Free Fillet Flap of Lower Extremity: 38 Amputations with Seven Examples of Targeted Muscle Reinnervation and Regenerative Peripheral Nerve Interfaces

Background: Extremely high-level lower extremity amputations are rare procedures that require significant soft-Tissue and bony reconstruction. This study describes the use of fillet flaps for oncologic reconstruction and the incorporation of targeted muscle reinnervation (TMR) and regenerative peripheral nerve interfaces (RPNIs) for chronic pain prevention. Methods: The authors performed a retrospective review of patients who underwent lower extremity fillet flaps at MD Anderson Cancer Center from January of 2004 through April of 2021. Surgical outcomes were summarized and compared. Numeric rating scale and patient-reported outcomes measures were collected. Results: Thirty-eight fillet flaps were performed for lower extremity reconstruction. Extirpative surgery included external hemipelvectomy (42%), external hemipelvectomy with sacrectomy (32%), and supratrochanteric above-knee amputation (26%). Median defect size was 600 cm², and 50% included a bony component. Twenty-one patients (55%) experienced postoperative complications, with 16 requiring operative intervention. There was an increased trend toward complications in patients with preoperative radiotherapy, although this was not significant (44% versus 65%; P = 0.203). Seven patients underwent TMR or RPNI. In these patients, the mean numeric rating scale residual limb pain score was 2.8 ± 3.4 (n = 5; range, 0 to 4/10) and phantom limb pain was 4 ± 3.2 (n = 6; range, 0 to 7/10). The mean Patient-Reported Outcomes Measures Information Systems T scores were as follows: pain intensity, 50.8 ± 10.6 (n = 6; range, 30.7 to 60.5); pain interference, 59.2 ± 12.1 (n = 5; range, 40.7 to 70.1); and pain behavior, 62.3 ± 6.7 (n = 3; range, 54.6 to 67.2). Conclusions: Lower limb fillet flaps are reliable sources of bone, soft tissue, and nerve for reconstruction of oncologic amputation. TMR or RPNI are important new treatment adjuncts that should be considered during every amputation. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.