Coronal alignment in osteoarthritic knees, does it change in flexion?


Total knee arthroplasty ; coronal alignment ; computer assisted navigation ; kinematics ; deformity ; osteoarthritis.

Published online: Feb 13 2021

Jef Neirynck, Leen Vanlaer, Donald Bobbaers, Jan Mathei, Geert Leirs

From the Department of Orthopaedic Surgery, MD, Mariaziekenhuis, Overpelt, Belgium


Changes in coronal alignment in osteoarthritic knees evolving from extension to flexion remain poorly studied.

Using an imageless computer-navigation system (Stryker©) we prospectively collected measurements of dynamic coronal pre-implant alignment during primary total knee arthroplasty. Coronal alignment of the osteoarthritic knee was determined at maxi- mal extension and 90° flexion. Measurements were subgrouped as varus (≤-3°), neutral (>-3°, <+3°) or valgus (≥+3°). Of 545 osteoarthritic knees (347 females), coronal alignment in extension was 261 (48%) varus, 197 (36%) neutral and 87 (16%) valgus. Varus extension alignment was more common in male versus female knees (p< .0001). Valgus ex- tension alignment was more common in female versus male knees (p= .002). In flexion, 174 (66%) of varus knees remained varus. Coronal alignment remained unchanged (within +3° ; -3°) in flexion versus extension in approximately half of the OA knees observed. This insight into a changing coronal deformity might contribute to a better understanding of osteoarthritic knee behaviour.