Is the Prognosis of Osgood-Schlatter Poorer Than Anticipated? A Prospective Cohort Study With 24-Month Follow-up

Background: Osgood-Schlatter disease (OSD), an apophyseal injury of the tibial tuberosity, affects up to 1 in 10 adolescents. This condition has previously been assumed to be innocuous and to self-resolve with limited intervention. Purpose: To investigate the 24-month prognosis of OSD and examine if ultrasound (US) classification is associated with outcomes. Study Design: Case series; Level of evidence, 4. Methods: This study included a preregistered prospective cohort of 51 adolescents (aged 10-14 years) diagnosed with OSD who were evaluated for 24 months. The primary outcome at 24-month follow-up was whether participants continued to experience OSD-related knee pain. Baseline US scans were collected and characterized by OSD type (De Flaviis classification) as well as maturation of the tibial tuberosity. Secondary outcomes included sports participation, Knee injury and Osteoarthritis Outcome Score (KOOS) Sport/Recreation subscale, and health-related quality of life (European Quality of Life-5 Dimensions-Youth [EQ-5D-Y]). All participants were invited for re-examination by US at follow-up. Results: A total of 51 patients preregistered for the study, with 90% (n = 46) available at follow-up. Of these 46 participants, 37% (n = 17) still reported knee pain due to OSD. In this subgroup, the median duration since symptom onset was 42 months (interquartile range, 38-51 months). More than 1 in 5 participants reported stopping sport due to knee pain, and those who continued to experience knee pain reported significantly worse KOOS Sport/Recreation scores at follow-up compared with patients with no knee pain (mean 74 [95% CI, 63-84] vs 91 [95% CI, 85-97]). Participants with continued OSD-related pain also had lower health-related quality of life (mean difference in EQ-5D-Y, 0.11 [95% CI, 0.06-0.13]). Higher De Flaviis classification at baseline was significantly associated with an increased risk of knee pain at 2 years. Diagnostic US at follow-up demonstrated primarily tendon changes (thickening, positive Doppler signal), as well as an ununited ossicle in 32% of participants who underwent US scanning at follow-up. Conclusion: Over one-third of the study participants had knee pain at 2-year follow-up, which was associated with lower sports related function and health related quality of life. This questions the assumption that all patients with OSD experience quick recovery. Participants without any changes on imaging at baseline were less likely to report pain at follow-up.