Summary and Perspective of Recent Literature
The aim of this multi-center prospective study was to investigate how classifying and treating patients with shoulder complaints according to MDT principles would affect the agreement levels of three commonly used Orthopedic Special Tests (OST) over time. This study ran concurrently with a study by the same authors that investigated the clinical application of MDT in patients with shoulder disorders1.
The authors have acknowledged the body of evidence on the complex nature of establishing a diagnosis that leads to the appropriate management of shoulder conditions, highlighting the limited validity of commonly taught and used Orthopedic Special Tests (OST) to diagnose and consequently guide treatment decision making. They suggest that the use of a more reliable non-pathoanatomical classification system of diagnosis and treatment, such as MDT, might decrease practice variation and promote increased treatment effectiveness.
Participants of the study presented to physiotherapy with shoulder disorders. They were excluded if they had had surgery in the previous six months. They were assessed and treated by 15 therapists either Diplomaed or Credentialed in Mechanical Diagnosis and Therapy with at least one-year experience using MDT for the extremities with other blinded clinicians performing the OSTs. The OSTs performed were: Empty Can, Hawkins-Kennedy and Speed’s. The data on the OSTs was collected at sessions one, three, five and eight, or at discharge from physiotherapy treatment, whichever came first.
One-way analysis of variance (ANOVA) and chi-square analysis was performed to compare baseline characteristics and potential confounding factors among MDT classifications. The Kappa coefficients were calculated to determine the level of agreement of OSTs during treatment within each MDT classification and the results were included in the analysis when they were available at least three out of four data collection points.
From the 105 recruited patients, 12 drop outs and other exclusions, left a total of 75 eligible patients.
There was no statistically significant difference among the three main MDT classifications of Derangement, Dysfunction and Spinal at baseline.
As illustrated on the table below, the overall kappa value for the Empty Can test was 0.28, with the highest level of agreement within the Dysfunction category (0.84 for articular and 0.49 for contractile). There was no agreement for the Spinal and Derangement classifications, as the P values were greater than 0.05.
For the Hawkins-Kennedy test, the overall kappa value was 0.28, with the highest level of agreement within the Dysfunction category 0.60 (0.42 for articular and 0.59 for contractile). The agreement for Spinal classification was 0.26 and there was no agreement for the Derangement classification as the P values were greater than 0.05.
The overall kappa value for the Speed’s test was 0.29, with the highest level of agreement within the Dysfunction category 0.46 (0.47 for articular and 0.45 for contractile). The agreement level for Spinal classification was 0.37 and there was no agreement for the Derangement classification as the P values were greater than 0.05.
Abbreviations: AD, Articular Dysfunction; CD, Contractile Dysfunction
Shoulder complaints are commonly encountered by healthcare professionals in the general population and have been reported to be the third most prevalent form of complaint in average physiotherapy practice2,3. However, the pathophysiology or pathoanatomy underlying shoulder disorders is unclear4. There appears to be a variety of issues in linking shoulder diagnosis to its management and these include a lack of standardized diagnostic labels, limited reliability5 and validity of most OSTs6. These issues may explain the persistent nature and high recurrence rates of shoulder disorders.
The gold standard for diagnostic comparison with clinical tests have traditionally been through direct intraoperative observation or imaging studies. As evidence has shown, not all structural failure correlates with symptoms7, and it is then evident that those gold standards are not ideal references. This might explain the high number of false positives and negatives observed on performing such tests in a clinical environment. Consequently, clinical decision making based on OSTs or imaging findings is flawed and does not provide an accurate pathoanatomical diagnosis, nor does it provide guidance to optimal management strategies.
This is an important study and the first of its kind to demonstrate and expose the low, or lack of, agreement of three common OSTs to diagnose shoulder disorder in the presence of either a shoulder or Cervical Derangement. The results are in agreement with the author’s predictions, and is no surprise to MDT clinicians who understand the variable and quickly changing nature of the Derangement. The better levels of agreement that were observed for Dysfunction Syndrome is also no surprise, as Dysfunctions are described as having a greater consistency on symptomatic and mechanical presentation.
The authors do report some limitations of their study, one of which being that they only examined three OSTs, consequently results cannot be extrapolated to all other OSTs intended to diagnose shoulder disorders.
The results of this study may give additional support to the position taken that OSTs cannot be relied upon as diagnostic or prognostic tools, but ruling out Derangements before testing may be useful. This could potentially increase the clinical value of performing such OSTs and possibly improve their diagnostic capability.
- Heidar Abady A, Rosedale R, Chesworth B, Rotondi M, Overend T. (2017). Application of the McKenzie system of Mechanical Diagnosis and Therapy (MDT) in patients with shoulder pain; a prospective longitudinal study. J Man Manip Ther; DOI:10.1080/10669817.2017.1313929.
- Van Der Windt, D. A., Koes, B. W., Boeke, A. J., Deville, W., De Jong, B. A. & Bouter, L. M. (1996). Shoulder disorders in general practice: prognostic indicators of outcome. Br J Gen Prac;, 46: 519-23.
- Kooijman et al. (2003). Patients with shoulder syndromes in general and physiotherapy practice: an observational study. BMC Musculoskeletal Disorders; 14:128.
- Lewis J, Green A, Dekel S. (2001). The aetiology of shoulder impingement syndrome. Physiotherapy; 87:458-469.
- May S, Greasley A, Reeve S, Withers S. (2008.) Expert therapists use specific clinical reasoning process in the assessment and management of patients with shoulder pain: a qualitative study. Australian Journal of Physiotherapy; 54:261-266.
- Hegedus EJ et al. (2008). Physical examination tests of the shoulder: a systematic review with meta-analysis of individual tests. BJSM; 42:80-92.
- Connor PM, Banks DM, Tyson AB, et al. (2003). Magnetic resonance imaging of the asymptomatic shoulder of overhead athletes. Am J Sports Med; 31:724-727.