Posterior-Stabilized and Cruciate-Retaining Total Knee Replacement: A Randomized Study

A randomized controlled study was done to compare the clinical, radiographic, and quality of life outcomes between posterior-stabilized and cruciate-retaining primary total knee implants. One hundred forty-three patients were enrolled in the study. Patients ranged in age from 57 to 89 years, had a primary diagnosis of osteoarthritis, and an intact functioning posterior cruciate ligament. Patients were excluded if they had a flexion contracture greater than 15°, a varus deformity greater than 20°, or a valgus deformity greater than 15°. Patients were randomized to one of two study groups, posterior-stabilized AMK total knee implants (76 patients) or cruciate-retaining AMK total knee implants (67 patients). One hundred eight patients have had a minimum 2-year followup including 57 patients in the posterior-stabilized group and 51 patients in the cruciate-retaining group. Seventy-three patients have had a minimum 3-year followup including 37 patients in the posterior stabilized group and 36 patients in the cruciate-retaining group. The overall total Knee Society clinical rating score at 2 years averaged 157.1 points in the posterior-stabilized group and 156.5 points in the cruciate-retaining group. At 3 years, the scores averaged 156.8 points in the posteriorstabilized group and 163.5 points in the cruciate-retaining group. The range of motion component of the Knee Society score averaged 113.6° for the posterior-stabilized group and 108.5° for the cruciate-retaining group at 2 years, and 108.3° in the cruciate-retaining group and 108.5° in the posterior-stabilized group. Based on the various parameters analyzed, there were no notable differences between the groups with a posterior-stabilized and a cruciate-retaining total knee implant at 2 years. This trend seemed to be the same at 3 years.