Very Low Preoperative Grip Strength Associated With Poor Pyrocarbon Metacarpophalangeal Implant Survivorship in Rheumatoid Arthritis

Abstract

Background:

Pyrocarbon metacarpophalangeal (MCP) arthroplasty is associated with high rates of recurrent deformity and reoperation in patients with rheumatoid arthritis (RA). We sought to determine the impact of preoperative hand grip strength (HGS) on implant survivorship in these patients.

Methods:

We included primary pyrocarbon MCP arthroplasties in patients with RA at our single institution from 2000 to 2022. Cox proportional hazard models with restricted cubic splines were used to model the continuous relationship between HGS and hazard for revision, all-cause reoperation, and development of any complication, accounting for multiple joints per patient and adjusting for sex. Kaplan-Meier estimates were used to report survivorship at 2, 5, and 10 years.

Results:

We included 75 joints in 27 patients with an average preoperative HGS of 8.6 kg (11.1 years of follow-up). There were 16 (21%) total revisions, most commonly for recurrent deformity, along with 8 nonrevision reoperations, most commonly for tendon/ligamentous repair. There was a significant, J-shaped relationship between HGS and hazard for revision (P = .001) and all-cause reoperation (P < .001). Patients with HGS below 5.5 and 5.3 kg had an increased risk for revision (hazard ratio [HR]: 13.5) and all-cause reoperation (HR: 9.8) compared with patients with sufficiently high HGS. The 10-year revision survival was 93% in patients with HGS >5.5 kg and 63% in patients ≤5.5 kg. Hand grip strength did not significantly affect hazard for developing a first complication.

Conclusion:

Very low preoperative HGS is associated with worsened implant survivorship following pyrocarbon MCP arthroplasty in patients with RA.