Outcomes of the Starfish procedure using muscle transfer for independent digital control of a myoelectric prosthesis.

Background: Surgical and technological advancements have revolutionized myoelectric prosthetic options for patients with upper extremity amputations, but partial hand amputations have remained a challenge. The Starfish procedure is a novel surgical technique that involves transferring intrinsic hand muscles to a subcutaneous location to allow immediate signal detection and independent digital control of a myoelectric prosthesis. We report the outcomes of our cohort of patients treated with this procedure.

Methods: Twenty-one patients underwent the Starfish procedure between 2015 and 2021. All patients had a postoperative evaluation with an Ottobock Myoboy to determine if they had viable signals from interossei transfers. All patients completed a specialized survey for amputees, depression, and PTSD surveys.

Results: All patients had recordable myoelectric signals at each muscle transfer. Three patients were lost to follow-up and three patients were multi-extremity amputees and therefore their DASH scores were not included given the confounding associated injuries thus 15 patients were available for outcomes data. 14 out of 15 remaining patients (93 %) obtained a myoelectric prosthesis. Patients reported using their prosthesis an average of 5.5 h per day and 5.5 days per week. The average DASH score prior to surgery was 67.9 and after surgery was 40.5 (p = 0.014). VAS Pain scores were 3.8 for residual limb pain and 2.7 for phantom pain. Mean follow-up was 2.1 years. 71 % of patients reported being "extremely" or "very" satisfied with the overall function of their prosthesis. The most common functional activities that the prosthesis allowed patients to perform include dressing, housework, meal preparation and eating. 73 % of previously working patients were able to return to employment.

Conclusions: The Starfish procedure provides immediately detectable superficial myoelectric signals that allow intuitive and independent finger control. At 2-year follow up, patients have a high satisfaction rate, consistent myoelectric prosthetic use, improved DASH scores, and a high rate of return to work.