Mixed grafting of small auto- and cryopreserved allo-skin for residual wound repair in severe burn patients: A retrospective study

Background: The wound repair process for extensively deep burn patients is a recurring and highly challenging endeavor. A prolonged healing time beyond 3 weeks after injury often leads to compromised healing outcomes. The limited availability of autologous skin grafts remains the primary obstacle in achieving timely wound repair. This study aimed to investigate an approach that minimizes the reliance on autologous skin grafts for repairing residual wounds in severe burn patients. Methods: This was a retrospective review of 74 burn patients with large residual wounds in the middle- and late- stages of treatment who were admitted to the Burn Center of the First Affiliated Hospital of Naval Medical University between 2012 and 2022. Mixed grafting of small auto- and cryopreserved allo-skin was used in 32 patients with an expansion ratio of 1:9-16. Routine microskin grafting was applied in 17 cases with an expansion ratio of 1:10-15. Meek grafting was employed in 25 patients with an expansion ratio of 1:4-6. The main outcomes of this study were the wound healing rate and scar formation. Results: The wound healing rate in the mixed grafting group was significantly greater than that in the microskin and Meek grafting groups (89 f 5.8 % vs. 66.5 f 6.9 % and 75.4 f 5.1 %, respectively; P < 0.001). Multiple linear regression analysis showed that under the same conditions, the wound healing rate of microskin grafting and Meek grafting decreased by 24.6 % and 16.8 % compared with mixed grafting respectively. Follow-up studies of 43 of total 74 burn patients over 1-2 years revealed that the mean VSS scores for pigmentation, pliability, scar height, and vascularity in the mixed grafting group (n = 23) were significantly lower (total score 4.23 f 2.17) than those in the microskin grafting group (n = 12; 6.02 f 2.73, P = 0.03), and not significantly different from those in the Meek grafting group (n = 18; 4.37 f 2.13, P = 0.74). Conclusions: Mixed grafting of small auto- and allo-skin minimizes the reliance on limited autologous skin resources while achieving superior healing rates and lower scar formation for repairing deep burn wounds. Compared with the microskin and Meek grafting methods, the mixed grafting approach significantly enhances wound healing rates and outcomes in patients with extensive deep burns. Our findings suggest that mixed grafting is a viable and effective strategy for improving wound repair and functional outcomes in severely burned patients.