It has been suggested historically that a kyphotic cervical spine is a “normal variant” in human posture. This appears to be an incorrect but worrying myth.
Drs. Harrison and Haas reviewed some of the papers in which this claim is made in their 2002 work, CBP Structural Rehabilitation of the Cervical Spine.
Juhl, in 1962, made the claim that in asymptomatic subjects 13.8% of them demonstrated a kyphotic cervical spine and that therefore this meant kyphosis of the cervical spine is merely a normal variant and not something of concern. The problems were two-fold; firstly that no measurements of pain or disability were used and therefore their designation as asymptomatic was entirely arbitrary and secondly, “Juhl et al offered no measurements on cervical lordosis which might have changed their subjective classification.”(1).
Haas et al, in 1999, stated that “In a study of 180 subjects, Borden et al concluded that a straight cervical spine is abnormal only in conjunction with decreased cervical flexibility.”(2). When Harrison and associates reviewed this claim they found that Borden’s original paper actually showed that of the 13 patients with an absent cervical neck curve, 85% has concomitant degenerative changes, and in the 3 with a reversed (or kyphotic) cervical curve (who together made up nearly 10% of the studied population) “there were generalised hypertrophic degenerative changes and fusion…”(3). Harrison et al note that it is possible Haas failed to read the paper he was referencing when he claims that loss of cervical curve is a normal variant(1).
The Journal of Manipulative and Physiological Therapeutics have published work discussing the effects of different postural loads on the central nervous system. It was noted in a discussion of transverse forces that they are “caused by an anterior displacement of the cord against an osteophyte as flexion is increased. This forces the cord to ride over the posterior wall of the vertebral bodies or the anterior aspect of the spinal canal during spinal flexion or in kyphotic configurations of the cervical and lumbar spines.”(4) It was further quoted that “Where stretch was exerted over a convexity, as normally in the thoracic spine, or in the neck after conversion of the normal lordosis to a flexion kyphosis, it appeared that there must be a considerable component of force directed anteriorly and holding the cord against the ventral wall of the canal.”(4)
Abnormal alignment of the spinal column has been shown to lead to degenerative changes in the structures part of and surrounding the spine – muscles, ligaments, discs and bones(5).
A 2001 article in Clinical Biomechanics noted that it is rare for calculations of stress to be made based on clinically occurring sagittal configurations of the cervical spine. They found that when the spine is in a normal lordotic configuration then the stresses, anterior and posterior, are nearly uniform and minimal. When the spine becomes kyphotic, the stresses at the anterior vertebral margins turn from tension to compression, these same forces increase by a factor of 6-10 times when compared to forces in normal lordotic spines. Kyphotic areas of the spine experience forces completely reversed from normal and at a significantly greater level. The authors note that with consideration of Wolff’s Law, the reversal and exaggeration of stresses on the vertebral body explains the formation of osteophytes on the anterior margins of vertebrae throughout the kyphotic regions of the cervical spine(6).
The loss or reduction of cervical curves have not been the target of major interventions until relatively recently. Chiropractors, while having a long history of employing traction devices with the aim of correcting compressive forces on a segmental level – such as the work of Dr. Langworthy which involved adding traction to his procedure of segmental adjusting – did not until recently target curvature reductions with things like traction interventions.
Dr Pettibon made one of the earliest attempts to use traction devices to correct curvature problems in the seventies and eighties. His methods evolved over the course of decades, progressing from his initial method of longitudinal distraction with a foam block behind the neck to a device where an occipital strap was used to effectively “hang” the patient.
This method was both ineffective and dangerous, as its tendency for inducing anterior head carriage meant it produced little to no change in the cervical spine and the necessity of extending the patient’s neck over the occipital strap meant that there was a possibility of basilar insufficiency(1).
Drs Donald and Deed Harrison have been prolific in the area of spinal postural alignment. Recently, Dr Deed Harrsion was a co-author in “Addition of a Sagittal Cervical Posture Corrective Orthotic Device to a Multimodal Rehabilitation Program Improves Short- and Long-Term Outcomes in Patients With Discogenic Cervical Radiculopathy” which investigated the addition of a denneroll cervical orthotic device to standard battery of interventions in people with discogenic cervical radiculopathy (DCR).
The study looked at 40 patients with chronic pain and disability as a consequence of DCR over both a short (10 week) and long (1 year) period. Outcomes measured included posture, neck disability, neck and arm pain, and measures of neurophysiology.
Patients were split into the standard care group and the standard care with the addition of the denneroll. The standard care included:
The treatments were undergone 3 times a week for 10 weeks for a total of 30 treatments. Patients were left alone for a day and then assessed, then all patients were assessed again 1 year later to see if changes from the 10 week program had held into long term follow up.
It was found that the addition of the cervical denneroll orthotic to the standard multi-modal approach improved the cervical lordotic curve by an average of 13 degrees, anterior head carriage by 12mm and was associated with a reduction in chronic neck and arm pain, neck disability and a reduction in medication intake. Peripheral nervous system speed was also found to increase by 24%, spinal cord central conduction time by 23%(7).
A similar study was carried out on 72 patients with cervicogenic dizziness, a clearly defined hypolordotic cervical spine and anterior head carriage.
It was noted by the authors that contemporary efforts of managing cervicogenic dizziness do not have strong support in the literature. There is moderate evidence for the use of manual therapy in improving cervicogenic dizziness disorders, but long term outcomes have not been assessed beyond a 6 month period(8-10). Lystad also noted that “Although it has been argued that manual therapy combined with vestibular rehabilitation may be superior in the treatment of cervicogenic dizziness, there are currently no observational and experimental studies demonstrating such effects.”(10).
The authors hypothesised that a key component missing from the management of cervicogenic dizziness may be the structural rehabilitation of the cervical spine – or correcting the curves.
They propose that the alterations noted to muscles, ligaments, bony structures and neural tissue when there are abnormalities of sagittal curvature, and the concomitant effects of altered cervical spine alignment on vertebral kinematics could potentially lead to altered sensorimotor integration by changing the inputs of the cervical spine to the brain. Theoretically, it is possible that improvements in altered cervical spine alignment could result in improved sensory feedback from the spine to the brain with consequential decreases in cervicogenic dizziness.
Both groups of this study again received standard multimodal approaches to care, with one group receiving the denneroll traction device. Researchers measured anterior head carriage distance, cervical lordosis, dizziness handicap inventory (DHI), the severity of dizziness and the frequency. They also checked head positioning accuracy and cervical pain.
Measurements were taken at baseline, 10 weeks and 1 year and 10 weeks.
At the 1 year and 10 week follow up, the between group analysis identified significant differences for all measured variables including anterior head translation, cervical lordosis, dizziness handicap inventory, severity and frequency of dizziness, as well as for head repositioning accuracy in both right and left rotations. Neck pain was also reduced.
This work showed that “restoring the cervical lordosis and reduction of forward head posture with a novel extension traction device had a positive impact at long-term follow-up in patients with cervicogenic dizziness.”(11)
While the field of study is currently small, it appears clear that chiropractic can offer a valuable leadership role in the maintenance of cervical lordotic curves.
It appears clear that not only is loss or reversal of the cervical curvature not a normal variant, but that the maintenance of the cervical lordosis may be crucially important for the ability of the body to maintain optimal afferent input from spine to brain, and respond appropriately to its environment.
It is not yet known what the full implications of abnormal cervical spine alignment may be and the existing studies have their limits – the impossibility in some cases of blinding participants or researchers for example – but these merely point to the need for more research, faster, as this interesting field of knowledge grows.