Evaluation of Outcomes Following Lesser Toe Metatarsophalangeal Interpositional Arthroplasty with Semitendinosus Allograft with Description of the Anchovy Technique

Abstract

Category: Lesser Toes Introduction/Purpose: Lesser toe metatarsal head degeneration and collapse can cause significant pain and disability. If conservative measures fail, there is not a clear surgical solution, particularly in the setting of bone loss. A wide variety of causes of lesser metatarsophalangeal (MTP) joint degeneration exist, including Freiberg’s disease, failure of previous surgery, and primary osteoarthritis. Previous studies have evaluated joint preserving osteotomies; however, they do not offer a solution for complete head collapse. Isolated metatarsal head excision is associated with poor outcomes. The purpose of our study was to evaluate clinical outcomes and review radiologic finding after lesser toe MTP interpositional arthroplasty with semitendinosus allograft and to describe the technique. To our knowledge, this technique and its outcomes have not been described for the lesser toes. Methods: We retrospectively reviewed a consecutive series of patients treated by three foot and ankle trained surgeons at one institution from 2007-2017. We identified sixteen patients who underwent allograft interpostional arthroplasty for the second or third MTP joint. We performed a retrospective chart review to obtain demographics, diagnosis, range of motion, and concomitant procedures. A phone survey was created to evaluate satisfaction, pain, and likelihood to repeat the surgery. Foot and Ankle Ability Measure (FAAM) scores were reviewed. Preoperative and postoperative radiographs were reviewed for preservation of metatarsal lengths and cascade. The procedure was performed through a dorsal midline approach to the MTP joint. Osteophytes were removed and a cannulated reamer created a concavity in the metatarsal head. A semitendinosus allograft was then rolled and sutured into a ball, which was approximately 1.5 cm in diameter. The allograft was secured to the medullary canal with a suture anchor. Results: Fourteen patients underwent 2nd MTP interposition, and two patients underwent 3 rd MTP interposition arthroplasty. The average age of the patients were 51.3 years (median 53.4, range 24-61), and the average follow up was 3.4 years. Seven patients had multiple procedures. The diagnoses included six primary osteoarthritis, four Freiberg’s disease, two failed prior surgery. Preoperative FAAM showed the patients were able to complete 73% of activities of daily living and 63% of sport specific activities. Average MTP dorsiflexion was 27 and 30 degrees before and after surgery, respectively. Radiographically, preoperative metatarsal length ranged from 9.36 - 12.63 cm. Postoperatively, the metatarsal length added to the space filled by the allograft ranged from 9.65 cm - 11.77 cm. Conclusion: Interpositional arthroplasty of the lesser MTP joints with a rolled semitendinosus allograft, secured with a suture anchor, provides a unique solution to a difficult problem. This procedure allows the surgeon to fill a bony void and replace collapsed metatarsal head. This study shows patient reported outcomes based on phone survey and FAAM scores, where pain caused significant limitations before surgery. This study also showed preservation of range of motion after surgery. Radiographic review suggests that length of the affected metatarsal can be maintained, bone voids can be filled, and the cascade of the metatarsals can be preserved.