Hyperextension/hyperflexion injuries resulting from automobile trauma more often cause soft-tissue damage than fractures or dislocations. The severity of these soft-tissue injuries often depends upon the relative movement of the head and neck as well as acceleration and deceleration forces. The type and degree of soft-tissue injuries are often subtle and require careful observation. The use of radiological evaluations can be valuable in assessing the integrity of osseous and ligamentous structures. Changes in the cervical curve can provide useful information for the health care provider in understanding the diagnosis, degree of injury, and the prognosis for the patient’s recovery.
The significance of changes to the normal cervical lordosis following an automobile trauma has been the subject of a number of studies. In the 1950 and 1960s, loss of the cervical lordotic curve was thought to be attributable to muscle spasm. Another study concluded that the loss of normal lordosis represented mechanical derangement of the posterior intervertebral joints. Rechtman and co-workers measured the cervical lordosis in a randomly selected population and concluded that loss of lordosis was an important finding because it can cause pain and serves as a “protective mechanism” in the cervical area to avoid further soft-tissue damage.
In 1974, Hohl conducted a study on 146 patients, 5 years or more after an automobile accident had caused cervical soft-tissue injuries, to examine factors influencing prognosis (such as reversal of cervical lordosis). None of the 146 patients examined in the study had pre-existing cervical degenerative changes at the time of injury. Hohl’s evaluation revealed a statistically significant positive correlation between poor prognosis and a sharp reversal of the cervical lordosis visible on x-rays. Hohl concluded:
A sharp reversal of the curve after injury, however, is a harbinger of degenerative changes in 60 percent of patients.
It was Hohl’s position that changes in the cervical curve were important findings in diagnosing soft-tissue injuries. Hohl also found that a sharp reversal of the curve, also known as kyphotic angulation, indicated a poor prognosis and spinal degenerative changes for the patient in the foreseeable future. According to Scher, kyphotic angulation was also a significant prognostic factor when localized at a particular level, indicating damage to the posterior spinal ligaments at that level. Disruption of the posterior ligaments causes the most unstable type of cervical spine injury. According to Scher, the kyphotic angulation may be caused by traumatic hyperflexion of the cervical area.
Scher’s conclusions support another study conducted by Hadley who could not reproduce angulation of the cervical spine on x-rays when the ligaments were intact. When the interspinous ligaments were damaged, however, hyperflexion stresses applied to the cervical spine of cadavers resulted in localized kyphotic angulation at the level of ligamentous damage.
Changes in the cervical spine may be so dramatic as to cause serious ligament instability requiring emergency surgical intervention. In a biomechanical analysis of the stability of the cervical spine, White and co-workers investigated the effects of kyphotic angulation by progressively destroying the spinal ligaments. They found that when a localized angulation of 11 degrees or greater was produced, the cervical spine became unstable or was on the verge of instability.
Cheshire is another researcher who found that localized angulation of 11 degrees or greater was associated with a relatively poor prognosis.
FALSE POSITIVE FINDINGS OF ANGULATION
As all practitioners are aware, x-ray findings need to be correlated with patient history and clinical examination findings before one can reliably assess the significance of loss of lordotic curve or kyphotic changes in the cervical spine. Moreover, the clinician must be aware of the “false positive” sign: a straightened cervical curve or a reserved cervical curve not resulting from trauma or pain. In 1975, Weir reviewed 360 asymptomatic patients and found 20 percent to have either straight or reversed cervical curves in the neutral lateral position. When the chin was depressed 2.5 cm (arguably, this would make the angle of the mandible overlapping the anterior portion of the atlas and/or axis), 70 percent showed a loss of lordosis (although it is not explained whether this is just a loss of lordotic curve, a flattening of the curve, reversed or kyphotic curve).
In clinical practice, all providers recognize that it is critical to determine the patient’s diagnosis, the cause of his/her injury, and which factors are likely to adversely affect their patients’ prognosis. The exact degree of injury and the probability of future pain in patients who have suffered cervical hyperextension/hyperflexion injuries may sometimes be difficult to ascertain. However, understanding the diagnostic and prognostic significance of cervical spine x-ray findings may provide useful information to the doctor, patient, insurance company, and attorney. For example:
The physician can predict with better accuracy the approximate length of treatment and probability of future care and problems;
The patient will have a clearer sense of what problems lie ahead and what type of restrictions on his activity may reasonably be imposed and for how long;
The at-fault party’s insurance company can establish accurate reserves;
The legal counsel will be in a better position to understand his client’s treatment needs and progress, knowing in advance the anticipated degree of improvement.
1 WE ARE GRATEFUL FOR THE WORK OF CONTRIBUTING AUTHOR, FRANK PRIMIANI, P.T., J.D.
2 Braaf and Rosner, Symptomatology and Treatment of Injuries of the Neck, New York State Journal of Medicine, Vol 55: 237 – 242 (1955); A. M. Rechtman, A. G. Bordon, and J. Gershon-Ghen, The Lordotic Curve of the Cervical Spine, Clinical Orthopedics, Vol 20: 208 – 215 (1961).
3 A G. Davis, Injuries of the Cervical Spine, Journal of the American Medical Association, Vol 127: 149 – 156 (1945).
4 A. M. Rechtman, A. G. Borden, and J. Gershon-Cohen, The Lordotic Curve of the Cervical Spine, Clinical Orthopedics, Vol 20: 208 – 215 (1961).
5 M. Hohl, Soft Tissue Injuries of the Neck in Automobile Accidents, Journal of Bone & Joint Surgery, Vol 56a, No. 8: 1675 – 1681 (December 1974).
6 Kyphosis is defined as a change in the alignment of a segment of the spine in a sagittal plane that increases the posterior convex angulation.
7 A. T. Scher, Ligamentous Injury of the Cervical Spine — Two Radiological Signs, South African Medical Journal, Vol 53: 807 (1978).
8 Foreman & Croft, Whiplash Injuries: The Cervical Acceleration/Deceleration Syndrome, Williams & Wilkins (1988); M. E. Woesmer, M. D. Mitz, The Evaluation of Cervical Spine Motion Below C2: A Comparison of Cineroentgenographic and Conventional Roentgenographic Methods, American Journal of Roentgenolo. Radium Ther. Nucl. Med., Vol 115: 148 – 154 (1972); A. T. Scher, Anterior Cervical
9 Subluxation: An Unstable Position, A. J. R., Vol 133: 275 – 280 (1979); and D. J. B. Cheshire, The Stability of the Cervical Spine Following Conservative Treatment of Fractures and Dislocations, International Journal Paraplegia, Vol 7: 193 – 203 (1970).
10 A. T. Scher, Ligamentous Injury of the Cervical Spine — Two Radiological Signs, South African Medical Journal, Vol 53: 807 (1978).
11 A. L. Hadley, The Spine, Springfield, Illinois: Charles C. Thomas, pp. 96 – 100 (1956).
12 A. A. White, R. M. Johnson, and M. M. Ranjabi, Clinical Orthopedics, Vol 109: 85 (1975).
13 D. J. B. Cheshire, The Stability of the Cervical Spine Following the Conservative Treatment of Fracture and Fracture Dislocation, Paraphelgia, Vol 7: 193 (1969).
14 D.C. Weir, Roentgenographic Signs of Cervical Spine Injury, Clinical Orthopedics, Vol 109:9 (1975).
