Hypothesis: The purpose was to review two surgeons’ medium-term results with the Ascension Pyrotitan Surface replacement and the Pyrocarbon Hemiarthroplasty. We hypothesized they would provide good medium-term outcomes with no significant difference between the two implants.

Methods: The first 21 implants were surface replacements and the subsequent 58 hemiarthroplasties making a total of 79. Overall, the minimum follow-up was two years and maximum was nine years and nine months (average = five years and six months). Average follow-up for the Ascension Pyrotitan was eight years and two months and Pyrocarbon hemiarthroplasty five years and two months. Survivorship, Oxford and SSV scores, and incidence of squeaking were recorded. Average age at implantation was 57.7 years (range 20-80). 35 were female and 44 male. The indication for surgery was osteoarthritis in 56, post-instability in 10, post-fracture in 7, avascular necrosis in 4, synovial osteochondromatosis in one and Rheumatoid arthritis in one.

Results: Of the 79 patients in the cohort, five were deceased, two were revised to reverse for cuff failure, one was revised for C. Acnes infection, and one was revised to Pyrocarbon hemiarthroplasty for fracture of a Pyrotitan surface replacement. This left 70 patients, all of whom were included in this review. Survivorship at final follow-up for the Pyrotitan surface replacement was 88.9% and Pyrocarbon hemiarthroplasty 96.4%. Average SSV for all patients reviewed was 86%, the Ascension Pyrotitan patients scoring 87% and the Pyrocarbon hemiarthroplasty 86%. Average Oxford Score for the whole cohort was 42 out of a maximum of 48, with Ascension Pyrotitan scoring 42.3 and Pyrocarbon hemiarthroplasty 41.9. Recent Oxford Score for the post-instability group was 44, osteoarthritis 42.6, post-fracture 39.5, and 35 for AVN (NSS). 14 of 70 patients reported squeaking (20%), 4 daily, 5 weekly and 5 monthly. Average Oxford Score in those who experienced squeaking was 39 compared with non-squeakers at 43 (p=0.02). Correlation between Oxford Score and SSV was high with a correlation coefficient of 0.79. Oxford Score for the Pyrotitan at 42.3 was significantly better than NZ Joint Registry score for the Global Cap at 34.5 (p=0.001) and the Pyrocarbon hemiarthroplasty at 41.9 significantly better than the Aequalis CoCr hemiarthroplasty at 36.8 (p=0.005). Case studies where wear can be measured will be presented indicating an extremely low wear rate for the Pyrocarbon implants.

Conclusion: Pyrocarbon looks to be a durable bearing surface and a good option for the younger osteoarthritic patient where risk of glenoid component failure is high.

Michael Caughey is an orthopaedic surgeon based in Auckland, specializing in shoulder, hip, and knee surgery. He performs a variety of procedures, including arthroscopic acromioplasty, arthroscopic repair for recurrent dislocation, arthroscopic rotator cuff repairs, and shoulder replacement surgery for shoulder conditions. For knee surgery, Mr. Caughey offers arthroscopic meniscectomy and joint replacement surgery. He also specializes in total hip replacement surgery.