Correlation analysis between femoral trochlear dysplasia and anterior cruciate ligament injury based on CT measurement.

Background: Anterior cruciate ligament (ACL) injury is the most common knee ligament injury. Femoral trochlear dysplasia (FTD) is an anatomic deformity characterized by a shallow trochlear angle and depth. There is limited research on the correlation between ACL injury and trochlear dysplasia.

Methods: A total of 423 patients with an ACL injury who underwent ACL reconstruction and plain computed tomography (CT) follow-up scan one week after the operation in our hospital between January 2017 and March 2019 were enrolled in this study. A total of 352 patients (369 knees) without ACL injury served as a control group. The sulcus angle, trochlear facet asymmetry, trochlear depth, and lateral trochlear inclination were measured at 3 cm above the tibiofemoral joint. The notch width index (NWI) was measured on the CT axis, and the FTD was divided into four types according to the Dejour classification.

Results: The prevalence of FTD was significantly higher in the ACL injury group than in the control group (30.7% 14.4%, χ=30.834, P<0.001). The trochlear sulcus angle was higher, while the trochlear facet asymmetry and lateral trochlear inclination were significantly lower in the ACL injury group than in the control group (P<0.01). The NWI was 0.232 in the ACL injury group and 0.245 in the control group (P<0.01). In the ACL injury group, the NWI of patients with FTD was slightly smaller than that of the patients without FTD (P<0.01).

Conclusions: Our findings indicate that FTD might be a significant risk factor for ACL injury. Whether FTD is related to ACL injury caused by smaller intercondylar notch needs further study.