Percutaneous Fifth Metatarsal Osteotomy for Bunionette Deformity Without Fixation or Strapping: A Retrospective Study.

BACKGROUND: Bunionette deformity (BD) is a painful condition of the fifth metatarsal characterized by an osseous prominence and fifth toe varus deformity. The purpose of this study is to assess the clinical, functional, and radiographic outcomes of percutaneous distal metatarsal metaphyseal osteotomy (DMMO) without fixation or postoperative strapping of the foot.

METHODS: A retrospective case series was performed on 111 patients (132 feet) with symptomatic BD who underwent percutaneous DMMO of the fifth metatarsal from September 2020 to January 2022 by an experienced minimally invasive surgeon. According to the Shimobayashi classification, we treated 1 type I deformity, 37 type II deformities, 52 type III deformities, 42 feet with type IV deformity, and no patient with a type V deformity. Ninety patients (81%) underwent unilateral osteotomy, and 21 (19%) had bilateral osteotomies. Most cases included other procedures including treatment of 114 associated deformities of the same feet: 68 bunions, 12 lesser metatarsal osteotomies (2-3-4 metatarsals), and 34 hammertoes (20 second hammertoes, 10 third hammertoes, 1 fourth hammertoes, 2 fifth hammertoes). Patient-reported clinical outcome measures, including the Foot Function Index (FFI) questionnaire, the visual analog score (VAS), and overall satisfaction were collected. Fourth-to-fifth intermetatarsal angle (IMA) correction, time to bone union, and complication rates were assessed in all patients.

RESULTS: Mean follow-up was 24.1 months (range, 14-39 months). Both radiographic parameters and patient-reported outcome measures significantly improved after DMMO procedure. The average fourth-to-fifth IMA improved from 12.2 degrees, preoperatively, to 4.4 degrees, postoperatively ( P  < .001). Patient outcomes reflect the overall outcomes of the combined surgeries on a per-patient basis. Preoperatively, patients had a mean VAS score of 7.6, which improved to 0.6 at the last follow-up ( P  < .001). Furthermore, the average FFI significantly decreased from pre- to postoperation from 19.2 to 4.4, respectively ( P  < .001). Overall, 108 of 111 patients reported being satisfied with the outcomes of the procedure. Average bone union was achieved at 12.6 weeks postoperation, with a minimum of 12 and a maximum of 25 weeks. The complication rate was 1.5%, including 1 case of an asymptomatic cock-up deformity and 1 case of lateral fifth metatarsal shaft bone overhang pain, which resolved with an exostectomy.

CONCLUSION: The results of this study of patients who had minimally invasive surgery from an experienced surgeon suggest that percutaneous DMMO of the fifth metatarsal without internal fixation or postoperative immobilization or strapping can be effective at improving radiographic alignment, pain, function, and overall satisfaction with minimal rates of complication.

LEVEL OF EVIDENCE: Level IV, case series.