Targeted Muscle Reinnervation after Hip Disarticulation and Hemipelvectomy: A Preliminary Study of Surgical Technique
Steven J Schneeberger, MD1, Julie M West, MS, PA-C2, Amy M Moore, MD3, Ian Valerio, MD, MBA4 and Steven A Schulz, MD2, (1)The Ohio State University Medical Center, Columbus, OH, (2)The Ohio State University Wexner Medical Center, Columbus, OH, (3)Division of Plastic and Reconstructive Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, (4)Massachusetts General Hospital, Boston, MA
Background
Proximal lower extremity amputations are indicated for management of oncologic, traumatic, infectious and vascular etiologies. The morbidity associated with these procedures is higher than more distal extremity amputations with significant reports of chronic pain. Targeted muscle reinnervation (TMR) is an effective technique used in the management of acute amputations to decrease phantom limb pain and neuroma formation. To improve post-operative pain in the setting of very proximal amputations, TMR is feasible if a multidisciplinary orthoplastic model is employed in combination with advanced surgical techniques. This includes meticulous flap design, wound optimization techniques, and utilization of spare parts nerve grafts.
Methods
Following IRB approval, a retrospective review was performed to identify patients who underwent a hip disarticulation or external hemipelvectomy with TMR performed at the time of amputation. Operative notes were reviewed and details of the surgical approach and flap design, number of nerves coapted, and use of nerve grafts were recorded. Oral Morphine Equivalent (OME) data was gathered from the medical record pre- and post-operatively to evaluate pain.
Results
From November 2018 to April 2020 nine patients were identified who underwent hip disarticulation (N=7) or external hemipelvectomy (N=2) and acute TMR. Eight patients had proximal amputations for an oncologic diagnosis or a delayed complication of an oncologic reconstruction. One patient had an amputation due to infection. The median number of nerve transfers was three (range 1-3). Four patients required autologous nerve grafting; one patient required an allograft and autologous nerve graft. Both external hemipelvectomy patients required the use of allograft and/or autograft due to the proximal nerve transections. The sciatic nerve was divided into its tibial and peroneal components then transferred into motor targets of the thigh flap muscles with direct coaptation performed in an end to end fashion between the femoral and obturator nerves. Pre-operatively five of the nine patients required chronic narcotics with an average of 369 OME per day (range 45 – 962). At three months postoperatively four patients required chronic narcotics, with an average of 268 OME per day (range 16 - 450). Post-operative complications included two patients with abscesses, one with wound dehiscence, and one with a hematoma.
Conclusion
Using a multidisciplinary orthoplastic team approach and performing TMR at the time of proximal lower extremity amputation may be a reliable technique to improve pain in this high-risk patient population.
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Coaptations of tibial and peroneal sciatic nerve branches and a femoral nerve autograft following hemipelvectomy.
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