This is far and away one of the best papers ever done on the efficacy of manual methods for managing musculoskeletal injuries. The lead author, Geoffrey Bove, practiced as a chiropractor prior to getting a PhD in Neurobiology and Anatomy at the University of North Carolina. In this study, Dr. Bove and colleagues set out to determine if massage and joint mobilization could reduce pain, improve motor function, and prevent the formation of scar tissue associated with high repetition overuse injuries. The authors point out that overuse work-related musculoskeletal disorders, such as carpal tunnel syndrome, are extremely common, affecting more than 600,000 people annually. Overuse musculoskeletal injuries are responsible for 34% of all lost workdays. 

To evaluate efficacy of manual therapies in managing overuse injuries, the authors took 28 rats and placed them in specially designed cages designed with shoulder high tubular portals. In order to eat, the rats had to fully insert their arm into the portal in order to pull a handle that would then release food. The rats underwent a 6-week training period to familiarize themselves with the reaching and handle-pulling task. The rats were then divided into 3 groups. One group served as a control, and the other 2 groups were placed into a physically stressful training protocol in which they were forced to use significantly more pulling force in order to obtain their food. This was an extremely elaborate study in which the force necessary to pull the handle was measured with a strain transducer, the frequency of pulls was measured (4 per minute), and the time spent pulling on the handle was recorded in milliseconds. Of the 2 groups of rats participating in the high-force high-frequency feeding task, one group received 10 minutes of massage and manual therapy 5 days a week, and the other did not. The massage and manual therapy consisted of gentle mobilization, skin rolling, and deep strokes to the forearm flexor muscles, coupled with joint mobilization of the wrists. The majority of treatments were administered by Dr. Bove, who previously practiced as a chiropractor and was skilled in manual techniques.

Throughout the 12-week study, the behavior of the rats was recorded, as researchers specifically looked for limb guarding, paw licking and/or limping. Also, a special device was used to measure grip strength in the rats’ forepaw every 2 weeks throughout the study. At the end of the study specific sections of various muscles, tendons, nerves and bones were meticulously prepared for histological and microscopic study. Figure 1 demonstrates longitudinal sections of the median nerve at the level of the carpal tunnel, showing that compared to the rats receiving massage, the untreated rats had significantly increased scar tissue formation (blue staining) between the individual nerve fibers. Figure 2 illustrates scar tissue formation between muscle fibers (arrows), which is not present in the group receiving massage and mobilization.

The authors state that their research clearly proves that manual therapy reduces scar tissue formation typically associated with overuse injuries. Grip strength analysis over the 12-week period also confirmed that the group that did not receive massage had significantly reduced strength, while the group receiving massage had no reduction in grip strength. This finding alone has huge implications for the management of sports related injuries, as strength can be maintained despite high physical loads. The group receiving massage also had better overall motor performance, as voluntary task performance measures were significantly better in the massage treatment group.

Overall, this study proves that manual therapy applied in the early stages of symptom development prevents the strength declines associated with overuse injuries and improves overall task performance. The authors also show that manual therapy reduces the formation of scar tissue in and around nerves and muscles, which could play an important role in the management of injuries like carpal tunnel syndrome. Given the overall safety and obvious benefit, massage and mobilization should be considered not just for high-resistance high-force overuse injuries, but for all musculoskeletal injuries, especially in the early stages following an initial injury. This is particularly important when you consider the vast majority of these injuries are treated with nonsteroidal anti-inflammatory drugs, such as ibuprofen, which have negative side effects, including gastrointestinal bleeding, renal toxicity, increased risk of myocardial infarction, and/or hypertension. Even short-term use of corticosteroids (i.e., less than 14 days) has been linked to severe adverse effects, even among relatively healthy users. In a recent study of more than 2.6 million patients receiving short-term oral corticosteroids, 2.7% of the treated population developed GI bleeds, and 1.3 per thousand developed heart failure. The authors of this study acknowledge that these numbers may represent an underestimation, because they excluded people under the age of 20 and over the age of 64.

References:

1. Yao T, et al. Association between oral corticosteroid bursts and severe ad adverse events. Ann Intern Med 7 July 2020.