Research Review Corner: October 2009

Readers should be familiar with shoulder impingement syndrome (SIS), a
generic term for a common ailment involving painful impingement of the
rotator cuff beneath the acromion. This condition (of variable origin)
is responsible for a large percentage of shoulder complaints.

Background Information:
Readers should be familiar with shoulder impingement syndrome (SIS), a generic term for a common ailment involving painful impingement of the rotator cuff beneath the acromion. This condition (of variable origin) is responsible for a large percentage of shoulder complaints. All-cause shoulder pain (including SIS) is prevalent, affecting up to 35 per cent of the adult population. It can be recurrent, and is often disabling. Numerous potential pain generators exist in this region, but unfortunately an exact diagnosis is often elusive as many common orthopedic tests are of limited value.

A relationship between cervical and thoracic spine joint dysfunction and shoulder pain has long been suggested, and makes sense based on the segmental innervation of shoulder structures as well as the functional anatomy of the region. Anecdotally, chiropractors have reported reduction of shoulder symptoms after treatment aimed at the cervical and/or thoracic spine regions, despite a lack of published literature to support this approach. Although the two studies discussed here are small and thus must be considered preliminary, taken together they provide some promising evidence that manipulation and mobilization represent viable treatment options shoulder complaints. Larger studies that address the inherent limitations of these study designs are needed to further develop this body of knowledge, but the potential benefit of these treatment strategies has certainly been established and we should be aware of this literature.

Study Descriptions and Results:
Study #1: McClatchie et al.:
This randomized, blinded, placebo-controlled cross-over trial assessed the immediate effects of C5-7 lateral glide mobilizations on shoulder pain intensity and abduction painful arc in 21 subjects with shoulder pain (average age ~49) who were asymptomatic in the cervical spine. Both male and female subjects were included who had insidious onset shoulder pain (with a painful abduction arc) of at least six weeks’ duration that was unresponsive to standard physiotherapy including “traditional” movement, strengthening, and/or electrotherapeutic modalities. Excluded were those with neurological deficits, neck pain in the previous year, or a history of injection therapy or shoulder surgery. All patients attended two study sessions (one mobilization and one placebo, four days apart). Lateral glide mobilizations (Grade IV+, two minutes at each level from C5-C7) were performed at one session with the patient seated. Placebo treatment involved the examiner simply resting their hands on the subject’s neck without the application of force. The order of the sessions was determined via coin toss. Outcome measures included a 10cm visual analogue scale (VAS), cervical and glenohumeral ROM, and electrodynamometer measurement of shoulder abduction strength at 90°. Pertinent results follow:

• After the cervical mobilization treatment, shoulder painful abduction arc (12.5° ± 15.6°, p = 0.002) and shoulder pain intensity (1.3cm ± 1.1cm, p < 0.001) both decreased significantly.
• 18/21 subjects (86%) showed an average VAS decrease of 1.5cm.
• Following the placebo treatment there was only a 0.2cm average reduction in VAS (not statistically significant), and shoulder painful arc was reduced by only 8.8°±12.7°.
• Mobilization and placebo were significantly different (p = 0.0002), with mobilization demonstrating a treatment effect of -1.038.
• Cervical ROM was not significantly different after mobilization or placebo treatments.

Study #2: Boyles et al.:
This study, featuring a larger, younger study group (n=56, average age 32), was an exploratory, one group pre-test/post-test study investigating the short-term effects of thoracic thrust manipulation on shoulder impingement subjects. All participants underwent a standard physical examination followed by one treatment session involving thrust manipulation directed at the thoracic spine. Before and 48 hours post-treatment, subjects completed two questionnaires: the Numeric Pain Rating Scale (NPRS) and a Shoulder Pain and Disability Index (SPADI). Pertinent results follow:

• Overall the results were promising: 48-hour post-treatment reductions in NPRS scores for the Neer impingement sign, Hawkins-Kennedy test, resisted empty-can, resisted external and internal rotation, and active abduction were all statistically significant (p < 0.01), as was the SPADI score (p < 0.01).
• After closer evaluation of the numbers – the individual responses to thoracic SMT were varied suggesting that subgroups of patients may exist – this is a topic for future studies.

Conclusions and Practical Application:
Despite their limitations and small size, the two studies summarized above paint a promising picture for the role of manipulation/mobilization in the management of shoulder conditions. Improvements were noted in pain levels, range of motion, and orthopedic test pain levels. Stay tuned for further research on this topic…

Dr. Shawn Thistle is the founder and president of Research Review Service Inc., an online, subscription-based service designed to help busy practitioners to integrate current, relevant scientific evidence into  their practice. Shawn graduated from CMCC and holds an Honours Degree in Kinesiology from McMaster University. He also holds a certificate in Contemporary Medical Acupuncture from McMaster University, and is a Certified Active Release Techniques (ART®) Provider.  For more information about the Research Review Service, visit  www.researchreviewservice.com .