The posterior tibial slope and Insall–Salvati index in operative and nonoperative adolescent athletes with Osgood–Schlatter disease

Introduction: Osgood–Schlatter disease (OSD) is a common cause of anterior knee pain in adolescent athletes due to repetitive stress on the tibial tubercle. The posterior tibial slope angle (PTSA) and the Insall–Salvati Index (ISI) play a role in knee biomechanics. However, to our knowledge, the posterior tibial slope and patellar height have not been compared in operated versus nonoperative OSD patients. The purpose of the current study is to compare the differences in the PTSA and the ISI between operative and nonoperative patients with OSD. Materials and methods: The study was approved by the College of Medicine’s Institutional Review Board. A retrospective review was performed on 75 adolescent athletes with OSD between 2008 and 2019. The data extracted included: age, sex, body mass index (BMI), sporting activity and type, mechanism of injury (MOI), chronicity of symptoms, PTSA, and the ISI. Descriptive and quantitative statistics were used. Results: Seventy-five patients (88 knees) with OSD were studied (28 boys, 47 girls). The average age was 12.2 years and the average BMI was 22.3. The mechanism of injury (MOI) included repetitive stress (77%) and trauma (23%). The duration of knee pain averaged 10.3 months. Sixty-six patients were included in the nonoperative cohort. Nine patients were included in the operative cohort and underwent surgery due to persistent symptoms after skeletal maturity with tubercleplasty and/or ossicle excision. The average PTSA was 12.1° ± 1.7° and average ISI was 1.05 ± 0.15. Comparing the operative and nonoperative patients, we found no significant difference in PTSA (11.2° ± 0.73° versus 12.8° ± 1.8°, p < 0.064). However, we did find that patients treated operatively had a lower ISI (0.95 ± 0.18 versus 1.14 ± 0.13, p < 0.001). Conclusion: In patients with OSD, operative and nonoperative patients demonstrated a similar PTSA. On the other hand, the ISI was higher in nonoperative patients. In the current paper, a decreased ISI was helpful in predicting the need for operative intervention in symptomatic patients after skeletal maturity.