Safe fixation with two acetabular screws after Ganz periacetabular osteotomy

Figures & data

Figure 1. Radiostereometric image with bone markers.

Figure 2. Preoperative radiograph with CE angle and Tönnis'angle.

Figure 3. Axes of rotation and translation of the acetabular fragment.

Figure 4. Mean translation and SD over time.

Figure 5. Mean rotation and SD over time,

Table 1. Migration of acetabular fragment 6 months after Ganz periacetabular osteotomy (n=32)

	Mean translation, mm			Mean rotation, degrees
	medial	proximal	posterior	anterior tilt	internal	adduction
Mean	0.66	0.68	0.35	0.23	0.37	0.45
95% CI	0.37–0.96	0.47–0.89	−0.10–0.59	−0.24–0.69	−0.10–0.84	−0.07–0.97
SD	0.76	0.54	0.63	1.18	1.19	1.31

Table 2. The precision as estimated from 7 double examinations

	medial	Translation proximal	posterior	anterior tilt	Rotation internal rotation	adduction
SD	0.54	0.37	0.58	0.51	0.47	0.56
95% CI	0.35–1.2	0.24–0.82	0.38–1.29	0.33–1.11	0.31–1.04	0.36–1.24

Table 3. Radiographic evaluation of preoperative and postoperative radiographs from 32 hips

Parameter degrees (range)	Preoperatively	Postoperatively	Change
Tönnis' angle	17 (7–39)	2 (−4–10)	−15
Wiberg angle	13 (−27–25)	32 (20–40)	19