Bone Tunnel Diameter Measured with CT after Anterior Cruciate Ligament Reconstruction Using Double-Bundle Auto-Hamstring Tendons: Clinical Implications

Objective: To evaluate the correlation between bone tunnel diameter after anterior cruciate ligament (ACL) reconstruction measured by computed tomography (CT) using multiplanar reconstruction (MPR) and stability or clinical scores. Materials and Methods: Forty-seven patients (41 men and 6 women, mean age: 34 years) who had undergone ACL reconstruction with the double bundle technique using auto-hamstring graft and had subsequently received CT scans immediately after the surgery (T1: range, 1-4 days, mean, 2.5 days) and at a later time (12: range, 297-644 days, mean, 410.4 days) were enrolled in this study. The diameter of each tunnel (two femoral and two tibial) at both T1 and T2 were independently measured using MPR technique by two radiologists. Stability and clinical scores were evaluated with a KT-2000 arthrometer, International Knee Documentation Committee objective scores, and the Lysholm score. Statistical analysis of the correlation between the diameter at 12 or the interval diameter change ratio ([T2 - T1] / T1) and clinical scores or stability was investigated. Results: The tibial bone tunnels for the anteromedial bundles were significantly widened at 12 compared with T1 (observer 1, 0.578 mm to 0.698 mm, p value of < 0.001; observer 2, 0.581 mm to 0.707 mm, p value of < 0.001). There was no significant correlation between the diameter at T2 and stability or clinical scores and between the interval change ratio ([T2 - T1] / T1) and stability or clinical scores (corrected p values for all were 1.0). Intraobserver agreement for measurements was excellent (> 0.8) for both observers. Interobserver agreement for measurement was excellent (> 0.8) except for the most distal portion of the femoral bone tunnel for anterior medial bundle in immediate postoperative CT, which showed moderate agreement (concordance correlation coefficient = 0.6311). Conclusion: Neither the diameter nor its change ratio during interval follow-up is correlated with stability or clinical scores.