Sensorimotor Dysfunction Following Anterior Cruciate Ligament Injury (Part 1). What Is It? How Can Clinicians Assess It?

BACKGROUND: The anterior cruciate ligament (ACL) plays an important sensory role within the sensorimotor system. Following ACL injury, sensorimotor dysfunction can have implications for rehabilitation and risk of reinjury. CLINICAL QUESTION: What dysfunction occurs within the sensorimotor system following ACL injury, and how can clinicians assess it? KEY RESULTS: Following ACL injury, dysfunction occurs across the sensorimotor system: afferent pathways, efferent pathways, and central processing. The afferent pathways exhibit dysfunction within the somatosensory system ([1] increased pain and swelling, [2] increased central cortical processing, and [3] reduced proprioception). There is also dysfunction in the visual system (increased visual-motor reliance and central cortical processing). The efferent pathways have reduced excitability of the central cortex, reduced descending motor pathway excitability and altered spinal reflexive excitability (acutely reduced but then chronically increased). CLINICAL APPLICATION: Protocols to assess athletes' sensorimotor function following ACL injury might help clinicians quantify the risk of reinjury. Assessing central processing requires specialized equipment, not typically accessible to clinicians. A practical approach to quantify the extent of sensorimotor dysfunction could focus on assessing the afferent and efferent pathways: tests of proprioception (eg, joint position sense test), pain (eg, visual analog scale and numerical pain rating scale), swelling (eg, sweep test and ballottement test), visual-motor reliance (eg, stepdown test), visual-motor processing ability (eg, sensory stations or neurocognitive tests), muscle strength (eg, repetition maximum testing or isokinetic dynamometry), and voluntary activation (eg, electromyography). J Orthop Sports Phys Ther 2025;55(6):1-17. Epub 25 April 2025. doi:10.2519/jospt.2025.12725.