Abstract
Background and aims
Hallux rigidus in the metatarsophalangeal joint (MTPJ) can be treated with arthroplasty to reduce pain and enhance motion. Few studies have investigated the functionality and the survival of HemiCap arthroplasty. Primarily we aimed to examine the medium to long-term functionality and the degree of pain after surgery. Secondarily the failure and revision rate of HemiCap implants.
Methods
A total of 106 patients were operated with HemiCap arthroplasty (n=114) from 2006 to 2014, median age 53 (16 to 80) years, 78 females, 37 dorsal flange (DF) implants. Patient charts were reviewed retrospectively to collect revision data. Pre operative Coughlin/Shurnas arthrosis degree, hallux valgus (HV), intermetatarsalintermetatarsal (IM) and Distal Metaphyseal Articular Angle (DMAA) angles was were measured. Pre- and post operative 3 weeks, 6 months, 1 and 2 year2-year pain levels of the first MTPJ by Visuel Analog Skala (VAS 1–10), American Orthopaedic Foot and Ankle Score (AOFAS 0 to 100 points) and, Range of Motion (ROM), were available for 51 patients. FortysevenForty-seven of the 70 available for reexamination partook in a cross sectional follow up where the Self-Reported Foot and Ankle Score (SEFAS 0–48 points) was added to the Patients Related Outcome Measures (PROMs).
Statistics
Kaplan-Meier for survival analysis, adjusted for sex, radiological angles, degree of arthrosis and dorsal flange. Prospective PROMs and ROM compared by paired t-test.
Results
At 3, 5 and 7 years we had an mean implant survival of 85%, 83% and 78%. Almost all were revised due to pain, one due to malalignment and one due to loosening of the Hemicap. Dorsal flange, gender, preoperative arthrosis degree, HV, IM or DMAA angles did not statistically influence the result. For those (n=23) that were re-examined, preoperative dorsal ROM changed from mean(sd) 21 (6) to 42 (18) degrees, VAS from 7 (2) to 2 (2) and AOFAS from 61 (11) to 87 (11) (p < 0.001).
At mean 5 year follow up (n=47), mean (sd) dorsal ROM was 46 (17) degrees,. AOFAS was 84 (9), VAS 2 (1) and SEFAS 42 (6) points. The dorsal flange made no statistical significant difference for ROM or PROMs, but DF displayed 51 degrees of extension vs. 44 without (p=0.1). Periprostethic lucency (<2 mm) was observed in 27/47.
Conclusions
In general, we saw an acceptable implant survival rate. We did not find any predictors that influenced implant failure and the design alterations with the dorsal flange are not evident clinically. Patients who were not revised had significantly less pain, greater ROM, and better overall foot and ankle conditions than preoperatively, but the data are biased by missing numbers and revisions.
