Wearable near-infrared spectroscopy device to quantify rehabilitation following anterior cruciate ligament reconstruction: A case study on division I collegiate football athletes

The anterior cruciate ligament (ACL) is critical for stabilizing the knee during high-performance activities. Anterior cruciate ligament reconstruction (ACLR) surgery, combined with rehabilitation, is the standard treatment for tears; however, determining readiness to return to sport (RTS) remains challenging. Traditional RTS assessments often fail to capture physiological recovery, emphasizing the need for precise, objective biomarkers. Near-infrared spectroscopy (NIRS) offers real-time, non-invasive insights into muscle oxygen saturation, providing an objective means to quantify recovery. This study investigated the utility of a wearable NIRS sensor to monitor muscle oxygen saturation levels in two Division 1 football athletes recovering from a torn ACL, with a focus on assessing inter-athlete recovery variability and its implications for RTS decisions. This longitudinal case study monitored muscle oxygen saturation using the Moxy Muscle Oxygen Monitor in the surgical and contralateral legs of two athletes at 1, 3-, 5-, 6-, and 7-months post-surgery during functional exercises (leg raises and quad sets). The study highlights the capacity of NIRS based wearable sensors to capture inter-individual variability over the rehabilitation continuum towards providing real-time physiological insights beyond traditional subjective or qualitative-based assessments. These findings support the integration of wearable technology into lower extremity rehabilitation protocols to enhance recovery evaluations and improve athlete RTS.