Literature Reviews - 2

Summary and Perspective of Recent Literature

Thackeray A, Fritz J, Childs J, Brennan G. (2016). The Effectiveness of Mechanical Traction Among Subgroups of Patients with Low Back Pain and Leg Pain: A Randomized Trial. J Orthop Sports Phys Ther; 46: 144-154.

The study had two purposes:

  • To examine the effectiveness of traction in patients with nerve root compromise within a specific subgroup in the Treatment Based Classification (TBC) system.
  • To determine if mechanical traction in addition to an extension oriented treatment approach (EOTA) will have better outcomes than an EOTA without traction after six weeks, six months and one year.

It has long been proposed that classifying LBP patients and making treatment decisions based on a patient’s clinical presentation would yield better outcomes. Mechanical traction in the treatment of LBP with nerve root involvement has been used for many decades, but, as yet, has unproven efficacy. Some clinicians feel that traction may have a place in musculoskeletal care with patients presenting with highly ‘irritable’ symptoms, a greater intensity of leg pain and exhibiting signs of neurological compromise. Initial studies conducted by Fritz (2010) found greater improvement in disability in the first two weeks of treatment using an EOTA with traction, but no difference at six weeks.

A subgroup criteria was first defined in the TBC system identifying patients who would likely benefit from traction. Patients who either peripheralised with extension movement on testing and/or those who exhibited a positive crossed straight leg raise (CSLR) test were proposed to benefit. 

This study examined changes over time (six weeks, six months and one year) and interaction between treatments and subgrouping status. An intention-to-treat analysis was used to account for lost participants. 120 patients with LBP and signs of nerve root compression were randomized using predefined subgroup criteria at baseline. Patients who peripheralized with one extension movement and/or had a positive crossed SLR were assigned to the EOTA with traction, and those who were negative on both of these findings were assigned to the EOTA. The study outcomes included the Oswestry Disability Index (ODI), global rating of improvement, as well as average LBP and leg pain.


At the end of 12 months, 49 participants were lost to follow-up and 71 completed the study. The proportion of patients reporting a successful outcome at six weeks, six months and one year did not differ between groups, even when analyzed by matched treatment.

The table below shows the percentage of participants reporting a successful outcome at each timeline. Furthermore, reports on treatment side effects were obtained at six weeks and found no significant differences between treatment groups in severity of reported side effects.

LiteratureReviews Vol5No2 2 GRAPH

A successful outcome was defined in the study as a patient who reported his/her change in global rating scale with treatment as “quite a bit better” or “a very great deal better.”

Correspondingly, the authors analyzed the impact on duration of symptoms as a predictor of poor prognosis, but this only had a ‘marginal effect’. Patients lost to follow-up (n=49) had a higher level of leg pain intensity, higher scores in Sciatica Bothersome Index, FABQ-work, and Pain Catastrophizing scale.


The aim of this well-designed study was to determine the clinical effectiveness of adding mechanical traction to a treatment approach utlising the extension principle (which they refer to as EOTA).  As MDT trained clinicians we can find many shortcomings in their EOTA treatment protocol, namely the lack of training (each clinician was given only 90 minutes of training), the lack of patient-specific clinical reasoning which should occur each treatment session according to the symptomatic and mechanical response, the lack of information of the specifics of the self-management programme (we are not informed as to whether the EOTA patients performed frequent sessions of the appropriate repeated movements throughout the day or not), and the significant number of treatments given (average 10 treatment sessions over six weeks). However, the purpose of the study was to prove the additional benefit mechanical traction can provide to patients within a specific subgroup, namely low back pain and radiculopathy, thereby justifying its continued use in some clinical settings. Their conclusion is that there is no clinical benefit to adding mechanical traction to this group of patients.

In their discussion, the authors suggest that perhaps mechanical traction could be used to determine if centralization can be achieved. However, if there is no clinical benefit to using traction, why not correctly use the repeated movement testing sequence and follow MDT protocols to determine centralisation instead?

It is certainly worth noting that despite all the patients having nerve root compromise, and the fact that it is acknowledged that this group can be “challenging and costly to manage”, significant improvements were gained and maintained for all these participants with a directional-oriented approach. Though, with no control group we cannot draw too many conclusions about this how much of this change is due to the effect of the treatment itself.

There are a couple of limitations to this study that need to be taken into consideration. One is that the 120 patients were spread over nine clinics in two cities, which could make it difficult to ensure the treatment protocols were strictly followed by the number of clinicians which must have been involved. The clinicians were only given one 90-minute training session, which could result in a lack of clinical reasoning process to ensure optimal outcome. This could have been addressed by close clinical supervision, but we are not told at what level this occurred, if at all.  Another limitation is the large percentage lost to follow up (41%). This resulted in a small number of patients having adequate data at one year follow up.

This study was very specific in its patient selection, targeting those that should, in theory, benefit from traction being applied to a lumbar spine with a compromised nerve root. However, there was no benefit found, as well as there being more side effects reported with the traction group.  It does, therefore, raise the question of why some clinicians are still choosing to use mechanical traction for treating their low back pain patients. Surely, this study is another nail in the coffin for the use of lumbar traction…maybe the final nail?