The Unified Classification System (UCS) was introduced
because of a growing need to have a standardised universal classification
system of periprosthetic fractures. It combines and simplifies many
existing classification systems, and can be applied to any fracture
around any partial or total joint replacement occurring during or
after operation. Our goal was to assess the inter- and intra-observer
reliability of the UCS in association with knee replacement when
classifying fractures affecting one or more of the femur, tibia
or patella. We used an international panel of ten orthopaedic surgeons with
subspecialty fellowship training and expertise in adult hip and
knee reconstruction (‘experts’) and ten residents of orthopaedic
surgery in the last two years of training (‘pre-experts’). They
each received 15 radiographs for evaluation. After six weeks they
evaluated the same radiographs again but in a different order. The reliability was assessed using the Kappa and weighted Kappa
values. The Kappa values for inter-observer reliability for the experts
and the pre-experts were 0.741 (95% confidence interval (CI) 0.707
to 0.774) and 0.765 (95% CI 0.733 to 0.797), respectively. The weighted
Kappa values for intra-observer reliability for the experts and
pre-experts were 0.898 (95% CI 0.846 to 0.950) and 0.878 (95% CI
0.815 to 0.942) respectively. The UCS has substantial inter-observer reliability and ‘near
perfect’ intra-observer reliability when used for periprosthetic
fractures in association with knee replacement in the hands of experienced
and inexperienced users. Cite this article:
Peri-prosthetic fracture after joint replacement in the lower limb is associated with significant morbidity. The primary aim of this study was to investigate the incidence of peri-prosthetic fracture after total hip replacement (THR) and total knee replacement (TKR) over a ten-year period using a population-based linked dataset. Between 1 April 1997 and 31 March 2008, 52 136 primary THRs, 8726 revision THRs, 44 511 primary TKRs, and 3222 revision TKRs were performed. Five years post-operatively, the rate of fracture was 0.9% after primary THR, 4.2% after revision THR, 0.6% after primary TKR and 1.7% after revision TKR. Comparison of survival analysis for all primary and revision arthroplasties showed peri-prosthetic fractures were more likely in females, patients aged >
70 and after revision arthroplasty. Female patients aged >
70 should be warned of a significantly increased risk of peri-prosthetic fracture after hip or knee replacement. The use of adjuvant medical treatment to reduce the effect of peri-prosthetic osteoporosis may be a direction of research for these patients.
