Pyrolytic Carbon Head Hemiarthroplasty Versus Cobalt-Chromium Head for Proximal Humerus Fractures - A Short-Term Follow-Up Study.

Abstract

Shoulder hemiarthroplasty (HA) is a viable treatment option for complex proximal humerus fractures in younger patients (<65 years), although clinical outcomes can vary. In recent years, the pyrolytic carbon head (PCH) prosthesis has emerged as an alternative to the cobalt-chromium (CoCr) head in shoulder osteoarthritis, potentially reducing glenoid erosion. This study aimed to compare the outcomes of the PCH prosthesis HA with the traditional CoCr head in the treatment of complex proximal humerus fractures (PHFs), with the hypothesis that the PCH group would demonstrate superior results. Patients under 65 years old, who underwent HA using the PCH prosthesis for complex PHFs between 2019 and 2023, were compared to a control group of patients who underwent traditional CoCr HA. Postoperative assessments at minimum one-year follow-up included range of motion, Numeric Rating Scale for pain (NRS), Subjective Shoulder Value (SSV) and Radiological evaluation including greater tuberosity union and glenoid erosion. Forty-six patients met the inclusion criteria, of which five were excluded due to lack of sufficient follow-up, leaving 41 patients (89%) for analysis: 21 patients in the PCH group and 20 in the CoCr HA group, with similar age and follow-up length. Clinical outcomes favored the PCH group, showing significantly better forward flexion (147 ± 30 vs. 94 ± 45 degrees, p < 0.001), external rotation (40 ± 19 vs. 27 ± 20 degrees, p = 0.05), and internal rotation (T12 vs. lumbosacral junction, p = 0.02). Pain scores (NRS) were significantly lower in the PCH group (1.9 ± 2.4 vs. 3.6 ± 2.5, p = 0.05), the difference of 1.7 points is close to the MCID for the pain score (1.65 points). SSV score showed no significant difference between the groups. Greater tuberosity union rates were significantly higher in the PCH group (95% vs. 60%, p = 0.01). Although glenoid erosion was milder in the PCH group, the difference was not statistically significant. The PCH group demonstrated superior clinical outcomes in most measures compared to the CoCr group. Differences in stem designs and surgeons' experience probably also influence these results, and the observed benefits cannot be attributed solely to the prosthesis head. While the main potential advantage of the PCH-reduced glenoid erosion-will require further investigation with longer follow-up, this is the first study to demonstrate the safety and short-term outcomes of the PCH in treating proximal humerus fractures.