A Controlled Randomized Trial with a 12-week Follow-Up Investigating the Effects of Medium-Frequency Neuromuscular Electrical Stimulation on Pain, VMO Thickness, and Functionality in Patients with Knee Osteoarthritis
Azar Moezy, Soheila Masoudi, Ahmad Nazari, Arezoo Abasi
Purpose
This study was conducted to assess the effectiveness of neuromuscular electrical stimulation (NMES) and exercise therapy (Exs) in improving pain, muscle weakness, and function in patients with knee osteoarthritis (KOA).
Methods:
- Participants: 75 female patients with mild-to-moderate KOA.
- Treatment: Participants were randomly assigned to one of three groups:
- NMES Only: Pre-Modulated Interferential two-pole currents were used. The proximal electrode was aligned with the Rectus Femoris and the distal electrode was placed over the vastus medialis oblique. Treatment parameters consisted of the following:
- Pulse Width: 600μs
- Carrier Frequencies: 4,000—4,050 Hz
- Beat Frequency: 50 Hz
- Duration: 15 minutes
- Current Intensity: Adjusted for effective muscle contractions while avoiding pain or discomfort
- Exs Only: Completed 5 exercises including quad contractions, straight leg raises, knee extensions, hip adductor contractions, and a wall-sit.
- NMES + Exs: Participants in this group completed both NMES and exercises as described above.
- NMES Only: Pre-Modulated Interferential two-pole currents were used. The proximal electrode was aligned with the Rectus Femoris and the distal electrode was placed over the vastus medialis oblique. Treatment parameters consisted of the following:
Participants completed 12 treatment sessions over 4 weeks. Prior to treatment, all participants received 20 minutes of transcutaneous electrical nerve stimulation for pain management. Participants were also instructed to not take non-steroidal anti-inflammatory drugs during the treatment period. A daily maximum of 2 g of acetaminophen was allowed if patients had pain.
- Assessments: Study outcome measures included the Visual Analog Scale (VAS), knee flexion range of motion (FROM), thigh muscle girth (TG), VMO thickness, timed up and go test (TUG), six-minute walk test (6MWT), and WOMAC scores. Outcome measures were assessed at baseline, post-treatment, and at 12 weeks follow-up.
Results
- Pain Reduction: The VAS scores in all 3 groups significantly improved post-treatment and at the 12 week follow-up. At the 12 week follow-up, the NMES Only group had the greatest reduction in pain compared to the other 2 groups.
- Functional Improvements: All 3 groups significantly improved post-treatment and at the 12 week follow-up in 6MWT, TUG, and WOMAC scores. The NMES Only and NMES + Exs groups also had significant improvement in VMO thickness and FROM.
- NMES Only: The NMES only group improved the most in the 6MWT and TUG tests compared to the other groups post-intervention and at the 12 week follow-up and had the best total WOMAC score at the 12 week follow-up.
- NMES + Exs: The group that received NMES along with exercise had better outcomes than the other groups in FROM, TG, and VMO thickness post-intervention and at follow-up. This group also achieved better WOMAC stiffness scores post-intervention and at follow-up compared to the other 2 groups.
Conclusion
- NMES is an effective treatment option for improving pain and physical function in KOA patients.
- Combining NMES with exercise is also an effective method of managing KOA as demonstrated by the enhanced FROM, increased muscle thickness, and improved WOMAC stiffness scores.