A Comparison of PROMIS Scores in Patients Treated with First Metatarsophalangeal Joint Arthrodesis and Polyvinyl Alcohol Hydrogel Implant Hemiarthroplasty for Hallux Rigidus
Authors: Masry Seif El , Boden Allison L. , DiGiovanni Grace , Cororaton Agnes , Ellis Scott J. 
Published: April 2024

Introduction/Purpose: Current literature shows similar clinical outcomes between first metatarsophalangeal joint arthrodesis and polyvinyl alcohol hydrogel (synthetic cartilage implant or SCI) hemiarthroplasty in the treatment of hallux rigidus; however, prior studies have not reported validated patient-reported outcome measures. To our knowledge, this is the first study to compare patient-reported outcome measures using the validated Patient Reported Outcomes Measurement Information System (PROMIS) in patients treated for hallux rigidus with metatarsophalangeal joint arthrodesis and SCI hemiarthroplasty. In addition, this novel study provides comparative data of the complication and revision rates for each procedure. Methods: A retrospective review of prospectively collected data within an institutional registry identified 101 patients who underwent metatarsophalangeal joint arthrodesis and 82 patients who underwent SCI hemiarthroplasty for treatment of hallux rigidus between January 2016 and June 2022. Chart review was performed to obtain demographic information, complications, and revision rates. Preoperative, 1-year, and 2-year PROMIS scores were obtained from the registry and confirmed via chart review. Equivalence testing was performed using two one sided t-tests (TOST) and setting a +/-5 unit margin of difference as the clinically meaningful difference to determine if there was a difference in PROMIS scores between groups. Linear regression models were also utilized to compare adjusted postoperative PROMIS scores between the two cohorts. For the equivalence testing, a p-value > 0.05 indicated a statistically significant result. Results: Demographic information and preoperative hallux rigidus severity between the cohorts showed no statistically significant difference (Table 1). The SCI cohort had no intra-operative or post-operative wound complications, but one patient within the MTP fusion cohort was treated for a superficial wound infection. The SCI group had six patients revised to MTP fusions within 3- years due to continued pain and/or implant subsidence. The MTP fusion group had 2 patients revised due to non-union and 13 patients that had symptomatic hardware requiring removal. Equivalence comparison of PROMIS scores showed the SCI cohort had significantly worse pain intensity scores at 2 years and significantly less improvement in pain intensity scores from pre- operative to 1-year post-op (Table 2). There were no differences found between cohorts for other PROMIS domains. Conclusion: For the treatment of hallux rigidus, the SCI hemiarthroplasty and metatarsophalangeal joint arthrodesis have equivalent outcomes for all PROMIS domains except the pain intensity domain. While patients in both cohorts had improvement in pain from pre-operative to post-operative time points, SCI was not as effective as first MTP fusion at relieving pain intensity at a follow-up of 2 years. While SCI is a motion-sparing procedure, patients with a primary goal of improving pain may be better suited for first MTP joint arthrodesis. Tables demonstrating the comparisons of both the preoperative demographic data as well as demonstrating the PROMIS scores across different time periods (preoperative, 1 year and 2 years).