Research Review By Dr. Michael Haneline©

Audio:

Download MP3

Date Posted:

April 2016

Study Title:

Does cervical lordosis change after spinal manipulation for non-specific neck pain? A prospective cohort study

Authors:

Shilton M, Branney j, de Vries BP, and Breen A

Author's Affiliations:

Faculty of Health and Social Sciences, Bournemouth University, Bournemouth, UK.

Publication Information:

Chiropractic & Manual Therapies 2015, 23: 33.

Background Information:

Neck pain affects approximately three quarters of all people at some point in their lives and is one of the most commonly reported reasons for ambulatory health care visits.

It has been reported that the degree of cervical lordosis (sagittal alignment) is an important outcome measure that may be helpful in directing treatment and in developing a prognosis. However, this perception has not been substantiated by high quality prospective research; neither has the notion that the degree of cervical lordosis is related is to neck pain. It has also been reported that cervical lordosis may change following injury or with disc degeneration.

Harrison et al. (1) carried out a study on 30 neck pain patients who received spinal manipulative therapy (SMT) and cervical traction, finding that there were increases in cervical lordosis that coincided with reduced pain. However, there were a number of flaws in the study that limit its usefulness.

The purpose of the present study was to explore the effects of cervical manipulation on cervical lordosis using the posterior tangent method to measure the degree of curvature.

This study had two main objectives:
  1. To determine the intra-observer and intra-subject repeatability (measurement error and reliability) for cervical lordosis measurement in healthy volunteers.
  2. To determine whether cervical lordosis changes at least as much as the minimum detectable change (MDC) after a course of spinal manipulation for non-specific neck pain.

Pertinent Results:

  • Groups were similar at baseline with regard to gender, age and amount of cervical lordosis.
  • In healthy volunteers, the intra-observer minimum detectable change (MDC) was 9.9°, which means that 2 measurements made on the same radiograph within 24 hours by one observer should differ by no more than 9.9° in 95% of subjects.
  • The intra-subject MDC was 13.5°, which means that the subjects’ lordosis measurements would be expected to change no more than 13.5° over a 4-week period. Accordingly, changes would have to be greater than 13.5° in order to be confident that they were associated with SMT.
  • Intra-observer error for measuring cervical lordosis was 3.6°, which was considered to be acceptable. The intraclass correlation coefficient (ICC) for the cervical lordosis measuring procedure was 0.98, which means the procedure would be considered reliable.
  • Patients’ cervical lordosis increased, on average, from +9.5° to +11.6°; however, the changes were not statistically significant. Furthermore, changes were highly variable, ranging from 0.1° to 24.9°.
  • Changes in patients’ cervical lordosis above the MDC of 9.9° occurred in only 14% (4/29) of patients.

Clinical Application & Conclusions:

This study reported that there was little change in patients’ cervical lordosis following SMT and the little amount of increase that was found was not statistically significant. Likewise, the increase was well below the natural variation that was observed in the healthy volunteers.

It has been suggested that a loss of cervical lordosis may cause neck pain (3), leading some practitioners to emphasize the importance of restoring reduced lordotic curves in the treatment and prevention of neck pain (2). However, several researchers have reported that a lack of cervical lordosis should be considered a normal variant that does not generally cause neck pain (4).

The findings of the current study support the view that a lack of cervical lordosis does not cause neck pain since no difference in cervical lordosis was found between neck pain patients and matched healthy volunteers.

Study Methods:

Thirty patients with nonspecific neck pain of at least 2 weeks’ duration were compared with a matched cohort of 30 healthy volunteers; only the patient group received cervical spine manipulation. Patients were recruited from people seeking treatment for neck pain at the Anglo-European College of Chiropractic outpatient clinic, whereas controls were recruited from staff and students at the chiropractic college.

Inclusion criteria for patients:
  1. non-specific neck pain (reproducible by neck movement/provocation tests);
  2. pain of at least two weeks' duration;
  3. self-reported pain rating of 3 or more on an 11-point numerical rating scale (NRS); and
  4. no suspected pathology.
Inclusion criteria for healthy volunteers:
  1. no current neck pain, dizziness or vertigo; and
  2. no neck pain that limited activity for more than 24 h in the last 12 months.
Fluoroscopic images were imported into ‘Image J’ digital geometric software to facilitate the measurement of cervical curves. A drawing tool in the software was used to draw a line along the posterior bodies of the C2 and C6 vertebrae. A protractor tool was then used to measure the angle between the constructed lines. Kyphotic and lordotic angles were recorded as negative and positive values, respectively.

Cervical SMT was administered twice a week for 4 weeks by a chiropractor with more than 5 years of clinical experience. Manipulation involved high velocity, low amplitude thrust (HVLA) using Diversified techniques, delivered to areas of segmental pain/restriction as identified by static and motion palpation. Patients received an average of 1.3 cervical manipulations per visit and 10.7 over the duration of the study. Most patients also received trigger point therapy and light massage to the neck region that was administered by final year chiropractic interns.

Study Strengths / Weaknesses

This was a well-designed study that was adequately executed, although randomization was not utilized. Several other design features lend strength to the study, as follows:
  • the data were collected prospectively,
  • images were taken under highly standardized conditions,
  • the degree of measurement error was calculated, and
  • the reliability of the method was reported.
The authors used the posterior tangent method (Gore method) to measure the degree of cervical lordosis because it has been shown to be superior to the Cobb angle analysis.

Studies by Harrison et al. reported improvements in cervical lordosis following SMT and traction, which appears to be in conflict with the current study. However, cervical traction was not included in the current study, so the comparison is actually incomplete. The Harrison et al. studies did not utilize randomization or even a control group, so there is also the possibility that the observed changes were due to natural variation rather than treatment. Further studies will be required to confirm these inconsistent findings.

It is possible that a study with a larger sample size might show a significant difference in cervical lordosis between neck pain patients and healthy volunteers.

Additional References:

  1. Harrison DE, Harrison DD, Betz JJ, Janik TJ, Holland B, Colloca CJ, et al. Increasing the cervical lordosis with chiropractic biophysics seated combined extension-compression and transverse load cervical traction with cervical manipulation: nonrandomized clinical control trial. J Manipulative Physiol Ther. 2003; 26(3): 139–51.
  2. Harrison DE, Cailliet R, Harrison DD, Janik TJ, Holland B. A new 3-point bending traction method for restoring cervical lordosis and cervical manipulation: a nonrandomized clinical controlled trial. Arch Phys Med Rehabil. 2002; 83(4): 447–53.
  3. McAviney J, Schulz D, Bock R, Harrison DE, Holland B. Determining the relationship between cervical lordosis and neck complaints. J Manipulative Physiol Ther. 2005; 28(3): 187–93.
  4. Grob D, Frauenfelder H, Mannion AF. The association between cervical spine curvature and neck pain. Eur Spine J. 2007; 16(5): 669–78.