Following completion of this chapter, the student will be able to:
Describe the mechanical characteristics of extracorporeal shock wave.
Identify musculoskeletal pathologies that may benefit from extracorporeal shock wave therapy.
Discuss the cellular effects of extracorporeal shock wave therapy on bone and tendons.
Discuss why these effects may be beneficial to these tissues.
Extracorporeal shock wave therapy (ESWT) is a therapeutic modality that utilizes acoustic energy. Therapeutic acoustic shock waves were first studied in the early 1970s and by the early 1980s were used in clinical practice for noninvasive lithotripsy, a procedure used to disintegrate kidney and urethral stones and later, gall stones. ESWT has been used in orthopedic medicine over the last three decades for treatment of a variety of musculoskeletal conditions including lateral epicondylitis, plantar fasciitis and rotator cuff, patellar, and Achilles tendinopathies in the United States.33
ESWT appears to be effective in particular for treatment of patients with chronic inflammation which is difficult to treat. It is becoming clear that “chronic inflammation” is not present and regeneration of tendocytes is needed to facilitate healing.1 The biologic effects of ESWT have been shown to stimulate growth factors and stem cells to foster new collagen.2,3,57 ESWT also seems to have a significant effect on pain for treatments of other musculoskeletal disorders including pseudoarthrosis, nonunion fractures, and during total joint revisions. Emerging literature suggests that ESWT is effective when compared to placebo injections, and augmented by eccentric exercise in the treatment of chronic tendinopathies.4
ESWT will continue to be used more specifically in the treatment of what has traditionally been referred to as chronic tendonitis. It is important to discuss this topic briefly before we begin. Traditionally, physical therapists, athletic trainers, and physicians have concluded that longstanding symptoms of tendonitis were the result of the healing process being “stuck” in the inflammatory phase. However this is not the mechanism underlying this chronic condition. Patients who clearly have chronic tendinosis or fasciosis on a clinical basis (i.e., duration of at least 6 months and failure of other conservative measures, especially NSAIDs and/or steroid injection) seem to respond best to ESWT. Observations that those who respond best have failed steroid injection and other conservative therapies likely indicate a better selection of those patients who have no inflammatory component to their condition.54–56 Current recommendations for treatment include a period of rest, followed by aggressive eccentric exercise to stimulate tendon regeneration.1–3,5–9 ESWT’s demonstrated biologic effects of decreasing pain and promoting tissue regeneration make it an ideal adjunct to the rehabilitation process.
This chapter will clarify the terminology and principles of shock wave therapy, discuss the potential biologic effects of shock waves, and review the current use of ESWT in the treatment of musculoskeletal conditions. Finally, evidence-based clinical guidelines for use of ESWT will be presented.