Atlantoaxial dislocation with high spinal cord compression is a common disease, which endangers people's health and is difficult to treat. Transoropharyngeal surgery is a very important method for the treatment of this disease. The author briefly reviews various operations of decompression and internal fixation through anterior transoropharyngeal approach and some correlative treatments conducted over the past few years. Although transoropharyngeal surgery has not been widely adopted at present, with increasing understanding of physiology and anatomy of the cranio-cervical junction, and development of microsurgical technic, and improvement in pre-vention and treatment of amplications, it has rapidly become a more acceptable approach for the treatment of atlantoaxial dislocation with cord compression. And with the application of new techniques, its treatment result will be conspicuously improved.

Objective To evaluate transoropharyngeal atlantoaxial reduction plate system (TARP) and its preliminary clinical effect. Methods The TARP system was designed to consist of a butterfly titanium alloy plate, self-locking screws, atlantoaxial reductor and other surgical instruments. The system was applied clinically to five irreducible atlantoaxial dislocations as a result of injury or congenital disorders. During the operation, the reduction was achieved through the combination of the plate and the atlantoaxial reductor after the transoropharyngeal brisement and decompression. Bone graft was implanted between the lateral atlantoaxial joints. Results The reduction mechanism of the TARP system was well designed. Its clinical application to five cases of irreducible atlantoaxial dislocation proved that TARP had the function of instant reduction and that the operation was feasible and had laudable effect. Conclusion TARP design is a novel strategy. Its operative procedure is simple and feasible. Both the instant reduction and stable fixation can be obtained during the operation. TARP is creative and has excellent prospect.

0.05). The ROM of flexion-extension, lateral bending and axial rotation of these two groups was smaller than that of the other three fixators(P0.05). Conclusion Experimentally, the effect of TARP was equal to that of Magerl+Brooks, but it was proved to be more stable than the other three clinically widely used atlantoaxial fixators: Magerl, Brooks and anterior transarticular screw fixation through C 2 vertebral body. TARP's C 1 and C 2 screws were strong enough for atlanto-axial arthrodesis. TARP's biomechanical performance was excellent.

Objective To provide anatomical profile of the cranio-cervical region for the surgical treatment of ventral atlantoaxial lesions through transoropharyngeal approach.Methods Ten fresh specimens of craniocervical region were dissected layer by layer with microsurgical technic in accordance with the transoropharyngeal approach for the surgical treatment of atlantoaxial lesion, with special attention to anatomical stratification of pharyngeal posterior wall, the course of the vertebral artery, anatomical relation between the atlas and the axis, and anatomical parameters pertaining to internal fixation for the atlantoaxial joint. Results Pharyngeal posterior wall consisted of two layers (mucosa and prevertebral fascia) and two spaces (posterior interspace of pharynx and anterior interspace of vertebrae). Through anterior transoropharyngeal approach, the region between the anterior rim of the foramen magnum down to C 3 could be exposed. The distance between the vertebral artery and midline of the atlar and axis was 25.2?2.3mm(20.4-29.7mm) and 18.4?2.6mm(13.1-23.0mm) respectively. The exposed areas of the atlas and axis were 39.4?2.2mm(36.2-42.7mm) and midline was 39.0?2.1mm(35.8-42.3mm), respectively. The distance(a) between the two screw inserting points on the atlas (middle point of C 1 lateral mass) was 31.4?3.3mm(25.4-36.6mm). The vertical distance(b) between the connecting line of two screw inserting points on the atlas and that of two screw inserting points on the axis (3-4mm lateral to the midline of C 2 vertebra) was 18.7?2.7mm(14.9-23.2mm). The odds of a/b ranged from 1.5 to 1.7. Conclusion Atlantoaxial surgery through transoropharygeal approach is safe and feasible. The approach is suitable for internal fixation of anterior atlantoaxial joint, and the design of the plate should be based on the above data.

BACKGROUND:C2 transpedicle screw fixation for Hangman fractures has been paid more attention due to reliability and no loss of physiological function.However,there are lacks of biomechanical evidences for indication treatment because the fixation is single segmental.OBJECTIVE:To investigate the biomechanical stability of C2 transpedicle screw fixation for Hangman fractures.DESIGN,TIME and SEITING:This was a contrast study which was performed at the General Key Laboratory of Biomechanics,First Military Medical University of Chinese PLA from May to August 2004.MATERIALS:AO-universal titanium alloy transpedicle screw of 18 25 mm in length and 3.5 mm in diameter was adopted in this study.Six fresh C1-C4 cervical vetebrae samples were ordiually made into type Ⅰ,ⅡA,and Ⅱ Hangman fracture models.METHODS:After transpedicle screw fixation.Hangman fracture models were measured by non-destroyed style with spinal anterior flexion/posterior extension,left/right lateral curvature,and left/right axial direction.Loading/unlonding circulation was performed three times during each testing.Kinematics indicators were measured on the 3rd circulation.MAIN OUTCOME MEASURES:Spinal motor images at zero load and maximal load were obtained with laser photoscanning(0.1% in precision),and the corresponding systematic software was adopted to calculate 3D range of movement.RESULTS:The relative stability of type Ⅰ Hangman fracture models after C2 transpedicle screw fixation was 100.62%(inflexion),96.91%(posterior extension),99.19%(lateral curvature),and 97.12%(rotation)as compared to control group (P＞0.05).The relative stability of type Ⅱ Hangman fracture models after C2 transpedicle screw fixation was 47.84%(inflexion),21.29%(posterior extension),65.98%(lateral curvature),and 41.69%(rotation)as compared to control group (P＜0.05).CONCLUSION:Biochemical evaluation suggests that type Ⅰ and Ⅱ A Hangman fractures do fit for C2 transpedicle screw fixation,and the fixation may generate well physiological fixation or stability.However,stability of type Ⅱ Hangman fracture is poor,so it is not suitably adopted single transpedicle screw fixation.

BACKGROUND: Decompression-internal fixation is needed in the treatment of atlantoaxial dislocation accompanying with spinal compression caused by cranium-neck junction area malformation and other diseases.Different internal fixation methods are chosen according to different conditions, including anterior atlantoaxial internal fixation, posterior atlantoaxial internal fixation or occipitocervical internal fixation. Transoralpharyngeal atlantoaxial plate internal fixation is a method for atlantoaxial anterior fixation. It is developed recently and used for difficult and complicated atlantoaxial dislocation induced by congenital disease, trauma or rheumatoid arthritis.OBJECTIVE: To probe into the clinical application of transoralpharyngeal atlantoaxial reduction plate system in the atlantoaxial dislocation caused by obsolete odontoid fracture.DESIGN: Single Sample observation SETTING: Department of Orthopaedics, Guangzhou General Hospital of Guangzhou Military Medical University of Chinese PLA PARTICIPANTS: Twelve patients with atlantoaxial dislocation caused by obsolete odontoid fracture were selected in the Department of Orthopaedics, General Hospital of Guangzhou Military Medical University of Chinese PLA from January 2003 to October 2005. Among them, 7 were male and 5 were female, they were aged 47 years on average ranging from 36 to 59 years. The mean injured time was 19 months ranging from 4.5 to 36 months; 6 patients were graded as C degree, 3 as D degree and 3 as E degree in Frank gradation.METHODS: Twelve obsolete odontoid fracture caused by atlantoaxial dislocation underwent transoralpharyngeal anterior decompression. Transoralpharyngeal atlantoaxial reduction plate system was used in reduction and fixation. Autogeneic ilium was implanted into bilateral articulatio atlantoepistrophica.MAIN OUTCOME MEASURES: ① Frank gradation of patients at the 4th week after operation. ② whether the internal fixation is loose or not after operationRESULTS: ①Frank gradation at the 4th week after operation: Among the 6 patients who were primarily graded as C degree, 4 patients improved to be E degree and 2 patients D degree; Three patients who were primarily graded as D degree all improved to be E degree; Patients who were primarily graded as E degree did not changed. ② Except for one patient who suffered dislocation again for loosening of screw caused by tumble, the other patients had firm fixation, ideal fusion and satisfying spinal decompression.CONCLUSION: Transoralpharyngeal atlantoaxial reduction plate system finishes atlantoaxial reduction and fixation once. It avoids conducting posterior fusion fixation operation after anterior decompression. It also avoids fetal injury for spinal cord caused by extreme atlantoaxial unsteadiness in the process of movement and turning over.

Objective To evaluate the biomechanical characteristics and the clinical advantage of transoral atlantoaxial reduction plate(TARP)Ⅲ.Methods Design of TARP-Ⅲ was based on TARP-Ⅱ.The screw hole in the axis was moved 1-2 mm upwards and inwards in a plate which turned a vertebral screw into a pedicle screw or an articular process screw.A polyaxial self-lock ring and polyaxial guiding drill were added to the crew hole of the plate.Finally,the withdrawal resist ence force of the three axis screws was tested and TARP-Ⅲ was used in 44 patients with complicated irreducible atlantoaxial dislocation.The axis was fixed with the pedicle screw or the articular process screw.Results The maximum withdrawal resist ence force of the anterior pedicle screw,the articular process screw and the vertebral screw in the axis was(593.1 ± 97.8)N,(469.9 ± 73.3)N and(395.2 ± 75.1)N respectively,with statistical difference between groups among three fixation methods(P ＜ 0.05).All 44 patients were followed up for 5-38 months(average 18 months),which showed complete anatomic reduction in 36 patients and appropriate anatomic reduction in eight,with basic correction of the angles between the brain stem and the spinal cord and sufficient decompression of the spinal cord.The decompression rate of the cervical spinal cord was average 88.2% according to the Yin evaluating method of cervical cord decompression.The improvement rate of spinal cord function was average 76.6% according to Japanese Orthopaedic Association(JOA)score.Conclusion With the design of polyaxial self-lock mechanism,TARP-Ⅲ with the pedicle screw or the articular process screw surpasses TARP-Ⅱ with vertebral screw in aspect of biomechanics.

Objective:To investigate the clinical efficacy of different grade transoral atlantoaxial release for the treatment of irreducible atlantoaxial dislocation.Methods:From January 2010 to December 2019, 297 patients with irreducible atlantoaxial dislocation treated by different grade releases were retrospectively analyzed, including 132 males and 165 females, aged 42.3±12.14 years (range, 10-63 years). All cases were treated by different grade releases, Grade I (196, 66.0%), Grade II (54, 18.2%), Grade III (28, 9.4%) and Grade IV (19, 6.4%). The American Spinal Injury Association (ASIA) grade and Japanese Orthopedic Association (JOA) score were recorded as the clinical evaluation index. The clivus-canal angle (CCA) and cervico-medullary angle (CMA) were measured to evaluate the reduction. The surgery time, blood loss, duration of bony fusion and complications were also analyzed.Results:The follow-up time was 14.8±10.2 months (range, 9-36 months). The surgery time of Grade I-IV were 2.02±0.35 min, 3.00±0.36 min, 4.07±0.96 min and 5.24±0.83 min, respectively ( F=385.43, P<0.001), blood loss was 84.08±27.21 ml, 153.61±31.36 ml, 268.93±48.94 ml and 444.21±109.51 ml, respectively ( F=582.39, P<0.001). The preoperative ASIA motor score of Grade I-IV were 83.85±6.68, 84.06±5.47, 84.07±5.99 and 85.00±4.11, respectively. The last follow-up were 98.34±2.38, 98.67±1.79, 98.86±1.58 and 98.32±2.11, respectively, with statistically significant differences from preoperative ( P<0.05). The preoperative JOA score of Grade I-IV were 11.44±1.73, 11.59±1.72, 11.61±1.47 and 11.32±1.80, respectively. The last follow-up were 16.22±1.00, 16.28±1.02, 16.14±1.04 and 16.16±1.07, respectively, with statistically significant differences from preoperative ( P<0.05). The preoperative CCA of Grade I-IV were 110.19°±8.76°, 112.48°±7.66°, 106.61°±6.54° and 109.05°±7.79°, respectively. The last follow-up were 140.22°±8.04°, 141.86°±7.04°, 142.35°±8.62° and 140.15°±6.49°, respectively, with statistically significant differences from preoperative ( P<0.05). The preoperative CMA of Grade I-IV were 113.48°±9.54°, 116.03°±8.38°, 109.55°±7.13°, and 112.46°±8.33°, respectively. The last follow-up were 144.28°±7.75°, 146.40°±6.98°, 145.81°±8.27° and 143.24°±6.36°, respectively, with statistically significant differences from preoperative ( P<0.05). Solid bony fusion was obtained except for 3 cases, the fusion time was 9.71±2.55 months (range 3-14 months). Altogether 33 complications occurred in all cases (11.1%), including 3 fusion failure, 3 cerebrospinal leak, 3 wound infection, 2 death (1 case caused by cerebrospinal leak), 11 pharyngeal discomfort, 4 postoperative pain surrounding iliac crest, and 8 malunion of iliac crest. Conclusion:Transoral stepped atlantoaxial release theory could provide guidelines for atlantoaxial dislocation treatment, and make the transoral release technique more effective and safer.