Radiographic and Patient-Reported Outcomes for First Tarsometatarsal Arthrodesis Using An Intramedullary Nail for Hallux Valgus Deformity: A Consecutive Case Series

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: First tarsometatarsal (TMT) arthrodesis is one of the most common procedures performed each year for the correction of hallux valgus deformity (HVD) and there are currently over 100 different techniques that have been described. Non-union rates for first TMT arthrodesis are commonly reported to be between 5-15%. A systematic review found that 10.6% of patients reported dissatisfaction following their surgery to correct HVD and 4.9% had recurrent deformity. Multiple techniques featuring an intramedullary nail for first TMT arthrodesis have been described with promising early results in biomechanical studies and studies involving small numbers of patients. The purpose of this study was to evaluate radiographic and patient-reported outcomes of an intramedullary nail system in patients requiring first TMT arthrodesis for HVD. Methods: An ambispective, multi-surgeon, consecutive case series was conducted, with retrospective and prospective collection of patient-reported outcome measure (PROM) data (Foot and Ankle Ability Measure (FAAM), Pain Interference, Pain Score (scale of 0-10), and Neuro-Quality-of-Life Mobility Lower Extremity (Neuro QOL)) and subsequent radiographic measures (intermetatarsal angle (IMA), hallux valgus angle (HVA), distal metatarsal articular angle (DMAA), Meary’s angle (MA), 1st metatarsal declination angle, tibial sesamoid position, and relative metatarsal length). Patients who underwent first TMT arthrodesis from July 2019–July 2022 for HVD with a Phantom ® Small Bone Intramedullary Nail system and had adequate records for a minimum of three months post-operation (±4 weeks) were included. The indication for surgery was a painful HVD with failure of conservative treatment options. A patient chart review was conducted to collect basic demographic data, surgical data, and patient comorbidities. Results: 70 patients were included in the final analysis (N =68 for radiographic measures), with a median prospective PROM follow-up of 1.6 years. There was an overall union rate of 91.4% (64/70 patients), with 92.4% (61/66) of primary hallux valgus surgeries achieving union. Nine patients required secondary procedures; two experienced migration of the proximal peg and two experienced irritation from the index device. Hardware was completely removed in the 5 primary nonunions, and it was broken in 3 of these 5 patients. PROMs demonstrated significant improvement in FAAM, Pain Interference, overall pain, and Neuro-QOL scores; IMA, HVA, DMAA, MA, and tibial sesamoid position showed significant improvement at follow-up (P< 0.05) (Table 1). 1st Metatarsal Declination angle was not significantly altered and there was minimal (2.4 mm) metatarsal shortening. Conclusion: In the current sample of 70 feet, there were 6 non-unions, resulting in an overall union rate of 91.4%. The overall nonunion rate for first TMT arthrodesis is commonly reported to be between 5 and 15%. Similarly, PROMs and radiographic measurements collected showed significant improvement post-surgery. The results suggest that this system parallels other procedures for first TMT arthrodesis in terms of nonunion, complication rate, and various PROMs. With over 100 different surgical techniques for TMT arthrodesis, the results of this case series support that the intramedullary nail system can be considered as an option for surgeons.