Structure and Function

In musculoskeletal medicine, there are two main schools of thought:

One, is the traditional ‘western’ structural approach.  This structural approach is rooted in anatomy and biomechanics.  Orthopedic medicine is greatly influenced by a structural approach to pathology, relying heavily on visualization of structures through imaging (X-Ray, MRI, CT Scan, etc.). Structural lesions are damage to physical structures such as ligaments, bones, cartilage, etc., that can be diagnosed by imaging and/or special clinical tests. These types of lesion are repaired through immobilization, surgery, or rehabilitation.  The diagnosis and treatment of structural lesions is well supported in the scientific literature.  The structural approach is a foundational aspect of medical education and practice, in the U.S.

In many patients, however, the diagnostic tests for structural lesions may be inconclusive, or altogether negative.  Or, immobilization, surgery, and/or rehabilitation do not cure the lesion, leaving the patient and clinician at a loss.  More than likely, a functional lesion is the cause of the problem.

In the functional approach, Janda defines functional pathology as impairment in the ability of a structure or physiological system to perform its job; muscle and movement impairment often manifest in the body through reflexive changes.  Typically, this type termed functional lesion, is more difficult to understand, assess, and treat, requiring an alternative way of thinking and seeing.

Functional lesions cannot be observed directly with structural tools such as MRI.  Clinicians must envision the dysfunction by understanding the complex interactions of the ‘sensorimotor’ system. This is a paradigm shift from thinking only in terms of structure, and not understanding the functional aspect.  The functional approach allows us to discover and treat the cause of the pathology rather than focus only on the pathology itself.

The traditional structural approach relies on visualizing static structures, where clinicians typically look at function from an origin/insertion point of view, suggesting that a muscle functions only to move the insertion closer to the origin.  The functional approach recognizes the true function of the muscle, which is based on coordinated movement in relation to other structures, and takes into account the stabilizing role of muscle.  For example, the primary function of the rotator cuff is not to rotate anything; (you knew that, right?), rather it is to adduct the humeral head and stabilize the glenohumeral joint.

Structure and function have been described as the ‘two sides of the same coin’.  They are not independent of each other, but deeply connected to and dependent on each other.  However, when our attention becomes imbalanced toward ‘structure’ our approach to evaluating, treating, and preventing ‘functional lesions’, becomes ineffective.

While understanding both the structural and functional approach is necessary for clinical practice, the fuctional approach is the key to rehabilitating dysfunctional muscle and movement syndromes.

Excerpted from:  (Page, Frank, Lardner.  Assessment and Treatment of Muscle Imbalance, The Janda Approach.  2010, Human Kinetics, Champagne IL.)

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