Research Review By Dr. Jeff Muir©

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Date Posted:

June 2018

Study Title:

Evidence of splinting in low back pain? A systematic review of perturbation studies

Authors:

Prins MR, Griffioen M, Veeger TTJ, et al.

Author's Affiliations:

Research and Development, Military Rehabilitation Centre, ‘Aardenburg’, Doorn, The Netherlands; Amsterdam Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands; Institute for Human Movement Studies, HU University of Applied Sciences Utrecht, Utrecht, The Netherlands; Orthopaedic Biomechanics Laboratory, Fujian Medical University, Quanzhou, Fujian, People’s Republic of China.

Publication Information:

European Spine Journal 2018; 27: 40-59.

Background Information:

A prevailing assumption among clinicians treating patients with low back pain (LBP) is that, as part of their reaction to the condition, patients tend to guard or splint their lumbar spines via co-contraction of the trunk muscles (1). This is thought to explain the rigidity of movement noted among many LBP patients when performing activities of daily living (2) and also the reduced range of motion and increased coupling of pelvic and thoracic movements during gait (3, 4). However, there is little evidence supporting these hypotheses. In this systematic review, the authors sought to assess whether LBP patients do, in fact, display signs of splinting by evaluating studies that used unexpected mechanical perturbation to evaluate: trunk muscle activity, kinetic and kinematic trunk responses and estimated mechanical properties of the trunk. The authors expected that patients splinting their lumbar spine would display increased trunk muscle activation prior to perturbation, which would translate to increased kinetic responses and higher estimates of trunk stiffness.

Pertinent Results:

Literature Search Results & Study Characteristics:
  • 19 studies were included in the review.
  • 592 patients (286 intervention, 306 control) were included across all studies.
  • Perturbations were applied in all studies as follows: with the patient in a standing position in 11 studies, semi-seated in 5 and seated in 3.
Muscle Activation:
Pre-perturbation muscle activation was higher in 1 study, lower in 1 study and showed no difference in 3 studies. Six of 11 studies showed longer response times in multiple trunk muscles. The remaining studies showed response times as shorter or no different. In 6 studies, muscle activation amplitude was also variable, being higher in 3 studies but lower in 3 other studies.

Kinematic Response: 5 studies assessed kinematic responses by inducing movement in a sagittal plane. Overall, smaller movements in the lumbar spine were noted in LBP patients, who compensated with hip mobility. Later initiation of movements was also noted in LBP patients.

Kinetic Response: 2 studies reported kinetic outcomes by either perturbing via release of a swing chair, which induced no differences in hip/trunk muscle power, or by translation of the standing surface, where the first peak in trunk movement occurred earlier in LBP patients.

Estimated Mechanical Properties of the Trunk: The same 2 studies assessed estimated mechanical trunk properties. Neither study noted significant differences between study groups in trunk damping.

Clinical Application & Conclusions:

The authors concluded that there was no convincing evidence for the presence of splinting behaviour among patients with LBP, despite this conventional thinking among clinicians. They do however, agree that the indication of delayed onset of muscle activation in reaction to perturbation warrants further study.

EDITOR’S NOTE: as mentioned, altered muscle activation or ‘splinting’ has been a popular theory surrounding the genesis of LBP in many patients. Unfortunately, the evidence doesn’t point to a consistent pattern that we might apply in patient care. Once again, this supports an individualized approach to assessment and management of this condition, as some patients certainly do present with splinting patterns or behaviours, which could represent a treatment target as part of a comprehensive management strategy.

Study Methods:

A comprehensive search strategy was used to identify randomized, clinical trials comparing mechanical trunk perturbation in LBP patients as compared with healthy controls. All relevant databases (CINAHL, EMBASE, MEDLINE, etc.) were searched. The search strategy contained 5 blocks: 1) low back pain; 2) perturbations; 3) muscular response; 4) kinematic and/or kinetic response; and 5) estimated mechanical trunk properties. Data was extracted by the first author. Results were pooled overall and, if three or more studies reported a statistically significant difference between groups, results in that group were also pooled.

Study Strengths / Weaknesses:

Strengths:
  • The authors employed a comprehensive and appropriate search strategy.
  • Appropriate data analysis and blinding maintained among review authors.
Weaknesses:
  • Overall there was a low number of eligible studies given the wide variety of outcomes. As such, the pooled results for many outcomes consist of few studies.
  • The total sample size across 19 studies was only 592, suggesting a need for larger studies.

Additional References:

  1. Wolf SL, Nacht M, Kelly JL. EMG feedback training during dynamic movement for low back pain patients. Behav Ther 1982; 13: 395–406.
  2. Keefe FJ, Hill RW. An objective approach to quantifying pain behavior and gait patterns in low back pain patients. Pain 1985; 21: 153–161.
  3. Lamoth CJC, Meijer OG, Wuisman PIJM, van Diee¨n JH, Levin MF, Beek PJ. Pelvis-thorax coordination in the transverse plane during walking in persons with nonspecific low back pain. Spine 2002; 27: E92–E99. doi:10.1097/00007632- 200202150-00016
  4. van den Hoorn W, Bruijn SM, Meijer OG, Hodges PW, van Dieen JH/ Mechanical coupling between transverse plane pelvis and thorax rotations during gait is higher in people with low back pain. J Biomech 2012; 45: 342–347. doi:10.1016/j.jbiomech. 2011.10.024