Morphological Measurement Of The Inferior Cervical Zygapophyseal Joint And Its Clinic Meaning

Background and Objective: It is reported that cervical spondylosis is a commonclinical disease and the incidence increased with the growth of age.25%of people inthe50-year-old group suffering from cervical spondylosis, the incidence of cervicalspondylosis in60years of age group rose to50%. The type of cervical spondylosisincluded cervical type, cervical radiculopathy, cervical spondylotic myelopathy,vertebral artery type, sympathetic nerve type and other type (such as esophagealcompression type). Cervical radiculopathy is caused by disc degeneration, Herniation,segmental instability, hyperosteogeny or osteophyte formation stimulate and oppress thecervical nerve root in the spinal canal and intervertebral foramen. Cervicalradiculopathy is a most common type of cervical spondylosis, accounting for about60%-70%. Zygapophysial joints at the cervical are one of the most important structurein cervical column constitutes and the basis of the mechanical structure of freedomactivities on the six degrees (such as spinal flexion and extension, rotation, lateralflexion). Zygapophysial joints at the cervical also are one of the cause of cervicaldegeneration, chronic neck pain, cervicogenic headache and cervical radiculopathy.Cervical spondylosis studies mainly in the intervertebral disc, rarely on the Morphologyof facet joint. Because their complicated geometric anatomic structures and concealedposition, we cannot easily carry out an overall observation of their shape on image or insurgery. In the past, cervical facet joints were observed and measured mainly throughX-ray image. X-ray image cannot see Three-dimensional morphology of the cervicalfacet joint as one-dimensional observation. With the development of the various way of auxiliary examination, multislice spiral CT become preferred by clinicians first, whichhave the superiority of the fine structure of the bone immediately to replace the X-ray.Although MRI can provide imaging of soft tissue, far less than CT in bone structure.This study aimed to observe and measure the three-dimensional quantitativemorphology and the angle of cervical zygapophyseal joint, as well as discuss their clinicsignificances, and provide the experimental basis for the design and production ofcervical facet braced device.Materials and methodsSpecimensNormal adults group: This study included60people without spinal complaints (30females,30males; age range from18to45years) who were referred to our departmentfor64-row multi-detector CT scans of the cervical spine. People with abnormalities，such as disc herniation, spinal stenosis, tumors, and infections，were excluded from thestudy. Case study group: This group included60out-patient service or hospitalizationpatients (30females,30males; average age,58.1years; age range from50to75years, Average duration of2.3years) who was diagnosed with cervical spondylosis.methodsThe cervical zygapophyseal joint in60normal specimens and60patients were scannedusing spiral CT and reconstructed three-dimensionally．The shapes, curvature andangulations of these joints were observed and measured in the horizontal and sagittalplanes by digital orthopedic post-processing software, respectively．Result1. the normal adult group of facet joint morphology and angleIn the horizontal plane, plane form occurs most frequently on the superior facet joint of C3and the inferior facet joint of C7. The C-shape articular surfaces were observed inC3,C4,C5and have no statistic significance. The angle of the articular facet orientationat C3/4,C4/5,C5/6,C6/7and C7/T1were（91.98±9.92）°（,96.64±9.01）°（,99.46±7.66）°,（94.20±8.72）°and（94.83±10.88）°respectively. the angle of C4/5and C5/6weresignificantly different compared to other levels (P<0.05).In coronal plane, ellipseoccurs most frequently on the segment of C6/7, round occurs most frequently on thesegment of C2/3and C3/4. In sagittal plane, The angulations of C3~C7were（52.09±6.28）°,（48.14±4.75）°,（45.81±4.07）°,（55.65±4.15）°and（58.32±5.77）°respectively. the angle of C3,C6and C7were significantly different compared to C5levels (P<0.05).2, The clinical relationship between the cervical zygapophyseal joint morphology andangle of the case study group and cervical spondylosis.The cervical facet joint morphology of the case study group the same as the normaladult group. Irregular type of cervical facet joint occurs most frequently on group ofmore than60years of age. Irregular type is mainly distributed in the C4/5which are themost frequently involved in the cervical spondylosis. The inclinations of thezygapophysial joints from C3to C7are smaller than the normal adult group. The overalltrend between the case study group similar with the normal adult group which is takeC5as the center of the distribution（C3>C4>C5<C6<C7）。The angle of the articularfacet orientation of the case study group were significantly different compared to thenormal adult group. That shows the angle of the articular facet orientation and cervicalspondylosis were no significant correlation. The probability of dissymmetry of thearticular facet orientation in cervical spondylosis is more than the normal adults.Compared to other segments, C4and C5are statistically significant(P<0.05).ConclusionsThe cervical zygapophyseal joint differ in morphology. In the horizontal plane, The C3 superior facet joint was the most frequent site for the posteromedial. Articular surfacefrom C3to C7gradually adapt to thoracic region which faced lateral. In sagittal plane,the average angulations in each segment were all beyond45°. The distribution ofinclinations of the zygapophysial joints center on C5. This study can provide theexperimental basis for the design and production of cervical facet braced device. Wespeculate that long-term course of cervical spondylosis may lead to changes ofmorphology and the angle of cervical zygapophyseal joint. On the contrary, changes ofmorphology and the angle of cervical zygapophyseal joint also may have a certainmeans on cervical spondylosis.