H-Wave^® Device Stimulation for Chronic Knee Pain Disorders: A Patient-Reported Outcome Measures Observational Study

Background and Objectives: Chronic knee pain (cKP) affects approximately 25% of adults worldwide, with prevalence increasing over recent decades. While conventional treatments have clinical limitations, several types of electrical stimulation have been suggested to improve patients' quality of life. The electrical stimulation literature contains inadequate patient-reported outcome measures (PROMs) data. Encouraging preliminary H-Wave^® device PROMs results for chronic neck, shoulder, and low back pain have previously been published. This PROMs study's goal is to similarly assess the efficacy of H-Wave^® device stimulation (HWDS) in patients with differing knee disorders. Materials and Methods: This is an independent, retrospective, observational cohort study analyzing H-Wave^® PROMs data, prospectively and sequentially collected over 4 years. In total, 34,192 pain management patient final surveys were screened for participants who were at least 18 years old, used H-Wave^® for any knee-related disorder, reporting chronic pain from 90 to 730 days, with device treatment duration from 22 to 365 days. PROMs included effects on function, pain, sleep quality, need for medications, ability to work, and patient satisfaction; additional data includes gender, age (when injured), chronicity of pain, prior treatments, and frequency and length of device use. Results: PROMs surveys from 34,192 HWDS patients included 1143 with "all knee", 985 "knee injury", and 124 "knee degeneration" diagnoses. Reported improvements in function/ADL (96.51%) and work performance (84.63%) were significant (p < 0.0001), with ≥20% pain relief in 86.76% (p < 0.0001), improving 2.96 points (average 0-10 NRS). Medication use decreased (69.85%, p = 0.0008), while sleep improved (55.33%) in knee injury patients. Patient satisfaction measures exceeded 96% (p < 0.0001). Subgroup analysis suggests that longer device use and shorter pain chronicity resulted in increased (p < 0.0001) HWDS benefits. Conclusions: HWDS PROMs data analysis demonstrated similarly encouraging outcomes for cKP patients, as previously reported for several other body regions. Knee injury and degeneration subgroups had near-equivalent benefits, as observed for all knee conditions. Despite many reported methodological limitations, which limit causal inference and preclude broader recommendations, HWDS appears to potentially offer several benefits for refractory cKP patients, requiring further studies.