Evaluation of the pathological anatomy of posteromedial corner in varus osteoarthritic knees using magnetic resonance imaging

Abstract

BackgroundUnderstanding the pathological changes in varus osteoarthritic knees will help the surgeon to correct the deformity while performing total knee arthroplasty. The currently available MRI resolution allows us to recognize the anatomical details of the posteromedial corner and the changes associated with osteoarthritic knees. The study aims to assess the pathological changes of the varus osteoarthritic knees on MRI and to compare it to non-arthritic knees. MethodsMRI of 26 patients with varus osteoarthritic knees (Kellgren and Lawrence grade 4) scheduled for total knee arthroplasty were reviewed and compared to MRI of 10 other patients without knee arthritis. The superficial Medial Collateral Ligament (sMCL) was assessed in terms of medial and posterior bowing, and the posteromedial corner (PMC) was evaluated in terms of thickness and signal integrity. ResultsThe superficial Medial Collateral Ligament (sMCL) was medially and posteriorly displaced in all severely varus arthritic knees compared to its position in non-arthritic knees, in addition to significant increase in posteromedial corner thickness with heterogenous appearance indicating scarring in the posteromedial corner (PMC). (p-value lower than 0.05). ConclusionThe apparent tightness of the superficial Medial Collateral Ligament can be secondary to the pathology that affects the posteromedial corner (scarring) where sMCL is retracted and bowed posteriorly and medially, not simply contracted and shortened. Understanding the pathological changes of severely varus osteoarthritic knees on MRI can lead to a better algorithm to perform soft tissue balance during Total knee replacement surgery without releasing sMCL and subsequent knee instability.