The anterior-posterior laxity after total knee arthroplasty inserted with a ligament tensor.

Goal of this study is to determine the anterior-posterior laxity in 30 degrees of knee flexion for a posterior cruciate retaining total knee arthroplasty with a relative dished insert and implanted with a ligament tensor. Furthermore, the correlation between these AP laxities and the postoperative range of motion (ROM) and postoperative Knee Society Score (KSS) is analysed. Fifty-one balanSys total knee arthroplasties were performed in 49 patients between 1998 and 2000. These arthroplasties are analysed with respect to AP laxity (Rolimeter), ROM and KSS with a mean follow-up of 4.6 years. The mean anterior laxity is 2.8 mm with no posterior laxities at all. The average postoperative ROM is 110 degrees with an average KSS of 142. No correlations between AP-laxity and postoperative ROM or between AP-laxity and postoperative KSS are found. A posterior cruciate retaining TKA with a relative dished insert and implanted with a tensor is very stable in the anterior-posterior direction in 30 degrees of knee flexion. This limited laxity does not seem to disadvantage the mean postoperative ROM and KSS, when compared to other TKA studies.