The Relationship Between The Angle Of The Tibial Tunnel And Risk Of Osteoarthritis After Anterior Cruciate Ligament Reconstruction

Objective In this study,the relationship between the angle of the tibial tunnel(? angle)and the longitudinal axis of the tibia and the occurrence of postoperative knee osteoarthritis(KOA)is determined to provide the evidence for the selection of the tibial tunnel position during anterior cruciate ligament(ACL)reconstruction and to improve the surgical effect of ACL reconstruction.Methods An observational cohort study was designed on a total of 90 patients approximately 24 months after arthroscopic ACL reconstruction.The angle of the tibial tunnel was measured on the X-ray and magnetic resonance imaging(MRI).The patients received at least two-year follow-up and were evaluated clinically with knee society score(KSS)and Lysholm score and radiologically with Kellgren-Lawrence grade and Outerbridge degree.A correlation study was done to analyze the relationship between the degree of cartilage damage and the ? angle.Results It is suggested that there is a significant difference in KSS and Lysholm score between patients before operation and patients followed-up(p<0.05).The incidence rate of OA in the affected side of knee is higher than that of the unaffected side of knee(p=0.006).Furthermore,The ? angle is found to be correlated to the Outerbridge degree(p<0.001)and Kellgren-Lawrence grades(p<0.001),but it is not relevant with KSS score(p = 0.495).Larger ? angles are observed with higher Outerbridge degree and Kellgren-Lawrence grades.The result is independent with factors such as meniscus injury,accompanying meniscorrhaphy and meniscoplasty.Conclusion Taken together,a larger angle of the tibial tunnel results in higher risk of cartilage degeneration and may contribute to consequent knee OA.Surgeons should be careful to improve the accuracy when drill the tibial tunnel.The optimal tunnel angle should be determined based on a further anatomic study and clinical trials.