This is a multi-centre, randomised, double-blind, placebo-controlled trial with two parallel groups in a 1:1 allocation to study the efficacy of Pulsed Electromagnetic Field Therapy (PEMF) in patients with mid-portion Achilles tendinopathy. All participants will be randomly divided into two groups: an intervention group (active PEMF and standard rehabilitation exercise) and a control group (sham PEMF and standard rehabilitation exercise). All self-reported, functional, and ultrasound findings will be evaluated by the investigator at baseline assessment, 1-month, 2-month, 3-month, 6-month and 12-month follow-up after initiating the intervention. The researcher will obtain written consent from all participants before the start of this study. All eligible participants will be informed about this study and given enough time to consider whether or not to participate; the clinician/research staff will answer all questions asked by the participants. The trial will be conducted in accordance with the Declaration of Helsinki and the ICH-GCP. Clinical research ethics approval for the trial will be obtained from the Joint Clinical Research Ethics Committee of The Chinese University of Hong Kong. All participants will be recruited from the clinics and centres of the participating institutions.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
200
The PEMF will be delivered using a BIXEPS device (Quantum Tx, Singapore) ; It is utilised by the patient placing the leg into the machine. This device is operated by participant individualized NFC cards, which will be centrally programmed to deliver either active PEMF (uniform 1mT, 50Hz) or sham PEMF (0mT, 0Hz) for 30 minutes. Because this biophysical intervention is non-invasive, and the electromagnetic fields emitted into the legs do not generate any sensation (e.g. heat, sound), participants will be blinded to the treatment. The protocol will be 180 minutes of PEMF therapy, performed in six 30-minute sessions 3 times a week and completed in 2 weeks.
All participants will be subject to a standardised rehabilitation exercise region consisting of stretching and eccentric exercises following the Alfredson protocol. The 12-week program will be taught by a physiotherapist or athletic trainer and supplemented by video tutorials. The regime begins with three 30-second static stretches for the gastrocnemius (knee extension) and soleus (knee flexion) muscles with 1-minute rest between each stretch. The 2nd part is eccentric exercises to the calves following the Alfredson protocol. This will be three sets of eccentric exercises lasting 12 weeks, with 15 sets twice a day. If participants are unable to complete three sets of 15 repetitions, they can start with fewer repetitions and sets (at least 2 sets of 10 repetitions each) and gradually increase to the total number of sets. Participants will perform the static stretching exercises from Step 1 at the end of each session
Victorian Institute of Sports Assessment (VISA-A)
The primary outcome measure will be the Victorian Institute of Sport Assessment (VISA-A) questionnaire, available in either the original English or validated Chinese version, depending on the participant's native language. This specific scoring system developed for the Achilles tendon is the most widely used score for clinical Achilles research. The VISA-A is scored on a scale of 0 to 100; lower scores indicate more severity of symptoms, while a score of 100 indicates a healthy and pain-free Achilles tendon.
Time frame: Baseline;2-month;3-month;6-month;12month follow-up after initiating the intervention
Numeric Pain Rating Scale (NPRS)
Numeric Pain Rating Scale (NPRS) is a pain screening tool, commonly used to assess pain severity using a 0-10 scale, with zero meaning "no pain" and 10 meaning "the worst pain imaginable
Time frame: Baseline;2-month;3-month;6-month;12month follow-up after initiating the intervention
Foot and Ankle Outcome Scores (FAOS)
The FAOS is a validated patient-reported scoring system used for general foot and ankle problems. It is split into five categories: symptoms, pain, daily activities, sporting function, and quality of life. Scores range from 0 to 100, with 100 denoting no problems and 0 denoting severe problems.
Time frame: Baseline;2-month;3-month;6-month;12month follow-up after initiating the intervention
Achilles tendon resting angle (ATRA)
The ATRA will measure participants' tendon length/tension. Participants should be positioned in a prone position with the knee flexed to 90 degrees. The assessor will use a dynamic joint goniometer to measure the angle at which the foot passively falls.
Time frame: Baseline;2-month;3-month;6-month;12month follow-up after initiating the intervention
Tendon thickness
Using B-mode ultrasound scanning, the probe is moved from the medial to the lateral aspect of the Achilles tendon until a planar image of the Achilles tendon is clearly shown. The probe was adjusted straight perpendicular to the tendon fibres. A greyscale sonogram is acquired, and the tendon thickness is measured using the maximum thickness. Less than 5.3 mm was considered a healthy value for the Achilles tendon.
Time frame: Baseline;2-month;3-month;6-month;12month follow-up after initiating the intervention
Tendon cross sectional area
The cross-sectional area will be measured using B mode. After identifying the region of interest (the thickest portion or pathological site) in the longitudinal view, the transducer is rotated 90° to switch to the short-axis view (axial ultrasound view, as shown in the figure) for cross-sectional measurement. The cross-sectional area (CSA) is then recorded.
Time frame: Baseline;2-month;3-month;6-month;12month follow-up after initiating the intervention
Tendon vascularity
Vascularity will be documented using the Ohberg score. Using the Doppler mode on the ultrasound machine, the transducer is placed vertically to obtain a sagittal view of the softest area of the Achilles tendon. Pressure on the skin from the transducer should be kept to a minimum to prevent occlusion of blood vessels. The colour box is focused on the dorsal aspect of the tendon. The assessor will spend one minute exploring the blood flow over the tendon to find the area of maximum Doppler flow. After locating the area, sonograms are taken to determine the Öhberg score. Higher scores indicate more Doppler blood flow in the peritendinous and intratendinous tissues. Healthy tendons (Ohberg score of 0) have no blood vessels in the Achilles tendon.
Time frame: Baseline;2-month;3-month;6-month;12month follow-up after initiating the intervention
Tendon elasticity
Shear wave elastography (SWE) can be used to quantify soft tissue stiffness. Once the optimal scan plane of the tendon is determined, the SWE function is activated. It enters penetration mode and the measured stiffness range is normalized to 0-600 kPa. The SWE color card (H × W: 1.4 cm × 1.3 cm) is placed immediately above the upper edge of the calcaneus. After the color signal stabilized for five seconds, the electrogram was recorded and stored. Tendon stiffness was measured using a Q-box stiffness meter. Depending on the size of the tendon, the diameter of the circular measuring area (Q-box) is set to 2 mm, which covers the Achilles tendon and excludes other adjacent soft tissues. The Q-box is located in the center of the tendon on the SWE color map. For each Q-box, the average tendon stiffness (in kPa) is measured.
Time frame: Baseline;2-month;3-month;6-month;12month follow-up after initiating the intervention
Calf muscle strength
The hand-held dynamometer will be used to quantify isometric muscle strength (in kilograms) during ankle dorsiflexion and plantarflexion. Participants will maintain a maximal voluntary isometric contraction for 3 seconds. Three trials will be performed for each movement, with 30-second rest intervals between trials to minimize fatigue.
Time frame: Baseline;2-month;3-month;6-month;12month follow-up after initiating the intervention
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.