Magnetic resonance imaging of tunnel placement in posterior cruciate ligament reconstruction

The aim of this study was to define a reproducible method for evaluating po sterior cruciate Ligament (PCL) reconstructions using magnetic resonance im aging (MRI). A 2-fold investigation was performed. In part I, the "footprin ts" 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 pl ane, and two femoral attachments on the sagittal and coronal oblique planes . In part II, stability of 20 PCL reconstructions with a bone-patellar tend on-bone (BPTB) autograft were evaluated and scored using the IKDC evaluatio n form after a 2-year follow-up. Stability was evaluated clinically and ins trumentally using a KT-2000 arthrometer at 89 N with the knee flexed at a n eutral 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 MRT after an average of 16 months (range, 12 to 24 mon ths, 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-fac tor analysis of variance (ANOVA), nonparametric ANOVA, and the Fisher Exact test were used to determine if clinical outcome of the 3 groups was influe nced by graft placement. At MRI evaluation, excessive deep placement was ob served in 4 cases and a correlation between improper femoral tunnel locatio n and stability was statistically significant (P < .05). A correct placemen t of tibial tunnel was observed in all patients. In our analysis, proper lo cation of the femoral tunnel seems to be more critical and difficult to ach ieve than tibial tunnel placement, probably because of the lack of specific anatomic landmarks during surgery.