The aim of the New Zealand National Shoulder Arthroplasty Register is to evaluate the provision of shoulder arthroplasty across the entire country by both recording accurate technical information and measuring the clinical outcomes of all shoulder replacements performed in New Zealand.

An initial form is completed at the time of surgery which includes details of the patient, surgical indications, the surgical procedure, the implant and the operating surgeon. Six months following surgery, all registered patients are asked to complete the Oxford Shoulder Score and comment on post-operative complications.

Data from 686 consecutive primary and 44 revision shoulder arthroplasties were prospectively collected from January 2000 until December 2003. 82 surgeons performed shoulder arthroplasty during the study period but only 9 performed on average more than 5 per year. Their results at 6 months were statistically superior to those provided by other surgeons. Amongst all diagnoses, osteoarthritis scored significantly better than the rest and for this condition total shoulder replacement scored higher than hemiarthroplasty. 15 different prostheses were used, many of them too infrequently. There was no difference in outcome amongst the 5 most commonly used prostheses. The number of complications reported by patients and the revision rate within the study period was low. No benefit was observed in the use of laminar flow theatre to prevent infection.

The combination of technical data about the joint implanted and the individual patient assessment has made the New Zealand Shoulder Arthroplasty Register unique in its own kind. Our findings are in general agreement with the current literature and supports the idea that shoulder arthroplasty is better provided by surgeons with a higher yearly case-load.