The Limping Child

Author: Charlotte Davies, Nikki Abela / Editor: Liz Herrieven / Reviewer: Katherine Stanley / Codes: / Published: 11/02/2020 / Reviewed: 17/12/2024

Elsie is a four year old who has come into the Emergency Department (ED) because her parents are concerned that she is not walking. Three days ago she was playing with her aunt and hurt her leg. Since then, she has not been weight-bearing and her parents have been carrying her everywhere.

She has been given regular paracetamol and ibuprofen at home for the pain. She has been off her food but is drinking well. She has no diarrhoea or vomiting. Her observations are: RR 18, SpO2 98% on room air, heart rate 89, capillary refill <2 seconds, temperature 37.5oC, GCS 15.

We’ve all seen limping children. Maybe some of us have even had limping children. Some departments have excellent management strategies and pathways. Some don’t. Here’s some of our thoughts, musings and suggestions.

What are your differential diagnoses at this point?

There are lots of things that can cause a child not to weight-bear. There is a history of trauma here so careful examination is needed to determine which bit of the leg might need imaging. The delay in presentation should make you question whether there are any concerns about non-accidental injury if in doubt, you will need to speak to the Paediatricians and your safeguarding team.

Clinical Examination Findings

The child looks very well. She is holding her hip in flexion and abduction. She is very tender on palpation of the greater trochanter and the iliac crest, but has no femoral pain. She will not move her leg, even when encouraged to do so by tickling her foot. When you try and move her leg she is sore on all hip movements but has a good range of movement. Because of her history of trauma and pain, you send her for a pelvis and hip x-ray. These x-rays are normal.

What next?

The history of trauma given doesnt account for the leg positioning in the child and the amount of pain that she is in. A fracture has been excluded so it would be sensible to think of atraumatic causes of a limping child. Perhaps the trauma history was a red herring? There are lots of causes for limp in children and many hospitals have detailed algorithms to follow – the protocol on Paediatric Pearls website has some very clear guidelines . Well ponder some of the differentials further.

Figure 1

Perthes Disease

Our patient is in the right age bracket for this (approximately 4 to 8 years), although the condition is more common in boys. However, Perthes disease, or avascular necrosis of the hip, is unlikely as the radiographs are normal. The signs of Perthes may be subtle ranging from almost normal, with a slightly wider epiphysis, to fragmentation and widening of the femoral neck (coxa magna). In Perthes, the joint capsule is under maximum pressure in the position of flexion and internal rotation the child may hold their hip in external rotation. A referral to orthopaedics (outpatients is usually ok, rather than as an emergency) if Perthes is suspected.

SUFE

A SUFE is unlikely shes too young! Slipped upper femoral epiphyses normally affect 10-15 year olds, boys more often than girls. Half of those affected have bilateral disease. Make sure you do the frog view which can reveal an early posterior slip. You may need to look carefully the S line may be useful. Kleins line will normally intersect with the lateral portion of the femoral epiphysis (Trethowans sign). If you suspect SUFE, treat this as an orthopaedic emergency! Get the child on a trolley, dont let them weightbear, and refer urgently to ortho.

Figure 2 X-ray image by Dr.Vijaya Chandar, via Wikimedia Commons

Irritable Hip

Transient synovitis or irritable hip is a possibility. Irritable hip is a common cause of limp in children and again is more common in boys than girls. There is no reliable way of differentiating irritable hip from septic arthritis. Clinical suspicion, supplemented with blood test results, is important and this formulates the kocher criteria.

Commonly, not much is known about transient synovitis (TS), and for many ED clinicians, it is a diagnosis of exclusion, as when a patient presenting with hip pain typical of TS will be suspected to have septic arthritis, until proven otherwise. That is of course, the safe approach. But what exactly is TS?

TS is a self-limiting synovial inflammation of the hip that occurs in childhood (there are only about three reported cases in adulthood in the literature). It is relatively common, with an average annual incidence of 0.2% of the general population. There is a male-to-female ratio of slightly more than 2:1. The disease typically presents at a mean age of 6 (38) years. The truth is we dont really know what actually causes TS.

There are theories of an autoimmune or post-traumatic process, but there is little proof behind them. Five main research papers support a link with viral infection two studies measured immunological parameters and three investigated clinical evidence of a preceding viral illness. However, there is much doubt on this hypothesis, and I will tell you why. First lets talk about the studies supporting this: Early work by Leibowitz, et al., and later by Tolat, et al. found that patients with TS have a higher serum interferon concentration and are more likely to be in an antiviral state compared with controls.

A few years later Landin et al. further supported this hypothesis when they noted a seasonal variation in the incidence of TS, with more cases presenting in October and fewer cases in February. Kastrissianakis and Beattie, raised the suspicion further when they found that TS patients are more likely to have preceding viral symptoms. In another paper, Fisher and Beattie found a preceding illness in 40% of patients with TS. However, studies attempting to single out viral pathogens, which would not only help diagnosis, but also prevention, have not been successful. If youre a bit of a sceptic, this fact alone will already begin to raise an eyebrow. However, one can argue that although the viral culprit hasnt been found, that doesnt mean they didnt do it. So, others have taken on the debate from different angles. For example, Harrison, et al. argue that the finding of raised interferon levels is not universal, nor specific to a virus, and is not made in comparison with a well-formed control group.

Clinical questions of viral illness are flawed by recall bias, they say, and the strongest evidence to support the viral association is the ecological evidence of an association between TS and seasonality. Harrisons well-powered study, which looked at the epidemiology of TS in my hometown- Liverpool, found no seasonal association. Interestingly though, these authors found a link with deprivation in Merseyside, however, this may be due to referral bias and further attempts to replicate this in other settings are needed. Ok FINE. So, we dont know what causes it. But how do we differentiate it from other hip pathology? As outlined already, the diagnosis is mainly one of exclusion. Several evidence-based algorithms have been presented for the limping child, mainly to ensure that emergencies or more serious diseases (like osteomyelitis, septic arthritis, orthopaedic oncological lesions, Perthes disease and SUFE) are not over-looked.

MRI may be considered in patients with equivocal clinical presentation and US results as this may be able to differentiate between TS and septic arthritis. However, MRI facilities are not always readily accessible, and they frequently require the administration of a general anaesthetic in small children. 

TS is self-limiting and resolves spontaneously. It is managed conservatively through observation and by encouraging rest. Parents should also be given advice to return if symptoms worsen or if a fever develops. The addition of NSAIDs has been studied by Kermond, et al., who found that ibuprofen reduced the average number of days with symptoms from 4.5 days in the placebo group to 2 days in those administered ibuprofen.

Figure 3

Toddlers Fractures

Toddlers Fracture normally affect younger children (1-3 years old). This is usually after a fall and normally affect the distal 1/3 of the tibia. Sometimes a long leg cast is needed. The x-ray findings can be subtle, and many places treat clinical symptoms without definite abnormal radiology.

Septic Arthritis

Septic arthritis is a differential diagnosis for the limping child in all age groups. Because the hip is very vascular, haematogenous spread of infection can happen easily, making it a common joint to be affected.

Figure 4 BMJ | 28 AUGUST 2010 | VOLUME 341

Pain is the most common presenting symptom of septic arthritis followed by joint swelling, fevers, sweats and rigors. Clinical suspicion is the most important diagnostic tool in diagnosis in these cases as even apyrexial patients with a normal white cell count can have septic arthritis.

Kocher’s Criteria for diagnosing Septic Arthritis is well validated, and “NEWT” is a useful mnemonic for remembering it.

Many places now use CRP instead of ESR. A high CRP has a strong association with septic arthritis, and a high CRP in a non-weight-bearing child gives a 74% probability of the diagnosis.

X-rays may show an effusion, if the effusion is big enough. Ultrasound normally identifies the presence of an effusion, and some sonographers can tell you whether it is thick fluid (pus) or not. Fluid may be present in both transient synovitis and septic arthritis.

Other Causes

Other causes of limp tend to be higher on paediatricians minds, but thats no reason why we in the ED shouldnt consider them too, especially in the child with slightly more chronic, or non-isolated symptoms. Could there be a limb-length discrepancy? Primary bone malignancy is rare Ewings sarcoma and osteogenic sarcoma are often found in older children, but limping may be a presenting symptom of leukaemia. Stroke and other neurologic causes are a possibility theres normally a risk factor like sickle cell disease that makes you suspicious.

Rickets is starting to become more common again in the UK. A wrist x-ray is often chosen to see whether there are the classic features of splaying and concavity of the metaphysis, and irregularity or fraying of the physis. A chest x-ray would demonstrate the rachitic rosary appearance.

Elsie had some blood tests which showed white cells of 8.9, neutrophils of 5.5 and a CRP of 95. She had two red flags or risk factors (non-weight-bearing and a raised ESR equivalent) and a presumed diagnosis of septic arthritis was made. She was taken to theatre and 5ml of pus was aseptically aspirated from her hip, confirming the diagnosis.

Summary

  • If the history of trauma doesn’t match the severity of the clinical findings, follow the atraumatic limp in children guidelines.
  • Red flags for limping children are non-weight-bearing, raised ESR or CRP, raised WCC and history of fever.
  • A limping child has septic arthritis until proven otherwise.
  • If in doubt, always refer the child to orthopaedics for review.

Other RCEMLearning Resources

Further Reading

References

  1. Harrison WD, Vooght AK, et al. The epidemiology of transient synovitis in Liverpool, UK. J Child Orthop. 2014 Feb;8(1):23-8.
  2. Landin LA, Danielsson LG, Wattsgrd C. Transient synovitis of the hip. Its incidence, epidemiology and relation to Perthes’ disease. J Bone Joint Surg Br. 1987 Mar;69(2):238-42.
  3. Fischer SU, Beattie TF. The limping child: epidemiology, assessment and outcome. J Bone Joint Surg Br. 1999 Nov;81(6):1029-34.
  4. Kocher MS, Zurakowski D, Kasser JR. Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm. J Bone Joint Surg Am. 1999 Dec;81(12):1662-70.
  5. Skinner J, Glancy S, Beattie TF, Hendry GM. Transient synovitis: is there a need to aspirate hip joint effusions? Eur J Emerg Med. 2002 Mar;9(1):15-8.
  6. Asche SS, van Rijn RM, et al. What is the clinical course of transient synovitis in children: a systematic review of the literature. Chiropr Man Therap. 2013 Nov 14;21(1):39.
  7. Nouri A, Walmsley D, Pruszczynski B, Synder M. Transient synovitis of the hip: a comprehensive review. J Pediatr Orthop B. 2014 Jan;23(1):32-6.
  8. Caird MS, Flynn JM, et al. Factors distinguishing septic arthritis from transient synovitis of the hip in children. A prospective study. J Bone Joint Surg Am. 2006 Jun;88(6):1251-7.
  9. Kastrissianakis K, Beattie TF. Transient synovitis of the hip: more evidence for a viral aetiology. Eur J Emerg Med. 2010 Oct;17(5):270-3.
  10. Leibowitz E, Levin S, Torten J, Meyer R. Interferon system in acute transient synovitis. Arch Dis Child. 1985 Oct;60(10):959-62.
  11. Lockhart GR, Longobardi YL, Ehrlich M. Transient synovitis: lack of serologic evidence for acute parvovirus B-19 or human herpesvirus-6 infection. J Pediatr Orthop. 1999 Mar-Apr;19(2):185-7.
  12. Tolat V, Carty H, Klenerman L, Hart CA. Evidence for a viral aetiology of transient synovitis of the hip. J Bone Joint Surg Br. 1993 Nov;75(6):973-4.
  13. Taekema HC, Landham PR, Maconochie I. Towards evidence based medicine for paediatricians. Distinguishing between transient synovitis and septic arthritis in the limping child: how useful are clinical prediction tools? Arch Dis Child. 2009 Feb;94(2):167-8.
  14. Kermond S, Fink M, Graham K, Carlin JB, Barnett P. A randomized clinical trial: should the child with transient synovitis of the hip be treated with nonsteroidal anti-inflammatory drugs? Ann Emerg Med. 2002 Sep;40(3):294-9.