Neonatal hip instability and risk of total hip replacement in young adulthood

Figures & data

Table 1.  Number of cases with total hip replacement (THR) and neonatal hip instability (NHI), and relative risk

	THR		Relative risk (95% CI)
		No	Yes
NHI
No	2,198,733	431	1 [reference]
Yes	19,421	11	2.6(1.4-4.8)
Sex
Male	1,139,835	192	1 [reference]
Female	1,075,914	250	1.4(1.1-1.6)
Year of birth
After 1975	1,636,904	102	1 [reference]
In 1975 or earlier	581,250	340	0.87 (0.67-1.1)

Table 2.  Reason(s) for total hip replacement recorded in the Norwegian Arthroplasty Register (NAR) for patients < 38 years of age who were registered in both the NAR and the Medical Birth Registry of Norway

Diagnoses^a	Individuals	Percentage (%)
Idiopathic coxarthrosis	16	3.5
Rheumatoid arthritis	83	18
Sequ. fractura colli femoris	27	5.9
Sequ. dysplasia	71	16
Sequ. dysplasia with dislocation	24	5.3
Sequ. Perthes/epiphysiolysis	83	18
Morbus Bechterew	20	4.4
Others	128	28
Missing diagnosis	3	0.7
^a More than one diagnosis is possible.

Table 3.  Occurrence of neonatal hip instability (NHI) in the 442 individuals registered in the Norwegian Arthroplasty Register (NAR), according to sex, year of birth, and age at time of total hip replacement, and among the 2,218,596 individuals in the Medical Birth Registry of Norway (MBRN), according to sex and year of birth

	MBRN			NAR
	Total	% Total	% NHI	Total	% Total	% NHI
Sex
Men	1,140,027	51	0.5	192	43	2.1
Women	1,076,164	49	1.3	250	57	2.8
Unknown	1,811	0.1	0.4	0	0	0.0
Year of birth
Before 1976	581, 590	26	0.91	340	77	2.6
1976-1985	516,838	23	1.1	97	22	1.0
1986-1995	591,101	27	1.0	5	1.1	2.0
After 1995	529,062	24	0.48	0	0.0	0.0
Age at prosthesis
< 25 years				183	41	2.7
25-29 years				134	30	2.2
30-34 years				97	22	3.1
> 35 years				28	6.3	0.0
Total	2,218,596	100	0.88	442	100	2.5