Clinical clanger: ‘I’m worried about this infant’s asymmetric skin creases’

Continuing our series of clinical scenarios that can commonly be mishandled in primary care, GP Dr Peter Bagshaw looks at case of potential hip dislocation in an infant

Scenario
Your experienced health visitor contacts you about a six-month-old boy she has just visited. She noticed asymmetric hip skin creases and told the mother the child will need referral for further investigation to exclude developmental dislocation of the hip (DDH), despite having passed his six-week check. 

Just to be sure, you consult your slightly battered copy of the newborn and infant screening programme physical examination (NIPE) handbook, which confirms the observation of asymmetric skin creases is ‘a screen positive finding which requires referral to a specialist for further investigation.’

What do you do?

The reality
Skin asymmetry is no longer regarded as a significant finding. Updated NIPE hip standards, which were implemented across England on 1 April 2021, states:

‘Please note that observation of skin creases for symmetry is no longer part of the NIPE screen. This is no longer regarded as a screen positive finding.’¹

The issue
Unnecessary investigation wastes resources and generates anxiety. The longer we are in medicine, the more we need to unlearn things we were taught – but this can be a challenge in such a wide field. 

Unfortunately, screening for DDH is fraught with problems: as BMJ Best Practice points out, it ‘represents a spectrum of conditions…ranging from acetabular immaturity to hip subluxation and frank hip dislocation. The Barlow and Ortolani screening tests… begin to lose their sensitivity and usefulness around 3-6 months’. 

Best Practice also comments that ultrasound ‘should be used with caution as a preliminary screening test due to the high number of false positive results [with] a high rate of spontaneous resolution of hips identified as mildly abnormal by both clinical examination and ultrasound in the neonatal period’.²

The evidence
NIPE changed its recommendation following a number of good-quality research papers showing the received wisdom about skin creases was wrong. In 2017, a paper concluded ‘this study confirms the opinions of experts and systemic reviews that isolated ASC (asymmetric skin creases) is an unreliable clinical sign in the diagnosis of pathological DDH’.³ In 2018 another study came to the same conclusion,⁴ as have a number of subsequent studies such as Toupozoulos and Markeas in 2020,⁵ who concluded ‘the positive predictive value of asymmetrical or isolated thigh creases for DDH in infants was found to be low’ and Sevencan and colleagues in 2022, who found that ‘the relationship of isolated thigh ASC with DDH could not be demonstrated statistically’. ⁶ 

A few studies have demurred (eg, Ömeroğlu et al)⁷  but the overall consensus is strong enough to drop skin asymmetry as a sign we should take note of.

Avoiding a clanger
It is always difficult to go against colleagues’ advice, particularly when faced with an anxious parent. We should do so in a way that avoids criticism of a fellow healthcare professional and explains the evolving nature of evidence-based medicine. In this case, safety-netting is important, explaining that no test is 100% accurate, and that the parent should return if they notice any limited hip mobility.  You might also wish to consider feeding back to colleagues or setting up an update or training session for the extended primary care team.

Caveats 
Female sex, a positive family history, breech presentation and postural deformity are all known risk factors for DDH. Apart from limited hip abduction, abnormal positioning of the leg or delayed crawling/walking, and toe-walking (especially unilateral) would raise suspicion and be indications for referral.

Current guidance flags the following as a positive screen for DDH:¹

• Difference in leg length.
• Knees at different levels when hips and knees are bilaterally flexed.
• Restricted unilateral limitation of hip abduction (≥20-degree difference between hips).
• Gross bilateral limitation of hip abduction (loss of ≥30 degrees).
• Palpable ‘clunk’ when performing Ortolani or Barlow manoeuvre. 

Key points

• Screening for DDH is important, and early treatment (eg, with a Pavlik harness) can prevent later disability.
• Use the current NIPE guidance flags as a positive screen for DDH.
• Isolated skin crease asymmetry is no longer regarded as a significant finding, and should not be looked for.
• Ultrasound and X-ray screening can give false positive results, with many minor changes regressing spontaneously.

Peter Bagshaw is a GP in Somerset

References

1. Public Health England. Newborn and infant physical examination (NIPE) screening programme Handbook, April 2021. Link
2. BMJ Best Practice. Developmental Dysplasia of the Hip. Reviewed July 2023. Link
3. Anderton M and Paton R. Isolated asymmetrical skin creases and their association with pathological developmental dysplasia of the hip: a 21-year observational longitudinal study. Orthop Proc 2017,99,15-15. Link
4. Anderton M et al. The positive predictive value of asymmetrical skin creases in the diagnosis of pathological developmental dysplasia of the hip. Bone Joint J 2018;100:675-9. Link
5. Touzopoulos P and Markeas N. Asymmetrical thigh creases or isolated thigh crease may be a false positive sign with low predictive value in the diagnosis of developmental dysplasia of the hip in infants: a prospective cohort study of 117 patients. Eur J Orthop Surg Traumatol 2020, 30,133–138. Link
6. Sevencan A et al. Multivariate analysis of the predictive value of asymmetric skin creases in diagnosis of decentralized developmental dysplasia of the hip. J Pediatr Orthop 2022,31,517-23. Link
7. Ömeroğlu H et al. Significance of Asymmetry of Groin and Thigh Skin Creases in Developmental Dysplasia of the Hip Revisited: Results of a Comparative Study. Journal of Pediatric Orthopaedics2020,40,761-65. Link

To read more articles from Pulse’s clinical clangers series, click here