Morphological Study Of The Posterior Osseous Structures Of Subaxial Cervical Spine Based On Digitized3D-CT Scan

Backgrouds:Pedicle screws, lateral mass screws and laminar screws are increasinglyapplied in the treatment of many kinds of cervical disease. The purpose of thisstudy is to determine the morphological characteristics of the posterioranatomical structures of the subaxial cervical in Chinese population.Furthermore, the results may be offer theoretical support for the development ofnew cervical instrumentation which is suitable for the anatomical characteristicsof Chinese people. Various types of cervical spinal instrumentations such aspedicle screws, laminar screws and lateral mass screws have been developed,and have enabled more rigid fixation of the cervical spine and correction ofmalalignment via a posterior-only approach, especially, in the case of thesubaxial cervical spine.One of the most frequent and complex proceduresinvolving this part of the spine is the placement of transpedicular screws. On onehand, transpedicular screws offer the strongest three columns fixation. On theother hand, this technique has many potential risks and complications. Therefore,the use of cervical pedicle screw has been limited to some extent. Laminarscrews and lateral mass screws have been increasingly used in the treatment ofcervical diseases. However, these techniques are beset with the risk ofsignificant neurologic and vascular injury too.Doubtlessly, It is essential that the implants used for these operations areappropriately designed and positioned. All these implants are closely related tothe morphological characteristics of posterior cervical osseous structures, which include the pedicles, laminae, and spinous processes. Knowing the dimensionsof these structures is a prerequisite for the development of appropriate implants.Furthermore, ethnic variations have been reported in these dimensions, and todate, there have been no spinal posterior instruments oriented morphometricstudies of this area in the northeastern Chinese population. Therefore, theobjective of this study is to determine the morphometric characteristics of thesubaxial cervical posterior osseous structures in northeastern Chinese persons.With rapid advances in imaging technology, thin-slice computedtomography (CT) scans and three-dimensional reconstruction techniques haveenabled the detailed study of the morphology of the subaxial cervical spine. Thisstudy aimed to analyze the features of the posterior structures of the subaxialcervical spine in northeastern Chinese persons by using high-resolution CTdevice (256-slice CT scanner).Materials and methods. One hundred patients complaining neck painwithout neurological deficits, congenital deformities, trauma of the spine andhistory of spinal surgery were enrolled in this study. All these patients underwenthigh-resolution CT scanning of the cervical spine. We analyzed a total of1000axial images,500coronal images and2000sagittal images to determine thedimensions of the following21parameters:1. Pedicle parameters: pedicle outerwidth (POW), pedicle inner width (PIW), pedicle outer height(POH), pedicleinner height(PIH), pedicle transverse angle (PTA), pedicle axial length (PAL);2.Lateral mass parameters: lateral mass longitudinal diameter (LMLD), lateralmass transverse diameter (LMTD), lateral mass coronal height(LMCH), superiorarticular process angle(SAPA);3. Laminar parameters: lamina outer width(LOW), lamina inner width (LIW), laminar outer height(LOH), laminar innerheight(LIH), lamina axis length (LAL), lamina transverse angle (LTA);4.Spinous process parameters: sagittal spinous process length (SSPL), axialspinous process length (ASPL);5. Spinal canal parameters: spinal canal transverse diameter (SCTD), spinal canal longitudinal diameter (SCLD),osseous spinal canal area (OSCA), and Pavlov ratio (PR). The participants wereclassified into male and female groups and developmental canal stenosis (DCS;PR≤0.75) and non-DCS (NDCS; PR>0.75) groups.Results.1. Significant differences were observed among the differentvertebral levels for almost all evaluated parameters, except for LTA and OSCA.2. The largest measurements of PIW, POW, POH, PIH were observed at C7level,while the smallest ones were observed at C3, C4levels.3. The smallest andlargest diameters of LIW, LOW, LIH, LOH were observed at C5and C7respectively.4. C5and C6had the largest dimensions of LMLD, while C7hadthe smallest LMLD and LMCH.5. The male all between the right and left sidesin all parameters, except for LTA.6. Between the male and female groups,Statistical differences were found in all parameters among levels except for PTA.Statistical differences of SAPA were found only at C4and C5levels. Statisticaldifferences of LTA were found only at C3and C6levels. Statistical differencesof SCLD were found only at C7level. Other linear parameters of male groupwere larger than the female group.7. Significant differences were foundbetween the DCS and NDCS groups in terms of LOH at all levels. Statisticaldifferences of SCLD were found at all levels except for C7level. Statisticaldifferences of LTA were found at C4, C6, C7levels. Statistical differences ofOSCA were only observed at C3level.Conclusions.1. Various measurements of the posterior structures ofsubaxial cervical vertebrae differed between the left and right sides, females andmales, and the DCS and NDCS groups.2. Different techniques for lateral massscrew insertion should be used according to different vertebral level. Magerltechnique is recommended at C3, C4, C7level, especially for C7level.3.Translaminar screw is not recommend in C5. Only C7laminar may be able tosafely accommodate a2.5mm translaminar screw.4. The recommend insertion angle of translaminar screw is about55degrees, and the recommended insertionlength is less than30mm.5. The recommend insertion angle of transpedicularscrew is about40degrees, and the recommended insertion length is less than32mm. The study data can help doctors to make better surgical decisions anddevelop more appropriate implants for northeastern Chinese patients.