Donor Site Morbidity in Skin Grafting: A Comparative Study of Cobbett Knife and Zimmer Electric Dermatome

Introduction: Skin grafting in many low resource centres is mostly harvested with Humby Knife and its various modifications. However, there is a gradual paradigm shift to the use of the electric dermatome. This study aimed to compare the rate of re-epithelialization of donor site wound, pain index, and scar formation using Cobbett Knife with Zimmer electric power dermatome in harvesting partial thickness skin grafts.

Materials and Methods: The study comprised 76 patients recruited over a one year period. The patients were randomized into two groups (A and B) using systematic sampling. Those in group A had their donor site harvested with Cobbett Knife, while those in group B had their donor site harvested with Zimmer electric power dermatome. The predictive variables were the percentage rate of re-epitheliliazation, assessment of pain index, and scar formation. The outcome variable was to use a photographic picture on the 10th, 14th, and 21st day respectively to assess the rate of re-epithialization. A Numerical rating scale was employed to assess the pain index.

Results: There was no significant difference in the donor site morbidities between Cobbett knife and Zimmer electric dermatome in the percentage rate of re-epithelialization and evaluation of scar formation with a P-value of 0.304 and 0.416 respectively. However, data analysis of donor site pain between Cobbett knife and Zimmer electric dermatome was statistically significant with a P- value of 0.042 and 0.031 respectively, in patients with mild pain at the 6th hour and 3rd day. There was no statistically significant difference on the 10th day with a p- value of 0.857.

Conclusion: From this study, the use of the Cobbett knife for the harvest of partial thickness skin graft is comparably the same as Zimmer electric power dermatome in terms of re-epitheliazation and scar formation. However, Cobbett knife is associated with more intense early post-operative pain compared to Zimmer electric power dermatome.