Affiliation:
1. Hospital for Special Surgery Department of Orthopaedic Surgery Computer Assisted Surgery Center and Sports Medicine Weill Medical College of Cornell University 535 East 70th Street 10021 New York NY USA
2. Department of Orthopaedic Surgery Amsterdam UMC Location University of Amsterdam Meibergdreef 9 Amsterdam The Netherlands
3. Amsterdam Movement Sciences, Sports Amsterdam The Netherlands
4. Department of Orthopaedic Surgery Medische Kliniek Velsen Velsen‐Noord The Netherlands
Abstract
AbstractPurposeThe primary aim of this study was to evaluate the phenotypic variation using the Coronal Plane Alignment of the Knee (CPAK) classification among 1000 knees with anteromedial osteoarthritis (OA) both prior to and following medial unicompartmental knee arthroplasty (UKA). The secondary aim of this study was to investigate whether knees maintained their preoperative CPAK phenotype and to evaluate the phenotypic alterations following medial UKA.MethodsThe CPAK classification was used to analyze 1000 knees that underwent medial UKA as treatment for anteromedial OA. Knees were categorized into nine distinct CPAK phenotypes based on their arithmetic hip–knee–ankle angle (aHKA), which estimates the pre‐arthritic alignment, and joint line obliquity (JLO), both pre‐ and postoperatively. Phenotypic variation was analyzed by sex and age, and the phenotypic alterations following medial UKA were evaluated by phenotype.ResultsPreoperatively, CPAK phenotype I had the highest prevalence (45.0%). Among males, the preoperative prevalence of CPAK phenotype I was significantly higher compared to females (53.2% vs. 35.0%, respectively; p ≤ .001), whereas females exhibited a significantly higher occurrence of CPAK phenotype V compared to males (9.8% vs. 4.4%, respectively; p ≤ .015). Following medial UKA, CPAK phenotype II had the highest prevalence (53.3%). Overall, 45.1% of knees maintained their preoperative CPAK phenotype following medial UKA, which was most frequently observed among CPAK phenotype II (67.7%) and III (65.8%).ConclusionThere is a substantial variation in CPAK phenotypes among knees with anteromedial OA, as well as following treatment with medial UKA. This variability challenges the assumption of uniform characteristics among knees with an identical wear pattern associated with anteromedial OA and emphasizes the complexity and variability of this specific form of OA.Level of evidenceIII, Retrospective cohort study.
Subject
Orthopedics and Sports Medicine,Surgery
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