A Regional Interdependence Model of Musculoskeletal Dysfunction: Research, Mechanisms, and Clinical Implications
SOURCE: J Man Manip Ther. 2013 (May); 21 (2): 90-102
Derrick G Sueki, Joshua A Cleland,
and Robert S Wainner
Department of Physical Therapy,
Mount St Mary’s College,
Los Angeles, CA, USA.
The term regional interdependence or RI has recently been introduced into the vernacular of physical therapy and rehabilitation literature as a clinical model of musculoskeletal assessment and intervention. The underlying premise of this model is that seemingly unrelated impairments in remote anatomical regions of the body may contribute to and be associated with a patient’s primary report of symptoms. The clinical implication of this premise is that interventions directed at one region of the body will often have effects at remote and seeming unrelated areas.
The formalized concept of RI is relatively new and was originally derived in an inductive manner from a variety of earlier publications and clinical observations. However, recent literature has provided additional support to the concept. The primary purpose of this article will be to further refine the operational definition for the concept of RI, examine supporting literature, discuss possible clinically relevant mechanisms, and conclude with a discussion of the implications of these findings on clinical practice and research.
KEYWORDS: Physical therapy; Regional interdependence; Rehabilitation
From the Full-Text Article:
Regional Interdependence or RI is the term that has been utilized to describe the clinical observations related to the relationship purported to exist between regions of the body, specifically with respect to the management of musculoskeletal disorders.  There is a growing body of literature demonstrating that interventions applied to one anatomical region can influence the outcome and function of other regions of the body that may be seemingly unrelated. [2–7] Despite the growing interest, controversy exists regarding the relevance of the RI model in physical therapy research and practice.  Therefore, RI warrants further examination and scientific scrutiny.
RI was initially defined and proposed as a part of a basic manipulation skills educational CD-ROM developed by Wainner et al. in 2001.  The concept of RI stemmed from the review of literature during which they observed that regions of the body appeared to be musculoskeletally linked. [10–12] Erhard and Bowling alluded to this concept in 1977 when they stated: ‘Dysfunction in any unit of the system will cause delivery of abnormal stresses to other segments of the system with the development of a subsequent dysfunction here as well’. 
Although Erhard’s observation preceded Wainner’s, RI was not proposed as a formal concept and did not gain wider recognition as a model of assessment and treatment in the peer-reviewed literature until Wainner et al. described it in an editorial in 2007.  At that time, it was proposed primarily as a clinical model to be considered and incorporated in the context of a ‘test-treat-retest’ approach  to treating patients with musculoskeletal disorders. Commentary in response to the original RI editorial countered the suggestion that RI was the result of musculoskeletal factors and suggested that RI may also involve a neurophysiological response.  The points made by Bialosky et al. in the response brought to light the fact that while the primary interest of RI has been physical manifestations (typically pain and range-of-motion) involving the musculoskeletal system, the mechanisms underlying these primary manifestations can be much more complex involving other physiological systems. 
Any condition or disorder initiates a series of responses that involves multiple systems of the body. Not only musculoskeletal but also neurophysiological, somatovisceral, and biopsychosocial responses occur when a disorder or condition disrupts homeostasis [16, 17] (Fig. 1).
Editor’s Note: The above paragraph sounds suspiciously like Palmer’s definition of a subluxation, doesn’t it?
These allostatic responses are all pieces of an integrated physiological process that functions to restore equilibrium and promote recovery [18, 19] (Fig. 2). The RI model as defined represents the musculoskeletal manifestation of a larger interdependent process by which other systems may be involved in eliciting these musculoskeletal changes.