Number of knee and ankle injuries is associated with poor physical but not mental health

The knee and ankle are among the most commonly injured joints in the body. Long-term strength and neuromuscular control deficits are common following these injuries, yielding lifelong disability and poor quality of life. However, it is unknown how the number of injuries sustained influences quality of life. Objectives: Determine the association between the number of ankle or knee injuries sustained and physical and mental quality of life. Methods: A total of 806 ankle-injured (age:45.2 ± 15.3 yrs; body mass index [BMI]:28.6 ± 7.4 kg/m²), 658 knee-injured (age:49.3 ± 16.1 yrs; BMI:28.4 ± 7.4 kg/m²), and 996 uninjured (age:43.4 ± 16.1 yrs; BMI:26.9 ± 6.5 kg/m²) adults completed the SF-8 survey to determine the physical (PCS) and mental (MCS) contributions to quality of life. Respondents were categorized by injury history (ankle, knee, none) and number of injuries (0, 1, 2, or 3 or more [3+]) to the same joint. Backward linear regression models were used to determine the association between quality of life, age, and injury history separately for SF-8 PCS and MCS, as well as ankle versus knee injury. Results: Reporting 1, 2, or 3+ ankle injuries along with age predicted SF-8 PCS (P < 0.001). Further, 1 or 2 ankle injuries and age (P < 0.001) predicted SF-8 MCS. Reporting 1, 2, or 3+ knee injuries along with age significantly predicted SF-8 PCS (P < 0.001). Age, but not knee injury history, significantly predicted SF-8 MCS (P < 0.001). Conclusion: Current age and history of sustaining at least one injury negatively impact physical quality of life following either a knee or ankle injury. However, mental quality of life was predicted most consistently by age. Efforts to reduce injuries should be employed to improve quality of life, but more research is needed to determine what other factors contribute to quality of life across the lifespan.