Application of force to C5 using a mechanically assisted instrument may improve internal rotation strength and frequency but not severity of extreme shoulder pain 6 months after treatment, according to a study published in Spine.

Investigators randomly assigned patients with referred shoulder pain to receive pressure with a mechanically assisted instrument (n=65) or no pressure with the same instrument (n=60; placebo). The mechanically assisted instrument used in this study was a handheld, spring-loaded instrument that the treating physician activated via compression of the handle on the shank of the device to deliver pressure to C5.

For the placebo group, the treating physician used 2 mechanically assisted instruments: 1 on C5 without applied pressure and the other in the other hand delivering a compression “click” to give the illusion of an action.

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The study’s primary outcome was patient-reported frequency and severity of shoulder pain at 24 weeks. Shoulder range of motion and strength assessed by both patient and examiner at time points ranging from 1 to 24 weeks were the study’s secondary outcomes.

Shoulder pain frequency and pain severity at rest were found to improve at 24 weeks in both groups compared with pretreatment levels (P <.05 and P <.001, respectively). Improvements in shoulder pain frequency and severity at rest were comparable at 24 weeks in the treatment and placebo groups.

The percentage of patients experiencing cervical pain on extension/rotation/lateral flexion and stiffness on cervical rotation at 24 weeks vs pretreatment levels was improved in both groups (P <.01 for both in treatment group; no difference between groups). Treatment with the mechanically assisted instrument led to improvements in shoulder strength internal rotation at 6 months compared with baseline levels. This improvement was thought to be due to treatment (P =.04) vs time.

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A limitation of this study is its relatively small sample size, which may have reduced the differences between the treatment and placebo groups.

”The major effect of a [mechanically assisted instrument] over placebo applied to the level of C5 of the spine two times per week for 6 weeks, then once a week for 3 weeks in patients who presented with referred shoulder pain was improved shoulder strength in internal rotation at 24 weeks. There was no effect found on referred shoulder pain,” concluded the study authors.

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Hardas GM, Murrell GAC. Prospective, randomized, double-blind, placebo-controlled clinical trial assessing the effects of applying a force to C5 by a mechanically assisted instrument on referred pain to the shoulder. Spine (Phila Pa 1976). 2018;43(7):461-466.