Platelet-rich plasma offers mixed success in treating tendinopathies
The concept of using growth factors contained in activated platelets to help wound healing dates back to the early 1980s. More recently, the use of platelet-rich plasma (PRP) to treat various musculoskeletal disorders, including tendinopathies, has increased tremendously.
Tendon healing is a complex process involving many growth factors, such as platelet-derived, transforming, vascular endothelial, insulin-like, and epidermal growth factors, which are detected in higher concentrations in PRP.
To date, the respective role of each type of growth factor requires further exploration. As well, recent evidence suggests varying concentration levels of these growth factors in PRP, depending on the protocol and devices used to spin the blood.
In April 2010, the WorkSafeBC Evidence-Based Practice Group conducted a systematic literature review of the effectiveness of PRP in treating tendinopathies.
They found five studies of varying quality and design investigating the application of PRP in treating chronic patellar tendinosis and chronic elbow tendinosis, during arthroscopic rotator cuff repair, during Achilles tendon surgery to promote healing, and treating Achilles tendinopathy.
Lower-quality and lower-level studies[1-4] showed the effectiveness of PRP in treating various tendinopathies. However, the only available high-quality evidence showed that PRP injection compared to saline injection did not result in significant improvement in pain and activity. These studies could not discount the value of co-interventions.
Shock therapy thought to ease pain from calcified supraspinatus tendinopathy
One cause of shoulder pain is calcific rotator cuff tendinopathy, which occurs in 7% to 17% of rotator cuff tendinopathies. Extracorporeal shock wave therapy (ESWT) has been promoted as an alternative to surgical intervention in treating rotator cuff tendinopathy that fails to respond to conventional and more conservative therapies.
While the mechanism is still unclear, this outpatient procedure is thought to provide long-lasting analgesia and stimulate the healing process.
In June 2010, the WorkSafeBC Evidence-Based Practice Group investigated the effectiveness of ESWT, using low- and high-level energy shock waves to treat calcific supraspinatus or rotator cuff tendinopathy in general. Their findings included two systematic reviews, one of high quality and one of low quality, three low-quality RCTs,[8-10] and one low-quality case-control study.
This included some high- and low-quality evidence to suggest high energy ESWT can provide pain relief and increased function, as measured by the Constant-Murley score, among patients suffering from calcific rotator cuff tendinopathy. There was no evidence on the effectiveness of ESWT in treating noncalcific rotator cuff tendinopathy.
Low-intensity ultrasound for nonunion fractures appears effective for some
Fracture healing is a complex process involving various factors that need to occur at a specific time and place. US data show up to 10% of healing fractures develop delayed union, and a significant proportion of these become nonunions. At present, some experts have demonstrated a lack of agreement regarding the diagnosis of fracture nonunions.
While ultrasound has been applied in treating fractures for half a century, its role in fracture healing is not well understood. In January 2010, the WorkSafeBC Evidence-Based Practice Group investigated the effectiveness of Exogen low-intensity ultrasound in treating fracture nonunion and found three high-quality systematic reviews[12-14] and one large case series (n = 1317)15 that showed as follows:
• No high-level primary studies exist to provide evidence of the effectiveness of low-level ultrasound.
• Low-level evidence, including large case series, showed that low-level ultrasound is effective as an adjunct to good immobilization, especially when provided by an external immobilizer.
• Low-level ultrasound may be effective among patients aged 31 to 60 with long bone or scaphoid fractures; who had comorbid illnesses; who had been treated with other drugs, such as steroids, NSAIDs, anticoagulants; or who are current smokers.
Other adjunct treatments, yet to be tested for effectiveness, are also available. These include pulsed electromagnetic field stimulation, direct current or capacitative coupling, extracorporeal shockwave stimulation, and orthobiologics, especially the bone morphogenic protein (BMP)-7.
Full documents and other systematic reviews can be downloaded from www.worksafebc.com/evidence.
—Kukuh Noertjojo, MD, MHSc, MSc
—Craig Martin, MD, MHSc
WorkSafeBC Evidence- Based Practice Group
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