Why All Patients Need Normal Cervical Curves

By Mark R. Payne DC

Fact: Loss of the cervical lordosis predisposes the capsular ligaments to higher risk of injury in the event of trauma. 1

Habitual carriage of the neck in a straightened or kyphotic posture pretensions both the capsular ligaments and the ligamentum flavum. This pre stressing effect can have severe ramifications in the event of sudden neck trauma such as whiplash injuries. A 2005 study in the Journal of Biomechanics, found that trauma to patients with such postures may elongate the capsular ligaments “by up to 70%”, “induce laxity to the facet joint”, and predispose the neck to “accelerated degenerative changes over time.” The authors con­cluded that “abnormal spinal curvatures enhance the likelihood of whiplash injury and may have long-term clinical and biome­chanical implications.” In the event your patient is involved in a future auto accident, and statistically the average American is in a car accident about once every six years, how severely they are injured may well depend upon the outcome of your corrective care ef­forts to restore the lordosis.

Fact: Hypolordotic/kyphotic neck postures predispose the discs to injury while a healthy lordosis provides a protective effect.

We know that flexed (hypolordotic) postures result in po­tentially damaging disc mechanics. The anterior disc space is nar­rowed as the posterior disc space is widened with the result that the nucleus is forced posterior against the tensioned posterior an­nulus. White and Panjabi have stated that “the risk of disc failure is greater with tensile loading as compared to com­pressive loading.” 2 The flip side of that fact is that restoration of the cervical lordosis provides an environment of protection to the posterior annulus both by removing/reducing tensile stress to the posterior disc fibers and encouraging the nucleus pulposus to remain in properly seated within the confines of the annulus.

Fact: Normal lordosis is vital for the neck to have maximum resilience to compressive loads.

A 2001 study in the Journal of Neurosurgery, looked at the effects of cervical posture on the loadbearing ability of the cervical spine. 3 During compressive loading, straight spines tended to fail through the anterior motor unit (disc and vertebral bodies). Those spine with a lordotic configuration supported more of the weight on the posterior joints thereby sparing the disc and vertebral bodies. The authors concluded “that a loss of a lordosis increases the risk of injury to the cervical spine following axial loading.” Some experi­ments have noted that in lordosis, it’s nearly impossible to get discs to fail with compressive loading because the vertebrae will always crush before the discs fail!
Healthy lordotic curves provide other protective effects as well. In lordosis, the spinal cord is relaxed and without tensile stress. That all changes as the curve is lost. As the neck moves into cervical kyphosis, there is a linear increase in tensile stretching of the cord. Brieg has indicated that such stresses may eventually lead to actual micro tearing and scarring of the cord over time. Addi­tionally, such tensile stresses produce a tethering effect, pulling the nerve root against the upper confines of the IVF. Root sleeve fibrosis and irritation is a likely consequence of long term teth­ering.

Add to this the protective effects of lordosis in re­ducing osseous remodeling forces over time and you have another powerful incentive to make every effort to restore the sagittal curves and to educate your patients as to the im­portance of doing so. The picture at right is of a patient in her mid eighties. The head is held in pronounced forward translation due to compression fractures in the mid tho­racics she received much earlier in life. Because of this pro­nounced forward head posture, she has been forced to keep the head pulled into a pronounce lordosis as she attempts to keep her head upright during her daily activities.

The result here is pronounced lordosis and very little disc degeneration or osseous re­modeling. Note the absence of pronounced spurring on the anterior vertebral bodies in spite of her advanced age. This is an excellent example of just how important the normal lordosis is in removing mechanical stress from the vertebral bodies. It is also a great example of just why loss of lordosis may well be more important in terms of long term spinal health than forward head translation. Anyway, I hope you find this stuff helpful. I’m always harping about all the bad fallout from long term spinal imbalance. This is my attempt to keep things a bit more on the positive side. As always, please drop me a note to share your thoughts and comments.
Mark R Payne DC

References

1) Stemper BD, Yoganandan N, Pintar FA. Effects of abnormal posture on capsular ligament elongations in a computational model subjected to whiplash loading. J Biomech 2005 Jun; 38(6) 1313-23.

2) White and Panjabi, Clinical Biomechanics of the Spine. J.B. Lippincott Company 1978. Pg. 153.

3) Oktenoğlu T, Ozer AF, Ferrara LA, Andalkar N, Sarioğlu AC, Benzel EC.J Neurosurg. 2001 Jan;94 (1 Suppl) 108-14 Effects of cervical spine posture on axial load bearing ability: a biomechanical study