Fluoroscopically based drilling of the femoral head in a model of adiposis

Figures & data

Figure 1. Overall view of the assembly, showing the positioned leg model with attached reference markers, the fluoroscope with its marker device, the infrared camera, and the touch-screen monitor of the navigation system. [Color version available online.]

Figure 2. Femoral sawbones with pelvis and tibia fitted into the custom-made, conical, soft synthetic brace. [Color version available online.]

Figure 3. Calibration of the drill fitted with reference markers using a calibration tool.

Figure 4. Real-time visualization of drilling on the associated touch-screen. [Color version available online.]

Figure 5. Section through a proximal femur after drilling with the drill left in situ. [Color version available online.]

Figure 6. Grouping of results into zones based on distance from the target. Bars 1–4 represent zones I–IV of the navigated group; bars 5–8 represent zones I–IV of the control group.

Table I.  Results for navigated group.

Sawbone #	Distance from target (mm)	Radiation time (s)	Procedure time (min)	Drilling corrections
1	0.4	<1	5.0	0
2	1	<1	4.5	0
3	0.8	<1	5.0	1
4	0.4	< 1	4.8	0
5	0	< 1	4.6	0
6	0.6	<1	5.4	1
7	1.2	< 1	5.0	0
8	0.2	< 1	5.2	1
9	0.4	< 1	5.0	1
10	0.6	< 1	4.6	0
11	0	< 1	4.5	0
12	1	< 1	5.1	1
13	0.4	< 1	4.9	0
14	1.2	<1	4.5	0
15	0.4	< 1	4.8	0
16	0.2	<1	4.9	1
17	1.2	< 1	4.4	0
18	0.6	< 1	4.7	1
19	0.2	< 1	4.4	0
20	0.4	< 1	4.3	0
Mean	0.56*	<1^**	4.78	0.35^***

*There was a statistically significant difference in the distance from the target compared to the control group (p < 0.001, t-test).

^**There was a statistically significant difference in the radiation exposure time compared to the control group, taking one second into account for the navigated group, even though less than one second was actually needed (p < 0.001, Mann-Whitney rank-sum test).

^***There was a statistically significant difference in the number of drilling corrections compared to the control group (p < 0.001, Mann-Whitney rank-sum test).

Table II.  Results for control group.

Sawbone #	Distance from target (mm)	Radiation time (s)	Procedure time (min)	Drilling corrections
1	1	5	5.5	3
2	1.2	3	4.2	2
3	0.8	6	6.0	5
4	1.4	4	4.1	2
5	0.6	5	5.4	3
6	2	2	3.5	0
7	0.8	5	5.6	4
8	1.8	4	4.5	2
9	2	3	3.7	1
10	0.4	6	6.1	5
11	1.2	4	5.3	3
12	0	2	3.2	0
13	1.6	3	4.5	2
14	2	2	3.9	1
15	0.6	5	5.0	3
16	1.4	3	4.1	2
17	0.8	3	4.4	2
18	1.8	3	4.3	2
19	0.4	6	5.6	4
20	1.2	3	5.1	3
Mean	1.15	3.85	4.7	2.45

Table III.  Distance of drill from the target (the lesion mid-point).

Zone	I	II	III	IV
Navigated group (n = 20)	11	7	2	0
Control group (n = 20)	3	6	5	6

Zone I: 0 to 0.5 mm. Zone II: 0.6 to 1 mm. Zone III: 1.1 to 1.5 mm. Zone IV: > 1.6 mm.