Do dual-mobility cups cemented into porous tantalum shells reduce the risk of dislocation after revision surgery?

Figures & data

Table 1. Study population

	PE (n = 115)	DMC (n = 69)
Sex:
Male	56	34
Female	59	35
Paprosky:
I	22	5
IIA	16	10
IIB	19	9
IIC	28	8
IIIA	12	18
IIIB	17	19
Reason for index procedure:
Loosening	98	56
Dislocation	3	2
Infection	6	6
Other	8	5
Number of revisions:
First-time revision	88	46
Previously revised	27	23
Bone graft:
No	84	49
Yes	26	16
Augments:
0	109	57
1	4	11
2	2	1
Stem revised at index procedure:
No	78	43
Yes	37	26

Note: We found only a statistically significant difference between groups concerning Paprosky classification (p = 0.003) and the use of augments (p = 0.01). Missing data concerning Paprosky classification (1 case in PE group) as well as bone grafting (4 cases in DMC group, 5 cases in PE group).

Figure 1. Description of the inclusion of the study population.

Figure 2. Kaplan–Meier survival curves with the endpoint dislocation with shaded area indicating CI (p = 0.01, derived from Mantel–Haenszel log-rank test). Numbers at risk for both subgroups are given above the X-axis.

Figure 3. Kaplan–Meier survival curves with the endpoint re-revision for instability with shaded area indicating CI (p = 0.006, derived from Mantel–Haenszel log-rank test). Numbers at risk for both subgroups are given above the X-axis.

Figure 4. Kaplan–Meier survival curves with the endpoint re-revision for any reason with shaded area indicating CI (p = 0.03, derived from Mantel–Haenszel log-rank test). Numbers at risk for both subgroups are given above the X-axis.

Table 2. Description of the re-revised study population

	PE (n = 15)	DMC (n = 2)
Sex:
Male	6	1
Female	9	1
Paprosky:
I	2	0
IIA	1	0
IIB	1	1
IIC	8	0
IIIA	2	0
IIIB	1	1
Reason for index procedure:
Loosening	12	2
Dislocation	1	0
Infection	0	0
Other	2	0
Number of revisions:
First-time revision	11	2
Previously revised	4	0
Bone graft:
No	11	0
Yes	3	2
Stem revised at index procedure:
No	9	2
Yes	6	0
Head size:
22	0	1
28	9	1
32	4	0
Other	2	0
Reason for re-revision:
Aseptic loosening	2	2
Dislocation	11	0
Pain	1	0
Infection	1	0

Note: There was no statistically significant difference between the 2 groups. Missing data for 1 patient in the PE group concerning bone grafting.

Table 3. EQ5D subdimensions

EQ5D	PE (n = 69)	DMC (n = 44)
Mobility:
No problems	11	17
Some problems	44	23
Extreme problems	13	4
Anxiety/depression:
No problems	16	23
Some problems	20	13
Extreme problems	33	8
Usual activities:
No problems	14	25
Some problems	22	11
Extreme problems	32	8
Pain/discomfort:
No problems	10	13
Some problems	39	24
Extreme problems	20	7
Self-care:
No problems	16	33
Some problems	12	4
Extreme problems	41	7

Note: 1 patient in the PE group did not answer all questions.

Table 4. HOOS subdimensions

HOOS	group	n	mean	SD	range
Pain:	PE	70	70	28	0–100
	DMC	43	73	25	5–100
Symptoms:	PE	70	68	25	10–100
	DMC	44	71	27	10–100
ADL:	PE	70	67	28	0–100
	DMC	44	69	27	12–100
Sport/recreation:	PE	70	44	33	0–100
	DMC	44	45	30	0–100
QOL:	PE	70	52	30	0–100
	DMC	44	58	30	0–100

Note: 1 patient did not answer all questions. No statistically significant difference was found.