Application of the McKenzie system of Mechanical Diagnosis and Therapy (MDT) in patients with shoulder pain

The primary objective was to determine if the pain and function response to the McKenzie system of Mechanical Diagnosis and Therapy (MDT) differs by MDT classification category at two and four weeks following the start of MDT treatment for shoulder complaints. The secondary objective was to describe the frequency of discharge over time by MDT classification.

International, MDT-trained study collaborators recruited 93 patients attending physiotherapy for rehabilitation of a shoulder problem. The Numeric Pain Rating Scale (NPRS) and the Upper Extremity Functional Index (UEFI) were collected at the initial assessment and two and four weeks after treatment commenced. A two-way mixed model analysis of variance with planned pairwise comparisons was performed to identify where the differences between MDT classification groups actually existed.

The Derangement and Spinal classifications had significantly lower NPRS scores than the Dysfunction group at week 2 and week 4 (p < 0.05). The Derangement and Spinal classifications had significantly higher UEFI scores than the Dysfunction group at week 2 and week 4 (p < 0.05). The frequency of discharge at week 2 was 37% for both Derangement and Spinal classifications, with no discharges for the Dysfunction classification at this time point. The frequency of discharge at week 4 was 83, 82 and 15% for the Derangement, Spinal and Dysfunction classifications, respectively.

Classifying patients with shoulder pain using the MDT system can impact treatment outcomes and the frequency of discharge. When MDT-trained clinicians are allowed to match the intervention to a specific MDT classification, the outcome is aligned with the response expectation of the classification.