No Radiographic Evidence of Medial Collateral Ligament Elongation in Valgus Osteoarthritic Knees Enables Treatment with Kinematically Aligned Total Knee Arthroplasty.

ABSTRACT

PURPOSE: When performing caliper-verified kinematically aligned total knee arthroplasty (KA TKA) in the osteoarthritic (OA) knee with valgus deformity, an elongated medial collateral ligament (MCL) could result in a valgus setting of the tibial component. The present study analyzed KA TKA in patients with valgus deformities (i.e., tibiofemoral angle > 10° valgus) and determined 1) the occurrence of radiograph-ic MCL elongation, 2) the incidence of lateral collateral ligament (LCL) and posterior cruciate ligament (PCL) release and the use of constrained components, and 3) whether the one-year Forgotten Joint Score (FJS), Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR), and Likert satisfaction score were comparable to KA TKAs for OA deformities ≤ 10° val-gus. METHODS: One hundred and two consecutive patients who underwent KA TKA by a single surgeon were analyzed radiographically and clinically at a minimum follow-up of 1 year. Radiographic MCL elongation was identified by a > 1° valgus orientation of the tibial component relative to the OA tibial joint line. RESULTS: Twenty-six patients had a radiographic anatomic tibiofemoral angle > 10° valgus (range of OA deformity 11° to 23° valgus). Seventy-six had an OA deformity ≤ 10° valgus (10° valgus to -14° varus). No patient had MCL elongation, a ligament release, or required constrained components. The median 78 FJS, 42 OKS, and 76 KOOS JR, and the 85% satisfaction rate of the patients with a > 10° OA valgus deformity were not significantly different from those with a ≤ 10° OA valgus deformity (p ≥ 0.17). CONCLUSIONS: Because MCL elongation was not detected in OA deformities up to 23° valgus, the risk of under-correcting the valgus deformity leading to instability and poor outcome scores is low when per-forming KA TKA using primary components without releasing the LCL and/or PCL.