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Medial Versus Lateral Parapatellar App roach

Background

When performing total knee arthroplasty (TKA) in the setting of osteoarthritis with valgus deformities, the surgeon can choose whether to approach the joint via a standard medial parapatellar approach, or via a lateral parapatellar approach. Keblish [4] recommended a lateral parapatellar approach for knees with a fixed valgus deformity as this method provides direct access to the lateral structures, facilitating ligament balance. But for many authors, the lateral approach is considered difficult, and is associated with greater complication rates. The purpose of this single center study was to compare surgical factors and short-term clinical and radiographic outcomes of the medial and lateral approach for TKA in knees with moderate valgus (<10°).

 

Methods

Four hundred and twenty four knees undergoing TKA with a pre-operative valgus deformity between 3 and 10 degrees were identified through queries of a prospectively collected TKA database. 109 knees were treated via a medial approach and 315 knees were treated via a lateral approach. The Tornier HLS TKA system was used for all knees. Intra-operative variables that were assessed included surgical time, tourniquet time, the type of lateral releases that were performed, and whether a tibial tubercle osteotomy was required. International Knee Society (IKS) knee and functional scores and radiographic alignment were compared post-operative with a minimum of two years follow-up. Fisher’s exact tests were used to compare categorical variables, and t-tests were used for continuous variables, with statistical significance defined as p < 0.05.

 

Results

Tourniquet time (p=0.25) and surgical time (p=0.62) were not significantly different between the two groups. The popliteus tendon was released more frequently in the medial approach group (p=0.04), while the iliotibial band was released more frequently in the lateral approach group (p<0.001). A tibial tuberosity osteotomy was performed more frequently in the lateral approach group than in the medial approach group (20.8% vs 8%). At final follow-up, no significant differences in limb alignment (p=0.78), IKS knee (p=0.32) or function (p=0.47) scores were noted based on surgical approach. The complication rates were similar in the two groups (p=0.53).