Does Treating Low Back Pain With Therapeutic Exercise Reduce the Risk of Subsequent Lower Extremity Injury? A Population-Level Cohort Analysis

Importance The trunk and lower extremities are the most common locations for injury in the military, but they are managed as isolated regions. This study suggests these regions are connected, and utilization of therapeutic exercise is protective of lower extremity injury following low-back-pain diagnosis. Objective The objective of this study was to determine whether therapeutic exercise for low back pain reduces risk of subsequent lower extremity injury. Design This study utilized a longitudinal cohort design based on routinely collected health information. Setting This study was conducted within the Military Health System. Participants Patients aged 18 to 65 who sought care for low back pain between January 2015 and July 2019 were identified using diagnosis codes from electronic medical records and claims data. Interventions Participants were dichotomized based on whether they received therapeutic exercise. Main Outcomes and Measures Cox proportional hazards regression with hazard ratios (HRs) was used to model the relationship between therapeutic exercise use and dosing and risk of subsequent hip, knee, and ankle injury. Results Out of 452,668 patients (34.8% female; age 35.5 [12.3] years), 74,912 (16.5%) received at least 1 therapeutic exercise session, with a median (IQR) of 3 (1-6) sessions. Therapeutic exercise receipt significantly decreased subsequent lower extremity injury risk (hip: HR=0.84, 95% CI=0.825-0.852; knee: HR=0.77, 95% CI=0.756-0.777; and ankle/foot: HR=0.80, 95% CI=0.788-0.809), and that risk decreased further with each additional exercise session (hip: HR=0.95, 95% CI=0.942-0.948; knee: HR=0.96, 95% CI=0.956-0.963; and ankle/foot: HR=0.96, 95% CI=0.961-0.967). Conclusions Patients with low back pain not treated with therapeutic exercise had an increased risk of subsequent lower extremity injury. For those who received therapeutic exercise, the risk for subsequent injury was reduced with additional sessions. Relevance Treating low-back-pain patients with therapeutic exercise may decrease the health-care burden.