Survival of uncemented acetabular monoblock cups

Figures & data

Table 1. Baseline characteristics

	Study group	Control group
	(n = 210)	(n = 1,130)
Cup design
Morscher press-fit cup	129 (61%)	–
Trabecular Metal Monoblock cup	81 (39%)	–
Trilogy cup	–	1,130 (100%)
Median age at surgery, years	47 (17–83)	56 (20–90)
Sex
Male	101 (48%)	577 (51%)
Female	109 (52%)	553 (49%)
Primary diagnosis
Primary osteoarthritis	106 (51%)	839 (74%)
Inflammatory disease	21 (10%)	34 (3%)
Pediatric hip disease	63 (30%)	154 (14%)
Idiopathic femoral head necrosis	15 (7%)	53 (5%)
Other	5 (2%)	50 (4%)
Surgical approach
Posterior	188 (90%)	252 (22%)
Anterior	19 (9%)	791 (70%)
Missing	3 (1%)	87 (8%)
Shell holes
Non-holed	–	2 (0%)
Multi-holed	–	59 (5%)
Cluster-holed	–	1,069 (95%)
Highly crosslinked polyethylene
No	210 (100%)	539 (48%)
Yes	–	573 (51%)
Missing	–	18 (1%)
Head size
22 mm	2 (1%)	65 (6%)
28 mm	159 (76%)	1,036 (92%)
≥ 32 mm	49 (23%)	11 (1%)
Missing	–	18 (1%)
Type of stem fixation
Uncemented	202 (96%)	967 (86%)
Cemented	7 (3%)	161 (14%)
Missing	1 (1%)	2 (0%)

Kaplan-Meier analysis (with 95% CI) of monoblock and modular cups with revision for any reason as the endpoint.

Table 2. Cox regression analysis, hazard ratios (HRs) of cup revision for any reason

			Simple Cox regression ^a			Multiple Cox regression ^b
Covariate	No. of cases	No. of revisions	HR	95% CI	p-value	HR	95% CI	p-value
Cup
Monoblock	210	8	1.3	0.6–2.7	0.6	2.2	0.8–5.8	0.1
Modular	1,130	40	Ref.			Ref.
Age
< 50	415	16	Ref.			Ref.
50–59	517	15	0.7	0.4–1.5	0.4	0.9	0.4–1.9	0.7
60–75	381	15	1.1	0.5–2.2	0.8	1.0	0.4–2.4	0.9
> 75	27	2	2.2	0.5–9.7	0.3	1.6	0.3–8.0	0.6
Sex
Male	678	24	1.0	0.6–1.7	0.9	1.5	0.8–2.7	0.2
Female	662	24	Ref.			Ref.
Primary diagnosis
Primary osteoarthritis	945	26	Ref.			Ref.
Inflammatory disease	55	2	1.3	0.3–5.6	0.7	1.1	0.2–4.9	0.9
Pediatric hip disease	217	9	1.5	0.7–3.1	0.3	0.9	0.3–2.2	0.7
Idiopathic femoral
head necrosis	68	4	2.1	0.7–6.1	0.2	2.1	0.7–6.1	0.2
Other	55	7	5.3	2.3–12	0.001	4.4	1.8–11	0.001
Surgical approach
Posterior	440	16	1.0	0.5–1.8	1.0	1.1	0.5–2.4	0.9
Anterior	810	29	Ref.			Ref.
Highly crosslinked polyethylene
Yes	573	22	1.3	0.7–2.3	0.4	1.4	0.7–3.0	0.4
No	749	26	Ref.			Ref.
Head size
22 mm	67	8	Ref.			Ref.
28 mm	1,195	40	0.3	0.1–0.6	0.001	0.2	0.1–0.5	0.001
> 32 mm	60	–	0	0–9.7	1.0	0	0–1.7	1.0
Type of stem fixation
Uncemented	1,169	42	1.4	0.6–3.5	0.5	1.1	0.4–3.1	0.9
Cemented	168	5	Ref.			Ref.

^a crude HR;

^b adjusted HR (all covariates mentioned above were entered in the Cox analysis).