The application of atlantoaxial screw and rod fixation in revision operations for postoperative re-dislocation in children.

Introduction: We evaluate the feasibility, safety, and efficacy of atlantoaxial screw and rod fixation for revision operations in the treatment of re-dislocation after atlantoaxial operations in children.

Methods: Eight consecutive children with atlantoaxial instability required a revision operation due to atlantoaxial re-dislocation caused by the failure of the initial posterior wire fixation. The children were 5-11 years of age with an average age of 8.

Treatment of basilar invagination with atlantoaxial dislocation: atlantoaxial joint distraction and fixation with transoral atlantoaxial reduction plate (TARP) without odontoidectomy.

Purpose: Although direct transoral decompression and one-stage posterior instrumentation can obtain satisfactory cord decompression for the treatment of basilar invagination with atlantoaxial dislocation, surgical injuries run high as combinative anterior-posterior approaches were necessary. Furthermore, the complications will rise notably when involvement of dens and/or clivus in the decompression necessitates relatively complicated surgical techniques. First initiated in 2005, transoral atlantoaxial reduction plate (TARP) works as an internal fixation for the treatment of basilar invagination with irreducible atlantoaxial dislocation.

New clinical classification system for atlantoaxial dislocation.

The purpose of this study was to define a new clinical classification of atlantoaxial dislocation based on its clinical manifestations, namely reducible atlantoaxial dislocation (RAAD), irreducible atlantoaxial dislocation (IAAD), and fixed atlantoaxial dislocation (FAAD). A total of 107 patients with atlantoaxial dislocation were respectively treated based on this clinical classification, including 66 patients with RAAD, 39 patients with IAAD, and 2 patients with FAAD. Six of the 66 patients with RAAD with rotatory atlantoaxial dislocation were treated with traction and a cervical collar, 9 with fresh type II dens fracture were treated with cannulated screw fixation, and 51 were treated with posterior atlantoaxial or occipitocervical arthrodesis.

C2 anatomy and dimensions relative to translaminar screw placement in an Asian population.

Study Design: A cadaveric specimen study.

Objectives: To determine the applicability of a modified C2 translaminar screw placement in the general adult population and to provide pertinent clinical data for screw insertion.

Summary Of Background Data: C2 intralaminar screw fixation has recently been popularized, but this technique carries a potential drawback that the screw may breakout ventrally into the spinal canal.

C1 pedicle screws versus C1 lateral mass screws: comparisons of pullout strengths and biomechanical stabilities.

Study Design: In vitro biomechanical study.

Objective: To compare the pullout strengths and the biomechanical stabilities afforded by C1 lateral mass screws and C1 pedicle screws using bicortical and unicortical fixation techniques.

Summary Of Background Data: Posterior screw fixation techniques in the atlas including C1 lateral mass screw and C1 pedicle screw.

[Anatomic evaluation the entry point of C2 pedicle screw].

Objective: To study the relevant position of C(2) pedicle to C(2) inferior articular process, set up a technique of C(2) pedicle screw placement with the inferior articular process of axis as an anatomic landmark.

Methods: Fifty C(2) bone specimens were used to measure the distance from the sagittal midline to the medial border, the midpoint and the lateral border of C(2) inferior articular process or C(2) pedicle; the width and the height of the C(2) pedicle were also evaluated. The anatomic relation between the measurements data of C(2) pedicle and that of C(2) inferior articular process were analyzed, and the technique of C(2) pedicle screw fixation was established.

A quasi-physical algorithm for the structure optimization in an off-lattice protein model.

In this paper, we study an off-lattice protein AB model with two species of monomers, hydrophobic and hydrophilic, and present a heuristic quasi-physical algorithm. First, by elaborately simulating the movement of the smooth solids in the physical world, we find low-energy conformations for a given monomer chain. A subsequent off-trap strategy is then proposed to trigger a jump for a stuck situation in order to get out of the local minima.

Applied anatomy of transoral atlantoaxial reduction plate internal fixation.

Study Design: A C1-C2 operation by the transoral approach was simulated to study the anatomic stratification, various structures, and adjacent relationships. The anatomic parameters in relation to transoral atlantoaxial reduction plate (TARP) internal fixation were measured.

Objectives: To study relevant anatomic features of the structures involved in TARP internal fixation through transoral approach for treating irreducible atlantoaxial dislocation, so as to provide anatomic basis for the clinical application of TARP.

Transoral atlantoaxial reduction plate fixation for irreducible atlantoaxial dislocation.

Objective: To design a clinically applicable transoralpharyngeal atlantoaxial reduction plate (TARP), introduce the operation procedure, and evaluate its preliminary clinical effects.

Methods: A novel TARP system, including butterfly titanium alloy plate, self-locking screws, atlantoaxial reductor and other operational instruments was developed. This system was applied clinically on five patients with irreducible atlantoaxial dislocation of congenital or traumatic origin.

The anatomical study of transoral atlantoaxial reduction plate internal fixation.

Objective: To study relevant anatomical features of the structures involved in transoral atlanto-axial reduction plate (TARP) internal fixation through transoral approach for treating irreducible atlanto-axial dislocation and providing anatomical basis for the clinical application of TARP.

Methods: Ten fresh craniocervical specimens were microsurgically dissected layer by layer through transoral approach. The stratification of the posterior pharyngeal wall, the course of the vertebral artery, anatomical relationships of the adjacent structures of the atlas and axis, and the closely relevant anatomical parameters for TARP internal fixation were measured.

[Anatomic identification of the location of the pedicle of atlas with the lateral mass of C2 to C4 as the landmark].

Objective: To study the relevant position of the pedicle of C1 to the lateral mass of C(2-4), set up an identification technique for the entry point decision of C1 pedicle screw by using the lateral mass of C(2-4) as anatomic landmarks.

Methods: Twenty cadaver specimens were used to measure the distance from the sagittal midline of spine to the medial border, the midpoint and the lateral border of C1 pedicle or the lateral mass of C2, C3 or C4. The anatomic relation between the measurements data of C1 pedicle and that of the lateral masses of the cervical vertebrae were analyzed, and the technique of C1 pedicle screw fixation was established.

Anatomic considerations for the pedicle screw placement in the first cervical vertebra.

Study Design: Anatomic bony measurements were manually performed on 50 dry atlantoaxial vertebral complexes with an electronic digital caliper, and a reliable landmark for insertion of a pedicle screw in C1 vertebra was described and evaluated.

Objectives: To investigate the feasibility of placing a screw in the C1 pedicle and evaluate the reliability of the C2 lateral mass as a landmark for determining the optimal site of screw entry.

Summary Of Background Data: The use of C1-C2 pedicle screws with the additional rods or plates has been an alternative method of stabilization for patients who are unsuitable for C1-C2 transarticular screw stabilization.

Irreducible anterior atlantoaxial dislocation: one-stage treatment with a transoral atlantoaxial reduction plate fixation and fusion. Report of 5 cases and review of the literature.

Study Design: Retrospective report of five surgical cases and review of the literature.

Objectives: To report the clinical application of a novel internal fixation device in the treatment of irreducible atlantoaxial dislocation with ventral spinal cord compression.

Summary And Background Data: Irreducible atlantoaxial dislocation with ventral spinal cord compression is difficult to treat.

[Results of 1310 knees of meniscal treatment evaluated by arthroscopy].

Objective: To evaluate results of 1310 knees of meniscal treatments by arthroscopy and to present good method of meniscal treatment.

Methods: Their age, traumatic mechanism and effects under arthroscopy were analysed in a series of 254 patients with meniscal injuries, there were 880 males and 374 females, the average of the patients was 25.5 years.

[Design and preliminary clinical application of transoralpharyngeal atlantoaxial reduction plate].

Objective: To design transoralpharyngeal atlantoaxial reduction plate (TARP), evaluate its biomechanical performance and observe its preliminary clinical effect.

Methods: A brand-new TARP system was designed, including butterfly titanium alloy plate, self-locking screws, atlantoaxial reductor and other operation instruments. Twelve fresh occipital bone-C(3) specimen were designed for biomechanical test including range of motion (ROM) (n = 6) and screw pull-out strength (n = 12).

[The reason and prevention of upper cervical reoperations].

Objective: To discuss the reasons for the operation performed on 13 patients with upper cervical disease and to explore the management and prevention of upper cervical disease.

Methods: Thirteen patients with upper cervical disease were retrospectively reviewed. The reason for of reoperations on these patients were analyzed.