Background

The skin is the largest organ in the human body and its vital functions are crucial for our survival. Skin grafting has gained increased popularity during the past two centuries and its practical utility has successively improved. The technique is crucial for permanent wound coverage including i.e. burns and for defects resulting after tumour surgery when other reconstructive regimens are not suitable. The evaluation of different treatments including skin grafting and secondary healing for skin defects, such as wounds that occur after burns and tumour surgery will be explored in this thesis.

Methods

The thesis includes two prospective studies, one retrospective and a methodological exploration. The patients were recruited in Linköping and Helsinki University Hospital. In the prospective randomised trials, functional and cosmetic outcome were evaluated with established validated tools, the Patient and Observer Scar Assessment Scale (POSAS) and the cutometer. Retrospectively, skin graft take rate and demographics were obtained from the local database and medical records. The methodological study was presented in a pilot set-up. Initially the apparatus prototype was refined and modified with technical improvements. Testing of the prototype was done ex vivo on excised tissue after abdominoplasties and subsequently on cadavers.

Results

The dermis graft (DG) method in burns of limited size presented a shorter healing duration at the donor site compared with wound coverage by using a conventional split-thickness skin graft (STSG), yet the healing duration was longer at the DG recipient site. The scar assessment was considered superior for the DG, especially at the donor site. Secondary healing of nasal defects after tumour surgery showed better POSAS values than full-thickness skin graft (FTSG) transplantation at follow-up. Our investigation showed that depth and size of the burn are the key factors affecting the success rate of skin grafts in cases of minor burns. The dermatome prototype facilitated the technical handling and produced corresponding grafts to the conventional STSG and DG. Histological analysis revealed a multilayer arrangement of all the skin layers with a clear epidermal architecture and deeper dermal characteristics. The median thickness of the superficial graft was slightly thinner than the deeper dermal graft.

Conclusion

The DG reduced donor site morbidity, while its elasticity and ability to expand allowed it to cover a larger wound area, leading to positive long-term outcomes at the recipient site. It did not necessitate the mesh procedure, although the strength of the previous statement is hampered due to the lack of specific expansion measures and ratios of the DG. However, longer healing time was seen at the DG recipient site.

Secondary healing intentions for nasal defects with limited size defects after tumour surgery may be beneficial for certain patients, especially in a cosmetic perspective with a better colour matching of the surrounding tissue. The longer healing duration in case of secondary healing is not a big issue and will not affect the long-term outcome. The depth and size of the burn are determinants affecting the success rate of skin grafts in minor burns, whereas the timing of the graft does not appear to affect the take rate. The dermatome prototype was able to simultaneously harvest two grafts in the same procedure, and moreover, it was possible to adjust the thickness of the grafts where caution should be taken to not harvest too deeply. The technique has the potential to reduce donor site morbidity and improve the aesthetic outcome at the recipient site, as the donor site is left non-exposed and the DG is not required to be meshed due to its enhanced elasticity. Despite the promising results indicating an advancement in skin grafting methodologies, the conclusion is hampered by the statement that the investigation was conducted on human cadavers. Additional research is essential to improve the prototype and broaden our understanding of the potential uses of dermal grafting in various clinical settings, where it could provide substantial benefits. Essential topics for future investigation include optimising the two-blade dermatome, examining the expansion scales and thickness variability of dermal grafts, conducting large clinical trials to confirm long-term advantages, and integrating dermal grafting with methods for tissue regeneration and reconstruction.