Coupling behavior of the thoracic spine: a systematic review of the literature

The knowledge of 3-dimensional spine coupling characteristics is important for treating patients with spinal pain. The purpose of this study was to examine the coupling directional pattern of the thoracic spine by systematic review. This review could help determine the use of coupling knowledge for manual therapy treatment.

A systematic review of studies examining in vivo and in vitro thoracic spine coupled motion was conducted using PubMed and Cumulative Index to Nursing and Allied Health Literature searches (1960-2006), as well as a separate hand-search. Study abstracts were independently reviewed and selected by two investigators based on face validity. The reliability between investigators was established using the Kappa (K) coefficient. A third investigator resolved any inclusion disagreement. Full studies were then evaluated for compliance with inclusion criteria. Coupling patterns from accepted studies were then qualitatively compared.

Of the 56 citations originally identified in the searches, the first two investigators reached consensus on 41 citations and required further assistance by the third investigator on 15 citations. The reliability between investigators was rated fair (K = 0.38). Twenty-one citations were deemed acceptable for further review. Of 21 citations, 8 met the inclusion criteria and were fully reviewed. No consistent coupling pattern was observed across the 8 studies, where they exhibited ipsilateral, contralateral, or mixed coupling behaviors.

Differences in study design, measurement method, and tissue preparation may have contributed to differences between studies. More quality, in vivo investigations are needed to evaluate thoracic coupling in symptomatic subjects in both a flexed and extended position.