The Varus Osteoarthritic Knee Has No Coronal Contractures in 90 Degrees of Flexion

J Knee SurgDOI: 10.1055/s-0036-1584539Medial and lateral coronal soft tissue laxity in 90 degrees of flexion in the varus osteoarthritic (OA) knee at the time of total knee arthroplasty (TKA) is unknown, meaning, key information as to how the flexion gap should be addressed by surgery is not available. The purpose of this study was to define the coronal plane medial and lateral laxity in 90 degrees of flexion in the end-stage OA knee. Computer assisted surgery (CAS) displays and direct joint observations were used to manipulate the knee to its neutral position in 90 degrees of flexion prior to any surgical releases. Laxity was measured as medial and lateral displacement from the neutral axis of the knee and compared with literature values for healthy subjects. The 72 knees examined had a mean varus deformity, measured in maximum extension, of −7.9 ± 3.1 degrees (−0.5 to −15 degrees). At 90 degrees of flexion, mean medial and lateral laxity as measured by displacement from the neutral axis of the knee was 3.8 ± 1.4 degrees and 4.7 ± 2 degrees respectively. This medial laxity was significantly greater −1.7 degrees (95% CI, −3.1 to −0.3 degrees) than that seen in healthy knees (p < 0.0001) whereas the measured lateral laxity displayed a nonsignificant difference compared with healthy knees. The mean difference in medial-lateral laxity was 1.5 ± 1.1 degrees. A medial-lateral difference of ≤2.5 degrees was present in 91.6% of knees. We foun...
Source: Journal of Knee Surgery - Category: Orthopaedics Authors: Tags: Original Article Source Type: research