KNEE RADIOGRAPHS DEMONSTRATE SMALL BUT STATISTICALLY SIGNIFICANT INCREASE IN POSTERIOR TIBIAL SLOPE IN PATIENTS WITH OSGOOD-SCHLATTER DISEASE

Abstract

Background:Previous research has demonstrated an association between Osgood-Schlatter disease (OSD) and increased posterior tibial slope (PTS) in a small subset of patients with MRI and clinical exam consistent with OSD.Hypothesis/Purpose:To determine if children diagnosed clinically with OSD have an increased PTS on routine radiographs compared to controls.Methods:Patients 10-18 years old with the clinical diagnosis of OSD and a true lateral knee X-ray between 2016 and 2019 were eligible for the OSD group. Subjects were excluded if they had other significant knee pathology (Figure 1). The same number of controls were selected from patients in the same age and date range with history of anterior knee pain and a true lateral knee X-ray but no evidence of OSD or other significant pathology on clinical exam or X-ray. Demographic data and HSS Functional Activity Brief Scale (HSS Pedi-FABS) scores were collected for each subject. PTS measurements were performed on true lateral X-Rays by three blinded investigators. Independent samples t-test and chi-squared test were used to compare variable means and frequency between OSD and control knees. Logistic regression analysis was used to investigate the effects of OSD, age, sex, height, weight, and HSS Pedi-FABS score on PTS (≥12º versus <12º).Results:258 total knees (129 with OSD and 129 controls) were included. Mean age was 12.9 ± 1.8 years and 53% knees were male. There were no differences in age, sex, BMI, or laterality of knees between groups (Table 1). Mean PTS was significantly higher in the OSD group (11.6º ± 2.9º) compared to the control group (9.3º ± 2.7º, p<0.0001). In the OSD group, 46% of knees had a PTS ≥12º and in the control group, 19% knees had a PTS >12º (p<0.001). Logistic regression analysis showed that patients with OSD had 3.63 greater odds (95% CI 1.78-7.40) of having PTS ≥12º compared to patients without OSD, when controlling for age, sex, height, weight, and HSS Pedi-FABS score (Table 2).Conclusion:This study further supports an association between OSD and a mild increase in PTS. Patients with OSD had 3.6 greater odds of having PTS≥12º. The clinical implications of this finding have not yet been elucidated. We speculate that in patients with OSD, stresses (or force) exerted from the quadriceps muscle group through the patellar tendon loads the anterior portion of the tibia tubercle disproportionately to the posterior segment and causes asymmetric growth and an increased PTS.Tables/ FiguresFigure 1.Flowchart depicting OSD group patient exclusion.