Effect of a too posterior placement of the tibial tunnel on the outcome 10-12 years after anterior cruciate ligament reconstruction using the 70-degree tibial guide.

Abstract

To examine the relationship between the radiographically assessed placement of the tibial tunnel and the long-term clinical and subjective outcome in anterior cruciate ligament-reconstructed patients. Patients were examined clinically, with subjective score systems and with standardised radiographs 10-12 years postoperatively. Only patients reconstructed with the aid of the 70-degree tibial drill guide were included. A posterior placement of the tibial tunnel was defined as >50% along the Amis and Jakob line (AJL). A high tunnel inclination was defined as >75° in the coronal plane. The possible linear relationships between clinical findings, subjective scores and tibial tunnel placement were investigated. Eighty-six percentage of the 96 patients were available for examination. Mean tibial tunnel inclination was 71.1° (SD 4.2). No difference was found in subjective scores and knee stability between high (14%) and low (86%) inclination groups. Mean placement of the tibial tunnel along the AJL was 46% (SD 5). Patients with a posterior tibial tunnel placement (24%) had a higher incidence of rotational instability (P = 0.02). Patients with rotational instability (grade 2 pivot shift) had significant lower Lysholm score than those with grade 0 and 1 rotational instability (P = 0.001). The use of a tibial drill guide that relates to the femoral roof leads to a posterior tibial tunnel placement (>50% of the tibial AP-diameter) in 24% of the patients. These patients have a significant higher proportion of rotational instability and worse subjective outcome. Case series, Level IV.