Comparison of medial and lateral posterior femoral condyle articular cartilage wear patterns.

BACKGROUND: While degenerative changes to the articular cartilage of the anterior and distal portions of the femoral condyles have been well studied in the literature, the changes that occur on the posterior femoral condyle are not as clear. The purpose of this study was to assess the difference in articular cartilage thickness between the medial and lateral posterior femoral condyles in knees undergoing unicompartmental knee arthroplasty.

METHODS: A retrospective review of prospectively gathered data on 107 consecutive patients undergoing unicompartmental knee arthroplasty performed by a single surgeon was performed. The remaining articular cartilage thickness after resection of the posterior femoral condyle was measured and simple analysis conducted to compare cartilage thickness between medial and lateral posterior femoral condyles.

RESULTS: Ninety-two medial unicompartmental arthroplasties and 15 lateral unicompartmental arthroplasties were performed during the 16 month study period. The majority of lateral UKA patients were female and had lower BMI than medial UKA patients. The articular cartilage thickness on the medial posterior femoral condyle was 3 mm ± 1 mm (mean ± standard deviation) and 1 mm ± 1 mm on the lateral side (p-value <0.001).

CONCLUSIONS: There is a significant difference in articular cartilage thickness between the medial and lateral posterior femoral condyles in patients undergoing unicompartmental knee arthroplasty. This coincides with a potentially inherently different pattern of articular cartilage degeneration between the medial and lateral compartments of the knee and has implications on implant designs and resurfacing techniques about the knee.