Effects of Temporary and Permanent Muscle Denervation on Fat Graft Retention in the Latissimus Dorsi Muscle: An Experimental Study in Rats

Background In breast reconstruction with a latissimus dorsi flap, immediate fat grafting is useful for increasing flap volume. However, factors such as latissimus dorsi muscle atrophy and fat graft retention affect the volume of the reconstructed breast, and reports are inconsistent regarding treatment of the thoracodorsal nerve. This study examined how thoracodorsal nerve treatment affects the rates of latissimus dorsi flap preservation and fat graft retention using a rat model. Methods Fat harvested from the inguinal region was grafted to the latissimus dorsi muscle elevated as a pedicled muscle flap on the experimental side and to the intact LD muscle on the contralateral side (control). Rats were divided into intact thoracodorsal nerve (Ni), temporary denervation (Ntd), and permanent denervation (Npd) groups ( n = 8 each). Fat retention and muscle preservation rates were determined, and histological changes were analyzed postoperatively. Results Fat retention rates did not significantly differ between the Ni and Ntd groups. Only the Npd group showed a significant decrease in fat retention rate relative to the control side ( p < 0.01). The quality of the grafted fat as reflected by histological parameters was significantly lower, and the viable adipocyte area and muscle fiber preservation rate significantly decreased, in the Npd group compared to the other groups. Conclusions Permanent thoracodorsal nerve denervation resulted in severe muscle atrophy and a significantly decreased fat retention rate. Temporary denervation had no significant benefit, suggesting that preserving the thoracodorsal nerve may be desirable for achieving sufficient volume in latissimus dorsi flap breast reconstruction with immediate fat grafting. No Level Assigned This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .