Noninvasive diagnosis of chronic exertional compartment syndrome using near-infrared spectroscopy: assessing tissue oxygenation dynamics

Purpose: To evaluate whether near-infrared spectroscopy (NIRS) can noninvasively characterize dynamic muscle oxygenation during treadmill running and differentiate healthy physiology from chronic exertional compartment syndrome (CECS). Methods: Bilateral anterior compartment NIRS monitoring was performed in 45 asymptomatic participants (90 legs) and in a female patient with bilateral exertional leg pain referred for CECS evaluation. Tissue oxygenation index (TOI) was measured during standardized treadmill running and supine recovery. Symptomatic limbs underwent invasive intercompartmental pressure (ICP) testing. Results: Asymptomatic legs demonstrated a consistent positive ΔTOI post-exercise signature (increased oxygenation during running), independent of sex, limb side, and fitness level. BMI, height, weight, and age modulated ΔTOI responses. In contrast, symptomatic limbs demonstrated negative ΔTOI post-exercise, concordant with post-exercise ICP elevation. Resting TOI did not differentiate cohorts; differences emerged only under dynamic loading. Conclusion: NIRS-derived ΔTOI reflects exertional perfusion-oxygenation coupling and may serve as a noninvasive physiological surrogate for CECS diagnosis. Optical signatures aligned qualitatively with ICP, supporting continued translational development.