Lumbar spine coupled motions: A literature review with clinical implications

Introduction Paris and Loubert defined coupled motions as combined motions that are mechanically forced to occur. Kaltenborn et al proposed a more clinically oriented definition describing coupled motions as movement combinations that result in the greatest ease of movement, i.e., producing the greatest range of motion and the softest endfeel. In biomechanical terms, coupled motion is the phenomenon of a consistent association of a motion along or about one axis, whether it be a translation or a rotation, with another motion about or along a second axis; the principal motion cannot be produced without the associated motion occurring as well. Coupled motion can also be defined as the motion that occurs in directions other than the direction of the load applied. Coupled motions have obvious implications for manual medicine and, therefore, text books on this topic usually provide descriptions of coupling behavior, e.g., in the lumbar spine (Table 1). However, these text book descriptions are generally not supported by primary references. If references are provided, they are frequently outdated and of questionable methodology. Evidencebased practice (EBP) requires the use of best available research evidence. Recently, Whitmore produced a case report using a limited review of the literature on lumbar motion coupling to provide an evidence-based rationale for a manual medicine approach to the rehabilitation of low back pain (LBP) hypothesized to originate in mechanical dysfunction of L5-S1. A limited review of the literature carries the risk of not uncovering contradictory evidence. This goal of this article is to review the research evidence available on lumbar motion coupling. We will discuss the studies retrieved, review evidence for clinically relevant possible determinants of coupling behavior, and conclude with clinical implications of the evidence presented.