The Mechanical Diagnosis and Therapy system has three broad treatment classifications: postural, dysfunction, and derangement syndromes. Each classification treats a distinct underlying cause of disablement. There are also sub-classifications in each group.
A postural syndrome is the result of prolonged postures or positions that can affect joint surfaces, muscles, or tendons. Pain may be local and reproducible when end range positions, such as slouching, are maintained for sustained periods of time. Repeated movements do not change symptoms in postural syndrome patients, and response (i.e. pain relief) is usually immediate.
It is valuable to have the patient perform poor postural positions followed by the symptom-abolishing positions in order for them to 'understand' what is leading to their discomfort and train patients to avoid them.
The dysfunction classification is so named because it implies some sort of adaptive shortening, scarring, or adherence of connective tissue causing discomfort. A dysfunction may be intermittent or chronic, but its hallmark is a consistent movement loss and pain at the end range of movement. When the patient moves away from end range their pain is decreased.
Successful treatment takes time because it focuses on tissue remodeling which requires constant attention. Patient education is critical for this syndrome, because the patient will need to understand that remodeling tissue can be slow and often uncomfortable because the exercises prescribed are intended to challenge any adhesions or tissue scarring that has occurred.
The derangement classification is the most common syndrome that presents clinically. Its hallmark is its sensitivity to certain movements and its preference for particular movement patterns. When certain movements are performed, such as a flexion and/or extension (bending or straightening) the symptoms (e.g. low back pain) become either more central (e.g. just in the low back) or less intense.
It is not uncommon for a patient to experience rapid reduction of their symptoms immediately during the assessment. That is to say, if their symptoms were pain in their right thigh, the pain may be moved more centrally to their buttock, or in some cases be completely abolished.1 Treatment for the patient with derangement syndrome, as with the postural and dysfunction syndromes, is directly guided by the patient's response to these provocative assessment movements.
While not all patients are successfully treated by Mechanical Diagnosis and Therapy exercise, it could be strongly argued that all patients with neck pain or low back pain may be successfully assessed by the Mechanical Diagnosis and Therapy method. Failure to find a mechanical component to the patient's pain is a significant finding, in that it is as important to know for whom McKenzie exercises will be successful and those for whom they will not.