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Methods for determining the accuracy ofradiostereometric analysis (RSA)
Orthopedic Surgery, University Hospital, Lund, Sweden.
Orthopedic Surgery, University Hospital, Lund, Sweden.
Neuro-Orthopedics, Ryhovs Hospital, Jönköping, Sweden.
2000 (English)In: Acta Orthopaedica Scandinavica, ISSN 0001-6470, Vol. 71, no 4, 403-408 p.Article in journal (Refereed) Published
Abstract [en]

The problem of determining the noise level in any measuring system remains urgent. Radiostereometric analysis (RSA) is a radiographic system of unique accuracy which has applications in areas where minute motions or no motion at all occurs. Examples are micromotion between endoprostheses and bone and in fracture healing.

We have determined the accuracy of the RSA system as applied to a clinical series of spinal fusions, where the conditions for RSA were not optimal. Using the usual test-retest methodology on a phantom, we showed that its accuracy can be grossly overestimated in the individual case.

We found considerable variations in the accuracy in the individual case, depending on the rigid-body configuration. The overall accuracy, expressed as 3-D "vectors" for rotation and translation, respectively, correlated with the condition number, a method for characterizing the marker configuration. Indeed, the condition number explained as much as 92% of the variation in overall rotation. This condition number, however, cannot be used to analyze the accuracy of one degree of freedom of rotation alone. Mathematical simulation of the accuracy in the individual case of the individual dimension, using in-house software, showed that the accuracy (95% confidence) varied between 0.4 and 4.6 degrees of rotation about the transverse axis, corresponding to a clinical stress series of extension and flexion.

Place, publisher, year, edition, pages
2000. Vol. 71, no 4, 403-408 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-27861DOI: 10.1080/000164700317393420Local ID: 12621OAI: oai:DiVA.org:liu-27861DiVA: diva2:248413
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2012-08-02Bibliographically approved
In thesis
1. Outcome and bone grafts in surgical treatment of cervical disc disease: A clinical evaluation using MRI, radiostereometry and measurements of microcirculation and the quality of life
Open this publication in new window or tab >>Outcome and bone grafts in surgical treatment of cervical disc disease: A clinical evaluation using MRI, radiostereometry and measurements of microcirculation and the quality of life
2000 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The purpose of this thesis was to evaluate the outcome after surgical treatment of cervical disc disease and the influence of different bone grafting methods.

192 patients were studied, of which 149 were treated surgically. They all presented with radiculopathy and/ or myelopathy, and were subjected to an anterior cervical discectomy and fusion as described by Cloward, except for 8 patients operated with a posterior decompression.

43 patients due for surgery were prospectively randomized to fusion with either auto-, allo- or xenograft. 33 of these patients were then monitored by radiostereornetric analysis (RSA) after 6, 12 and 24-50 (mean 37) months, including conventional radiography at the final follow-up. All 43 patients were examined clinically, including pain rating pre- and postoperatively with a final follow-up by an unbiased observer. Mobility could be demonstrated by RSA in 9 patients after one year and at the final follow-up in 6, with no difference between bone grafts. Conventional radiography showed final mobility in only 1 out of these 6 patients. The clinical results were not influenced by whether mobility could be demon strated or not. There was a tendency towards better clinical results in the patients fused with an autograft.

13 patients operated without bone graft had a less favourable clinical outcome compared with 11 patients operated with autograft, retrospectively studied 6- 9 years postoperatively.

The normal postoperative course was followed prospectively in 25 consecutive patients by MRI and clinical reviews, preoperatively and 3 days, 3, 6, 12 and 24 months postoperatively. The results demonstrated that the decompression by an anterior procedure should not be evaluated by MRI until at least 3 months postoperatively. This is because surgical debris behind the bone dowel is impossible to distinguish from remaining osteophytes or disc fragments. MRI-findings of foraminal narrowing were common postoperatively among patients with no remaining radiculopathy. A rim sign was permanent with high signal enhancement around the bovine xenograft after i. v. contrast, indicating fibrous healing.

Surgically treated patients experienced a pain reduction as measured by visual analogue pain scales (VAS) and showed an improvement in clinical findings, when followed by unbiased observers at least 2 years after surgery. Some recurrence of pain and other symptoms was common 3 to 6 months postoperatively. The improvement in quality of life measured by Sickness Impact Profile (SIP) in 43 operated patients was mainly temporary, even if a sustained improvement after 2 years was observed among the operated patients that were referred directly to us.

No corresponding changes in pain, clinical findings or SIP were seen among 41 conservatively treated patients, matched for gender and age.

Measurements of microcirculation and electromyography in the trapezius muscles during increased static load before and 9 months after surgery (27 patients) showed a tendency towards increased microcirculation and increased muscle activation. There was a more evident response on the less painful side, as well as among the 8 patients operated using a posterior approach.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2000. 58 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 621
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-28059 (URN)12823 (Local ID)91-7219-578-9 (ISBN)12823 (Archive number)12823 (OAI)
Public defence
2000-03-31, Berzeliussalen, Universitetssjukhuset, Linköping, 13:00 (Swedish)
Opponent
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2012-10-25Bibliographically approved

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Ryd, LeifLöfgren, Håkan

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