Purpose: Osteoarthritis (OA) is the fastest growing health condition based on Years Lived with Disability. Knee OA contributes to 80% of this burden. Meta-analyses indicate a 3.9 fold (95%CI 2.7,5.6) increased risk of radiographic (<= 2 Kellgren Lawrence grade) post-traumatic OA (PTOA) after significant knee joint injury. There is a paucity of research examining outcomes associated with PTOA early in the period between joint injury and disease onset (<10 years post-injury). Improved understanding of this interval could inform the definition and diagnosis of early pre-radiographic PTOA. This study aimed to determine if structural changes consistent with MRI defined OA (MRI OA) were associated with knee pain, symptoms and function in young adults 3-10 years following a sport-related knee joint injury in youth compared to matched controls. Methods: Participants included a sub-sample (n=100, ages 15-26 years) of individuals from the Alberta PrE-OA cohort for which clinical MRI studies were available. Specifically, 50 individuals who had sustained a sport-related intra-articular knee injury 3-10 years previously (median age; range: 22; 15-26yrs: 19 males, 31 females) were compared to 50 age, sex and sport matched uninjured controls. Intraarticular injury was defined as a clinical diagnosis including bone, cartilage, ligament or meniscal injury requiring medical attention and time loss from sport. Outcome measures included; MRI OA derived from the MRI OA knee score (MOAKS), Knee OA and Injury Outcome Score (KOOS; clinical), normalized knee extensor and flexor strength (Nm/kg, dynamometry; functional), side-to-side asymmetry in Triple Single Leg Hop (TSLH; functional) and Star Excursion Balance Test (SEBT; functional) scores. Descriptive statistics (mean within-pair difference; 95% CI) and conditional logistic regression (OR; 95%CI) were used to compare study groups. Multivariable linear regression (clustered by matched-pair and adjusted for injury history) was used to investigate the association between MRI OA and each of the clinical and functional outcomes. Results: Injured participants had poorer KOOS scores (mean withinpair difference; 95%CI: symptoms -7.3; -12.1, -2.5: pain -5.1; -8.1, -2.1: daily living function -2.8: -4.7, -0.8: sport participation -5.3; -8.5, -2.2: knee quality-of-life -9.5; -12.0, -6.9) and weaker knee flexors (-0.02 Nm/kg; -0.03, -0.01) than uninjured controls. No between group differences were found for knee extensor strength (-0.01 Nm/kg; -0.04,0.01) or side-to-side difference in TSLH (-1.9%; -2.0,6.0) or SEBT (0.4%; -1.4,2.2). Injured participants had more MRI abnormalities consistent with future PTOA and were 8.5 times more likely (95%CI 2.0,36.8) to have a structural diagnosis of MRI OA than controls. Within the injured group 43% of those who sustained a complete ACL tear (n=28, all reconstructed) had MRI OA as opposed to only 11% of those (n=9) who sustained a 1st to 3rd degree collateral ligament injury. After adjusting for injury history, MRI OA was not associated with knee pain, symptoms or functional outcomes (see Table). Conclusions: A 3-10 year history of youth sport-related intra-articular knee injury is associated with a higher risk of MRI defined OA, poorer KOOS sub-scale scores, and reduced knee flexor strength. However, MRI defined OA was not associated with outcomes of knee pain, symptoms or function after adjusting for injury history. These findings suggest that 3-10 years post injury; structure may not dictate clinical symptomology (pain or function). Thus, the definition and investigation of early pre-radiographic PTOA should include measures of clinical symptoms and function. Further investigation to determine the value of monitoring clinical symptoms and function as a method to identify those who would benefit most from a targeted secondary prevention intervention after knee injury is recommended. (Table Presented).
Whittaker, J. L., Toomey, C., Woodhouse, L., Jaremko, J., Nettel-Aguirre, A., & Emery, C. (2016). MRI defined osteoarthritis is discordant with clinical and functional outcomes associated with post-traumatic osteoarthritis 3–10 years following SPORT-related knee joint injury in youth. Osteoarthritis and Cartilage, 24, S255–S256. https://doi.org/10.1016/j.joca.2016.01.486