The accuracy and the safety of individualized 3D printing screws insertion templates for cervical screw insertion

Figures & data

Figure 1. The 3D computer model of cervical vertebra and screw insert templates in case1 (A) and case 2 (B).

Table 1. Master table.

Patient no.	Age	Sex	Etiology	Procedure	Follow-up (Mo)	3.5-mm screw, length, mm
1	12	F	Os odontoideum and atlanto-axial dislocation	C1–C2 fusion	6	24(2)\22(1)\20(1)
2	72	F	Cervical spine fracture	C4–C6 fusion	10	14 (2)\16 (4)
3	51	F	Cervical tumor	C3–C5 fusion	23	28(6)
4	48	M	Cervical spine fracture	C4–C5 fusion	13	30(4)
5	46	M	Cervical tumor	C5,C6–T2,T3 fusion	1	26(4)\28(4)
6	60	M	CSM and cervical instability	C3–C4 fusion	8	28(4)
7	47	F	Cervical spine fracture	C3–C4 fusion	11	26(4)
8	56	M	CSM and cervical instability	C4–C5 fusion	13	28(4)
9	54	F	Cervical spine fracture	C6–C7 right fusion	1	24(2)
10	61	M	CSM and cervical instability	C3–C5 fusion	8	28(6)

Table 2. Accuracy and safety of cervical screw insertion with individualized 3D printing screw insertion templates.

Screw	Class 1	Class 2	Class 3	Accuracy (%)	Deviation, mean ± SD (range) (mm)
48	47	1	0	97.9 (%)	0.58 ± 0.74 mm (0.0–3.1 mm)
Screw	Grade 0	Grade 1	Grade 2	Grade 3	Safety (% contain)
48	46	2	0	0	95.8%

Figure 2. The planned screw trajectories of among C1 (A), left C2 (B), and right C2 (C). Postoperative CT demonstrated that the trajectory deviations were 3.1 mm at the left C1, which broke the inside wall of lateral mass (grade 1), 0.3 mm at the right C1 (D), 0.2 mm at the left C2 (E), and 0.5 mm at the right C2 (F).

Figure 3. The planned screw trajectories of C1 (A) and C2 (B). Postoperative CT demonstrated that the trajectory deviations were 0.3 mm at the left C5 pedicle, 0.2 mm at the right C5(C), 0.1 mm at the right C6, and 0.4 mm at the left C6 (D). They were accurately at the planned location (class 1) and within the pedicle cortex (grade 0) (the mask in A and B reveals the C5 and C6 after reduction as we simulate on the computer).