BIOMECHANICAL CHANGES TO THE DISC

Classic research regarding biomechanical effects of manipulation and mobilization set the foundation for today’s current study. Onel, Willen, Wildermuth, Schonstrom, Choi, and Schmid must be acknowledged. Onel (1989) showed on CT how traction load of 45 kg reduced 79% of medial disc herniations, 67% of posterolateral, and 57% of lateral and concluded that distraction widens disc space, reduces intradiscal pressure to “suck back” (his term) herniated nuclear material, stretches the posterior longitudinal ligament, thins the flaval ligament, and separates the apophyseal joints. (2) Willen (1997) used CT myelography to note the spinal canal’s response to compression of sciatic- and/or neurogenic claudication patients. 66 of 84 showed statistically significant reduction of dural sac cross sectional area in axial compression in extension and widening in flexion. (3) Wildermuth et al (1998) documented on MRI and myelography of disc herniations that flexion increases the foraminal size while extension increased the disc bulge and foraminal stenosis. (4) Schonstrom et al (1989) noted the dimensional changes of the lumbar spinal canal as reduced by 16% (2mm) from flexion to extension with the midsagittal diameter of the canal reduced by 2mm. (5) Schmid (1999) noted changes in the cross-sectional measurements of the spinal canal: neural foramen CSA decreased 23.2% from upright neutral to extension and flexion increased the area by 19.2%. The CSA of the spinal canal decreased 16.4% going from flexion to extension. Ligamentum flavum thickens to 4.3mm in extension from 1.8mm in flexion. 7 of the 12 asymptomatic volunteers noted pain when going into extension. (6) A bit more recent, Choi (2014) reported that manual therapy using joint mobilization techniques and flexion distraction techniques is considered an effective intervention for addressing disc heights in patients with chronic low back pain. (7)

In the interim, researchers documented findings on pre and post MRI changes (despite knowing that seen reductions don’t really matter since 76% of people have discs on MRI as much as the reduction in chemical irritation on the disc that may be the irritant more than a mechanical pressure on the spinal nerve). (8) BenEiliyah (1996) reported that 80% of cervical and lumbar spine disc herniations were helped by flexion distraction with 63% showing reduced size on post-treatment MRI. (9) Beira (1998) recorded a mean percentage for the flexion-distraction group of patients showed the pre-treatment intervertebral disc to occupy 33.51% of the spinal canal and a post-treatment reduction of occupancy to 29.28%. (10)

On such pioneering concepts, today’s most recent studies stand. Gudavalli et al (2022) reported on decreases in intradiscal pressure with flexion distraction - 5.6 kPa at L2-L3, 20.6 kPa at L3-L4, and 22.0 kPa at L4-L5 – and concluded that “this procedure may be able to draw a protruded nucleus pulposus back toward the intervertebral disc's center and allow for the nutrients flow into the disc.” (11) Gudavalli et al (2023) reported on the effects of f/d on vertebral motions - mean and standard deviation (SD) values of movements at L4–L5 were (1) 4.2° (0.78) in flexion and mean and SD values of vertebral separations were 1.10 (0.20) mm, respectively, and at L5-S1, 3.68° (0.69) in flexion and mean and SD values of vertebral separations were 0.80 (0.15) mm, respectively. Further, increases (mean and SD values) were observed in IVF dimensions in terms of area, height, and width - L4–L5 were 21.12 (3.87)%, 12.13 (1.89)%, and 5.12 (1.88)%, respectively, and L5–S1 were 18.02 (2.97)%, 8.11 (1.68)%, and 4.11 (1.40)%, respectively. (12) Pi and Chung (2021) showed the immediate effect of flexion-distraction spinal manipulation on intervertebral disc height (in addition to pain and spinal mobility) in patients with lumbar degenerative disc disease - intervertebral height increased from 6.32±1.90 to 6.93±1.85 mm (p<0.05) – concluding that this suggests flexion-distraction spinal manipulation could be an effective treatment for decreasing pain and improving function in patients with degenerative disc disease. (13) Billham et al (2024) reported on use of magnetic resonance spectroscopy to note biochemical and structural components of discogenic low back pain and its response to spinal manipulation before and after 16 flexion distraction treatments. They found improved IVD spectral features including decreased biochemical pain markers and increased glycoprotein biosynthesis, suggesting that SMT management of chronic DLBP may improve IVD structural integrity and alter pain biochemistry. (14) Using ultrasound to measure the cross-sectional area (CSA), Pagnez et al (2019) noted a reduction in CSA of the sciatic nerve. (15) Gudavalli et al (2024) presented observed in-vivo measurements of spinal process separation during Cox® Technic with 12 pounds of axial distraction: L3-L4 increased 1.28mm, L4-L5 increased 1.25mm, L5-S1 increased 1.27 mm. (16) Kruse presented a paper at the International Consortium of Manual Therapy in May 2022 on the intra-observer reliability of ultrasound measures of lumbar spinous process separation with flexion-distraction to assess intersegmental movements while volunteers were in a prone position: intra-class correlation co-efficients were 0.982 for L3-L4, 0.992 for L4-L5, and 0.997 for L5-S1 signifying excellent reliability. (17)

Future papers will elucidate more on the biochemical effects of CTFDD as will future desired studies that will give researchers and, by translation, practicing clinical chiropractors and their patients the hope for relief of spinal and radicular pain.

Click here for a list of published articles referencing Cox® Technic (F/D, flexion distraction, low velocity low amplitude, low velocity variable amplitude) protocols, research, case reports, etc.

1. Trager RJ, Daniels CJ, Meyer KW, Stout AC, Dusek JA. Clinician approaches to spinal manipulation for persistent spinal pain after lumbar surgery: systematic review and meta-analysis of individual patient data. Chiropr Man Therap. 2023 Mar 9;31(1):10. doi: 10.1186/s12998-023-00481-5. PMID: 36895028; PMCID: PMC9999664.
2. Onel D, Tuzlaci M, Sari H, Demir K. Computed tomographic investigation of the effect of traction on lumbar disc herniations. Spine (Phila Pa 1976). 1989 Jan;14(1):82-90. doi: 10.1097/00007632-198901000-00017. PMID: 2913674.
3. Willén J, Danielson B, Gaulitz A, Niklason T, Schönström N, Hansson T. Dynamic effects on the lumbar spinal canal: axially loaded CT-myelography and MRI in patients with sciatica and/or neurogenic claudication. Spine (Phila Pa 1976). 1997 Dec 15;22(24):2968-76. doi: 10.1097/00007632-199712150-00021. PMID: 9431634.
4. Wildermuth S. et al: Lumbar spine: quantitative and qualitative assessment of positional (upright flexion and extension) MRI and myelography. Radiology 1998:207:391-398
5. Schönström N, Lindahl S, Willén J, Hansson T. Dynamic changes in the dimensions of the lumbar spinal canal: an experimental study in vitro. J Orthop Res. 1989;7(1):115-21. doi: 10.1002/jor.1100070116. PMID: 2908901.
6. Schmid MR, Stucki G, Duewell S, Wildermuth S, Romanowski B, Hodler J. Changes in cross-sectional measurements of the spinal canal and intervertebral foramina as a function of body position: in vivo studies on an open-configuration MR system. AJR Am J Roentgenol. 1999 Apr;172(4):1095-102. doi: 10.2214/ajr.172.4.10587155. PMID: 10587155.
7. Choi J, Hwangbo G, Park J, Lee S. The Effects of Manual Therapy Using Joint Mobilization and Flexion-distraction Techniques on Chronic Low Back Pain and Disc Heights. J Phys Ther Sci. 2014 Aug;26(8):1259-62. doi: 10.1589/jpts.26.1259. Epub 2014 Aug 30.
8. Boos N, Rieder R, Schade V, Spratt KF, Semmer N, Aebi M. 1995 Volvo Award in clinical sciences. The diagnostic accuracy of magnetic resonance imaging, work perception, and psychosocial factors in identifying symptomatic disc herniations. Spine (Phila Pa 1976). 1995 Dec 15;20(24):2613-25. doi: 10.1097/00007632-199512150-00002. PMID: 8747239.
9. BenEliyahu DJ: Magnetic resonance imaging and clinical follow-up: study of 27 patients receiving chiropractic care for cervical and lumbar disc herniations. Journal Of Manipulative And Physiological Therapeutics  1996; 19(9):597-606
10. Beira B, Peers A: A study of the effects of chiropractic therapy on the diameter of the spinal canal in patients with low back pain and radiculopathy. J Of The Neuromusculoskeletal System 1998; 6(3):114-126
11. Maruti R. Gudavalli, Gregory D. Cramer, and Avinash G. Patwardhan. Changes in Intradiscal Pressure During Flexion-Distraction Type of Chiropractic Procedure: A Pilot Cadaveric Study. Integrative Medicine Reports. Nov 2022.209-214.
12. Maruti R. Gudavalli, Gregory D. Cramer, and Avinash G. Patwardhan. Intervertebral Movements and Changes in Intervertebral Foraminal Morphology in the Lumbar Spine During a Chiropractic Procedure: A Cadaveric Study. Integrative Medicine Reports. Jan 2023.7-13.http://doi.org/10.1089/imr.2022.0022
13. Pi T, Chung Y: Immediate Effect of Flexion-Distraction Spinal Manipulation on Intervertebral Height, Pain, and Spine Mobility in Patients with Lumbar Degenerative Disc Disease. Phys Ther Rehabil Sci 2021;10:235-43
14. Billham J F, Shi D, Evans Roland E, et al. (October 23, 2024) Intervertebral Disc Magnetic Resonance Spectroscopy Changes After Spinal Manipulative Therapy for Lumbar Discogenic Pain. Cureus 16(10): e72225. doi:10.7759/cureus.72225
15. Pagnez MAM1, Corrêa LA2, Almeida RS3, Meziat-Filho NA2, Mathieson S4, Ricard F5, Nogueira LAC6. The Variation of Cross-Sectional Area of the Sciatic Nerve in Flexion-Distraction Technique: A Cross-Sectional Study. J Manipulative Physiol Ther. 2019 Apr 24. pii: S0161-4754(17)30264-6. doi: 10.1016/j.jmpt.2019.03.003. [Epub ahead of print] [Article in Spanish]
16. Gudavalli RM, Kruse R, White B, Rider S. In-vivo Measurement of Spinal Process Separation during Axial Distraction. Poster presentation for North American Congress on Biomechanics 2022 conference in Ottawa, Canada, August 20-25, 2022. Page 5 https://nacob.org/wp-content/uploads/2022/08/MergedPostersTo220.pdf Kruse R presented “Gudavalli MR, Kruse R, White B, Rider S. Intra-Observer Reliability Of Ultrasound Measurements Of Lumbar Spinous Processes In A Prone Position On A Chiropractic Table.” at the International Consortium on Manual Therapies. Virtual Live Conference. May 21, 2022. Sponsored by AT Still College of Osteopathic Medicine.