Spinal Alignment & Cervical Curve

This section was compiled by Frank M. Painter, D.C.
Make comments or suggestions to   Frankp@chiro.org

Introduction

Structure and Function

Our spine is a “structural” unit.   There are 4 curves to the spine. Loss of structural integrity and/or normal function of the spine is the basis for the evolution of the vertebral subluxation. Abnormal stresses occur in the facets, discs and supporting tissues when normal motion of the spine is impaired. Chiropractic analysis should be aimed at locating the specific segments which are subluxated, as well as providing the means to “free” those segments.

The normal cervical lordosis (which extends from C1 to T2) should have a 17–24 cm. radius , based on the patient's height. This is easily measured with the AcuArc ruler. Kim Christensen D.C. in his book “Clinical Chiropractic Biomechanics” states, “Spinal biomechanical stability requires an optimal lordotic structure. The lordotic cervical & lumbar spine are the basis of the spine's ability to resist axial stressors.”

A resistance factor in mechanical structure is expressed by the formula:

R = C² + 1

where   R = resistance to axial pressure and   C = the number of curvatures.
Thus, the spine's ability to resist axial stress, taking into account the cervical, thoracic and lumbar curves is:

R = 3²+ 1 = 10

If we lose the cervical or lumbar curves, the formula is reduced to:

R = 2² + 1 = 5

Thus, a reduced cervical curve may result in a 50% reduction in the overall resistance of the spine to axial stress.

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To define the cervical curve of the spine with a compass:

1.     Dot the posterior inferior aspect of C1's anterior arch. (see Figure 2)

2.     Dot the anterior superior aspect of the vertebral body of T2. (see Figure 2)

3.     Set your compass for the distance between these 2 points. This length becomes the “chord” length of that patient's curve.   Now, swing arcs back from the C1 and T2 points, with the compass set using the chord length, to locate the point which will describe the optimum spinal curve. (See Figure 1 + 2)

Then set the compass on that radius center-point, and use that same chord length to strike the radius of the cervical curve at the anterior vertebral bodies. (See Figure 2)   Note that ALL the vertebra should be on this curved line, with a radius between 17–24 cm., depending on patient height.


                       Figure 1

Figure 2

The picture on the left is an example of perfect cervical lordosis. All segments should be on Georges's line (one curved line).   There should be an even spacing between each spinous process. Positioning of the head and spine should also be assessed for anterior head placement (also known as Forward Head Posture). The normal cervical lordosis (which extends from C1 to T2) should have a 17–24 cm. radius, based on the patient's height. This is easily measured with the AcuArc ruler. The posterior arch of Atlas should be centered in the space between occiput and the C2 spinous process. If C1's posterior arch “crowds” occiput, it is labelled as an “inferior” Atlas. If it crowds C2, it is labelled “superior”. The normal Atlas Plane line would be 18–24 degrees superior to the bottom of the film. A line under the bottom of the C2 body (Whitehorn's line) should be parallel with the floor.

Spinal Alignment and Cervical Curve Articles

	The Forward Head Posture Page A Chiro.Org article collection Persistent forward head posture (a.k.a “hyperkyphotic posture”) puts compressive loads upon the upper thoracic vertebra, and is also associated with the development of Upper Thoracic Hump, which can devolve into Dowager Hump when the vertebra develop compression fractures (anterior wedging).   A recent study found this hyperkyphotic posture was associated with a 1.44 greater rate of mortality.
	The Vast Majority of Patients With Fibromyalgia Have a Straight Neck Observed on a Lateral View Radiograph of the Cervical Spine: An Aid in the Diagnosis of Fibromyalgia and a Possible Clue to the Etiology J Clinical Rheumatology 2022 (Nov 3) [EPUB] Most patients with fibromyalgia share an abnormality in common that is verifiable by a simple radiograph. In 83.2% of the patients, the cervical spine was essentially straight (Cobb angle ≤10 degrees). In fibromyalgia patients, the loss of cervical curvature was approximately 6.5 times greater than in control subjects (50.3% vs. 7.8%). A straight neck without other radiographic abnormalities may be a major anatomical abnormality in fibromyalgia that has gone unnoticed. It may assist in the diagnosis, as well as suggest increased muscle tension/pressure as a possible etiology.
	A Videofluoroscopy-based Tracking Algorithm for Quantifying the Time Course of Human Intervertebral Displacements Comput Methods Biomech Biomed Engin. 2017 (Mar 15): 1–9 When applied to two patient cases, aberrant intervertebral motions in the cervical spine were typically found to correlate with patient-specific anatomical features such as disc height loss and osteophytes.   The case studies suggest that intervertebral kinematic time-course data could have value in clinical assessments, lead to broader understanding of how specific anatomical features influence joint motions, and in due course inform clinical treatments.
	Sagittal Standing Posture and its Association with Spinal Pain: A School-based Epidemiological Study of 1196 Flemish Adolescents Before Age at Peak Height Velocity Spine (Phila Pa 1976). 2012 (Sep 1); 37 (19): 1657-1666 ~ FULL TEXT The orientation of gross body segments with respect to the gravity line seems superior to local spinopelvic features in terms of clinical importance, at least in the current pre-PHV cohort. Opportunities may exist for postural subgrouping strategies to begin with global alignment parameters in order to gain further insight into the relationship between sagittal alignment and the relative risk of developing spinal pain/seeking medical consultation for this pain.
	Does Cervical Kyphosis Relate to Symptoms Following Whiplash Injury? Manual Therapy 2011 (Aug); 16 (4): 378–383 Editorial Comment: This is an intersting study.   I have an issue with the fact that these studies were taken in the supine position (based on the limitations of MRI technology.)   Chiropractors have noted since the 1920s that sitting vs. standing films of the same subject made significant changes in the positional architecture of the cervical spine.   Sitting films made the neck *look* like it had more lordosis than it displays in the standing position.   Further, the presence of Forward Head Posture is impossible to determine in supine films.   How can you address a problem you can't observe in a special study?
	Alteration of Motion Segment Integrity Dynamic Chiropractic (November 18, 2010) Alteration of motion segment integrity is determined by exact mensuration procedure published in the AMA Guides to the Evaluation of Permanent Impairment.   It is a spinal subluxation that can be objectively identified with a high degree of accuracy, especially when one acknowledges the advancements that have occurred in assessment of stress imaging (X-ray, DMX).
	Accurate Prognosis in Personal-Injury Cases Using George's Line Dynamic Chiropractic (March 26, 2010) The AMA's Guides to the Evaluation of Permanent Impairments uses George's Line to rate neck impairments.   A moderate (3.5 mm) break in George's Line on the flexion and extension lateral X-ray films is a permanent impairment, equivalent to a post-surgical fusion of two cervical vertebra.   Most chiropractors see small anterolisthesis and/or retrolisthesis on the films and ignore it or fail to appreciate its significance.   Since 35 percent to 45 percent of trauma patients have this injury, it is very likely you have failed to diagnose it many, many times.   By failing to diagnose this injury, you have failed to accurately, thoroughly and honestly describe your patient's injuries to the claim adjusters and attorneys, who will use the facts in your patient chart as the basis for the personal-injury settlement.   These people need you, the doctor, to give them all the facts so a fair settlement can be reached.   The jury also needs to understand whether your patient had this injury in order to decide how much to award your patient in a trial verdict.
	Kinematic Analysis of the Relationship Between Sagittal Alignment and Disc Degeneration in the Cervical Spine Spine (Phila Pa 1976). 2008 (Nov 1); 33 (23): E870—876 ~ FULL TEXT The present study demonstrated that the changes in sagittal alignment of the cervical spine affect the kinematics. Consequently, it may cause changes in the segment subjected to maximum load for overall motion and accelerate its degeneration.
	Effects of Abnormal Posture on Capsular Ligament Elongations in a Computational Model Subjected to Whiplash Loading J Biomech 2005 (Jun); 38 (6): 1313–1323 Although considerable biomechanical investigations have been conducted to understand the response of the cervical spine under whiplash (rear impact-induced postero-anterior loading to the thorax), studies delineating the effects of initial spinal curvature are limited.   Results from the present study, while providing quantified level- and region-specific kinematic data, concur with clinical findings that abnormal spinal curvatures enhance the likelihood of whiplash injury and may have long-term clinical and biomechanical implications.
	Determining the Relationship Between Cervical Lordosis and Neck Complaints J Manipulative Physiol Ther 2005 (Mar); 28 (3): 187–193 ~ FULL TEXT In a study of 277 lateral cervical x-rays, patients with lordosis of 20° or less were more likely to have cervicogenic symptoms (P < .001). The association between cervical pain and lordosis of 0° or less was significant (P < .0001).   The odds that a patient with cervical pain had a lordosis of 0° or less was 18 times greater than for a patient with a noncervical complaint.   Patients with cervical pain had less lordosis and this was consistent over all age ranges.
	Cervical Kyphosis is a Possible Link to Attention-deficit/hyperactivity Disorder J Manipulative Physiol Ther 2004 (Oct); 27 (8): e14 ~ FULL TEXT A 5–year-old patient was diagnosed with ADHD and treated by a pediatrician unsuccessfully with methylphenidate (Ritalin), Adderall, and Haldol for 3 years.   The patient received 35 chiropractic treatments during the course of 8 weeks.   A change from a 12 degrees C2–7 kyphosis to a 32 degrees C2–7 lordosis was observed after treatment.   During chiropractic care, the child's facial tics resolved and his behavior vastly improved.   After 27 chiropractic visits, the child's pediatrician stated that the child no longer exhibited symptoms of ADHD.   The changes in structure and function may be related to the correction of cervical kyphosis.
	Cervical Spine Curvature During Simulated Whiplash Clin Biomech 2004 (Jan); 19 (1): 1–9 Average peak lower cervical spine extension first exceeded the physiological limits (P<0.05) at a horizontal T1 acceleration of 5 g. Average peak upper cervical spine extension exceeded the physiological limit at 8 g, while peak upper cervical spine flexion never exceeded the physiological limit. In the S-shape phase, lower cervical spine extension reached 84% of peak extension during whiplash. Both the upper and lower cervical spine are at risk for extension injury during rear-impact. Flexion injury is unlikely.
	Cervical Spine Geometry Correlated to Cervical Degenerative Disease in a Symptomatic Group J Manipulative Physiol Ther 2003 (Jul); 26 (6): 341–346 ~ FULL TEXT Chiropractors have long maintained that loss of spinal curvature was a sign of loss of function that leads to degenerative joint disease. This paper discusses "5 geometric variables from the lateral cervical spine that were predictive 79% of the time for cervical degenerative joint disease."
	The Use of Flexion and Extension MR in the Evaluation of Cervical Spine Trauma: Initial Experience in 100 Trauma Patients Compared with 100 Normal Subjects Emerg Radiol 2002 (Nov); 9 (5): 249–253 The cervical spines of 100 consecutive uninjured normal asymptomatic adults and 100 adult accident victims following rear low-impact motor vehicle accidents were evaluated using rapid T2-weighted MRI. Injured subjects were evaluated during the subacute period, at 12 to 14 weeks after injury. The "normal subjects" showed: Loss of normal cervical lordosis (hypolordosis) in 4% (4 of 100) patients: Range of motion of 50° flexion, and 60° extension; and asymptomatic disk herniations were observed in 2% (2 of 100) patients. In the subacute post-traumatic subjects, there was a loss of the normal segmental motion pattern, with hypolordosis in 98% (98 of 100) patients. Range of motion was restricted, quantified as 25° flexion and 35°; and disk herniations were observed in 28% of the patients. The authors conclude that flexion and extension MR can be a valuable adjunct examination in the evaluation of patients in the clinical setting of subacute cervical spine trauma.
	Is the Sagittal Configuration of the Cervical Spine Changed in Women with Chronic Whiplash Syndrome? A Comparative Computer-assisted Radiographic Assessment J Manipulative Physiol Ther 2002 (Nov); 25 (9): 550–555 ~ FULL TEXT The whiplash group showed a decreased ratio between the lower versus upper cervical spine but comparisons between groups were not statistically significant. The whiplash group was in a significantly more flexed position at the C4–C5 level compared with the asymptomatic group (P =.007). The reliability measures have to be strengthened to render these results definitely conclusive.
	Sagittal Alignment of Cervical Flexion and Extension: Lateral Radiographic Analysis Spine Journal 2002 (Aug 1); 27 (15): E348–E355 The results suggest that alterations in the static alignment of the cervical curvature cause alterations in the dynamic kinematics of the cervical spine during cervical flexion-extension. This information should aid in the interpretation of kinematic studies of the cervical spine.
	Characteristics of Sagittal Vertebral Alignment in Flexion Determined by Dynamic Radiographs of the Cervical Spine SPINE (Phila Pa 1976) 2001 (Feb 1); 26 (3): 256–261 This study was conducted to depict the change patterns of intervertebral motion of the cervical spine during flexion, upright, and extension positions using dynamic radiographs. Special interest was focused on the flexion position.
	Abnormal Spinal Curvature and its Relationship to Pelvic Organ Prolapse Am J Obstet Gynecol 2000 (Dec); 183 (6): 1381–1384 This Study found that an abnormal change in spinal curvature, specifically, a loss of lumbar lordosis, appears to be a significant risk factor in the development of pelvic organ prolapse.

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Updated 11-20-2023