Knee pain is 1 of 5 leading causes of disability by altering lower-extremity muscle function and gait mechanics. While transcutaneous electrical nerve stimulation (TENS) mitigates deficits of muscle function due to pain, it is unclear whether TENS improves gait mechanics. Each of 15 participant (24±3yrs, 71±12kg, 178±7cm) was assigned to the TENS or matched placebo group (23±2yrs, 72±14kg, 177±9cm). Participants underwent 3 different experimental saline infusion sessions (hypertonic, isotonic, control) in a counterbalanced order, separated by 48-h. Hypertonic (5% NaCl) or isotonic (0.9% NaCl) saline was infused into the infrapatellar fat pad for 50-min. No infusion was administered to the control session. Participants and investigators were blinded to the saline solution. A 20-min TENS or placebo treatment was administered, which was blinded to participants. Gait kinematic data were collected using the high-speed video (240 Hz) and force-sending tandem treadmill (1200 Hz) at each time interval (baseline, infusion, treatment, post-treatment). Functional ANOVA (α=0.05) were used to evaluate difference between 2 groups (TENS, placebo) over time. Pairwise comparison functions with 95% confidence interval were plotted to determine specific difference. Hypertonic saline infusion (pain) resulted in increased (1) ankle dorsiflexion (38-75% of stance), (2) knee valgus (20-40%), (3) knee flexion (40-90%), (4) hip adduction (72-100%), (5) hip flexion (50-90%). However, there was no group x time interaction for all kinematics. Altered gait strategies due to pain may play a role in long-term compensation that could have consequences for the joint. TENS treatment, however, did not acutely reduce the deficits in aforementioned kinematic variables.
Listed In: Biomechanics, Gait, Neuroscience, Physical Therapy