The curve of the cervical spine: variations and significance.

OBJECTIVE: To review the literature regarding the curve of the cervical spine in normal and injured persons, emphasizing common variations in cervical curvature and their possible clinical significance. DATA SOURCE: A MEDLINE literature search of the English-language, human literature was performed using multiple search strategies relevant to radiography, posture, lordosis, injury, diagnosis and prognosis of the cervical spine (MESH: cervical vertebrae). Additionally, article bibliographies were searched for further relevant articles. No publication time limit was imposed. STUDY SELECTION: Articles were identified by the author as being directly relevant to the objective and scope of this review. DATA EXTRACTION: Data was extracted as presented in each original article. DATA SYNTHESIS: The articles reviewed indicate that a wide range of normal exists in the posture and configuration of the cervical spine. Although kyphotic angulation and straightening or reversal of cervical lordosis are commonly seen following trauma, they may be normal variants. Muscle spasm is a widely used explanation for these variations when seen in patients with pain or trauma. Kyphotic angulation is often associated with posterior ligamentous injury of a motion segment. Prognostic significance of these variations is claimed by some authors.
CONCLUSION: There is little evidence to support the contention that altered cervical curvatures are of prognostic significance. Although kyphotic angulation is associated with anterior subluxation (hyperflexion sprain), it is not a reliable diagnostic criterion for that condition. It is reasonable to assume that straightening or reversal of a previously lordotic cervical curve is the result of muscular spasm, but more specific interpretation is not supported by the literature. More study is needed to characterize the specific dynamics and etiologies involved in the determination of cervical spine configuration.