Clinical Relevance of Cervical Kinematic Quality Parameters in Planar Movement

Abstract

Comprehending cervical spinal motion underlies the understanding of the mechanisms of cervical disorders. We aimed to better define the clinical relevance of cervical spine kinematics, focusing on quality parameters describing cervical spine planar motion. The most common study focuses were kinematic quality parameters after cervical arthroplasty and in normal subjects, patients with cervical degeneration, and patients with cervical deformities. Kinematic quality parameters are important for cervical degeneration prevention, being detected sooner than differences on imaging examinations and being significantly related to the degree of cervical degeneration. Kinematic quality parameters are effective for evaluating the changes of cervical motion pattern after cervical fusion and non‐fusion, assessing operative and adjacent segments in the early stages, and predicting adjacent segment degeneration. However, owing to current research limitations, and controversy about the changes of kinematic quality parameters after different surgical procedures, current assessments are limited to cervical spine flexion and extension. Different osteotomy methods of cervical deformity have different effects on cervical motion patterns and quality parameters. Choosing the most effective surgical method remains a challenge and kinematic quality parameters in cervical deformity are important future research topics. This review highlights the instantaneous center of rotation, the center of rotation, and the instantaneous axis of rotation as being important kinematic quality parameters of cervical spinal motion. These can be used to detect abnormal cervical mobility, to diagnose cervical degeneration, to design disc protheses, and to evaluate surgical effects earlier than other methods. Owing to limitations of research methods there is variation in the way parameters are defined by various researchers. No uniform standard exists for defining degenerative motion quality parameters in normal asymptomatic, degenerative, and postoperative patients. Therefore, further study is required. New study techniques and defining kinematic quality parameters in normal subjects will clarify the definitions of these parameters, enhancing their future clinical usefulness.

Prospective Multicenter Trial of Cervical Arthroplasty with the ROTAIO® Cervical Disc Prosthesis

“…After ACDA, emphasis is often placed on presence and magnitude of motion as assessed by ROM, while quality of motion by parameters like instantaneous COR, COR, and instantaneous axis of rotation has just recently been identified as important for evaluating changes in the cervical motion pattern. 40 - 43 Anderst et al demonstrated that the instantaneous COR was generally fixed in the longitudinal direction, but it translated in the anterior-posterior direction during flexion-extension. 42 If translation is not adequately possible, non-physiologic stress on the facet joints at the index level ensues, which may cause facet joint syndrome, as it has commonly been seen in lumbar disc arthroplasty.…”

“… 44 It has been postulated that these further findings should be considered in clinical practice and when designing disc prostheses. 40 …”

“…Liu et al evaluated the instantaneous COR located at the superior half of the lower vertebral body height and the posterior half of its width, and changing with age (Liu et al, 2014). It has been postulated that these further ndings should be considered in clinical practice and when designing disc prostheses (Guo et al, 2019).…”

In vivo kinematic study of lumbar center of rotation under different loads

“…This technique is known as perpendicular bisector method. [19][20][21] COR was measured in millimeters (mm). The COR coordinates were measured and standardized by dividing the length, width, and height of the upper vertebrae to eliminate individual differences.…”

Mid-long-term follow-up of operated level kinematics after single-level artificial cervical disc replacement with Bryan disc

“…Due to the lack of a simple and effective method to evaluate three-dimensional cervical motion, cervical kinematics studies are mainly based on sagittal flexionextension motion [7]. The center of rotation (COR) is the sagittal motion center of the functional spinal unit (FSU) measured using cervical flexion-extension radiographs [7,8]. COR is relatively simple to measure and can be readily subjected to statistical analysis and comparison.…”