Effectiveness of non-invasive ultrasound-guided electrical stimulation of genicular nerves for chronic knee pain: A case report.

Rationale: Chronic knee pain is a common health issue that requires effective and noninvasive treatment. We devised a novel noninvasive approach using ultrasound-guided electrical nerve reactivation (ENR) in which ultrasound is used to identify the genicular nerve (GN). Then, transcutaneous low-frequency stimulation is applied for 10 seconds. The aim of this study was to clarify the pain-relieving effects of ENR on the GN innervating the knee joint.

Patient Concerns: Patients had visited our hospital with the complaint of knee joint pain.

Diagnoses: This study included 21 osteoarthritic knees from 16 patients with a mean age of 78.3 ± 8.5 years.

Interventions: Baseline measurements included the range of motion of the knee joint, Visual Analogue Scale (VAS) scores for pain, and maximum knee flexion angle during squatting. A therapist conducted an interview to locate the painful area of the knee and then performed ultrasound-guided ENR by targeting the GN.

Outcomes: The preintervention VAS score was 49.3 (95% confidence interval: 41.0, 57.5). Postintervention VAS scores showed significant reductions: 27.0 (19.0, 35.1) immediately after the intervention (P < .0001), 27.7 (22.6, 32.8) at 1-day postintervention (P = .002), and 29.0 (22.9, 35.1) at 1-week postintervention (P = .001). The knee flexion angle during squatting significantly improved from 108.1° (101.6, 114.5) preintervention to 121.9° (115.1, 128.7) postintervention (P < .001). There was a significant increase in flexion angle preintervention and postintervention (P = .02); however, no significant change was observed in the extension angle. In addition, no adverse events were reported.

Lessons: This study is the first to demonstrate the effects of ultrasound-guided low-frequency stimulation of the GN for knee osteoarthritis. Although the exact mechanism of pain relief is unclear, we hypothesize that alterations in neurotransmission, with or without endorphin release, may play a role. Moreover, ENR may improve nerve entrapment by causing contraction of surrounding muscles.This study demonstrated that ultrasound-guided ENR targets the GN and effectively reduces pain without complications. This treatment addresses the limitations of invasive methods, such as hydrorelease and radiofrequency ablation. Furthermore, ultrasound-guided ENR has diverse applications in diagnostics, physical therapy, and pre-exercise pain management and will greatly benefit patients and healthcare professionals.