Richard Storey, Chris Frampton, David Kieser, Ramez Ailabouni, Gary Hooper

This study investigates knee joint arthroplasty and compares the outcomes between attending (consultant) orthopedic surgeons and resident (trainee) surgeons. Retrospective review and comparison of knee joint arthroplasty outcomes between 4 surgeon groups (attending, supervised senior and junior residents, and unsupervised senior residents). Measured outcomes were implant survival (revision rate) and patient reported functional outcomes, measured by Oxford knee score (OKS). New Zealand arthroplasty service. Seventeen years of knee joint arthroplasty data from the New Zealand Joint Registry (NZJR) was reviewed. The New Zealand Joint Registry (NZJR) data showed 79,671 total knee arthroplasties (TKA) and 8854 unicompartmental knee arthroplasties (UKA) performed between 1999 and 2016. Attending surgeons performed 90% and 97% of TKA and UKA, respectively. The number and proportion of resident performed knee joint arthroplasty has decreased. Faster operation times was observed in the attending surgeon group. Attending surgeon revision rate was 0.49 and 1.19/100 component years for TKA and UKA, respectively, this was not significantly increased in resident surgeon groups. Postoperative OKS was 37.7 and 39.7 for attending surgeon performed TKA and UKA, respectively. Mean OKS were less than 2 points worse in resident groups (resident range: 36.3-36.9) compared to attending colleagues for TKA, but for UKA scores were up to 11 points worse (resident range: 28.9-38.8). New Zealand has a high rate of attending surgeon performed TKA and UKA. Revision rates were not increased in resident surgeon groups. Postoperative function was not reduced by a clinically significant amount in TKA in any of the resident surgeon groups but was reduced in supervised junior resident and unsupervised senior resident surgeon groups for UKA.