Cancellous and cortical bone mineral density around an elastic press-fit socket in total hip arthroplasty

Figures & data

Figure 1. RM cementless press-fit socket (Mathys AG, Bettlach, Switzerland).

Figure 2. A. Scanogram. B. Sequential CT slices surrounding the acetabular component. C. measurement of cancellous BMD. In total, 6 axial scans were performed starting 10 mm above the socket, parallel to the horizontal teardrop line.

Table 1. Study demographics

No. of patients	25
Sex distribution, M/F	7/18
Age, mean (SD) (range)	64 (4) (56–71)
BMI, mean (SD) (range)	27 (3.1) (23–36)

Figure 3. Box plots of the cancellous bone mineral density in the 6 slices for the baseline, 6-month, and 24-month follow-up measurements. Blue bars indicate the BMD in the prosthetic hip; red bars indicate the BMD in the contralateral hip. The median is indicated by the central circle, thick lines are interquartile range, and the thin lines are total range excluding outliers, which are indicated by circles.

Table 2. Changes in BMD (%) relative to immediately postoperatively

	6 months postoperatively	24 months postoperatively
	Prosthetic side	Prosthetic side	Control side
Cancellous bone
1	−9.6	−14
2	−17	−26
3	−29	−35	−12
4	−23	−32
5	−16	−31
6	−20	−31	−5
Cortical bone
1	−1	−3
2	−4	−5
3	−3	−4	5
4	−1	0
5	0	5
6	−5	−1	0

Figure 4. Box plots of the cortical bone mineral density in the 6 slices for the baseline, 6-month, and 24-month follow-up measurements. Blue bars indicate the BMD on the prosthetic side and red bars indicate the BMD on the control side.

Table 3. Clinical scores. Values are median (range)

	Preoperative	2 months		6 months		12 months		24 months
		postoperative	p-value^a	postoperative	p-value^a	postoperative	p-value^a	postoperative	p-value^a
OHS	24 (15–34)	34 (14–47)	0.04	45 (11–48)	< 0.001	47 (22–48)	< 0.001	45 (19–48)	< 0.001
HHS	61 (39–81)	77 (47–100)	0.03	95 (32–100)	< 0.001	98 (65–100)	< 0.001	96 (57–100)	< 0.001
VAS	50 (6–87)	13 (0–50)	0.001	0 (0–80)	< 0.001	0 (0–70)	< 0.001	0 (0–70)	< 0.001

a p-values are derived from the comparison with preoperative values, with the Wilcoxon signed-rank test.