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American Association for Hand Surgery

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The Octopus Procedure, Combined with Targeted Muscle Reinnervation, for Elective Transhumeral Amputation
Nikhil A. Agrawal, MD, Long Island Plastic Surgery Group, Garden City, NY, TX, Sigurast Olafsson, BS, Harvard Medical School, Boston, MA, Brent Pickrell, MD, Harvard Plastic Surgery, Boston, MA, Marilyn Heng, MD, Massachusetts General Hospital - Harvard Medical School, Boston, MA, Ian Valerio, MD, MBA, Massachusetts General Hospital, Boston, MA and Kyle R. Eberlin, MD, Orthopaedic Hand and Upper Extremity Service, Massachusetts General Hospital, Massachusetts General Hospital / Harvard Medical School, Boston, MA

Optimizing prosthetic function and tolerance are key principles of performing an elective upper extremity (UE) amputation. It is common for UE amputees to experience issues related to non-optimal prosthetic control and pain. Targeted muscle reinnervation (TMR) and regenerative peripheral nerve interfaces (RPNI) in elective transhumeral amputations have been introduced as techniques to address the paucity of signals that may exist for myoelectric control post-amputation. These techniques require the denervation of muscle and rely on delayed muscle reinnervation to provide eventual signal amplification for prosthetic function. In addition, the fascicles cannot be separated enough to provide signals to each individual muscle. Use of native innervated forearm musculature can provide more immediate and specific signals for prosthetic use.

These native muscles are often not available for use due to trauma, denervation, or dysvascularization. In elective amputations, they can be used as spare parts to provide more signals for the sensors on a myoelectric prosthetic. The concept has been used in partial hand amputations and allowed a for individual digital control at the terminal prosthetic device. In this manuscript, we describe a novel technique used for an elective transhumeral amputation utilizing native innervated, vascularized musculature to provide intuitive control of a myoelectric prosthetic.

The forearm flexors and extensors were first isolated and pedicled to preserve the native innervation and perfusion. The osteotomy was then performed and the forearm and hand amputated, along with the prior elbow arthroplasty. The isolated pedicled, vascularized and innervated muscle flaps were transposed proximally over the amputation stump with the FCR in an anterior position and proceeding medially to place each flap sequentially over the stump (FDS, FDP, FCU). Next, the brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, the extensor digitorum communis, and extensor pollicus longus were placed lateral to posterior on the stump. Each of these innervated, pedicled flaps was secured proximally in an orientation that will allow for potential signal targets to be used by a myoelectric prosthetic with intraoperative innervation confirmed with a handheld nerve stimulator.

The Octopus procedure can provide individuals undergoing elective amputation the opportunity to gain greater function for myoelectric prosthetic control while also minimizing pain. The case described here is illustrative of one application of combining the Octopus Procedure with TMR. Greater patient numbers and long-term follow-up will be necessary to validate the potential benefits of this technique.

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