Effects of Transcranial Direct Current Stimulation Combined with Rehabilitation Therapy on Patients with Knee Osteoarthritis

<bold>Objective</bold>To observe the clinical efficacy of transcranial direct current stimulation (tDCS) combined with rehabilitation therapy on patients with knee osteoarthritis (KOA).<bold>Methods</bold>A total of 44 KOA patients who were treated in the outpatient department of Rehabilitation of the First Hospital of Hebei Medical University from November 2023 to July 2024 were enrolled and randomly divided into control group and experimental group, with 22 cases in each group. Allocation concealment was performed. Both groups received conventional rehabilitation therapy, which included microwave therapy (20 minutes a time, three times per week for two consecutive weeks) and exercise training (30 minutes a time, with a three-minute rest every 10 minutes, three times a week for three consecutive weeks). The control group received sham transcranial direct current stimulation in addition to the conventional rehabilitation therapy. The electrodes were placed in the relevant cerebral motor response areas, with the anode placed at the primary motor cortex (M1 area) contralateral to the affected knee and the cathode placed at the supraorbital area (SO area) ipsilateral to the affected knee, without actual stimulation current. The experimental group received active transcranial direct current stimulation in addition to the conventional rehabilitation therapy, with the same electrode placement as the control group, a stimulation current of 2 mA and a duration of 20 minutes, three times a week, continuous treatment for 12 times. One day before the start of treatment and one day after the completion of treatment, the whole-body three-dimensional gait and motion analysis system was used to evaluate the walking function (step length, stride length, walking speed, cadence and stance phase percentage) and joint kinematic parameters (range of motion of the hip/knee/ankle joints in the sagittal, horizontal and frontal plane ); Knee Injury and Osteoarthritis Outcome Score (KOOS) was used to evaluate the functional status of the knee joint (pain, other symptoms, activities of daily living, sports and recreation functions, and knee joint-related quality of life); the Timed Up and Go Test (TUGT) was used to evaluate the patients' functional mobility; adverse reactions between the two groups were compared.<bold>Results</bold>(1) Walking function: compared with that before treatment, the step length, walking speed and stride length of both groups increased significantly after treatment (<italic>P</italic>&lt;0.05), and the stance phase percentage decreased significantly (<italic>P</italic>&lt;0.05). Compared with the control group, the step length and walking speed of the experimental group after treatment were significantly higher (<italic>P</italic>&lt;0.05). (2) Range of motion of hip, knee and ankle joints: compared with those before treatment, the hip and knee joint flexion angles and sagittal plane range of motion of both groups after treatment increased significantly (<italic>P</italic>&lt;0.05); the ankle joint adduction angle and hip joint abduction angle decreased significantly (<italic>P</italic>&lt;0.05); and the ankle joint varus angle was significantly lower (<italic>P</italic>&lt;0.05). Compared with the control group, the hip joint flexion angle and sagittal plane range of motion of the experimental group were significantly higher after treatment (<italic>P</italic>&lt;0.05); the knee joint sagittal plane range of motion was significantly higher (<italic>P</italic>&lt;0.05). (3) KOOS score: compared with those before treatment, the scores of symptoms, pain, daily activities, sports and recreation functions, knee joint-related quality of life and total KOOS score of both groups after treatment increased significantly (<italic>P</italic>&lt;0.05). Compared with the control group, the scores of symptoms, pain, daily activities, sports and recreation functions, knee joint-related quality of life and total KOOS score of the experimental group after treatment were significantly higher (<italic>P</italic>&lt;0.05). (4) TUGT: compared with before treatment, the TUGT of both groups after treatment decreased significantly (<italic>P</italic>&lt;0.05). Compared with the control group, the TUGT of the experimental group after treatment was significantly shorter (<italic>P</italic>&lt;0.05). (5) Safety: during the treatment period, no adverse reactions related to skin irritation or exercise training were reported in both groups.<bold>Conclusion</bold>Transcranial direct current stimulation combined with rehabilitation therapy can effectively improve the walking function, hip flexion angle, sagittal plane range of motion of hip and knee joints, knee joint functional status and functional mobility of patients with knee osteoarthritis, with high safety and worthy of clinical generalization and application.