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

Li, Xue-Shi; Wu, Zeng-Hui; Xia, Hong; Ma, Xiang-Yang; Ai, Fu-Zhi; Zhang, Kai; Wang, Jian-Hua; Mai, Xiao-Hong; Yin, Qing-Shui

doi:10.6061/clinics/2014(11)08

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CLINICAL SCIENCES • Clinics 69 (11) • Nov 2014 • https://doi.org/10.6061/clinics/2014(11)08 copy

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

Authorship SCIMAGO INSTITUTIONS RANKINGS

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; Accuracy; Atlantoaxial Dislocation; Transoral Transpedicular Screw

	Entry Point Differences		Angle Differences
Cadaver	Dx	Dy	Transverse	Sagittal	Accuracy Evaluation
1R	0.18	-0.75	0.29	-15.26	I
1 L	3.45	-0.24	11.02	-5.76	III
2R	1.44	0.62	-0.63	-7.40	I
2 L	0.52	0.66	12.75	-3.85	III
M	1.40	0.07	5.86	-8.07
S	1.47	0.69	7.01	5.01

	Entry Point Differences		Angle Differences
Cadaver	Dx	Dy	Transverse	Sagittal	Accuracy Evaluation
3R	1.07	-0.83	3.79	-15.21	I
3 L	0.70	-0.84	-9.02	-18.26	II
4R	0.29	0.36	2.80	-8.81	I
4 L	1.15	0.75	-4.40	-12.23	I
5R	-0.56	-0.61	2.93	-1.56	I
5 L	-0.40	-0.67	1.11	-3.69	I
6R	0.34	-0.84	2.43	-9.60	I
6 L	0.54	-0.41	-1.09	-7.45	I
7R	0.71	0.91	0.82	-8.71	II
7 L	-0.43	0.96	-0.07	-13.68	I
8R	0.05	0.13	-2.51	-6.06	I
8 L	-0.28	-0.55	2.4	-15.02	II
9R	0.48	0.5	3.21	-12.65	I
9 L	-0.07	0.64	-2.49	-20.06	I
10R	-0.38	0.28	2.07	1.23	I
10 L	0.78	0.63	-1.36	-1.23	I
M	0.25	0.03	0.04	-9.56
S	0.56	0.68	3.42	6.24

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E-mail: clinics@hc.fm.usp.br

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[1] Li XS conceived and designed the study, was responsible for data acquisition analysis and interpretation, and manuscript drafting. Ai FZ, Xia H and Wu ZH were responsible for data analysis and interpretation, manuscript drafting, proofreading and revision as native English speakers. Ma XY, Zhang K, Wang JH, Mai XH study conceived and designed the study, and were responsible for the manuscript critical revision. Wu ZH and Yin QS conceived and designed the study, were responsible for the data analysis and interpretation and critical revision of the manuscript. Wu ZH and Yin QS contributed equally as co-corresponding authors.