Current review of midterm outcomes of synthetic cartilage implant hemiarthroplasty of the first metatarsophalangeal joint in advanced hallux rigidus

H. Davies, C. Blundell, T. Daniels, M. Glazebrook, J. Baumhauer, A. Younger, I. Le, E. Pedersen, Cartiva Study Group

Introduction: A randomized clinical trial of first metatarsophalangeal (MTP) joint hemiarthroplasty with a synthetic cartilage implant demonstrated equivalent pain, function and safety outcomes to first MTP joint arthrodesis at 2 years. The implant cohort continues to be followed under an extension of the original study and we report on prospectively determined 5+ year outcomes for subjects assessed to date.

Methods: Patients treated with hemiarthroplasty implant as part of the previously mentioned trial are eligible for enrollment in the extended study (n=135). At the time of this report, 57 patients had reached the 5+ years postoperative time point, of which 5 were lost to follow-up. The remaining 52 patients with mean age of 58.5 (range, 38.0-72.0) underwent physical examination, radiographic evaluation, assessment of implant survivorship and collection of patient completed VAS pain, and Foot and Ankle Ability Measure (FAAM) sports subscale and activities of daily living (ADL) subscale scores. Mean follow-up is 5.8 (range, 4.8-7.4) years.

Results: Patient reported pain and function outcome measures showed clinically and statistically meaningful improvements over baseline at 5.8 years. Mean VAS pain scores decreased 57.9 points (86% pain reduction). The mean FAAM Sports and ADL subscale scores increased from baseline 47.9 points (126%) and 32.7 points (55%) respectively. Patients maintained first MTP joint motion with mean active peak MTP dorsiflexion of 25.9° (range, 0-54°) which was a 3° improvement from baseline. Implant survivorship at 5.8 years was 92%; four were converted to fusion because of persistent pain at mean time 42 months post-operation (range, 26-52 months). These results are equivalent to the outcomes reported at 2 years follow-up.¹

Conclusion: The synthetic cartilage hemiarthroplasty implant continues to demonstrate safety and efficacy for the treatment of advanced first MTP joint osteoarthritis with mid-term evidence of a therapeutic effect and an acceptable safety profile at 5.8 years.