Machine Learning-Based Diagnosis in Laser Resonance Frequency Analysis for Implant Stability of Orthopedic Pedicle Screws

Evaluation of the initial stability of implants is essential to reduce the number of implant failures of pedicle screws after orthopedic surgeries. Laser resonance frequency analysis (L-RFA) has been recently proposed as a viable diagnostic scheme in this regard. In a previous study, L-RFA was used to demonstrate the diagnosis of implant stability of monoaxial screws with a fixed head. However, polyaxial screws with movable heads are also frequently used in practice. In this paper, we clarify the characteristics of the laser-induced vibrational spectra of polyaxial screws which are required for making L-RFA diagnoses of implant stability. In addition, a novel analysis scheme of a vibrational spectrum using L-RFA based on machine learning is demonstrated and proposed. The proposed machine learning-based diagnosis method demonstrates a highly accurate prediction of implant stability (peak torque) for polyaxial pedicle screws. This achievement will contribute an important analytical method for implant stability diagnosis using L-RFA for implants with moving parts and shapes used in various clinical situations.

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.

Minimally invasive reduction of thoracolumbar burst fracture using monoaxial percutaneous pedicle screws: Surgical technique and report of radiological outcome

Purpose: To describe the reduction technique of thoracolumbar burst fracture using percutaneous monoaxial screws and its radiological outcomes compared to polyaxial screws. Methods: All surgeries were performed by minimally invasive technique with either percutaneous monoaxial or percutaneous polyaxial screws inserted at adjacent fracture levels perpendicular to both superior end plates. Fracture reduction is achieved with adequate rod contouring and distraction maneuver. Radiological parameters were measured during preoperation, postoperation, and follow-up. Results: A total of 21 patients were included. Eleven patients were performed with monoaxial pedicle screws and 10 patients performed with polyaxial pedicle screws. Based on AO thoracolumbar classification system, 10 patients in the monoaxial group had A3 fracture type and 1 had A4. In the polyaxial group, six patients had A3 and four patients had A4. Total correction of anterior vertebral height (AVH) ratio was 0.30 ± 0.10 and 0.08 ± 0.07 in monoaxial and polyaxial groups, respectively ( p < 0.001). Total correction of posterior vertebral height (PVH) ratio was 0.11 ± 0.05 and 0.02 ± 0.02 in monoaxial and polyaxial groups, respectively ( p < 0.001). Monoaxial group achieved more correction of 13° (62.6%) in local kyphotic angle compared to 8.2° (48.0%) in polyaxial group. Similarly, in regional kyphotic angle, 16.5° (103.1%) in the monoaxial group and 8.1° (76.4%) in the polyaxial group were achieved. Conclusions: Monoaxial percutaneous pedicle screws inserted at adjacent fracture levels provided significantly better fracture reduction compared to polyaxial screws in thoracolumbar fractures.

Case series of clinical study and surgical management of atlanto axial dislocation our institute experience

Background: Atlantoaxial dislocation refers to a loss of stability between the atlas and axis (C1-C2), resulting in loss of normal articulation. Cervical spine C1-C2 motion segment is the most technically challenging.Methods: This is a prospective and retrospective Study which included 34 patients admitted in King George hospital, Andhra medical college, Visakhapatnam over the past two years (January 2014- January 2016) with AAD.Results: The age of the patients ranged from 3 to 60 years with mean age being 37.67 years. Commonest presenting sign is local tenderness at the back of upper cervical region in 91.17%. Most common procedure done was single sitting trans oral odontoid decompression with posterior occipito cervical fusion with occipital plate and C2, C4 polyaxial screws and lateral mass rods in 18 cases out of 34. The next common procedure performed was C1 lateral mass and C2 pars screw fixation 8 out of 34.Conclusions: Trans oral odentoidectomy and posterior ocipito cervical fusion is ideal and still holds good for irreducible AAD with ventral compressive pathology.