Posterior laxity increases over time after PCL reconstruction.

Abstract

Restoration of posterior tibial translation (PTT) after reconstruction of the posterior cruciate ligament (PCL) is deemed necessary to restore physiological knee kinematics. However, current surgical techniques have failed to show a complete reduction of posterior laxity. It was hypothesized that early postoperative PTT increases over time. The study comprised of 46 patients (10 female, 36 male; 30 ± 9years), who underwent PCL reconstruction in a single-surgeon series. Patients were evaluated by bilateral stress radiographs in a prospective manner preoperatively; at 3, 6, 12 and 24months; and at a final follow-up (FFU) of at least 5years. Covariants included age, gender, BMI, tibial slope (TS) and the number of operated ligaments. Two blinded observers reviewed all radiographs, evaluating the TS and the posterior tibial translation. All patients were evaluated at a mean final follow-up of 102 (range 65-187) months. Mean side-to-side difference of the PTT significantly improved from preoperative to 3-month postoperative values (10.9 ± 3.1 vs. 3.6 ± 3.8mm; P < 0.0001). The PTT increased to 4.6 ± 3.7mm at 6months, to 4.8 ± 3.3mm at 12months, to 4.8 ± 3.2mm at 24months, to 5.4 ± 3.4mm at FFU. Consequently, there was a significant increase of PTT between 3-month and final follow-up (3.6 ± 3.8 vs. 5.4 ± 3.4mm; P = 0.02). Flattening of the TS resulted in a significantly higher PTT compared to subjects with a high TS at 24months and FFU. There was no significant influence by BMI, age, gender and the number of operated ligaments. Early results after PCL reconstruction seem promising as posterior tibial translation is significantly improved. However, there is a significant increase in PTT from early postoperative values to the final follow-up of at least 5years. This is particularly notable in patients with flattening of the TS. As a consequence, surgeons and patients need to be aware that initial posterior stability should not be equated with the final outcome. Cohort study, Level III.