Managing Refractory Tendinopathy: Shock Wave Therapy Explained
Previously, we have discussed the use of topical nitroglycerin, needle tenotomy, and dextrose prolotherapy for refractory tendinopathies. In this post, we will review the rationale and literature behind Extracorporeal Shock Wave Therapy (SWT).
SWT provides “shock waves” via mechanical, low energy sound waves to pathologic tissue to promote healing and reduce pain. Shockwaves are generated through a combination of electrohydraulic, electromagnetic, and piezoelectric principles. It has been theorized to help modulate pain receptors by increasing blood flow. The electrophysiological pathways and molecular mechanisms of the proposed anti-nociceptive effect of the treatment are still unknown . SWT is safe, complication rates are low and negligible .
Extracorporeal shock wave therapy can be performed following two modalities: repetitive low-energy extracorporeal shock waves, which do not require local anesthesia, or high-energy extracorporeal shock waves, which require local or regional anesthesia . It is unclear if one modality is superior to the other, however in a study of calcific tendonitis of the rotator cuff, high energy SWT appeared to be superior .
SWT appears to help for common upper extremity tendinopathies. A 2007 systematic review attempt to summarize the research on SWT for lateral epicondylitis but was limited by significant heterogeneity among included studies. Nonetheless, they concluded there was evidence for effectiveness of shock wave treatment for tennis elbow . One randomized, multicenter trial found no difference . In patients with calcific tendonitis of the rotator cuff, SWT was beneficial for function, pain and size of calcifications compared to placebo [7, 11].
SWT also appears to help with several lower extremity tendinopathies. A systematic review found SWT was also helpful in treating greater trochanteric pain syndrome . In patients with patellar tendinopathy, SWT was superior to controls up to 3 years following initiation of therapy . In patients with Achilles tendinopathy, SWT produced similar improvements in pain and function when compared to eccentric loading . Additionally, eccentric exercises combined with SWT was superior to eccentric exercises only . In another study compared to control group managed nonoperatively, SWT improved pain and function .
Image 1: Example of shock wave therapy on plantar fasciitis (courtesy of myankle.co.uk)f
There is some literature that SWT is not helpful for certain musculoskeletal conditions. A randomized, blinded, controlled study found SWT was not superior to placebo for the treatment of plantar fasciitis . Conversely, a single blinded pilot study did find improvement in pain and function . SWT may help with other pathologies in addition to tendinopathies; SWT appears to help with fracture non-union, delayed bone healing , avascular necrosis, wound healing , diabetic ulcers and ischemic heart disease .
In conclusion, extracorporeal shock wave therapy has mild to moderate evidence of efficacy in some common upper and lower extremity tendinopathies, including lateral epicondylitis, calcific tendinitis, patellar tendonitis and achilles tendonitis. It may have some other non-MSK related applications. Overall, the evidence is weakly positive and more robust studies are needed to better clarify its role in the landscape of tendinopathy management, especially when compared to other modalities.
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