Clinical Effectiveness of PEMF as a Treatment Adjunct to Eccentric Exercise for Achilles Tendinopathy

This study aims to investigate the clinical effectiveness of PEMF as an adjunct to a program of eccentric exercise for the treatment of Achilles tendinopathy. The study objective is to establish whether PEMF plus eccentric exercise in people with Achilles tendinopathy will improve rehabilitation outcomes compared to eccentric exercise only. This study also investigates the effects of PEMF on pain, functional outcomes, mechanical and morphological properties of tendon among patients with Achilles tendinopathy. Investigators hypothesize that pulsed electromagnetic field therapy is effective in reducing pain, improving functional outcomes, and restoring mechanical and morphological properties of tendons in patients with Achilles tendinopathy.

This study is a double-blinded, randomized controlled trial to investigate the clinical effects of pulsed electromagnetic field therapy (PEMF) for Achilles tendinopathy. Participants will be recruited from the outpatient clinic of the orthopedic and traumatology department at Prince of Wales Hospital. Fifty-four patients aged between 18 and 70 with Achilles tendinopathy will be invited to join this trial after informed consent. Participants will be randomized to any of the 2 groups: the intervention group (n=27; PEMF (Quantum Tx) treatment), and the control group (n=27; sham treatment with dummy exposure to PEMF).

Baseline measurements of all self-reported outcomes, functional outcomes, and ultrasound imaging assessments, such as ankle range of motion, jumping ability, pain level, calf muscle strength, calf muscle endurance, physical activity level, quality of life by SF-36 will be measured.

Randomization and blinding Participants will be randomized into 1:1 allocation, blocked randomization with 27 participants in the PEMF group and 27 participants in the sham group. Each allocation will be assigned with a unique RFID (generated during block randomization by the PEMF supplier service) recognizable by the PEMF machine. The participants will be assigned an RFID by which the PEMF or sham treatment will be randomly assigned to the RFID. A biostatistician who does not participate in the recruitment of patients will oversee the randomization. Hence, both participants and the research personnel are blinded, and participants will use the RFID to complete the assigned treatment without knowing which treatment they are receiving.

Intervention The intervention will be held at the Chinese University of Hong Kong. Participants in the intervention group will be exposed to PEMF treatment by a PEMF device (Quantum Tx, Singapore). The active PEMF device does not produce heat or cause any sensation to the tissue which allows the participants to be blinded to the treatment. Participants in the control group will receive a sham exposure with the same PEMF device. The diseased leg will be exposed to PEMF or sham treatment for 10 minutes per session, and the treatment regime will run twice a week for 8 weeks, summing up 16 sessions of PEMF or sham exposure in total.

The procedure of PEMF treatment is shown as follows:

The subject will be seated at a 90 degrees position on a chair. The solenoids of the PEMF device will be adjusted to be over the foot and ankle (Achilles tendon and lower calf muscle).

The options of the appliance will be adjusted to 1.5mT, 10Hz on the diseased leg for 10 minutes.

In addition to PEMF, all participants will also perform eccentric calf muscle exercise. The first step is stretching exercises for the calf muscles. The stretching is a static stretch of the gastrocnemius (knee in extension) and soleus (knee in flexion). The participants are instructed to hold these at least for 30s and repeat each exercise three times. There is a 1-min rest between each stretch. 3 sets of 10 repetitions of the eccentric exercises are carried out once daily for 6 weeks and after 6 weeks, the participants are instructed to carry out 3 sets of 10 repetitions, 3 times per week for 6 more weeks. The intensity of the exercise should be such that pain, or discomfort, is experienced in the last set of 10 repetitions. Every session ended with the same static stretch exercise as in step 1. If a participant is unable to complete 3 sets of 15 repetitions, the participant is instructed to start with a lower number of repetitions and/or sets (a minimum of 2 sets of 10) and progress to the full amount as able.

Eligibility Criteria:
Inclusion Criteria:

* Age between 18 and 70
* Tenderness with palpation 2-6 cm above the Achilles tendon insertion on the calcaneus (midportion Achilles tendinopathy)
* Recurrent complaints in 1 or both Achilles' tendons at rest and/or during exercise for the preceding 3 month
* Structural changes of the tendon were confirmed via sonographic examination during the initial physical exam
* Achilles tendinopathy affecting the insertional and mid-portion of the Achilles tendon
* Clinical symptoms associated with Achilles tendinopathy that do not respond well to conventional conservative treatments before entering the study
* Informed consent

Exclusion Criteria:

* History of surgery on the affected lower limb in the past year
* Mental/physical limitation rendering participant to follow instructions
* With medical or musculoskeletal problems that could affect the ability to complete assessments (i.e. with walking aids or wheel-chaired)
* Severe cognitive impairments and neurological disorders that will affect data collection by questionnaires
* Fractures of the trained body parts within the past 12 months