Summary

The postoperative posterior laxity at 90° was significantly less in DB PCL reconstruction than in SB reconstruction, although there were no significant differences between the 2 procedures concerning the other clinical evaluations.

Abstract

Introduction

Several studies have reported favorable results of posterior cruciate ligament (PCL) reconstruction using single-bundle (SB) techniques. However, the clinical results of this surgery have shown that mild residual posterior knee laxity is a common occurrence after surgery. Recently, biomechanical studies have demonstrated that double-bundle (DB) PCL reconstruction provides better posterior stability than SB reconstruction. Based on these studies, we have developed a DB PCL reconstruction procedure with hamstring tendon autografts. However, the superiority of SB or DB PCL reconstruction remains unproven not only in isolated PCL deficiency but also in multiple ligament knee injuries. We hypothesized that DB PCL procedure may be significantly better concerning the posterior laxity than SB procedure, while there may be no significant differences in the subjective and objective clinical outcomes between the 2 procedures. The purpose of this study was to test this hypothesis.

Methods

A retrospective, comparative study was conducted with fifty-one patients (51 knees) who underwent PCL reconstruction between 2010 and 2020. There were 44 men and 7 women with a mean age of 35 years at the time of surgery. Seventeen cases required isolated PCL reconstruction, and the others had the following additional ligament reconstruction; 25 cases required anterior cruciate ligament (ACL) reconstruction, 11 cases required posteromedial corner (PMC) reconstruction, and 8 cases required posterolateral corner (PLC) reconstruction. All patients were divided into the groups; SB PCL reconstruction (Group S: 20 knees) or DB PCL reconstruction (Group D: 31 knees). Two years after surgery, each patient was examined with the standard clinical evaluation methods. The paired Student t test, Mann–Whitney U test, and chi square test were used to test for significance. The significance level was set at p=0.05.

Results

The side-to-side difference in the total anteroposterior translation measured at 20° and 70° of flexion and the relative femur-tibia position in the posterior stress radiographs at 90° significantly improved postoperatively in both groups (p<0.0335). The postoperative position on the posterior stress radiographs averaged 43.8% and 54.0%, in Groups S and D, respectively. The relative femur-tibia positions in Group D showed no significant differences in comparison with that in the uninjured knee (mean; 56.8%). Postoperative posterior stress radiographs showed that Group D was significantly less in the posterior translation than Group S (p<0.0001). The Lysholm score averaged 83 points and 90 points in Groups S and D, respectively. There were no significant differences in the subjective and objective clinical evaluations between the 2 procedures.

Discussion

The important findings of the present study were that, first, the postoperative anteroposterior translation at 20° and 70° and posterior drawer test at 90° with posterior stress radiographs significantly improved postoperatively in both SB and DB PCL reconstruction groups. Second, the postoperative posterior laxity at 90° with posterior stress radiographs was significantly less in the DB PCL reconstruction group than in the SB reconstruction group. Although Lysholm score, objective International Knee Documentation Committee evaluation form, Knee Injury and Osteoarthritis Outcome Score (KOOS) evaluation, Tegner score, and isokinetic peak torque of quadriceps and hamstrings significantly improved after surgery in both group, there were no significant differences between the 2 procedures.