Comparison of notch width indexes between tibial intercondylar eminence avulsion fracture and anterior cruciate ligament injury

Abstract

Objective To find out if there is any difference in intercondylar fossa width and notch width index (NWI) between tibial intercondylar eminence avulsion fracture and anterior cruciate ligament (ACL) injury. Methods A retrospective study was conducted of the patients who had sought medical attention at Department of Sports Medicine and Adult Reconstructive Surgery, Drum Tower Hospital from June 2014 to May 2018. There were 10 patients with tibial intercondylar eminence avulsion fracture (4 males and 6 females with an average age of 32.7±9.2 years), 13 patients with ACL injury (8 males and 5 females with an average age of 31.8±10.9 years) and 22 patients with simple meniscus injury as controls (13 males and 9 females with an average age of 30.9±10.6 years). They all had MRI examination of the knee before surgery. The width of intercondylar fossa and the width and height of bilateral femoral condyles were measured on high resolution images of MRI axial view. NWI was calculated. The 3 groups were compared in intercondylar fossa width and NWI. Results The 3 groups of patients were comparable because there were no significant differences in gender, age, height, weight or BMI between them (P>0.05). The intercondylar fossa width in the ACL injury group (17.4±3.5 mm) was significantly smaller than that in the avulsion fracture group (20.8±1.1 mm) or in the control group (20.2±2.6 mm) (P 0.05). NWI in the avulsion fracture group (0.301±0.011) was similar to that in the control group (0.280±0.039) (P>0.05) but significantly higher than that in the ACL injury group (0.25±0.05) (P<0.05). NWI in the ACL injury group was significantly lower than that in the control group (P<0.05). Conclusions Intercondylar notch stenosis may be a risk factor for ACL injury but may not be associated with tibial intercondylar eminence avulsion fracture. The difference in pathogenesis between tibial intercondylar eminence avulsion fracture and ACL injury may be associated with their difference in NWI. Key words: Knee joint; Anterior cruciate ligament; Magnetic resonance imaging; Tibial intercondylar eminence avulsion fracture; Notch width index