October 2001

Lateral Thoracic Cage Translation:

Biomechanics, Pain, and Treatment

by Deed Harrison, D.C.

 In the last issue, July 2001, I discussed the need for a reliable and valid definition of spinal subluxation. I suggested that the Chiropractic profession adopt the Harrison Spinal Model as their definition of “normal alignment” for the human spinal column. In addition, I listed and discussed the following seven items as they relate to the detection, correction, and prevention of spinal subluxation:

            1) We need to strictly define what normal is,

            2) We need to strictly define what abnormal is,

            3) We need to have reliable and valid methods for measuring or detecting abnormal,

            4) We need to provide evidence that the abnormal(s) cause or are associated with known disorders,

            5) We need to develop methods to correct this abnormal subluxation,

            6) We need to use the same valid and reliable methods in the third section to verify the correction of the abnormal,

            7) Finally, we need to document that correcting these abnormals will improve/resolve the known disorders in number four above.

            In this issue and upcoming issues I will discuss individual postural/structural abnormalities and apply the above seven items to them when appropriate.  For my first topic, I have chosen the postural displacement of lateral thoracic cage translation relative to the pelvis.

Literature Review

            Clinically, lateral thoracic cage translations are common postural displacements in low back pain patient populations (see Figure 1). Mechanically, this postural displacement would cause large compressive and shear stresses to the distal lumbo-sacral spine. Since the trunk is approximately 60% of body mass,21 a 200 lb. male with one inch of lateral trunk translation would have a minimum of 120 inch lbs. of increased load acting on the lumbo-sacral spine. However, due to the increased muscle effort required to stabilize this displacement, the actual increase in load on the spine will likely be much higher.

            Most often, lateral thoracic translations have been observed in patients with acute lumbar disc herniations.1-7 However, this postural displacement can occur in low back pain patients without disc herniations and in individuals without low back pain.8,9 Looking at the literature on this topic, one can start to identify controversy between this postural displacement and its’ clinical significance.

            There are at least three reasons for the controversy or discrepancies between studies:

            1) The terminology for the description of this postural/spinal displacement in different studies is vague, confusing, and non-descriptive. For example, descriptions such as “lumbosacral list,”8 “trunk list,”4,5,7,9 “sciatic spinal deformity,”1 “alternating lumbar scoliosis,”10,11 “windswept spine,”12 and “side-gliding”2,3 have all been utilized for the description of lateral thoracic cage translation.

            2) Different methods of measuring the observed spinal and postural displacement have been proposed. McLean et al.9 suggested a simple plumb line method where the lateral displacement, in millimeters, of a surface marking of the spinous process of T12 compared to that of S1 is used. Arangio et al.,8 on AP lumbo-pelvic x-rays, used an angle formed by the L2 vertebral body endplate to horizontal and a best fit line through the lumbar spinous processes to vertical. The dilemma with these methods is that they cannot discriminate between the true lateral thoracic translations and other physiologic movements of the thorax such as axial rotation and lateral bending.

            3) Prior to the study by Harrison et al.,13 no one accurately determined the AP radiographic spinal coupling/displacement patterns of the thoraco-lumbar spine for the postural displacement of lateral thoracic translation. Without knowledge of normal kinematics of the spine during this posture, how can you use an x-ray to determine if the patient actually has this posture?

            Although, the reliability of determining the postural displacement of lateral thoracic cage translation has not been fully established, Harrison et al.13 have accurately determined the 2-D thoraco-lumbar spinal coupling patterns visible on the AP x-ray for this postural main motion (see Figure 2). Harrison et al.13 demonstrated that the lateral displacement of T12 relative to S1, for their average subject, was 52.0mm to the left or right as measured on AP lumbar radiographs. The vertebral segments were found to couple/move into lateral flexion. Vertebral segments L2-S1 were found to laterally bend to the side of thoracic translation, while above L2 the vertebral segments were found to laterally bend away from the side of translation (Figure 2).

Figure 1	Figure 2	Figure 3	Figure 4
Figure 5	Figure 6

Treatment

            Until adequate studies are performed on the reliability of measuring lateral translations of the thorax in upright posture, we (CBP®) suggest that you always compare the patient’s posture to the spinal coupling patterns depicted in Figure 2.

            In regards to the patient’s posture, if there is more space between the arm and the ribcage and pelvis on one side’ the shoulders are level or one is slightly on the side of increased arm space, then we suspect the patient has a lateral translation of the thorax relative to the pelvis.

            This posture should project with the previously described coupling patterns on the AP x-ray. Note: the AP x-ray coupling patterns might be different if the individual patient has spinal anomalies or deformities such as a lateral listhesis, anatomical short leg, transitional segment, and/or true lumbar scoliosis.

            Harrison14-17 has developed unique postural adjustments and exercises for the postural displacement of lateral thoracic translation. These procedures are termed Mirror Image Adjusting and Mirror image exercises.

            Figure 3 depicts one example of a Mirror Image Adjustment using the CBP® hand-held instrument to correct the postural displacement of right lateral thoracic translation in Figure 1.        

            Figure 4 depicts the Mirror Image Exercise for the correction of right lateral thoracic cage translation.

            Lastly, Figure 5 depicts the Mirror Image® Traction (developed by Dr. Bob Berry) in order to correct right lateral thoracic translation.

            According to CBP® protocol,18 a patient will be progressed depending upon tolerance (over a 10 +/- 2 week program) into all three Mirror Image Postural procedures, adjustment, exercise, and raction.                     

            The patient is required to treat at a frequency of 3-5 times per week for the duration of the program. After completion, a re-evaluation with appropriate spinal x-rays and posture analysis are performed and the progress of the patient is noted.

            Recent data indicates that reverse postural exercise therapy can reduce the magnitude of the lateral translation posture verified by post treatment x-rays.19 Unpublished data from my clinic (Harrison et al.) demonstrated that an improvement of 8.0-9.0 mm in the lateral shift of T12 — relative to the sacrum was obtained in 35-40 chiropractic office visits where the patient received Mirror Image® Adjustments, Exercises, and Berry Translation Traction.20

            Figure 6 depicts an example before and after treatment AP lumbo-pelvic x-ray. This individual came to my clinic seeking treatment for chronic low back pain and was not antalgic. In this case dramatic correction in the spinal coupling/displacement patterns and improvement in the patients visual analog pain scale (VAS pre 5 and VAS post 0, where 0=pain free and 10=bed ridden/incapacitated) were obtained following CBP® Mirror Image® procedures and treatment protocols.

            In the future, we at CBP® plan to study the reliability and validity of measuring lateral thoracic cage translations.

            Additionally, we plan to document improvement in the spinal coupling patterns and VAS pain scales following the application of CBP® Mirror Image® procedures in patients with chronic low back pain and thoracic lateral translations.

References

1. Lorio MP, Bernstein AJ, Simmons EH. Sciatic spinal deformity-lumbosacral list: an “unusual” presentation with review of the literature. J Spinal Disord 1995;10:201-205.

2. Donelson R, Grant W, Kamps C, Metcalf R. Pain response to end-range spinal motion in the frontal plane: a multi-centered, prospective trial. Presented at the ISSLS conference, Heidelburg, Germany, May 1991.

3. Donelson R, April C, Medcalf R, Grant W. A prospective study of centralization of  lumbar and referred pain. A predictor of symptomatic discs and annular competence. Spine 1997;22:1115-1122.

4. Porter DM, Miller CG. Back pain and trunk list. Spine 1986;11:586-600.

5. Wadell G, Main CJ, Morris EW et al. Normality and reliability in the clinical assessment of backache. BMJ 1982;284:1519-1523.

6. Duncan W, Hoen TI. A new approach to the diagnosis of herniation of the intervertebral disc. Surg Gynecol Obstet 1992;75:257-267.

7. Khuffash B, Porter RW. Cross leg pain and trunk list. Spine 1986;14:602-603.

8. Arangio GA, Hartzell SM, Reed JF. Significance of lumbosacral list and low-back pain: acontroleled radiographic study. Spine 1990;15:208-210.

9. McLean IP, Gillan MGC, Ross JC, Aspden RM, Porter RW. A comparison of methods for measuring trunk list: a simple plumgline is the best. Spine 1996;21:1667-1670.

10. Capener N. Alternating sciatic scoliosis. Proc R Soc Med 1933;24:426-429.

11. Remak E. Alternirende Scoliose bei Ischias. Dtsch Med Wochenschr 1891;17:257-259.

12. Grieve GP. Treating backache: a topical comment. Physiotherapy 1983;69:316.

13. Harrison DE, Cailliet R, Harrison DD, Janik TJ, Troyanovich SJ, Coleman RR. Lumbar coupling during lateral translations of the thoracic cage relative to a fixed pelvis. Clinical Biomechanics 1999;14(10):704-709

14. Harrison DD, Janik TJ, Harrison GR, Troyanovich SJ, Harrison DE, Harrison SO.  Chiropractic Biophysics Technique:  A Linear Algebra Approach to Posture in  Chiropractic. J Manipulative Physiol Ther 1996;19(8):525-535.

15. Harrison DD.  CBP®( Technique: The Physics of Spinal Correction. National Library of Medicine #WE 725 4318C, 1982-97. Harrison DD.  CBP® Technique:  The Physics of Spinal Correction.

16. Harrison DD.  Spinal Biomechanics: A Chiropractic Perspective. National Library of Medicine #WE 725 4318C, 1982-97. Harrison DD.  CBP® Technique:  The Physics of Spinal Correction.

17. Harrison DD.  Abnormal postural permutations calculated as rotations and translations from an ideal normal upright static spine.  In: JJ Sweere, editor, Chiropractic Family Practice. Gaithersburg: Aspen Publishers, pp.6-1:1-22, 1992.

18. Troyanovich SJ, Harrison DE, Harrison DD.  Review of the Scientific Literature Relevant to Structural Rehabilitation of the Spine and Posture:  Rationale for Treatment Beyond the Resolution of Symptoms. J Manipulative Physiol Ther 1998; 21(1): 37-50.

19. Boer WA, Anderson PG, Limbeck JV, Kooijman MAP. Treatment of idiopathic scoliosis with side-shift therapy: an initial comparison with a brace treatment historical cohort. Eur Spine J 1999;8:406-410.

20. Harrison DE, Harrison DD, Harrison SO, Janik TJ, Holland B. Conservative methods to correct lateral translations (trunklist) of the thoracic cage: a consective case analysis of 50 subjects with comparison to a control group. Unpublished data.

21. Clauser, C.E., McConville, J.T., and Young, J.W.  Weight, Volume, and Center of Mass of  Segments of the Human Body.  pp. 3, AMRL-TR-69-70,  Aerospace Medical Research Library, Aerospace Medical Division, Air Force Systems Command, Wright-Patterson Air Force Base, Ohio, 1969.