title: Field testing the Unified Classification System for periprosthetic fractures of the femur, tibia and patella in association with knee replacement: an international collaboration.
abstract: 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.
authors.affiliation: University of Saskatchewan, Department of Orthopaedics, 103 Hospital Drive, 5th Floor, Saskatoon, SK, S7N 0W7, Canada.
authors.forename: J M
authors.initials: JM
authors.lastname: Van der Merwe
authors.affiliation: University College London Hospitals, 235 Euston Road, London NW1 2BU, UK.
authors.forename: F S
authors.initials: FS
authors.lastname: Haddad
authors.affiliation: University of British Columbia, Department of Orthopaedics, 3rd Floor, 2775 Laurel Street, Vancouver, BC, V5Z 1M9, Canada.
authors.forename: C P
authors.initials: CP
authors.lastname: Duncan
mesh_terms: D000328:Adult; D019645:Arthroplasty, Replacement, Knee; D005264:Femoral Fractures / Q000145:classification*; D050723:Fractures, Bone / Q000145:classification*; D006801:Humans; D007391:International Cooperation; D007396:Internship and Residency; D015588:Observer Variation; D009985:Orthopedics; D010329:Patella / Q000293:injuries*; D011183:Postoperative Complications; D015203:Reproducibility of Results; D013978:Tibial Fractures / Q000145:classification*
keywords: Classification system; Knee replacement; Periprosthetic fractures; Reliability; UCS; Unified Classification System