Medial Capsular Interpositional Arthroplasty for Severe Hallux Rigidus

Background: Multiple surgical options have been described for severe hallux rigidus. One option is capsular interpositional arthroplasty. We report our initial results with a technique using the thicker medial capsule as our interpositional material instead of the dorsal capsule and extensor hallucis brevis (EHB). Materials and Methods: Twenty-two patients with grade IV hallux rigidus underwent minimal proximal phalanx resection (modified Keller) with preservation of the flexor hallucis brevis (FHB) insertion and medial capsular interpositional arthroplasty. Results: Postoperative AOFAS hallux MTP-IP scores (mean 77.8), and SF-36 scores (mean 68.7 on physical function, 79.5 role limitations) demonstrated clinical improvement compared to historical controls. Alignment and stability were well maintained (mean preoperative HV angle of 11.8 degrees, mean postoperative HV angle of 13.0 degrees). Dorsilexion/plantarflexion arc of motion showed sustained improvement (mean 38.4 degrees preoperative, mean 62.3 degrees postoperative). Conclusion: These results are comparable to other forms of interpositional arthroplasty and arthrodesis for end stage arthritis of the hallux MTPJ.