The limping child — when to worry and when to refer: a GP’s guide

HISTORY

There are many causes for a limp in a child; many are age specific (Box 1).

It is important to take a detailed history from the patient, if possible, and parents. A key starting point is establishing whether the limp is secondary to trauma or atraumatic. Non-accidental injury (NAI) should always be considered in children presenting with trauma.

If the limp is atraumatic, the important cause to rule out is septic arthritis. A common dilemma is to differentiate between septic arthritis and transient synovitis (that is, irritable hip). Septic arthritis is an infection of the synovium and joint space, and is an orthopaedic emergency as it can lead to destruction of the joint within 24–48 hours and permanent loss of joint function. The incidence is 4–5 cases per 100 000 per year.⁴ Transient synovitis is a self-limiting (3–10 days) inflammation of the synovium of the hip that is thought to be triggered by viral illness. These two conditions can both present with similar signs and symptoms. It is, therefore, important to ask about current or recent (preceding weeks) systemic symptoms consistent with a viral infection, which would lean towards a diagnosis of transient synovitis. Children may be poor historians and may not be able to identify the location of the pain because of referred pain (for example, hip pathology presenting as knee pain). A common scoring system used to quantify the risk of septic arthritis is Kocher’s criteria, from his paper in 1999.⁵ The higher the score using the four risk factors, the likelier it is to be septic arthritis (Box 2).

In younger children a birth and development history should be included. It is important to identify risk factors for developmental dysplasia of the hip (DDH), which include: sex (9:1 female predominance); first born; family history of DDH; breech position; and oligohydramnios.

EXAMINATION

Clinical examination of a child can be challenging, but assessment of a child’s limb starts from the moment they walk through the door:

WHEN TO REFER TO THE EMERGENCY DEPARTMENT

Referral to the emergency department (ED) should be made if the diagnosis is thought to be acute. A chronic problem should be referred to the elective paediatric orthopaedic team.

Any suspicion of trauma, septic arthritis, or NAI should be referred immediately to the ED. A suspected SCFE should also be referred immediately, as this may be unstable and require surgical fixation.

National Institute for Health and Care Excellence guidance⁶ recommends urgent referral to the ED if a child has an acute-onset limp and is:

• <3 years of age;

• >9 years of age with painful or restricted hip movements (in particular internal rotation), to exclude an SCFE. Clinical judgement should be used in each case, for example, a younger child with risk factors would also need urgent investigation;

• unable to weight bear;

• pyrexial and/or has red-flag symptoms (Box 3) suggesting serious pathology;

• in severe pain, agitated, or has reduced peripheral pulses or muscle weakness that may indicate neurovascular compromise or impending compartment syndrome; and

• any suspicion of maltreatment/NAI.

WHEN TO REFER TO OUTPATIENT SERVICES

Children with no red-flag symptoms or suspicion of trauma/infection may be more suitable for referral to outpatient services. These include referral to a paediatric rheumatologist if suspicious of juvenile idiopathic arthritis (JIA), or paediatric orthopaedic services for limb length discrepancy or non-acute hip pathology such as DDH or Perthes’. In cases where neuromuscular conditions are suspected then referral to paediatric neurology as well as orthopaedics may be required.

TAKE HOME MESSAGE

A limping child can be caused by many things but it is important to exclude a septic joint using the above algorithm. Using the above systematic approach, it is hoped that referring clinicians become more confident in approaching a child with a limp and refer appropriately.