Early treatment with the von Rosen splint for neonatal instability of the hip is safe regarding avascular necrosis of the femoral head

Figures & data

Figure 1. Measurement of the maximum diameter of the ossific nuclei.

Figure 2. A. A girl with fragmentation of the left ossific nucleus (grade-1 AVN) at 12-month follow-up. Treatment had been initiated at 2 days of age for left-sided instability. B. Normal appearance of the femoral head at 3 years. C. Normal hip development at final check-up. The observation time was 5 years 7 months.

Figure 3. A. A boy with mottled appearance of the left ossific nucleus (grade-1 AVN) at 12-month follow-up. Treatment had been initiated at 2 days of age for left-sided dislocation (Barlow-positive). B. Normal appearance of the femoral head at 8 years.

Figure 4. Flow chart detailing inclusion of patients in the study. Assessment of AVN was performed by review of 1-year and subsequent radiographs (Kalamchi-MacEwen grading), hospital files, and a diagnosis registry to a mean observation time of 6.5 years.

Figure 5. A higher degree of neonatal instability was associated with a smaller ossific nucleus at 12 months. Treatment differed between these groups (red dots).

Hips with a positive Ortolani test (i.e. dislocated in resting position) had smaller ossific nuclei than hips with a positive Barlow test (i.e. resting in the acetabulum but dislocatable) at 12 months. All these hips had 12 weeks of treatment (blue dots, subgroup analysis of dislocated hips). (n denotes the number of hips in each group. Error bars represent the 95% CI of the mean).

Table. 1 Comparison of the mean size of the ossific nucleus between study groups

	No. of hips (% of referrals)	Size of ossific nucleus, mm (95% CI)	p-value
Treatment
12 weeks	292 (27) ^a	9.7 (9.5–10.0)	< 0.001 ^b
6 weeks	138 (14)	10.1 (9.8–10.4)	< 0.001 ^b
Reference group	502 (59)	11.3 (11.1–11.5)
12 weeks, stable hips	67	10.4 (9.9–10.9)	0.002 ^b
6 weeks, stable hips	51	10.3 (9.8–10.8)	0.003 ^b
Clinical findings
Dislocated	194	9.4 (9.1–9.8)	0.01 ^c
Unstable	118	10.1 (9.7–10.4)
Stable	620	11.1 (10.9–11.3)	< 0.001 ^c
Ortolani-positive	64	8.7 (8.0–9.3)	0.001 ^d
Barlow-positive	130	9.8 (9.4–10.2)
Sex
Girls, reference group	342	11.6 (11.3–11.9)	< 0.001 ^e
Boys, reference group	160	10.7 (10.2–11.3)

a In total, neonatal instability of the hip (NIH) was left-sided in 103 (43%), right-sided in 31 (13%), and bilateral in 105 (44%) of 239 children. In the 152 children with dislocated hips, 60 (39%) were bilateral and 23 (15%) had an unstable contralateral hip. Note that the percentages given relate to all referrals, including those that did not meet inclusion criteria for analysis of the diameter of the ossific nucleus.

b Comparison with reference group.

c Comparison with unstable group.

d Comparison with Barlow-positive.

e Girls compared to boys in cases with bilaterally stable hips.