After reading these articles, it would appear that, while there are many hypotheses to the changes in shoulder impairments following thoracic spine manipulation, we still are uncertain about the mechanism. Strunce et al looked at the effect of thoracic and rib manipulations had on shoulder pain in general. The authors found both an increase in shoulder ROM and a decrease in pain. This study, like many others related to this topic, had several methodological errors. There was no blinding, randomization, or control. That doesn't mean the results of this study should be disregarded. It at least should bring the idea of regional interdependence to consideration in your differential diagnosis. Walser et al performed a systematic review for the effect of thoracic manipulations on various musculoskeletal conditions. The authors reported that significant differences were found between those who had a thoracic manipulation and those who did not, in the short-term. In the long-term, there was no difference.
Scapular upward rotation is one of the usual suspects in regards to causes of subacromial impingement and rotator cuff tendinopathy. Interestingly, the literature varies on findings of decreased upward rotation to increased upward rotation in these patients (Muth et al, 2012). This study found that thoracic manipulation resulted in minimal decreases in scapular upward rotation, along with little to no change in EMG activity of the shoulder musculature. On the other hand, t-spine manipulation was found to increase shoulder elevation force production and improve both level of function and pain. While no change in shoulder elevation ROM was found, this may have been due to the fact that ROM was measured with weighted glenohumeral elevation. Strunce et al, however, did find an increase in glenohumeral motion following thoracic manipulation.
Boyles et al performed an exploratory study on the effects of a single thoracic spine manipulation on subacromial impingement syndrome. While no additional treatment was performed, the authors were able to find statistically significant changes in both pain and disability scores in just 48 hours; however, these results were not found to be clinically significant, based on the established minimal change for clinical significance. The methods of this study were lacking in several areas: low participant number, no randomization, no control group, and more. The authors realized this and emphasized the fact that this study should be used as a launching point for further studies. The fact that significant changes were created after one treatment alone in just 48 hours suggests the potential for a component of care in dealing with patient suffering from subacromial impingement syndrome. Just as manual therapy + exercise was found to be greater than exercise alone for cervical pain, maybe the same applies to these conditions. Additionally, when using thoracic manipulations for cervical pain or lumbar manipulations for low back pain, there exists specific inclusion criteria in order to have the desired results. Again, maybe the same applies to thoracic manipulation for subacromial impingement (or other should pathologies) and we just need to discover the criteria. Sounds like a perfect research opportunity! Obviously, solid evidence on this topic is still lacking, but we hope that this research has at least opened your mind to the possibility of regional interdependence in your patients and maybe treating either the cervical or thoracic spine (or both) the next time you have a patient with a shoulder pathology.
Boyles RE, Ritland BM, Miracle BM, Barclay DM, Faul MS, Moore JH, Koppenhaver SL, Wainner RS. (2009). The short-term effects of thoracic spine thrust manipulation on patients with shoulder impingement syndrome. Man Ther. 2009 Aug;14(4):375-80. Web. 15 May 2013.
Muth S, Barbe MF, Lauer R, McClure PW. (2012). The effects of thoracic spine manipulation in subjects with signs of rotator cuff tendinopathy. J Orthop Sports Phys Ther. 2012 Dec;42(12):1005-16. Web. 15 May 2013.
Strunce JB, Walker MJ, Boyles RE, Young BA. (2009). The immediate effects of thoracic spine and rib manipulation on subjects with primary complaints of shoulder pain. J Man Manip Ther. 2009;17(4):230-6. Web. 15 May 2013.
Walser RF, Meserve BB, Boucher TR. (2009). The effectiveness of thoracic spine manipulation for the management of musculoskeletal conditions: a systematic review and meta-analysis of randomized clinical trials. J Man Manip Ther. 2009;17(4):237-46. Web. 15 May 2013.