Research Review Corner: Mechanical Traction

Shawn Thistle
February 13, 2008
Written by Shawn Thistle
Can it benefit a subgroup of LBP patients?

Study title:
Is there a subgroup of patients with low back pain likely to
benefit from mechanical traction? Results of a randomized clinical trial and
subgrouping analysis
Author: Fritz, JM., et al. 
Publication information:  Spine 2007; 32(26): E793-E800.
Summary:  Below

Recent evidence-based practice guidelines1, a narrative literature review2, and even a Cochrane Collaboration Review3 have indicated that mechanical traction for treatment of low back pain (LBP) with or without sciatica cannot be endorsed.   This lack of support is based upon clinical trials that compared traction to a sham treatment, placebo, or other treatments using heterogenous samples of LBP patients.  Recent evidence has suggested that matching LBP patients to interventions based on a Clinical Prediction Rule (or CPR) which incorporates historical and physical examination factors can improve outcomes, and hence improve the power of clinical research.  Most research conducted on traction has not utilized such an approach. 

Expert opinion, and research thus far on the LBP CPR has identified the
following defining factors as those most likely to identify patients who will benefit
from traction:

• presence of sciatica

• signs of nerve root compression

• a positive straight leg raise test

• failure to demonstrate centralization on clinical examination

The purpose of this study was to determine whether a subgroup of patients could be identified who would respond favourably to mechanical traction.  Sixty-four subjects (average age 41.1) with pain and/or numbness extending distal to the buttock, signs or nerve root compression, and Oswestry score ≥ 30% were randomized into one of two treatment groups:

1) Extension Oriented Treatment Approach (EOTA) (n=33) – received exercises and mobilization to promote lumbar extension and centralization of symptoms (nine sessions in six weeks plus home exercise).

2) Traction plus EOTA (n=31) – exact intervention as EOTA group plus mechanical traction using an adjustable table for the first two weeks (three-dimensional ActiveTrac Table, The Saunders Group Inc.) with the patient prone.  Traction was performed for 12 minutes (including one minute ramp-up and down) using 40-60% of the patient’s body weight.

Outcomes were assessed at baseline, and at two and six weeks, and included: pain intensity on an eleven-point Numeric Pain Rating Scale, Oswestry Disability Index (ODI), Fear-Avoidance Beliefs Questionnaire (FABQ), and a fifteen-point Global Rating of Change Questionnaire.

Pertinent Results of this Study Include:

• the traction group displayed greater improvements in disability (mean adjusted ODI difference of 7.2 points) and fear-avoidance (mean adjusted FABQ difference 2.6 points) at two weeks (remember, traction was only utilized for the first two weeks)

• there were no between-group differences as six weeks (using intent-to-treat analysis)

• after six weeks – 82.6% of traction/EOTA patients reported improvement versus 73.1% in the EOTA group

• rates of success based on 50% ODI improvement were almost identical – 60.9% and 61.5% respectively

• two baseline variables were associated with greater improvements with traction: peripheralization with extension movement, and a positive crossed-SLR
Conclusions and Practical Application:

This study suggests that a subgroup of LBP patients does exist that is more likely to benefit from mechanical traction, which supports previous research on the LBP CPR, and expert opinion.  Greater reductions in disability and fear-avoidance were noted in the traction group at two week follow-up, but not at six weeks.  This suggests that the addition of traction has no lasting benefit.  However, the fact that this benefit disappeared at six weeks may suggest that the two week traction intervention needs to be longer to maximize efficacy.  

This study should be considered preliminary due to the short follow-up period and small sample size – further research is required.


1) Airaksinen O et al.  European guidelines for the management of chronic non-specific low back pain.  European Spine Journal 2006; 15(suppl): S192-S300.

2) Daniel DM. Non-surgical spinal decompression therapy: Does the scientific literature support efficacy claims made in the advertising media? BMC Chiropractic & Osteopathy 2007; 15:7.

3) Clarke J et al.  Traction for low back pain with or without sciatica: An updated systematic review within the framework of the Cochrane Collaboration. Spine 2006; 31(14): 1591-1599.

Dr. Shawn Thistle is the founder and president of Research Review Service, Inc., an online, subscription-based service designed to help busy practitioners to integrate current, relevant scientific evidence into their practice.  Shawn graduated from CMCC and holds an Honours Degree in Kinesiology from McMaster University.  He also holds a certificate in Contemporary Medical Accupuncture from McMaster University, and is a Certified Active Release Techniques (ART) Provider.  For more information about the Research Review Service, visit 


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