Morphologic Factors Associated With Secondary Anterior Cruciate Ligament Injury After Primary Anterior Cruciate Ligament Reconstruction

Background: Bone morphology is a well-recognized risk factor for primary and secondary anterior cruciate ligament (ACL) injury. Purpose: To evaluate lower-extremity bone morphology using computed tomography (CT) in patients after primary ACL reconstruction and investigate the association between the risk of ipsilateral graft rupture and contralateral ACL injury. Study Design: Case-control study; Level of evidence, 3. Methods: This study included 224 consecutive patients who underwent primary ACL reconstruction at our hospital. Postoperative CT scans obtained within 1 week were used to determine the following morphological parameters: femoral neck anteversion, medial and lateral posterior tibial slope (PTS), femoral notch width, notch width index, medial tibial spinal height (MTSH), lateral tibial spinal height, and tibial torsion. These bony morphological parameters were compared between patients with and without graft rupture and between those with and without contralateral injury. Multivariate logistic regression was performed to identify independent risk factors for graft failure and contralateral ACL injury. Results: Graft rupture occurred in 16 patients (7.1%), and contralateral ACL injuries occurred in 22 patients (9.8%). Patients with graft rupture had smaller MTSH than those without graft rupture ( P < .01), and it was significantly associated with graft rupture risk (odds ratio [OR], 0.59). Patients with contralateral injuries had a greater tibial torsion ( P = .01), which was associated with contralateral injury risk (OR, 1.08). Conclusion: In patients who underwent primary ACL reconstruction, a smaller MTSH was associated with a higher risk of graft rupture, whereas a greater tibial torsion was associated with a higher risk of contralateral ACL injury.