A Radiographic Analysis of Hallux Valgus Interphalangeus and Biplanar Proximal Phalanx Closing Wedge “MoAkin” Osteotomy in Hallux Rigidus Treated with a Synthetic Cartilage Implant

CATEGORY: Midfoot/Forefoot INTRODUCTION/PURPOSE: 'MoAkin' biplanar proximal phalanx closing wedge osteotomy with dorsal cheilectomy has been described as an effective procedure for treatment of hallux rigidus with hallux valgus interphalangeus (HVI). Its role as an adjunct procedure to first metatarsophalangeal joint hemiarthroplasty using a synthetic cartilage implant has not been well described. The purpose of this radiographic analysis was to examine radiographic changes associated with the MoAkin osteotomy performed in patients who underwent first MTPJ hemiarthroplasty using the Cartiva implant. METHODS: A retrospective study of all patients with hallux rigidus and HVI treated with a synthetic cartilage implant and MoAkin osteotomy between 2009 and 2020 was conducted. Radiographs were performed preoperatively and at six- and/or twelve-month postoperatively, and evaluated using standardized measurement techniques. Hallux valgus angle (HVA), interphalangeal angle (IPA), and intermetatarsal angle (IMA) were measured. RESULTS: Fifty-four patients were included in the study (37 male; 17 female). Mean preoperative HVA, IPA, and IMA were 11.7+- 4.2 degrees, 15.8+-4.6 degrees, and 8.2+-2.4 degrees, respectively. Mean six-month postoperative HVA, IMA, IPA were 7.7+-4.2 degrees, 15.7+-5.7 degrees, and 8.2 +- 3.0 degrees. Mean twelve-month postoperative HVA, IMA, IPA were 8.0+-4.5 degrees, 15.2+-6.1 degrees, and 8.1+-2.9 degrees. No statistical differences were found between the six-month and twelve-month radiographic analysis (p>=0.59). There was a statistically significant reduction in the hallux valgus angle at six and twelve-month follow up compared to the preoperative angles (p<0.001, d=0.73-1.16). No statistically significant differences were noted in terms of IPA and IMA (p>=0.31). CONCLUSION: MoAkin osteotomy improves the hallux valgus angle in patients with hallux rigidus and HVI undergoing first MTPJ hemiarthroplasty with the Cartiva implant. Further studies are warranted to evaluate the impact of these radiographic findings on patient-reported outcomes and other clinical outcomes.