Summary and Perspective of Recent Literature
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
The aim of this study was to investigate if the response to MDT treatment with regard to pain and function for patients with shoulder pain varied by classification over time. An additional aim was to document the discharge rate by classification over time.
The MDT literature on shoulder conditions consists of Shoulder Derangement case reports (Aina and May, 2005; Kidd, 2013) and a case series (Aytona, 2013), a Contractile Dysfunction case report (Littlewood and May, 2007), and case reports of Cervical Derangements presenting as local shoulder pain (Menon and May, 2013; Pheasant, 2016). One survey of MDT Diplomats showed very good reliability in classifying shoulder patients according to the MDT system (Heidar A, et al., 2014).There have not been any previous large cohort studies evaluating the use of MDT in the shoulder. A previous survey of MDT clinicians (May and Rosedale, 2012) found that Derangement (42.5%), Contractile Dysfunction (11.7%) and Articular Dysfunction (10.8%) were common classifications in the shoulder.
A prospective longitudinal design was used to collect data on consecutive shoulder patients. 15 international physiotherapists with either Credential or Diploma level training were recruited with at least one year of experience using MDT for upper extremity problems. Patients were required to be over 18, speak English and were ineligible if they had a shoulder surgery in the previous six months. No other inclusion/exclusion criteria were applied. Patients were assessed using MDT and were treated “as-usual” depending on the determined classification.
Primary outcome measures were Upper Extremity Functional Index (UEFI) scores (0-80/80 with greater scores indicating better function) and Numeric Pain Rating Scale (NPRS) scores (0-10/10). Data collection points were at the initial assessment, two weeks later and four weeks later. The secondary outcome was the frequency of discharge for each classification at two and four weeks. The main groups compared in data analysis were Spinal (Cervical Derangement), Derangement (Shoulder Derangement) and Dysfunction (articular and contractile); the latter group combined both Dysfunctions together to balance out sample sizes between the groups and were considered by the authors to behave similarly.
Results
11 of these patients were excluded from final data analysis: seven had two concurrent MDT classifications (i.e.. Shoulder Derangement with residual Articular Dysfunction) and four were classified under OTHER. The group sizes were 35 for Derangement, 27 for Spinal and 20 for Dysfunction.
There were no significant differences between the three groups at the initial assessment for age, sex, hand dominancy, previous episodes, medication use, symptom duration, activity levels, NPRS scores or UEFI scores. Statistically significant differences were seen between the Dysfunction and Derangement groups and between Dysfunction and Spinal for NPRS and UEFI scores at two and four weeks. No significant differences were seen at any time points between the Shoulder Derangement and Spinal Derangement groups.
105 patients were recruited for the study, with 12 drop-outs. A breakdown of the final classifications of the 93 remaining patients is given below:
The Derangement and Spinal Derangement groups showed similar frequency of discharge at weeks two and four, while discharge frequency was significantly less in the Dysfunction group at both time points:
Commentary
This work is an important contribution to the growing body of MDT literature on the extremity, as it is the first study to provide evidence that classifying and matching treatment to shoulder patients using MDT is a valid approach. Because there were minimal exclusion criteria and 15 international physiotherapists were recruited using a treatment-as-usual approach, the results are generalizable to MDT clinicians seeing shoulder patients. As anticipated, based on clinical practice, a majority of patients were rapid responders; two-thirds of this cohort had either a Cervical or Shoulder Derangement. Remarkably, despite different anatomical origins, they responded in a virtually identical way, lending further weight to Derangement as a valid clinical entity. Additionally, though expected based on clinical experience, the slower response of Dysfunction patients was nicely captured in this study.
Several limitations were noted by the authors. The number of treatment sessions was not fixed which may have affected results, but because the recruited therapists were unaware of the study intentions it is likely they strove for the best possible outcome with each patient. No exercise compliance was tracked with implications for the slower responses in the Dysfunction group, although anecdotal evidence indicates that this response rate is typical for this group. There was no control group or randomization and only MDT trained clinicians were used; however, given the aim of the study, this design was justified.
Interestingly, a high proportion (29%) of Cervical Derangements was found, compared to 2% reported in the May and Rosedale study (2012). In a recent smaller study, Maccio et al. (2017) found two out of 19 wrist patients had a Cervical Derangement (10.5%). Together this suggests that Spinal Derangements masquerading as extremity problems are increasingly being recognized and the importance of a thorough spinal examination in all extremity patients cannot be understated. This may partially account for the low prevalence of OTHER (4.3%) compared to the 35% seen for shoulder patients in May and Rosedale (2012). Thus, 95.7% of the cohort could be classified into one or more of the mechanical syndromes, suggesting that the clear majority of the shoulder population can be managed with simple mechanical interventions.
The results of this study along with the expanding extremity literature should give MDT practitioners even greater confidence to use the system for extremity classification. Well-designed studies such as this are continuing to endorse the system as a comprehensive assessment and management paradigm and support what is seen clinically on a daily basis.
References
- Aina A, May S. (2005). A shoulder derangement. Manual Therapy; 10(2): 159-63.
- Aytona M, Dudley K. (2013). Rapid resolution of chronic shoulder pain classified as derangement using the McKenzie method: a case series. Journal of Manual & Manipulative Therapy; 21(4): 207-12.
- Heidar Abady A, Rosedale R, Overend T, Chesworth B, Rotondi M. (2014). Inter-examiner reliability of diplomats in the mechanical diagnosis and therapy system in assessing patients with shoulder pain. Journal of Manual and Manipulative Therapy; 22(4): 199-205.
- Kidd J. (2013) Treatment of shoulder pain utilizing mechanical diagnosis and therapy principles. Journal of Manual & Manipulative Therapy; 21(3): 168-73.
- Littlewood C, May S. (2007.) A contractile dysfunction of the shoulder. Manual Therapy; 12(1): 80-83.
- May S, Rosedale R. (2012). A survey of the McKenzie Classification System in the Extremities: prevalence of mechanical syndromes and preferred loading strategies. Physical Therapy; 92(9): 1175-86.
- Maccio J, Carlton L, Fink S, Ninan C, Van Vranken C, Biese G, McGowan C, Maccio J, Tranquillo J. (2017). Directional preference of the wrist: a preliminary investigation. Journal of Manual and Manipulative Therapy; (published online ahead of print 9 February). Available at: http://www.tandfonline.com/doi/full/10.1080/10669817.2017.1283767. (Accessed July 5, 2017).
- Menon A, May S. (2013). Shoulder pain: differential diagnosis with mechanical diagnosis and therapy extremity assessment - a case report. Manual Therapy; 18(4): 354-7.
- Pheasant S. (2016). Cervical contribution to functional shoulder impingement: two case reports. The International Journal of Sports Physical Therapy; 11(6): 980-991.