Safety and Efficacy of Repetitive Peripheral Magnetic Stimulation in Patients With Achilles Tendinopathy

With this prospective, randomized, controlled trial the investigators want to investigate effects of a prolonged repetitive Peripheral Magnetic Stimulation (rPMS) intervention on Achilles tendinopathy and compare it to a well established intervention. This may provide clinicians with a new, non-pharmacological, non-invasive, near painless approach to treat tendinopathy.

Although promising results with comparable devices exist, a direct and valid conclusion on the overall clinical performance of the investigational device cannot be drawn. This is mainly due to different treatment protocols used in the literature and due to the lack of insight in the technical documentation of comparable devices. Further, the applied magnetic fields vary in their amplitude, frequency, waveform and/or stimulation durations.

Therefore, the main goal of this clinical investigation is the collection of clinical data on the clinical performance of the investigational device. This clinical data will subsequently serve as a main source for the clinical evaluation of the medical device.

Tendons are collagenous tissues that link muscle to bone, and in best case, a painless transmission of force allows voluntary movement over a life time. Although tendons show long time underestimated repair and remodelling capacities, some of them (e.g. the human patellar or Achilles tendon) remain quite prone to injury. To make things worse, tendinous tissue reveals incomplete healing capacities and treatments seem to be ineffective to avoid the high injury recurrence rate and/or the occurrence of chronic tendon pain. Thus, both elite and recreational athletes, as well as the non-sporting population or workplace employees often suffer from symptoms like tendon swelling, localized tenderness, activity related pain and impaired performance, also known as tendinopathy. Such pain-induced restriction of mobility frequently means the end of a sporting carrier, deteriorates the quality of life and patients have to live with all harmful consequences of physical inactivity. One tendon most commonly afflicted by this debilitating musculoskeletal injury is the Achilles tendon. Although it is the strongest tendon in our body, the prevalence for tendinopathy can be as high as 56% among certain athletes.

The repetitive peripheral magnetic stimulation (rPMS) works through a deep operating, focused and painless stimulation mechanism generated by pulsed magnetic fields. This intervention is already successfully in use to accelerate the healing of bone fractures and to enhance the healing of operated rotator cuff tears. Additionally, data on in vitro tendon cells indicate the positive effect of rPMS on tendon tissue by stimulating cell proliferation, up-regulating tendon-specific gene expression and releasing anti-inflammatory cytokines and growth factors. More interestingly, intervention studies on the healing of rotator cuff tendon-to-bone injuries in rat models show increases in tendon stiffness and modulus and enhanced collagen organization, and type I collagen expression after prolonged rPMS without showing adverse effects in any mechanical or histological property. These results strongly support the hypothesis that rPMS might be effective in treating Achilles tendinopathy in humans. This intervention might reduce pain and functional limitations, reverse tendon degenerative changes and increase the impaired tendon mechanical and material properties.

Eligibility Criteria:
Inclusion Criteria:

* Men and non-pregnant women aged 18-60 years
* Patients suffering from a gradually evolving painful condition in the Achilles tendon located at the midportion for at least 12 weeks (Diagnosis based on clinical examination showing a painful thickening of the Achilles tendon located at a level of 2 to 6cm above the tendon insertion, and confirmed by ultrasonography: local thickening of the tendon, irregular tendon structure with hypoechoic areas and irregular fiber orientation).
* VISA-A score less than 65 at baseline.
* Be informed of the nature of the study and provide written informed consent.

Exclusion Criteria:

* Clinical suspicion of insertional disorders (pain at the site of the insertion of the Achilles tendon on the calcaneum)
* Concomitant or previous participation in a clinical investigation within the last 3 months (wash out) prior to study inclusion
* Clinical suspicion of an Achilles tendon rupture.
* Suspicion of internal disorders: spondylarthropathy, gout, hyperlipidemia, Rheumatoid Arthritis and sarcoidosis.
* Severe foot deformity
* Condition that prevents the patients from executing an active exercise program
* Pregnant or lactating females
* History of treatment with corticosteroids, estrogens, long term quinolone antibiotics, and cholesterol drugs
* Persons with electronic implants (e.g. pacemaker, cochlear implants, drug pump, deep brain stimulator, etc.)
* Patients with organ transplants
* Patients with closed, circular metal implants (e.g. subdermal implants, etc.)
* Epilepsy