Biomechanics of skin grafts: effect of pattern size, spacing and orientation

Skin graft expansion is the key to the treatment of severe burn injuries requiring skin transplantation. While high expansions have been claimed by a majority of graft manufacturers, the realistic expansions reported to date with skin grafts are much lower. To clarify this discrepancy, we attempted to understand the biomechanics of skin grafts through the study of common graft pattern sizes, spacing, and orientation, and their influence on mesh expansion and induced stress. A novel skin simulant material and additive manufacturing were employed to develop the skin graft models. Tensile testing experiments were conducted to study expansion and overall stresses, and a finite element model (FEM) was used to characterize the local trends. At low strains (i.e., <1), the mesh expansion ratio was reported to be below 1, which increased up to 1.93 at a high strain of 2. The pattern size and spacing were not observed to affect the expansion much (i.e., <10%). With a change in orientation, the expansion decreased across all graft models and strains. High localized induced stresses were reported for high strains, which varied with graft orientation. The novel observations highlight the achievable expansions without overstressing, with standard slit patterning in skin grafts. These findings will not only help achieve better mesh expansion outcomes in burn surgeries but also guide the development of novel graft patterns for enhanced expansion in the future.

The First Stage of Acquired Syndactyly Reconstruction - A Rare Case Report

Background: Acquired syndactyly is a very rare disorder on the interdigital area. Syndactyly with only soft tissue involvement can be a sequela of trauma, such as burn, inflammation or infection in the interdigital area, resulting in bony fusion following crush injury. Case Report: An 8-year-old boy came to our department with fusion from the base to the tip of the first to fourth right toes since the accidental step on burnt plastic 5 years ago. He complained of a poor appearance and discomfort when walking. Then we performed zigzag incision for first to second toes and third to fourth toes. Skin graft closure was performed to cover the defect on third to fourth toes. The second reconstruction surgery will be scheduled 6 months later. Discussion: The surgical techniques for foot syndactyly were derived from those for hand syndactyly, which are to separate the digital fusion by creating local skin flap. Additionally, skin graft might be necessary when recent surgeons avoid the use of skin graft for open treatment, primary closure by defatting, or intricate local flaps. These can shorten the operation time and minimize donor site morbidity. However, surgeons should consider the free tension closure of the wound by combining the skin graft after the flap. Conclusion: Reconstruction procedure for foot syndactyly aims to improve the appearance and function of the toes as well as to avoid progressive deformity through development. The skin graft addition in combination of skin flap shows promising outcome. Key words: acquired syndactyly, syndactyly reconstruction, zigzag flap, skin graft.

Acral perineurioma: a case report of a rare neoplasm successfully treated with autologous skin graft reconstructive surgery

Soft tissues perineurioma is a rare nerve sheath tumor that affects most of all the subcutaneous tissue. Even if it could present as a large mass, it is a benign neoplasm for whom a complete surgical excision represents the gold standard treatment. Considering that it usually affects acral sites of young people, can be challenging to perform a reconstructive surgery that allows a full functional recovery. We report the case of a woman in her 20s presenting a perineurioma of the sole of the foot, a nodule of about 2 cm of diameter that compromised the support of the foot on the ground. We performed a radical surgical excision with no recurrence after 3 years of follow up and we obtained a full functional recovery thanks to an autologous full-thickness skin graft.

Comparison of Efficacy among Three Dermal Substitutes in the Management of Critical Lower-Limb Wounds: The Largest Biases-Reduced Single-Center Retrospective Cohort Study in Literature

Background and objectives: The skin recently became the main focus of regenerative medicine and, in this context, skin substitutes are fully entering into the plastic surgeon’s armamentarium. Among the various types of skin substitutes, dermal substitutes (DSs) are the most used. Our study aims to retrospectively compare three renowned and extremely similar DS in the management of critical lower limb wounds in the largest cohort analysis currently present in literature. Materials and Methods: We followed a strict protocol of application and evaluation of the DS for each patient and wound and, after a meticulous bias reduction process, we compared final outcomes in terms of efficacy and speed in achieving the defect coverage. Results: Among patients who did not receive a skin graft after the DS, we registered a wound healed surface of 50% for Pelnac, 52% for Integra, and 19% for Nevelia, after 30 days from the external silicon layer removal; among those who received a skin graft after the DS, we observed a significantly lower mean percentage of graft take after 7 days with Pelnac (53%) compared to Integra and Nevelia (92% and 80%, respectively). The overall percentage of wound healed surface obtained after 30 days from the external silicon sheet removal, either with or without skin graft, was 71% for Pelnac, 63% for Integra and 63% for Nevelia. We also ran a sub-group analysis only including grafted wounds with a negative microbiological test and the mean percentage of graft take was similar this time. Eventually, we assessed the influence of the wound’s “chronicity” on its healing, comparing the mean graft take only in “acute” wounds who received a skin graft and it resulted 63% for Pelnac, 91% for Integra and 75% for Nevelia. Conclusions: Integra demonstrates the highest rate of skin graft viability and the highest rate of skin graft takes after 7 days. Pelnac shows the quickest induction of secondary healing in acute wounds. Nevelia is not different from Integra and shows a superior graft take compared to Pelnac, but features the lowest secondary healing induction rate. No differences exist between the three DSs in terms of wound healing after 30 days from the skin graft or from the removal of the external silicon layer.