Contents lists available at ScienceDirect Clinical Imaging journal homepage: www.elsevier.com/locate/clinimag Analysis of the risk factors for anterior cruciate ligament injury: an investigation of structural tendencies Volkan Kızılgöz a, ⁎ , Ali Kemal Sivrioğlu b , Gökhan Ragıp Ulusoy c , Hasan Aydın d , Sunay Sibel Karayol a , Utku Menderes e a Kafkas University, Faculty of Medicine, Department of Radiology, Kars, Turkey b Okmeydanı Training and Research Hospital, Department of Radiology, Istanbul, Turkey c Kafkas University, Faculty of Medicine, Department of Orthopaedics, Kars, Turkey d Abdurrahman Yurtaslan Ankara Oncology Research and Training Hospital, Department of Radiology, Ankara, Turkey e Eskişehir State Hospital, Department of Radiology, Eskişehir, Turkey ARTICLE INFO Keywords: Anterior cruciate ligament Knee injury Risk factors Knee morphology Magnetic resonance imaging ABSTRACT Objective: The aim of this study was to determine the most important anatomical risk factors for injury of the anterior cruciate ligament (ACL) of the knee. Materials and methods: After study approval by our institutional ethics committee, 3 radiologists reinterpreted the preoperative magnetic resonance (MR) images of 86 patients who had undergone surgery for ACL rupture. The measurements were compared with those for a control group comprising 109 patients with intact ACL who had undergone MR examinations for other reasons, such as meniscal injuries or Baker cyst ruptures. Interobserver differences were calculated after measurement of the notch width (NW), NW index (NWI), medial condyle width (MCW), lateral condyle width (LCW), MCW/LCW ratios, alpha (α) angle, NW angle, quadriceps angle (Q angle), posterior medial tibial slope (MTS), posterior lateral tibial slope, coronal tibial slope, and depth of medial tibial plateau for each group. The relationships between these parameters and ACL injury were studied by performing logistic regression and receiver operating characteristic curve analyses in comparison with those in the control group. Results: We found that there were significant differences in the anatomical parameters of the NW, MCW, NWI, α angle, and MTS between the ACL injured and noninjured groups (p < 0.05). There were also significant dif- ferences in the bicondylar width, α angle, Q angle, and MTS between the patients with ACL rupture because of noncontact injuries and the control group (p < 0.05). The NWI and MTS had the highest predicted relative risk for both the male and female groups. Conclusion: We found that the NW, NWI, and MTS were the most important parameters in risk assessment of ACL injuries. 1. Introduction The anterior cruciate ligament (ACL) is a major stabilizer of the knee joint and is the knee ligament most often involved in injuries and related functional instability [1–3]. Researchers have studied the structural bony morphology, functional anatomy of the knee, and bio- mechanics of ligament injury to understand the mechanism of ACL injuries. Some researchers have emphasized the relationship between ACL injury and the anatomical morphology of the bones. The notch width (NW) and NW index (NWI) have been studied to analyze the relationship between the bony morphology and ACL in- juries in an attempt to explain why ACL rupture occurs. Souryal et al. described a method to measure the intercondylar NW and NWI. They used plain tunnel-view radiographs and measured the NWI by de- termining the ratio of the femoral NW to the femoral bicondylar width (BCW). In their research, the NWI was statistically smaller in patients who had suffered from bilateral ACL than in patients without ACL in- juries [4–5]. Sex-related variations in the femoral notch morphometry have also been studied to determine if they can explain the increased risk of ACL tears in females; however, biological sex alone has not been correlated with femoral notch stenosis according to some researchers [4–7]. ACL morphology has been investigated as a possible risk factor for ACL injuries. Some researchers have found a correlation between the ACL ligament width and ACL rupture [8,9]. A high angle between https://doi.org/10.1016/j.clinimag.2017.12.004 Received 15 May 2017; Received in revised form 27 October 2017; Accepted 8 December 2017 ⁎ Corresponding author. E-mail address: vkizilgoz@kafkas.edu.tr (V. Kızılgöz). Clinical Imaging 50 (2018) 20–30 0899-7071/ © 2017 Elsevier Inc. All rights reserved. T