Regarding: Radial Extracorporeal Shockwave Therapy Is No More Effective Than Placebo in the Management of Lateral Epicondylitis
This letter is regarding the article “Radial Extracorporeal Shockwave Therapy is No More Effective than Placebo in the Management of Lateral Epicondylitis: A Double-Blind, Randomized, Placebo-Controlled Trial.”1
The author read with interest this report, which at its conclusion, proved to be as inconclusive as were many of the 48 references cited in this communication. Shock therapy in the treatment of lateral epicondylitis as well as many other cited conservative therapeutic approaches to treatment continues to remain controversial. Although the methodology employed in executing this study was well thought out, it could have been enhanced by a prestudy magnetic resonance imaging serving to ascertain the severity of the injury to the common extensor tendon at its attachment to the lateral epicondyle.
In a 2014 publication, LaBan2 described the utility of magnetic resonance imaging in identifying the severity of injury to the common extensor tendon at its proximal osseous attachment on the lateral epicondyle. In this study, the pathology ranged from a low-grade enthesitis to a heretofore clinically unrecognized complete tear of the extensor tendon off its osseous attachment, i.e., a “bald” lateral epicondyle. With magnetic resonance imaging technology now readily available, with certainty, the extent of injury between comparison groups can easily be matched. Beyond an issue of research, the extent of injury to the tendon as well as to its proximal attachment has “real-world” clinical significance not only to appreciate the severity of the patient's pain, but also to prognosticate the duration of morbidity especially because it relates to issues of employment.
Although the authors in this study eliminated potential subjects with one well-recognized co-morbidity, i.e., proximal radial nerve compromise, a far more frequent occurrence, but less recognized is not appreciated, i.e., a loss of ipsilateral shoulder internal rotation. As described by LaBan et al3 in 2005, a restriction in shoulder internal rotation can incite and/or aggravate a lateral epicondylitis. Kinesiologically, compensating for this reduction in shoulder mobility, distal wrist flexion is substituted in an effort to unconsciously extend the heretofore restricted arc of internal rotation. During this maneuver, the involved “two-joint” muscles, i.e., the extensor carpi radialis longus and brevis repeatedly reverse their origins and insertions cycling in turn from a concentric to an eccentric contraction and then back again. An age-related loss of tissue elasticity may significantly reduce the muscle's ability to internally absorb the generated recoil as the muscles reverse from one phase to another. In this scenario, the undamped generated force is transmitted centripetally to the proximal epicondylar attachment of the common extensor intermittently acting as the functional “origin,” potentially inciting a tendinous disruption.
The authors stated in their conclusion “There is a need for further double-blind studies of radial extracorporeal shockwave therapy to make decisive remarks” as to the effects on the lateral epicondyle. The authors would suggest with the addition of magnetic resonance imaging–guided attention to both patient selection as well as an awareness of the presence of restricted shoulder internal rotation.