The effect of neuromuscular electrical stimulation superimposed on quadriceps training on gait dynamics after anterior cruciate ligament reconstruction

Background: Abnormal gait dynamics are an important risk factor responsible for the high incidence of traumatic knee osteoarthritis in patients undergoing anterior cruciate ligament (ACL) reconstruction. Objective: To evaluate the effect of neuromuscular electrical stimulation (NMES) superimposed quadriceps training on gait dynamics. Methods: A total of 32 postoperative patients were randomly allocated to the NMES and conventional training (CT) groups, with 16 patients per group. Patients in the CT group received the standardized conventional training for 60 min per day, 3 days per week for 6 weeks, while those in the NMES group received the same conventional training, but with NMES superimposed on the conventional open chain training of the quadriceps. The amount of time for training was equal between the two groups. Patients were evaluated at 8 and 14 weeks after surgery. The outcome measurements were maximum voluntary isometric contraction (MVIC) of the quadriceps used to assess the quadriceps strength, Lysholm score used to assess knee function and peak vertical ground reaction force (PvGRF), heel medial (HM) peak pressure and heel lateral (HL) peak pressure used to assess gait dynamics. Results: Compared to the CT group, the NMES group had greater improvements in quadriceps strength (p<0.001, effect size = 2.93), knee function (p = 0.049, effect size = 2.06), and gait loading (including HL peak pressure (P = 0.007, effect size = 0.89) and PvGRF (P = 0.019, effect size = 0.62)). After the intervention, participants in both groups had a significantly lower rearfoot impulse and significantly higher forefoot impulse. Conclusions: The NMES superimposed on conventional quadriceps open chain training has shown additional improvements in gait loading in patients after ACL reconstruction, which suggests it may contribute to delaying the onset of early postoperative traumatic knee osteoarthritis. In addition, changes in foot impulse may suggest a progressive trend in quadriceps avoidance gait in the early postoperative period.