Mid-term outcomes of pyrolytic carbon humeral resurfacing hemiarthroplasty compared with metal humeral resurfacing and metal stemmed hemiarthroplasty for osteoarthritis in young patients: analysis from the Australian Orthopaedic Association National Joint Replacement Registry

Background: The optimal surgical management of glenohumeral osteoarthritis in young patients remains an unsolved problem. Humeral resurfacing hemiarthroplasty and stemmed hemiarthroplasty using metallic heads are 2 surgical options that avoid the complications of loosening or wear of the glenoid component seen in total shoulder arthroplasty. Despite the potential benefits, improvement in survivorship has not been demonstrated from joint registry studies or other studies at mid-term follow-up. This is predominantly because of glenoid erosion and pain that occur when the metal resurfaced head articulates with the native glenoid. The use of pyrolytic carbon (pyrocarbon) as a resurfacing material has been proposed as an alternative bearing surface thought to reduce glenoid erosion owing to a marked reduction in wear rates in vitro. This study aimed to compare the survivorship of shoulder hemi-resurfacing using pyrocarbon with shoulder hemi-resurfacing and stemmed hemiarthroplasty using metallic heads.

Methods: Data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) were analyzed for all patients aged <55 years who had undergone a primary shoulder replacement for osteoarthritis from April 16, 2004, to December 31, 2019. The outcomes of shoulder procedures using pyrocarbon hemi-resurfacing were compared with procedures using metal hemi-resurfacing and metal stemmed hemiarthroplasty. The reasons for revision in each arthroplasty class were analyzed. The analyses were undertaken using Kaplan-Meier estimates of survivorship and hazard ratios (HRs) from Cox proportional hazards models.

Results: We analyzed 393 primary shoulder procedures, of which 163 were pyrocarbon hemi-resurfacing procedures, 163 were metal hemi-resurfacing procedures, and 67 were metal stemmed hemiarthroplasties.The cumulative percentage of revision at 6 years was 8.9% for pyrocarbon hemi-resurfacing, 17.1% for metal hemi-resurfacing, and 17.5% for metal stemmed hemiarthroplasty. Pyrocarbon hemi-resurfacing prostheses had a statistically lower revision rate than other hemi-resurfacing prostheses (HR, 0.41; 95% confidence interval, 0.18-0.93; P = .032). Pain, prosthesis fracture, and infection were the key reasons for revision. No pyrocarbon hemi-resurfacing cases were revised for glenoid erosion. In male patients, pyrocarbon humeral resurfacing had a lower cumulative percentage of revision compared with metal stemmed hemiarthroplasty (HR, 0.32; 95% confidence interval, 0.11-0.93; P = .037).

Conclusion: Pyrocarbon humeral resurfacing arthroplasty had statistically lower revision rates at mid-term follow-up in patients aged <55 years compared with other hemi-resurfacing procedures.