Effects of neuromuscular electrical stimulation and low-level laser therapy on the muscle architecture and functional capacity in elderly patients with knee osteoarthritis: a randomized controlled trial

Objectives: To determine the effects of low-level laser therapy in combination with neuromuscular electrical stimulation on the muscle architecture and functional capacity of elderly patients with knee osteoarthritis. Design: A randomized, evaluator-blinded clinical trial with sequential allocation of patients to three different treatment groups. Setting: Exercise Research Laboratory. Subjects: A total of 45 elderly females with knee osteoarthritis, 2-4 osteoarthritis degrees, aged 66–75 years. Intervention: Participants were randomized into one of the following three intervention groups: electrical stimulation group (18–32 minutes of pulsed current, stimulation frequency of 80 Hz, pulse duration of 200 μs and stimulation intensity fixed near the maximal tolerated), laser group (low-level laser therapy dose of 4–6 J per point, six points at the knee joint) or combined group (electrical stimulation and low-level laser therapy). All groups underwent a four-week control period (without intervention) followed by an eight-week intervention period. Main measures: The muscle thickness, pennation angle and fascicle length were assessed by ultrasonography, and the functional capacity was assessed using the 6-minute walk test and the Timed Up and Go Test. Results: After intervention, only the electrical stimulation and combined groups exhibited significant increases in the muscle thickness (27%–29%) and pennation angle (24%–34%) values. The three groups exhibited increased performance on the walk test (5%–9%). However, no significant differences in terms of functional improvements were observed between the groups. Conclusions: Neuromuscular electrical stimulation reduced the deleterious effects of osteoarthritis on the quadriceps structure. Low-level laser therapy did not potentiate the effects of electrical stimulation on the evaluated parameters.