with patients who did not develop leakage. There were no differences between the groups for other MMPs and TIMPs.

    Conclusion  Matrix metalloproteinase-8 and -9 appear to have an important role in the development of anastomotic leakage and may be promising pharmacological targets to protect anastomotic integrity. We suggest further investigation of MMPs as markers for anastomotic leakage.

  • 147.
    Pasternak, Björn
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Missios, Anna
    Askendal, Agneta
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Tengvall, Pentti
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Doxycycline-coated sutures improve the suture-holding capacity of the rat Achilles tendon2007Inngår i: Acta Orthopaedica, ISSN 1745-3674, Vol. 78, nr 5, s. 680-686Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is evidence of high matrix metalloproteinase (MMP) activity around sutures inserted into tendons. This probably results in tissue breakdown, allowing the suture to cut through the tendon, and thus contributes to repair-site elongation and gap formation. We therefore hypothesized that treatment with the MMP inhibitor doxycycline would improve the sutureholding capacity of tendon. Animals, methods and results In the first sub-study, rats received a suture in the Achilles tendon. One group was treated with systemic doxycycline and the other received no treatment. At 3, 5, and 7 days, suture-holding capacity was measured mechanically. The pull-out force and energy were reduced in all tendons, at 3 days compared to freshly inserted sutures, but no further reduction was detected at later time points. Doxycycline- treated tendons showed improved suture-holding capacity as measured by higher energy uptake than in untreated tendons. Force at failure showed a trend towards improvement. The effect was most evident on day 3. In the second sub-study, sutures were coated with doxycycline. At 3 days, local doxycycline treatment caused improved suture-holding capacity—as measured by higher force at failure and higher energy uptake.

  • 148.
    Pasternak, Björn
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Rehn, Martin
    Malmö University Hospital.
    Andersen, Line
    University of Copenhagen.
    Ågren, Magnus S.
    Copenhagen University Hospital.
    Heegaard, Anne-Marie
    University of Copenhagen.
    Tengvall, Pentti
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Doxycycline-coated sutures improve mechanical strength of intestinal anastomoses2008Inngår i: International Journal of Colorectal Disease, ISSN 0179-1958, E-ISSN 1432-1262, Vol. 23, nr 3, s. 271-276Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background and aims: After resection and repair of the intestines, tissue degradation leads to weakening of the repair site and a risk of postoperative leakage. Matrix metalloproteinases (MMPs) are thought to be responsible for collagenolysis in the direct vicinity of surgical sutures in many tissues. Several experimental studies show that MMP-inhibitors administered systemically alleviate postoperative weakening of intestinal anastomoses. We hypothesised that local delivery of MMP-inhibitors would achieve a similar effect.

    Methods: Implementing a novel method for the coating of biomaterials, we coated sutures with a crosslinked fibrinogen film and bound the MMP-inhibitor doxycycline into this film. The sutures were then used in a standard rat model for evaluating mechanical properties of colonic anastomoses 3 days after surgery.

    Results: The breaking strength of the anastomoses on the critical third day after operation was 17 % higher with doxycycline-coated sutures compared to controls (P=0.026). Energy uptake at failure was enhanced by 20 % (P=0.047).

    Conclusion: Drug delivery by means of MMP-inhibitor-coated sutures appears to improve tissue integrity during anastomotic repair and may reduce postoperative complications.

  • 149.
    Pasternak, Björn
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Schepull, Thorsten
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Eliasson, Pernilla
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Elevation of systemic matrix metalloproteinase-2 and -7 and tissue inhibitor of metalloproteinases-2 in patients with a history of Achilles tendon rupture2010Inngår i: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 38, s. 308-317Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objectives: To compare serum levels of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) between patients with a history of Achilles tendon rupture and blood donor controls, and to relate MMPs and TIMPs to mechanical properties of the tendons during healing.

    Methods: More than three years after injury, we measured serum levels of MMP-1, -2, -3, -7, -8, -9 and -13 and TIMP-1 and -2 in eight patients who had suffered Achilles tendon rupture. Twelve blood donors served as controls. During the early phase of healing, the tendon modulus of elasticity was calculated from radiostereometric data and tendon cross-sectional area.

    Results: Patients with a history of Achilles tendon rupture had increased levels of MMP-2 (median difference (m.d.) 10 %; p = 0.01), MMP-7 (m.d. 15 %; p = 0.02) and TIMP-2 (m.d. 36%; p = 0.02), as compared to controls. Levels of MMP-7, measured three years after injury, correlated inversely to tendon modulus of elasticity (rs = -0.83; p = 0.02), and positively to tendon elongation (rs = 0.74; p = 0.05) during the early phase of healing. There was a trend towards positive correlation between MMP-7 and cross-sectional area during the early phase of healing (rs = 0.67; p = 0.08).

    Conclusions: Patients with a history of Achilles tendon rupture appear to have elevated levels of MMP-2, MMP-7 and TIMP-2 in serum. These pilot data support the view that the MMP-TIMP system is involved in tendinopathy and suggest that disturbances in proteolytic control might be generalised.

  • 150.
    Sandberg, Olof
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Hälsouniversitetet.
    Aspenberg, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Hälsouniversitetet. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Different effects of indomethacin on healing of shaft and metaphyseal fractures2015Inngår i: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 86, nr 2, s. 243-247Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background and purpose - NSAIDs are commonly used in the clinic, and there is a general perception that this does not influence healing in common types of human fractures. Still, NSAIDs impair fracture healing dramatically in animal models. These models mainly pertain to fractures of cortical bone in shafts, whereas patients more often have corticocancellous fractures in metaphyses. We therefore tested the hypothesis that the effect of an NSAID is different in shaft healing and metaphyseal healing. Methods - 26 mice were given an osteotomy of their left femur with an intramedullary nail. 13 received injections of indomethacin, 1 mg/kg twice daily. After 17 days of healing, the femurs were analyzed with 3-point bending and microCT. 24 other mice had holes drilled in both proximal tibias, to mimic a stable metaphyseal injury. A screw was inserted in the right tibial hole only. After 7 days of indomethacin injections or control injections, screw fixation was measured with mechanical pull-out testing and the side without a screw was analyzed with microCT. Results - In the shaft model, indomethacin led to a 35% decrease in force at failure (95% CI: 14-54). Callus size was reduced to a similar degree, as seen by microCT. Metaphyseal healing was less affected by indomethacin, as no effect on pull-out force could be seen (95% CI: - 27 to 17) and there was only a small drop in new bone volume inside the drill hole. The difference in the relative effect of indomethacin between the 2 models was statistically significant (p = 0.006). Interpretation - Indomethacin had a minimal effect on stable metaphyseal fractures, but greatly impaired healing of unstable shaft fractures. This could explain some of the differences found between animal models and clinical experience.

12345 101 - 150 of 207
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf