Extracorporeal Shockwave Therapy (SWT) is a modality used for the treatment of a variety of musculoskeletal conditions, primarily applied to chronic conditions, particularly those affecting medium to large sized tendons and their insertions on bone such as:
- Plantar Fasciitis
- Achilles Tendonopathy
- Retrocalcaneal Bursitis
- Lateral Epicondylosis (Tennis Elbow)
- Medial Epicondylosis (Golfer’s Elbow)
- Calcific Tendonitis (supraspinatus tendon, etc.)
- Patellar Tendinosis (Jumper’s Knee)
- Morton’s Neuroma
- Chronic Stress/Non-union Fractures
SWT has been available in Canada since the mid-90s but has recently been popularized with the advent of low energy SWT. SWT is an intervention that stimulates the body’s natural healing process. Additionally, SWT has been shown to have a direct effect on local nerve endings resulting in a decrease in pain. It is important to understand the difference between low energy and high energy SWT when considering whether you are an appropriate candidate for SWT and which type of SWT is most likely to yield positive results in the treatment of your condition.
High energy SWT or “true” shockwaves are classified as short duration (approx. 10msec) high energy pulses (5-100MPa) that break the sound barrier resulting in a shockwave. Our high energy shockwave technology allows the shockwave to be focused directly through the affected tissue resulting in several effects:
- Mechanical pressure and tension forces on the tissue which has been shown to increase cell membrane permeability thereby increasing microscopic circulation and therefore the metabolism within the treated area. This promotes healing and may result in the dissolution of calcific deposits.
- The pressure front creates behind it a “cavitation bubble” which are small empty cavities created behind a pressure front. When the bubbles collapse they create a resultant force that has a mechanical impact on the treated tissue. This force helps to break down calcific deposits embedded in damaged tissue.
- Shockwaves stimulate osteoblasts that are cells responsible for bone healing and new bone production.
- Shockwaves stimulate fibroblasts that are cells responsible for healing of connective tissue such as tendons.
- Diminishes pain by two mechanisms. Hyperstimulation anesthesia – local nerve endings are overwhelmed with so many stimuli that their activity diminishes resulting in short-term reduction in pain. Gate-control mechanism – whereby local nerves are stimulated to recalibrate perception of pain and result in longer-term reduction in pain.
There are three different mechanisms for generating high energy shock waves resulting in three different types of SWT device:
- Electromagnetic shockwave (Sonocur and Dornier Epos machines)
- Piezoelectric shockwave (Piezoson) * Electrohydraulic shockwave (I.E. HMT OssaTron machine) Low energy shockwaves are generated by a radial pressure wave (I.E. Storz and Dolorcast machines).
This type of shockwave is more accurately described as a pressure wave and differs from “True” shock wave technology in the following ways:
- Low energy shockwaves travel at a much slower speed and don’t break the sound barrier and hence a “True” shockwave is not produced.
- Low energy shockwaves are longer, slower and less intense.
- Radial pressure waves diverge from the source unlike high energy shockwaves that converge on a target, resulting in less energy applied to the tissue with low energy SWT vs. high energy SWT.
Due to the reduced cost of low energy shockwave machines many patients may have the impression that they have received “True” shockwave therapy. This impression is often generated by misinformed patients and uninformed practitioners. There certainly can be differences in effectiveness of high energy vs. low energy shockwave therapy. In general the effectiveness of SWT tends to be between 60%-80%. Compliance with treatment and rehabilitation recommendations are important factors in achieving optimal results.