Is Pyrocarbon the Future?

The treatment of glenohumeral osteoarthritis in the young patient is controversial, and surgeons should weigh the patient’s activity expectations and implant longevity when counseling them regarding treatment options. Hemiarthroplasty has emerged as a surgical option to avoid glenoid component loosening in anatomic arthroplasty (aTSA), and the development of the pyrocarbon wear surface has expanded hemiarthroplasty indications. Hoy et al. present a prospective review of 119 shoulders in 115 patients that underwent PyroTITAN pyrocarbon humeral resurfacing (Integra LifeSciences) for glenohumeral osteoarthritis at 5-year follow-up. They found that range of motion, strength, and the Western Ontario Osteoarthritis of the Shoulder Index (WOOS) and American Shoulder and Elbow Surgeons score (ASES) improved significantly and by more than the minimally clinically important difference. Glenoid wear was examined radiographically using the glenoid-medial spinoglenoid notch (GmSGN) distance, and patients had an average decrease of 2.01 mm at 3-year follow-up. Interestingly, the authors found that the wear rate declined over time in a semilogarithmic pattern. Finally, this patient cohort had a 5.9% rate of adverse events and 97.5% 5-year implant survival, with 2 revisions to aTSA at 2 to 3 years after the index procedure and 1 patient who underwent revision due to a fracture of the prosthesis. This survival rate is nearly identical to the 5-year survival of a similar stemless pyrocarbon hemiarthroplasty1 and to the 7-year survival of a stemmed pyrocarbon hemiarthroplasty2. Importantly, this study shows that implant fracture is now an uncommon reason for revision. The authors conclude that PyroTITAN pyrocarbon hemiarthroplasty is a viable option for the treatment of glenohumeral osteoarthritis in young patients, with excellent medium-term outcomes. This study is one of the few medium-term evaluations of pyrocarbon shoulder hemiarthroplasty, is the largest single-implant patient cohort in the literature, and provides several unique analyses. First, the implant is a completely pyrocarbon humeral head resurfacing and is distinct from the traditional understanding of a pyrocarbon hemiarthroplasty. Prior work has focused on implant survivorship and has shown comparable longevity to that of aTSA1. Second, patients with rheumatologic disease and inflammatory arthropathies were included in the analysis, yet found no increased rate of glenoid wear or rotator cuff failure in their cohort compared with prior 2-year3 and 7-year4 follow-up evaluations. Finally, the GmSGN distance was used to quantify glenoid erosion. Comparison with previous studies is limited, as most literature uses the Sperling classification and shows an increase in moderate to severe erosion over 3 to 10-year follow-up3–5. Griswold et al. utilized image processing software and reported 2.9 ± 2.8 mm of glenoid medialization at 5-year follow-up2, similar to the findings of Hoy et al. The authors do note limitations, primarily involving loss to follow-up and generalizability due to the single-surgeon cohort. Glenoid morphology was not addressed; however, the authors plan a future subgroup analysis that will include stratification by Walch classification. Techniques to address glenoid deformity vary from benign neglect to concentric reaming3, reshaping2, and microfracture (Hoy et al.), and further work should focus on treatment strategies and long-term outcomes. Surgeons should thoughtfully indicate patients for pyrocarbon hemiarthroplasty, as myriad factors can affect long-term outcomes in this young patient population. Future studies should examine implant longevity in patients performing high-impact activities and evaluate outcomes at ≥10 years. Hoy et al. provide an excellent start in outlining the medium-term outcomes and implant longevity for PyroTITAN pyrocarbon hemiarthroplasty.