Versatile Usage of the Modified Lateral Mass Screw as an Alternative to Cervical Pedicle Screw Fixation

Objective Posterior subaxial cervical screw fixation is commonly performed using the cervical pedicle screws (CPS) and lateral mass screws (LMS); however, their compatibility is low. Modified lateral mass screws (mLMS, also called paravertebral foramen screw) fixation was introduced as a salvage technique for LMS fixation and has features of both LMS and CPS techniques. In the present study, the use of mLMS as an alternative to CPS was analyzed based on clinical results. Methods Seventy-eight screws (38 CPSs and 40 mLMSs) were inserted into 12 patients. The misplacement of the screws was evaluated by computed tomography (CT). The failure of instrumentation and instability were evaluated using plain radiographs. Results The total number of CPS misplacements was 3 (10.5%); however, neurologic complications were not observed. mLMSs were used in the middle segments of the fusion in 10 patients and 2 patients had mLMS fixation for single-level fusion. An additional bridging implant was not required for connecting both CPSs and mLMSs. Instability was not observed during the observation period (4–51 months). Complete fusion was seen in 10 patients. Conclusions The alternative mLMS fixation can decrease the risk of screw misplacement compared with CPS fixation alone and achieves adequate stability leading to fusion.

Intraoperative Computed Tomography Scanner-Guided Craniovertebral Junction Surgery in a Patient with an Occipitalized C1

Craniovertebral junction surgery is associated with unique difficulties. Type 2 odontoid fractures (Anderson and D Alonzo) have a great potential for nonunion and malunion. These fracture patients may require a circumferential decompression and fixation. The addition of intraoperative CT with neuronavigation greatly aids in craniovertebral junction surgery. We operated on a 59-year-old-male with a type 2 fracture with posterior subluxation of C1 anterior arch and a cranially displaced odontoid peg. First, a transoral odontoidectomy was performed followed by a craniocervical fixation. Occipital plates and C3–C4 lateral mass screws were used as C1 was discovered to be occipitalized intraoperatively and atlantoaxial facet joints could not be reduced as discovered by intraoperative CT resconstruction. Intraoperative CT scan was crucial to this circumferential decompression and fixation, allowed us to resect the odontoid peg safely and completely and to confirm adequate screw trajectory making this complex surgery easier for us and safer for the patient. The patient was discharged 4 months after admission with stable neurology. Intraoperative CT was fundamental to correct decision making.

Posterior hemivertebra resection and short-segment fusion with lateral mass screws in congenital scoliosis: a novel strategy for the resource-limited setting

Background Posterior hemivertebra resection and short-segment fusion with pedicle screws are an established treatment in congenital scoliosis, which require pediatric-specific instrumentation. The purpose of this study was to report the results of utilizing cervical lateral mass screws instead of pedicle screws in the treatment of congenital scoliosis in children younger than 5 years old. Methods In an IRB-approved retrospective chart review study, patients <5 years old with congenital scoliosis who underwent posterior hemivertebra resection and fusion with lateral mass screws from 2013 to 2017 were included. Demographic information, pre- and post-operative radiographs, complications, and outcomes were extracted from the charts. Results Twenty-three patients were included in the final analysis with a mean age of 40 months, of which 14 were female. Patients were followed for a mean of 51.3±13.2 months. The mean blood loss was 210ml, and patients were hospitalized for a mean of 4 days post-operatively. The correction rate of the main coronal curve, compensatory cranial curve, compensatory caudal curve, and segmental sagittal curve was 74.8%, 68%, 65.2%, and 68.9%, respectively. Three complications were observed: one intra-operative pedicle fracture, one case of implant failure, and one deep surgical-site infection, all of which were successfully managed. Conclusions Our findings suggest that adult lateral mass screws can be used for transpedicular fixation of the thoracic and lumbar vertebrae in low-resource settings where pediatric-specific pedicle instruments are not readily available. The correction rate, outcomes, and complications are similar and comparable to pediatric-specific pedicle screws, in addition to being low-profile and less bulky compared to adult implants.

Outcome of Lateral Mass Fixation and Fusion – A Comprehensive Analytical Study of 205 Lateral Mass Screws in 35 Patients at Punjab Institute of Neurosciences

Objective: To see outcome, accuracy and expected complications in passing lateral mass screws in patients with cervical spine injury, degenerative disease at the cervical spine level and neoplastic lesions.Materials and Methods: In this study, 35 patients were included and 205 screws passed in lateral mass patients’age ranged from 12-70 years (25 males and 10 females) with trauma to the cervical spine, degenerative disease at the cervical spine level and Intradural extramedullary benigntumors and extradural malignant neoplasm.Patients less than 12 years and more than 65 years of age,patients with traumatic ruptured disc causingspinal cord compression anteriorly and operated for cervical spine were excluded from our study.In all patients,we did lateral mass fixation with polyaxial screws and rods under fluoroscopic assistance.For assessment of screws trajectory and position, CT scan cervical spine with 3D reconstruction was performed on a first post op day to confirm screw orientation and direction and for fascet, foraminal, foramen transversarium violations.Results: All screws were passed by using Megrel’s trajectories. Not a single patient had nerve root, cord injury nor vertebral artery injury. One patient had screw pullouts requiring reoperation.12 to 14mm size screws were used under fluoro guidance. On postoperative CT cervical spine with 3D reconstruction shows no breach or violations of any foramen transversarium, nerve root injury or neural foramen penetration by screws. In all patients polyaxial screw/rod construct was used. Conclusion: Cervical spine lateral mass fixation with polyaxial screws is a safe and effective technique in expert hands under fluoroscopic assistance.