Factors Associated With Functional Outcomes in Former Professional American-Style Football Players With Symptomatic Knee and Hip Osteoarthritis

Background: Functional outcomes and patient characteristics of knee and hip osteoarthritis (OA) have been described in general populations; however, this has yet to be investigated in former professional American-style football (ASF) players. Purpose: To explore ASF exposures, previous injuries, health factors, and radiographs in order to understand contributions to function using the Knee injury and Osteoarthritis Outcome Score (KOOS) and Hip Disability and Osteoarthritis Outcome Score (HOOS) in former ASF players. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Living former ASF players who participated in ASF between 1960 and 2022 were identified through the NFL Players Association and invited to participate in the study. Enrolled participants were selectively recruited by condition (cardiometabolic disease, chronic pain, neurocognitive impairment, or sleep apnea) and completed the KOOS, HOOS, and a survey on comorbidities, previous injuries, and ASF exposures. Weightbearing radiographs were obtained for hips and knees for radiographic severity. Backward stepwise linear regression examined the association between KOOS or HOOS subscales and function, reported health, and ASF characteristics, and results were weighted for selection effects. Results: Most former ASF players (n = 90; age, 48.3 ± 7.7 years; Black, 55.6%) had evidence of knee (n = 89; 89.9%) or hip (n = 95; 95.9%) OA. Higher pain severity, higher body mass index (BMI), prior anterior cruciate ligament (ACL) surgery, and greater radiographic severity were associated with lower KOOS values corresponding to worse knee functional outcomes. Higher HOOS values indicating better hip function were associated with meeting physical activity standards and longer professional careers, but there was no association with radiographic severity. Conclusion: Variability was found within HOOS and KOOS measures. Radiographic findings appeared to correspond with functional status in former ASF players with knee OA but not hip OA. Higher BMI and pain severity were associated with worse function in knee OA, and ACL surgery was associated with worse function in symptom severity and sports function on KOOS. These findings may contribute to obtaining functional measures, history, and radiographs to evaluate limitations associated with knee and hip OA in this population.