Arthrogenic muscle inhibition (AMI) is the key neurophysiological cause of impeding quadriceps activation following anterior cruciate ligament reconstruction (ACLR). Blood flow restriction training (BFRT) may induce neuroplasticity whereas the neurophysiological responses remain uncertain. In this study, we aimed to explore the effects of constant pressure blood flow restriction training (CP-BFRT) on neurophysiological responses and physical function. Patients will receive the same standardized progressive physical rehabilitation for 2 weeks after the surgery and then start the BRFT or sham BRFT intervention for the following 12 weeks.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
56
A personalized constant-pressure system served as the active BFRT unit, with restrictive pressure set at 60%-80% of limb arterial occlusion pressure; it auto-inflates to maintain constant pressure and automatically monitors, assesses, and adjusts pressure during training.
Standard postoperative rehabilitation protocol after knee arthroscopic surgery, without blood flow restriction training. The rehabilitation program includes range of motion exercises, muscle strength training, balance training and functional activity training, with the same schedule, frequency and duration as the experimental group.
The Affiliated Hospital of Southwest Medical University
Luzhou, Sichuan, China
H-reflex Hmax/Mmax Ratio
H-reflex is a validated neurophysiological indicator for evaluating spinal-level AMI after knee surgery which is applied to assess resting spinal reflex excitability of the knee extensor motor pool vastus medialis. Unit of Measure: Ratio (dimensionless)
Time frame: From enrollment to the end of treatment at 12 weeks.
Knee Joint Position Sense (JPS) Accuracy
Knee proprioceptive acuity was evaluated using a calibrated isokinetic dynamometer. Participants were blindfolded to exclude visual interference and seated with the tested lower limb securely strapped to the dynamometer lever arm. The knee was passively positioned at three target flexion angles (30°, 60°, and 90°). After passive positioning and a 3-second holding phase, participants actively reproduced the perceived target angle independently. Absolute angular error was calculated as the absolute discrepancy between the preset target angle and the actively reproduced angle. Unit of Measure: Degrees (°)
Time frame: From enrollment to the end of treatment at 12 weeks.
Somatosensory Evoked Potential (SEP) P40 Latency
Cortical somatosensory afferent function was assessed via tibial nerve somatosensory evoked potentials (SEP). The P40 latency was defined as the time interval from stimulus onset to the occurrence of the P40 positive wave, representing the conduction efficiency and temporal characteristics of peripheral proprioceptive signals transmitting to the primary somatosensory cortex. Unit of Measure: Milliseconds (ms)
Time frame: From enrollment to the end of treatment at 12 weeks.
Somatosensory Evoked Potential (SEP) N45-P40 Peak-to-peak Amplitude
Central sensory integration plasticity was assessed via tibial nerve somatosensory evoked potentials (SEP). The N45-P40 peak-to-peak amplitude was calculated to evaluate cortical sensory gain and central inhibitory/excitatory balance. Unit of Measure: Microvolts (μV)
Time frame: From enrollment to the end of treatment at 12 weeks.
Quadriceps rapid torque development rate (RTD)
Quadriceps rapid torque development rate (RTD) was measured to quantify the efficiency of central motor unit recruitment and neuromuscular rapid-driving capability. Quadriceps RTD was calculated as the rate of torque increase within the early contraction phase, reflecting the recruitment efficacy of high-threshold type II muscle fibers and synchronous firing of motor units. Unit of Measure: Nm/s
Time frame: From enrollment to the end of treatment at 12 weeks.
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