Abstract
BACKGROUND: People suffering anterior cruciate ligament (ACL) injuries are at increased risk for development of osteoarthritis (OA). This study investigated associations between daily step count, cartilage degeneration and patient-reported outcomes 2 years after ACL reconstruction (ACLR). HYPOTHESIS: Daily step count is associated with cartilage health and patient-reported knee symptoms and function 2 years after ACLR. STUDY DESIGN: Cross-sectional. LEVEL OF EVIDENCE: Level 4. METHODS: We analyzed data from 34 patients (18 female), aged 33.4 ± 10.8 years with stable knees recruited from the community 2 years after primary ACLR. Mean daily step count was measured using an activity tracker (FitBit) over a 7-day collection period. Cartilage morphology on magnetic resonance imaging (MRI) was graded across multiple joint areas. Knee symptoms and function were assessed by the Knee injury and Osteoarthritis Outcome Score (KOOS) subscales pain, symptoms, activity of daily living (ADL), sport/recreation (sport/rec), and knee-related quality of life (QoL) using published thresholds for patient acceptable symptom state (PASS). Analyses were adjusted for age, sex, and body mass index. RESULTS: The mean (SD) daily step count was 9276 (3199). At least 1 cartilage abnormality was present on morphological MRI in 20% of ACLR knees. The mean (SD) KOOS values were: pain 94 (7), symptoms 92 (8), ADL 91 (10), function in sport/rec 85 (14), and knee-related QoL 56 (22). Failure to achieve PASS rates were 76% for ADL; 59% for QoL, 18% for pain, 35% for sport/rec, and 0% for symptoms. CONCLUSION: Daily step count was not associated with cartilage health or knee symptoms and function 2 years after ACLR. However, a high proportion of participants with reported unacceptable ADL and QoL 2 years after ACLR. CLINICAL RELEVANCE: The proportion with unacceptable PASS for ADL and QoL in participants with stable knees after ACLR indicates a need to optimize rehabilitation and improve post-ACLR recovery.