Clinical Applications Of C2Laminar Screws In Upper Cervical Surgery

ObjectivePosterior instrumentation of C2is important in treating many upper cervicaldiseases, providing one of the strongest points of fixation for the stability in the uppercervical region. However, the variability of C2anatomy may make fixation at thislevel challenging and prone to potentially life-threatening complications, such asvertebral artery or spinal cord injuries. Technological advances in instrumentationhave facilitated the treatment of the upper cervical pathology by providing significantimprovements in construct stability and strength, and by allowing for multiple optionswith respect to the entry points of screw placement. Although pedicle screw and C2transarticular screw have been frequently used for upper cervical fixation, thealternative C2instrumentation methods should be chosen for ideal fixation in somepatients with C2anatomical variation. Presently, C2posterior instrumentation mainlyincludes C2pedicle screw, C1–C2transarticular screw, C2lateral mass screw and C2translaminar screw fixation. C2pedicle screw and C1–C2transarticular screwplacement are difficulty with high risk of vertebral artery injury.C2lateral mass screwfixation cannot provide construct stability and strength. C2translaminar screwsfixation method was first proposed by Wright in2004, and has not gained highpopularity in clinical application. The purpose of this study was to explore the clinicaloutcomes of C2translaminar screw technique in the treatment of upper cervicaldiseases.MethodsThirty four patients with upper cervical diseases underwent the C2translaminarscrew fixation in the department of orthopedic surgery of the first affiliated hospitalof Zhengzhou university from July2009to October2012were analyzedretrospectively There were15males and19females with a mean age of46years (24to70years). There were10cases of atlantoaxial instability with C2malformations,8cases of atlantoaxial instability with vertebral artery malformation, one atypicalHangman fracture with C2-3instability, one congenital os odontoideum withatlantoaxial instability,2case of the rupture of Axis transverse ligament,6cases ofJefferson fracture combined with atlantoaxial instability, and6cases of traumaticinstability of C2-3. All patients had the symptoms of atlantoaxial instability such as pain, sensory dysfunction, motion limitation in cervical-occipital junction. All patientsreceived cervical spine DR,64-slice CTA, MRI and other imaging studies forpreoperative evaluation of the cranio-cervical junction about the degree of fracturedislocation and spinal cord compression, one week after the surgery, cervical DR,thin slice scanning CT and MRI examinations were used to check the screws position,fracture healing and the degree of spinal cord decompression. The AP and lateralviews of cervical spine were obtained in follow up DR examination. JOA (JapaneseOrthopaedic Association) scores were adopted to evaluate neural functions recoverybefore surgery and6months and24months postoperatively.ResultsFourteen patients underwent the bilateral C2translaminar screw fixation, and20patients received an combination of one C2translaminar screw and one C2pediclescrew fixation. A total of48C2translaminar screws were placed. Thirty-one31patients were followed-up for24months (all patients,3-24months).There were noneurologic or vertebral artery injury during surgery was noted,4patients had venousplexus injury and were successfully treated with gelatin sponge or fibril cottoncompression in surgery, one patient with postoperative leakage of cerebrospinal fluidhad a good wound healing by removing the draining tube3days after surgery andsymptomatic treatment,2patients has postoperative wounds fat liquefaction weretreated with timely dressing changes, and the wounds healed at day7.Thepreoperative, postoperative(6months and24months) JOA scoreswere(6.7±1.1),(14.8±1.7),(15.3±1.3) respectively. The overall improvement rate was(84±11)%. The follow-up imaging studies verified that all screws had a good position.No screw loosening, implant breakage or loss of atlantoaxial reduction was observedin all patients. One older woman obtained bony union12months after surgery and thebony union was evidenced in other cases at3to6months.ConclusionThe clinical result of the C2translaminar screw technique in the treatment ofupper cervical diseases is satisfactory, the surgical procedure is less complicated andsafe which may be a reliable alternative to traditional C2screw fixation.