New or Recurrent Knee Injury, Physical Activity, and Osteoarthritis Beliefs in a Cohort of Female Athletes 2 to 3 Years After ACL Reconstruction and Matched Healthy Peers

Background: At 2 to 3 years after anterior cruciate ligament reconstruction (ACLR), the relationship between known modifiable osteoarthritis (OA) risk factors and recurrent knee injury is unknown. This study aimed to determine the odds of new or recurrent traumatic knee injury in a cohort of young female athletes with ACLR 2 to 3 years postsurgery compared with healthy control participants. Secondary objectives were to explore the relationships of moderate and vigorous physical activity (MVPA) and body mass index (BMI) with knee injury, and to document self-reported MVPA satisfaction and beliefs about OA.

Study design: Prospective cohort.

Level of evidence: Level 2.

Methods: A total of 51 female athletes with unilateral ACLR 1 to 2 years previously and 51 age and sport-matched control participants underwent assessment of MVPA (GT3X accelerometers) and BMI. One year later, participants self-reported knee injuries. Bivariable conditional logistic regression explored the association between knee injury, MVPA, and BMI in each group (injury/control).

Results: At 1-year follow-up (n = 101), 19.6% of the injured cohort and 6.0% of control participants sustained a new or recurrent knee injury. The odds of knee injury for the injury group increased 7-fold over controls [odds ratio (OR) = 7.00 (95% CI = 0.86, 56.90)], although this was not statistically significant. The OR for MVPA was 0.98 (95% CI = 0.93, 1.03) and BMI was OR = 1.24 (95% CI = 0.85, 1.82). Half (56.0%) of injury participants and 66% of controls were satisfied with their MVPA; 81.6% of injury participants believed they had increased knee OA risk compared with someone who had never had a knee injury.

Conclusion: In the 2 to 3 years after ACLR, 1 in 5 young female athletes had a new or recurrent knee injury. Based on the point estimate, injured participants were more likely to suffer a traumatic knee injury than matched control participants. MVPA and BMI were not associated with increased odds of knee injury.

Clinical relevance: Clinicians should be encouraged to have in-depth conversations with female athletes with previous ACLR regarding enjoyable and sustainable MVPA participation to promote long-term joint health.