Changes in Femoral Posterior Condylar Offset, Tibial Posterior Slope Angle, and Joint Line Height after Cruciate-Retaining Total Knee Arthroplasty

Song, Sang Jun; Bae, Dae Kyung; Kim, Kang Il; Jeong, Ho Yeon

Abstract

PURPOSE
Changes in the femoral posterior condylar offset (PCO), tibial posterior slope angle (PSA), and joint line height (JLH) after cruciate-retaining total knee arthroplasty (CR-TKA) were evaluated to determine their influence on the flexion angle.
MATERIALS AND METHODS
A total of 125 CR-TKAs performed on 110 patients were retrospectively reviewed. Pre- and postoperative PCO, PSA, and JLH were compared using correlation analysis. Independent factors affecting the postoperative flexion angle of the knee were analyzed.
RESULTS
The PCO was 28.2+/-2.0 mm (range, 24.5 to 33.1 mm) preoperatively and 26.7+/-1.8 mm (range, 22.2 to 31.2 mm) postoperatively (r=0.807, p<0.001). The PSA was 10.4degrees+/-4.9degrees (range, 1.6degrees to 21.2degrees) preoperatively and decreased to 4.9degrees+/-2.0degrees (2.2degrees to 10.7degrees) postoperatively (r=-0.023, p=0.800). The JLH was 16.2+/-3.0 mm (range, 10.2 to 27.5 mm) preoperatively and 16.1+/-2.6 mm (range, 11.1 to 24.8 mm) postoperatively (r=0.505, p<0.001). None of the independent factors affected the flexion angle (p>0.291).
CONCLUSIONS
Although the PCO and JLH did not change significantly after CR-TKA, the PSA decreased by 5.5degrees with a small range of variation. Restoration of the PCO and JLH could promote optimization of knee flexion in spite of the decreased PSA after CR-TKA.