Magnetic resonance imaging of tunnel placement in posterior cruciate ligament reconstruction.

The aim of this study was to define a reproducible method for evaluating posterior cruciate ligament (PCL) reconstructions using magnetic resonance imaging (MRI). A 2-fold investigation was performed. In part I, the "footprints" of an intact PCL were located on MRI and their coordinates were defined. Measurements were made on the images of 50 subjects using axial, coronal, and sagittal planes. Interobserver variability was calculated by averaging the measurements of the 2 reviewers and using the Kappa coefficient. Three points of reference were located: tibial attachment on the tibial axial plane, and two femoral attachments on the sagittal and coronal oblique planes. In part II, stability of 20 PCL reconstructions with a bone-patellar tendon-bone (BPTB) autograft were evaluated and scored using the IKDC evaluation form after a 2-year follow-up. Stability was evaluated clinically and instrumentally using a KT-2000 arthrometer at 89 N with the knee flexed at a neutral quadriceps knee angle of approximately 70 degrees . Seven cases were graded A (0 to 2 mm), 11 graded B (3 to 5 mm), and 2 graded C (6 to 10 mm). All patients had an MRI after an average of 16 months (range, 12 to 24 months, 2 SD). The previous measurements from part I of the study were used to make a correlation between achieved stability and tunnel location. A 1-factor analysis of variance (ANOVA), nonparametric ANOVA, and the Fisher Exact test were used to determine if clinical outcome of the 3 groups was influenced by graft placement. At MRI evaluation, excessive deep placement was observed in 4 cases and a correlation between improper femoral tunnel location and stability was statistically significant (P < .05). A correct placement of tibial tunnel was observed in all patients. In our analysis, proper location of the femoral tunnel seems to be more critical and difficult to achieve than tibial tunnel placement, probably because of the lack of specific anatomic landmarks during surgery.