Early Failures of Polyvinyl Alcohol Hydrogel Implant for the Treatment of Hallux Rigidus

Background: The purpose of this study was to evaluate the clinical and radiological outcomes following a polyvinyl alcohol hydrogel implant in the treatment of hallux rigidus. Methods: A retrospective cohort study investigating patients treated with a polyvinyl alcohol hydrogel implant for hallux rigidus was performed. Clinical outcomes were evaluated with the Foot and Ankle Outcomes Score (FAOS) and visual analog scale (VAS) score at the final follow-up. Plain radiographs were assessed postoperatively. Eleven patients (11 feet) with a mean follow-up of 20.9 months (range, 14-27 months) were included. The mean age was 60.3 years. Results: All FAOS subscales showed pre- to postoperative improvements, but there was no statistical significance in all subscales. The mean VAS score showed improvement from 4.1 to 3.0 (P = .012). On postoperative plain radiographs, implant subsidence was observed 60% (6/10) at 4 weeks after surgery and 90% (9/10) at the final follow-up. Fifty percent (5/10) showed radiologic lucency around the implant. Forty percent (4/10) had erosion of the proximal phalanx of the great toe. Four patients (36%) reported no improvement following surgery at the final follow-up, which were considered as failures. Three patients required additional surgery related to the implants. An additional patient is waiting to revise the implant. Conclusion: Our current cohort study demonstrated a high failure rate with the polyvinyl alcohol hydrogel implant in patients with hallux rigidus. Significant radiologic subsidence with lysis around the implant, erosion of the proximal phalanx countersurface, and implant wear are harbingers for concern in the long term.