This review attempts to provide an extensive overview on published literature in the field of cervical spine kinematics under healthy and degenerative conditions in vivo. 83 Summarizing the relevant knowledge, identifying the knowledge gaps and resolving contradicting outcomes is necessary for the integration of spinal kinematics in translational research and clinical practice. 70 Performing these measurements in either laboratory or clinical settings adds up to the diversity of the results. In the literature, the described methods for studying physiological and pathological motion patterns span from simple static end-position image comparison to sophisticated techniques like 3D motion reconstructions. Studying spine kinematics is not without challenges. 1, 2, 4, 5, 10 This knowledge can also help surgeons in preoperative planning, in conditions such as degenerative spondylolisthesis, which accounts for the largest proportion of these procedures and associated operative time and cost.

In the same manner we need to be able to differentiate between normal and abnormal motion to know when we are dealing with a spinal disorder. The latter is especially important for new artificial disc replacement designs that aim to restore the natural movement of a motion segment and require precise knowledge of their relations.

1, 2, 10 The mobility can be characterized as general mobility of a whole spinal segment or between two consecutive vertebrae. 4, 6, 7 Knowing the kinematic behavior can help clinicians identify numerous spinal diseases as well as promote improvement to motion sustaining products and prosthesis. 3, 6 The assessment of the kinematics of the cervical spine therefore is of great interest and reason for many studies in the last decades. 1, 2, 8, 10 Interrupted kinematics of the neck can cause clinical symptoms that we want to be able to diagnose and treat appropriately. One of the main functions of the cervical spine is to facilitate and control the motion of the head in a three-dimensional manner. Large-scale in vivo studies can complement the existing evidence, cover the gaps and pave the way to technological and clinical breakthroughs. While the kinematics of the healthy cervical spine have been addressed by multiple studies, the entire nosological and kinematic spectrum of cervical spine degeneration is partially addressed. However, the progression of degeneration restrains mobility, which seems to be maintained or compensated by adjacent non-affected segments. The affected segments seem to maintain translational and angular motion in early and moderate degeneration. In degenerative settings, concurrent or subsequent lesions render the association between diseases and mobility alterations challenging. Motion migrates caudally from C1–C2 and the center of rotation (COR) translocates anteriorly and superiorly for each successive subaxial segment. In coupled motion rotation is quantitatively predominant over translation. FE range of motion (ROM) is distributed between the atlantoaxial and subaxial segments, while AR ROM stems mainly from the former and LB ROM from the latter. Axial rotation (AR) greatly depends on C1–C2. C4–C5 and C5–C6 were the major FE contributors in the reported studies, exceeding the motion contribution of sub-adjacent segments. Among healthy/asymptomatic individuals, flexion extension (FE) and lateral bending (LB) are mainly facilitated by the subaxial cervical spine. Although the majority of the studies identified repeating motion patterns for most motion planes, discrepancies associated with limited sample sizes and different imaging techniques and/or spine configurations, were noted. As far as the degenerative conditions are concerned, kinematic data regarding disc degeneration and spondylolisthesis were available. Data was obtained through a systematic MEDLINE search including studies on angular/translational segmental motion contribution, range of motion, coupling and center of rotation. This includes an illustrated description of the spectrum of physiological cervical spine kinematics, followed by a comparable presentation of kinematics of the degenerative cervical spine. The authors aimed to summarize and compare the evidence about cervical spine kinematics under healthy and degenerative conditions. During the last decades, numerous studies based on diverse methodologies attempted to elucidate spinal mobility in different planes of motion. Distinguishing between physiological and pathological motion patterns can help diagnose these diseases, plan surgical interventions and improve relevant tools and software. Knowledge of spinal kinematics is essential for the diagnosis and management of spinal diseases.

Healthy cervical spine x ray