Comparison of expected vs. actual tunnel position in anterior cruciate ligament reconstruction

In a prospective blinded non-randomised cohort study, 32 patients were assessed following anterior cruciate ligament reconstruction using autograft middle-third bone-patellar tendon-bone, over a period of 10 months. Two experienced surgeons performed the procedures, one using an arthroscopically assisted technique (16 patients) and the other by mini-arthrotomy (16 patients). A comparison was made between the positions of the tunnels as perceived by the surgeon intra-operatively with the actual position as shown on the post-operative X-ray. An independent blinded observer made the latter assessment. Actual vs. expected tunnel placement was analysed using the coefficient of correlation. The anteroposterior femoral tunnel position indicated perfect correlation (R2=1.00, P=0), and on the lateral view showed good correlation (R2=0.55, P=0.005). However, the tibial tunnel position anteroposteriorly showed poor correlation (R2=0.14, P=0.22), and on the lateral view no correlation (R2=0.07, P=0.36). The ideal tibial tunnel position is controversial, and in this study, two tibial tunnels were just anterior to the acceptable position and one was posterior. Altogether these three, and one other, were in very different positions to that expected by the surgeon. Surgeons may consider that before drilling the tibial tunnel, intra-operative confirmation of the guide-wire position would be helpful.