Posterior Tibial Slope is Increased in Patients With Tibial Tubercle Fractures and Osgood-Schlatter Disease.

BACKGROUND Osgood-Schlatter disease (OSD) and tibial tubercle fractures are pathologies that affect the tibial tubercle apophysis in preadolescents and adolescents. Anatomic alignment of the proximal tibia may explain why some children develop OSD or sustain tibial tubercle fractures and some do not. Recent data has shown an association between posterior tibial slope angle (PTSA) and both OSD and proximal tibia physeal fractures. In this study, we compare radiographic parameters between patients with non-OSD knee pain, knees with OSD, and knees with tibial tubercle fracture to elucidate a difference between these groups. METHODS Patients treated for OSD, tibial tubercle fractures, and knee pain, from 2012 to 2018, were retrospectively reviewed. Radiographic parameters for each study group included PTSA, anatomic lateral distal femoral angle, anatomic medial proximal tibial angle, patellar articular height, and the distance from the inferior aspect of the patellar articular surface. Caton-Deschamps index was then calculated. Demographic data was collected including age, sex, and body mass index. Demographic and radiographic data was compared using analysis of variance tests, χ2 tests, 2-sample t tests, and multiple linear regression. RESULTS Two hundred fifty-one knees in 229 patients met inclusion criteria for the study. In all, 76% were male and the average age of the overall cohort was 14 years old. In patients with tibial tubercle fractures, the majority of fractures were Ogden type 3b (65%). After controlling for demographic variability, average PTSA in the fracture cohort was significantly greater than that in the control cohort (β=3.49, P<0.001). The OSD cohort had a significantly greater posterior slope (β=3.14) than the control cohort (P<0.001). There was no statistically significant difference between the fracture and OSD cohorts. There was also no difference in Caton-Deschamps index between the 2 study groups when compared with the control group. CONCLUSION This study demonstrates that patients with tibial tubercle fractures and patients with OSD have an increased PTSA when compared with the control group. This information adds to the body of evidence that increased tibial slope places the proximal tibial physis under abnormal stress which may contribute to the development of pathologic conditions of proximal tibia such as OSD and tibial tubercle fractures. LEVEL OF EVIDENCE Level III; retrospective comparative study.