This randomized, double-blind clinical trial aims to evaluate the effect of high-intensity pulsed electromagnetic field therapy (HI-PEMF) applied either exclusively on the knee joint or bimodally on the knee and quadriceps, in older adults with knee osteoarthritis. Both groups will also receive a structured home-based exercise program. The primary outcome is pain reduction, and secondary outcomes include functional performance.
Knee osteoarthritis (OA) is a highly prevalent and disabling condition in older adults. It often coexists with quadriceps muscle weakness, sarcopenia, and frailty, all of which contribute to pain, functional decline, and loss of independence. Pulsed electromagnetic field therapy (PEMF) has emerged as a non-invasive alternative for pain relief in OA, with growing interest in its application at both articular and muscular levels. High-intensity pulsed electromagnetic field (HI-PEMF) therapy-also known as the super inductive system-generates magnetic fields up to 2.5 Tesla, capable of stimulating both joint structures and skeletal muscle via deep tissue electric induction. HI-PEMF has shown promising results for pain reduction, anti-inflammatory modulation, and muscle bioactivation, particularly when applied over the quadriceps. This randomized, double-blind, parallel-assignment clinical trial aims to compare the effects of two HI-PEMF treatment modalities in older adults with moderate to severe knee OA (Kellgren-Lawrence grade II-IV): * Group A: HI-PEMF applied exclusively over the symptomatic knee. * Group 2: HI-PEMF applied both over the knee and the quadriceps (bimodal). Both groups will also perform a standardized home-based strengthening and mobility exercise program. A total of 64 participants (32 per group) will receive 9 sessions of HI-PEMF (2 per week for 5 weeks), using the BTL-6000 Super Inductive System. Outcomes will be assessed at baseline and post-intervention. The primary outcome is change in pain intensity using the Numeric Analog Scale (NAS). Secondary outcomes include functional tests (Timed Up and Go and 5-times Sit-to-Stand), and paracetamol use. Exploratory subgroup analyses will assess associations with frailty status (FRAIL), probable sarcopenia (SARC-F), and radiological OA grade. This study seeks to generate evidence on the potential synergistic benefits of combining articular and muscular HI-PEMF therapy in geriatric rehabilitation. It is designed for implementation in a public hospital setting in Mexico, with minimal risk and high feasibility. All procedures follow ethical guidelines and have received institutional review board approval.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
64
High-intensity pulsed electromagnetic field (HI-PEMF) therapy applied to the symptomatic knee using the "Chronic Pain" protocol of the BTL-6000 Super Inductive System, 10-minute duration per session, applied twice per week over 5 weeks (total of 9 sessions). The applicator is positioned 2-3 cm above the patella, without skin contact, with the patient seated or in supine position.
HI-PEMF therapy will be applied to both the symptomatic knee and the quadriceps muscle (rectus femoris). The knee application will follow the same procedure as in Group A, using the "Chronic Pain" protocol of the BTL-6000 Super Inductive System. In addition, the quadriceps will be treated using the "Muscle Strengthening" protocol. Each site will receive 10 minutes of therapy per session, twice per week over 5 weeks (total of 9 sessions). The applicator for the quadriceps will be positioned perpendicular to the muscle belly, without skin contact, with the patient lying supine and a cushion under the knee for slight flexion.
Standardized home-based exercise program prescribed to both groups. It includes five exercises: isometric quadriceps contractions, straight leg raises, seated knee extensions, sit-to-stand from chair, and stationary marching. Participants are instructed to perform the exercises three times per week during the 5-week intervention. Printed instructions and a video guide are provided. Adherence is reinforced via weekly follow-up.
Hospital Civil de Guadalajara "Fray Antonio Alcalde"
Guadalajara, Jalisco, Mexico
RECRUITINGChange in pain intensity measured by the Numeric Analog Scale (NAS)
Pain intensity will be assessed using the 11-point Numeric Analog Scale (0 = no pain, 10 = worst possible pain), reported by the patient at rest and related to the most symptomatic knee. The primary endpoint is the change in NAS score from baseline to end of the 5-week intervention and at 2-month follow-up (approximately week 13). This will allow evaluation of both immediate and sustained effects of the intervention.
Time frame: Baseline, end of intervention (week 5), and 2-month follow-up
Change in functional mobility measured by the Timed Up and Go (TUG) test
Functional mobility will be assessed using the Timed Up and Go (TUG) test. Participants are instructed to stand up from a chair, walk 3 meters, turn around, return, and sit down. The total time (in seconds) will be recorded using a stopwatch. The outcome measure is the change in time from baseline to the end of the 5-week intervention and at 2-month follow-up. This assesses both short-term and sustained improvements in functional mobility.
Time frame: Baseline, end of intervention (week 5), and 2-month follow-up
Change in lower-limb functional strength measured by the 5-times Sit-to-Stand (5STS) test
Lower-limb functional strength will be assessed using the 5-times Sit-to-Stand (5STS) test. Participants will be instructed to rise from a standard chair and sit back down five times as quickly as possible without using their arms. The total time (in seconds) to complete the task will be recorded using a stopwatch. The outcome measure is the change in time from baseline to the end of the 5-week intervention and at 2-month follow-up. This evaluates improvements in functional lower-limb strength and endurance over time.
Time frame: Baseline, end of intervention (week 5), and 2-month follow-up
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