Sensory and Pain Outcomes of Neurotized Skin-grafted Free Gracilis Muscle Flaps for Lower Extremity Reconstruction

Background Skin-grafted free gracilis muscle flaps are commonly performed for lower extremity reconstruction. However, loss of sensory function may lead to increased patient morbidity. This study prospectively analyzes the sensory and neuropathic pain outcomes of neurotized skin-grafted free gracilis muscle flaps for reconstruction of lower extremity defects. Methods Patients undergoing lower extremity reconstruction between 2020 and 2022 with neurotized skin-grafted free gracilis muscle flaps were prospectively enrolled. Sensation was assessed at 3, 6 and 12 months postoperatively using monofilaments, two-point discrimination, a vibration device, and cold and warm metal rods. Sensation was tested in the center and periphery of the flap, as well as on the surrounding skin. The contralateral side served as control. Patients completed the McGill Pain Questionnaire to evaluate patient-reported neuropathic pain. Results 10 patients were included. At 12 months postoperatively, monofilament values were 44.5% improved as compared to the control site, two-point discrimination 36.2%, cold detection 48%, warm detection 50% and vibration 88.2% improved at the reconstructed site as compared to the control site. All sensory tests were significantly better than 3 and 6 months values (p<0.05), but remained significantly poorer than the control site (p<0.05). Central flap areas were similar to peripheral flap areas throughout follow-up (p>0.05). The surrounding skin reached values similar to the control site at 12 months (p>0.05). 50% of patients reported neuropathic pain at 3 months postoperatively, 40% at 6 months and 0% at 12 months (p<0.05). Conclusion Mechanical detection, vibration detection, temperature detection and two-point discrimination significantly improved over time but without reaching normal sensory function at 12 months postoperatively. Neuropathic pain resolved at 12 months.