No effect of delivery on total hip replacement survival: a nationwide register study in Finland

Figures & data

Figure 1. Flow chart of study population and events of total hip replacement (THR) survival among fertile-aged (15 to 45) women having delivery compared with women not having delivery after THR.

Table 1. Background characteristics of the study population, types of hip prosthesis, and indications for revisions between the delivery group and the reference group. Values are frequency (%) unless otherwise specified

Factor	Delivery group n = 133	Reference group n = 2,343
Age at primary THR^a	29 (8)	40 (8)
Follow-up period (years)^a	9.1 (6)	8.0 (8)
Rheumatoid arthritis	62 (47)	774 (33)
Other chronic disease^b	5 (4)	208 (9)
Nulliparous at primary THR	78 (64)	778 (33)
Indication for THR
Inflammatory arthritis (RA + others)	62 (47)	731 (31)
Primary osteoarthritis	12 (9)	532 (23)
Secondary arthrosis	21 (16)	363 (16)
DDH^c	22 (17)	493 (21)
Other	16 (12)	224 (10)
Metal-on-metal bearing	16 (12)	390 (17)
Type of primary THR fixation
Uncemented	114 (86)	1,859 (79)
Hybrid	7 (5)	237 (10)
Inverse hybrid	0 (0)	1 (0)
Cemented	12 (9)	245 (10)
Revisions	51 (38)	645 (28)
Revision indications
Aseptic loosening	30 (59)	318 (50)
Deep infection	1 (2)	11 (2)
Periprosthetic fracture	0 (0)	12 (2)
Dislocation	1 (2)	30 (5)
Others	14 (27)	193 (30)
Missing	5 (10)	81 (12)

a Median and interquartiles.

b Includes: asthma, diabetes mellitus type 1, epilepsy, hypothyroidism, hypertension, inflammatory bowel disease, major psychiatric disease.

c DDH = developmental dysplasia of the hip.

Table 2. Comparison of primary diagnoses and revision indications in the delivery group between women with at least 1 vaginal delivery after total hip replacement (THR) with women with only Cesarean sections after THR

Factor	Vaginal delivery after THR n = 53	Cesarean section after THR n = 80
Indication for THR
Inflammatory arthritis (RA + others)	19	43
Primary osteoarthritis	4	8
Secondary arthrosis	13	8
DDH	10	12
Other	7	9
Revisions	15	36
Revision indications:
Aseptic loosening	10	20
Deep infection	1	0
Dislocation	0	1
Others	4	10
Missing	0	5

DDH = developmental dysplasia of the hip.

Figure 2. Kaplan–Meier survival curves (with 95% confidence intervals) of primary total hip replacement (THR) among fertile-aged women aged 15 to 45 years at the time of THR having 1 or more deliveries after THR (delivery group) compared with no deliveries after THR (reference group).

Table 3. Kaplan–Meier 6- and 13-year survival rates with 95% confidence intervals (CI) of primary total hip replacement of fertile-aged women aged 15 to 45 years at the time of THR

Delivery	No. of hips	No. of revisions	K–M survivorship at 6 years		at 13 years
			No. at risk	survival % (CI)	No. at risk	survival % (CI)
Yes	133	51	100	91 (85–96)	22	50 (39–62)
No	2,343	645	1,411	88 (87–90)	456	62 (59–64)