An 11-Year Review of the TARP Procedure in the Treatment of Atlantoaxial Dislocation.

STUDY DESIGN: Retrospective study. OBJECTIVE: The aim of the study was to introduce the surgical techniques and evaluate the clinical outcomes of transoral atlantoaxial reduction plate (TARP) for the treatment of atlantoaxial dislocation. SUMMARY OF BACKGROUND DATA: Researchers have reported on transoral plate internal fixation for the treatment of irreducible atlantoaxial dislocation (IAAD) without long-term follow-up and detailed clinical experience. METHODS: The clinical records of 388 patients with atlantoaxial dislocation (IAAD, 340 cases; fixed atlantoaxial dislocation [FAAD], 48 cases) who received the TARP procedure from April 2003 to September 2014 were retrospectively reviewed. They were treated separately with TARP-I or TARP-II (82 cases), TARP-III (248 cases), or TARP-IV (58 cases). X-ray and magnetic resonance imaging were used to evaluate the efficacy of reduction and the degree of decompression, respectively. The long-term clinical outcome was evaluated by Japanese Orthopaedic Association scoring and the Symon and Lavender standard. RESULTS: Immediate reduction was achieved for all the patients with IAAD (340/340), whereas anatomical reduction was achieved for 98.2% of patients (334/340). Anatomical reduction was achieved in 87.5% of patients with FAAD (42/48). The average degree of spinal cord decompression ranged from 75% to 100% with an average of 88.4%. The clinical data of 106 patients were evaluated in the latest follow-up (12-108 mo, average 60.5 mo). The average spinal cord improvement rate by Japanese Orthopaedic Association scoring was 62.1%. According to the Symon and Lavender standard, there were 85 cases rated as markedly effective, 104 cases as effective, and 2 cases as noneffective. The overall markedly effective rate was 80% and the effective rate was 98%. CONCLUSION: The TARP procedure showed good anterior atlantoaxial release, reduction, decompression, and internal fixation for patients with IAAD and FAAD through a single anterior approach. It has the advantages of three-dimensional immediate atlantoaxial reduction and sufficient decompression. LEVEL OF EVIDENCE: 3.

The development and evaluation of individualized templates to assist transoral C2 articular mass or transpedicular screw placement in TARP-IV procedures: adult cadaver specimen study.

OBJECTIVES: The transoral atlantoaxial reduction plate system treats irreducible atlantoaxial dislocation from transoral atlantoaxial reduction plate-I to transoral atlantoaxial reduction plate-III. However, this system has demonstrated problems associated with screw loosening, atlantoaxial fixation and concealed or manifest neurovascular injuries. This study sought to design a set of individualized templates to improve the accuracy of anterior C2 screw placement in the transoral atlantoaxial reduction plate-IV procedure. METHODS: A set of individualized templates was designed according to thin-slice computed tomography data obtained from 10 human cadavers. The templates contained cubic modules and drill guides to facilitate transoral atlantoaxial reduction plate positioning and anterior C2 screw placement. We performed 2 stages of cadaveric experiments with 2 cadavers in stage one and 8 in stage two. Finally, guided C2 screw placement was evaluated by reading postoperative computed tomography images and comparing the planned and inserted screw trajectories. RESULTS: There were two cortical breaching screws in stage one and three in stage two, but only the cortical breaching screws in stage one were ranked critical. In stage two, the planned entry points and the transverse angles of the anterior C2 screws could be simulated, whereas the declination angles could not be simulated due to intraoperative blockage of the drill bit and screwdriver by the upper teeth. CONCLUSIONS: It was feasible to use individualized templates to guide transoral C2 screw placement. Thus, these drill templates combined with transoral atlantoaxial reduction plate-IV, may improve the accuracy of transoral C2 screw placement and reduce related neurovascular complications.

The development and evaluation of individualized templates to assist transoral C2 articular mass or transpedicular screw placement in TARP-IV procedures: adult cadaver specimen study

OBJECTIVES: The transoral atlantoaxial reduction plate system treats irreducible atlantoaxial dislocation from transoral atlantoaxial reduction plate-I to transoral atlantoaxial reduction plate-III. However, this system has demonstrated problems associated with screw loosening, atlantoaxial fixation and concealed or manifest neurovascular injuries. This study sought to design a set of individualized templates to improve the accuracy of anterior C2 screw placement in the transoral atlantoaxial reduction plate-IV procedure. METHODS: A set of individualized templates was designed according to thin-slice computed tomography data obtained from 10 human cadavers. The templates contained cubic modules and drill guides to facilitate transoral atlantoaxial reduction plate positioning and anterior C2 screw placement. We performed 2 stages of cadaveric experiments with 2 cadavers in stage one and 8 in stage two. Finally, guided C2 screw placement was evaluated by reading postoperative computed tomography images and comparing the planned and inserted screw trajectories. RESULTS: There were two cortical breaching screws in stage one and three in stage two, but only the cortical breaching screws in stage one were ranked critical. In stage two, the planned entry points and the transverse angles of the anterior C2 screws could be simulated, whereas the declination angles could not be simulated due to intraoperative blockage of the drill bit and screwdriver by the upper teeth. CONCLUSIONS: It was feasible to use individualized templates to guide transoral C2 screw placement. Thus, these drill templates combined with transoral atlantoaxial reduction plate-IV, may improve the accuracy of transoral C2 screw placement and reduce related neurovascular complications. .

Transoral atlantoaxial reduction plate internal fixation with transoral transpedicular or articular mass screw of c2 for the treatment of irreducible atlantoaxial dislocation: two case reports.

STUDY DESIGN: Retrospective report of two surgical cases and review of the literature. OBJECTIVE: To report the clinical application of transoral atlantoaxial reduction plate (TARP) internal fixation with a novel technique of transoral transpedicular or articular mass screw of C2 in the treatment of irreducible atlantoaxial dislocation and basilar invagination with ventral spinal cord compression. SUMMARY OF BACKGROUND DATA: Current surgical treatments for IAAD have various disadvantages, such as posterior decompression followed by atlantoaxial or occipitocervical fusion with unsatisfactory decompression, transoral decompression, and one-stage posterior instrumentation needing two approaches although with satisfactory decompression, resection of dens and/or clivus with potential risk of spinal cord injury and CSF leakeage. METHODS: TARP system with a novel technique of transoral transpedicular screw or articular mass screw of C2 was designed and employed for two patients with irreducible atlantoaxial dislocation, during which one case was with basilar invagination. The histories of the cases and the novel technique of transoral articular mass screw and transpedicular screw insertion of C2 were reported in detail. RESULTS: The two case examples demonstrate the efficacy of this one-stage single transoral approach to the surgical treatment of irreducible anterior atlantoaxial dislocation with spinal cord compression especially in the case of basilar invagination. The role of the TARP in affecting and maintaining the reduction while promoting successful fusion is illustrated. CONCLUSION: The authors' one-stage anterior procedure employing the TARP for the surgical treatment of irreducible anterior atlantoaxial dislocation and basilar invagination was effective in these two cases. This method was able to avoid the need for dens and clivus resection and/or a posterior instrumentation and fusion procedure. The technique of transoral articular mass screw and transpedicular screw insertion of C2 was valuable for transoral atlantoaxial plate internal fixation.

[Diagnosis and treatment for complicated atlantoaxial dislocation].

OBJECTIVE: To explore the clinical characteristics and treatment methods for complicated atlantoaxial dislocation. METHODS: A retrospective evaluation was done to summarize and analyze the clinical characteristics and complicated factors of 54 patients with complicated atlantoaxial dislocation who could not to be treated effectively by using conventional therapy in our hospital from February 2005 to October 2008. According to different complicated factors, different treatment methods mainly including transoral atlantoaxial reduction plate-III (TARP-III) operation, decompression procedure with deep grinding guided by computer aided design-rapid prototyping (CAD-RP), screw placement technique with CAD-RP guide plate and extensile approach surgery were performed. RESULTS: The average follow-up period was 24 months. Among 54 cases, 48 cases achieved immediate anatomic reduction completely and 6 cases almost achieved anatomical reduction. All the compressed spinal cords were decompressed sufficiently. The decompression rate was 86.0% and the improvement rate of nerve function was 77.8%. Two cases suffered postoperative intracranial infection. CONCLUSION: Some cases of complicated atlantoaxial dislocation can be effectively treated by using TARP-III operation, decompression procedure with deep grinding guided by CAD-RP, individualized screw placement technique with CAD-RP guide plate and extensile approach surgery.

Transoral atlantoaxial reduction plate internal fixation for the treatment of irreducible atlantoaxial dislocation: a 2- to 4-year follow-up.

OBJECTIVE: To evaluate the mid-term outcomes of transoral atlantoaxial reduction plate (TARP) internal fixation for the treatment of irreducible atlantoaxial dislocation. METHODS: From April 2003 to April 2005, 31 patients with irreducible atlantoaxial dislocation were treated with TARP internal fixation. The average age was 37.9 years (range, 15-69 years). The subjective symptoms, objective signs, and neurological function of the patients were assessed. Radiography and magnetic resonance imaging (MRI) were performed and the results analyzed according to the Symon and Lavender clinical standard, Japanese Orthopaedic Association (JOA) score for spinal cord function and imaging standard for spinal cord decompression. RESULTS: Complete or almost complete anatomical reduction was obtained in all 31 patients. No screw-loosening or atlantoaxial redislocation was found in 29 cases. According to the Symon and Lavender clinical standard, 14 cases had recovered completely, 7 to mild, 6 to moderate, and 4 to severe type by final follow-up, compared to the preoperative classifications of 4 as moderate, 15 as severe, and 12 as extra severe type. The outcome for 26 patients was evaluated as excellent and in 5 as adequate. The average postoperative improvement in spinal cord function was 73.3% and of decompression of the cervical cord 92.6%. The only complication was loosening of screws in two cases with senile osteoporosis. One case underwent TARP revision surgery and the other posterior occipitocervical internal fixation. Both of them were eventually cured. CONCLUSION: The TARP operation is a good choice for patients with irreducible atlantoaxial dislocation and has valuable clinical application.

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. During operation, the reduction was completed by the combined action of the plate and the atlantoaxial reductor after transoral joint release and cord decompression. Bone graft granules were implanted between the bilateral atlantoaxial joints and TARP was used to immobilize subsequently the atlas and axis. RESULTS: Clinical application demonstrated that TARP could induce instant reduction and that the method was operationally feasible and its postoperational effect was satisfactory. CONCLUSIONS: The design of TARP is novel. The operational procedure is simple and easy to use. Furthermore, instant reduction can be completed during the operation and the fixation is relatively stable. TARP is an ideal alternative for irreducible atlantoaxial dislocation and may have excellent prospects for further clinical applications.

[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). Preliminary clinical application of TARP was reported. RESULTS: The reduction mechanism of the TARP system was designed cleverly. TARP had equal effect with Magerl + Brooks and it was 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 atlantoaxial arthrodesis and their antipull-out performance was excellent. Clinical application on irreducible atlantoaxial dislocation proved that TARP had the function of instant reduction, the operation was feasible and the operation effect was significant. CONCLUSION: TARP's design is novel and it has excellent biomechanical performance. The operation procedure is simple and reasonable. Furthermore, instant reduction could be completed during the operation and the fixation is strong. Above all, TARP is creative and will have excellent prospect.