Acute Limp in Child

Background

Definition

A limp is defined as an abnormal gait pattern caused by either weakness, deformity or pain.

The word limp is normally used to describe an antalgic gait in a with a shortened ‘stance phase’ in the gait cycle.

Causes of an Acute Limp in Children

Fracture or Soft Tissue Injury

Trauma is the most common cause of an acute limp in children.

In children, growth plates are much more vulnerable to injury than ligaments. Hence, any sprain should also raise suspicion of injury to the growth plate.

Toddler’s fracture:

  • Subtle undisplaced spiral fracture of the tibia
  • Usually occurs in pre-school children
  • Caused by a sudden twisting motion of the leg, normally when the child is falling while walking

Generally, fractures and soft tissue injuries will present with:

  • A history of trauma
  • Focal bony tenderness on examination

Treatment will either be:

  • Conservative – immobilisation by plaster cast or splint
  • Surgical – fixation of the fracture

It is VERY IMPORTANT to rule out any possibility of mistreatment or abuse.

Transient Synovitis

A cause of non-traumatic limp.

It is a synovial inflammation of the hip.

There is some evidence to state that this condition follows a viral infection.

Most commonly occurs in boys aged between 4 to 8 years.

On assessment, there will be no pain at rest but decreased range of movement, particularly internal rotation.

Definitive diagnosis is by demonstration of an effusion of the hip.

Management is with bed rest.

Usually self-limiting with symptoms resolving within 2 weeks.

Can be difficult to differentiate from septic arthritis so any suspicion of septic arthritis must be followed up with joint aspiration and blood cultures.

++++ Septic Arthritis

An infection of the synovium and joint space.
Usually due to one of the following pathogens:

  • Staphylococcus aureus
  • Haemophilus influenza
  • Group B Streptococcus

Most likely to occur in the following joints:

  • Hip
  • Knee
  • Ankle
  • Elbow

THIS IS A MEDICAL EMERGENCY!

The child will need an urgent joint washout and intravenous antibiotics.

Diagnosis is based on joint aspirate and positive blood cultures.

If missed, it can lead to joint destruction, permanent loss of function and SEPSIS

Contrast Between Transient Synovitis and Septic Arthritis

header Transient Synovitis Septic Arthritis
Onset Acute, non-weight bearing Acute, non-weight bearing
Fever Mild/absent Moderate/high
Appearance Child looks well Child looks ill, lethargic
White cell count Normal Normal/high
ESR Slight increase/normal Normal
Ultrasound Fluid in the joint Fluid in the joint
Management Rest, analgesia Joint aspiration, prolonged antibiotic

Perthes’ Disease

This is an idiopathic avascular necrosis of the femoral head.

Typically occurs in boys aged 4 to 8 years.

Normally presents as a subacute limp with referred pain to the groin, knee or thigh.

Can be confused with transient synovitis but symptoms do not resolve.

Diagnosis is by X-ray of both hips (including frog views):

  • Early signs may show increased density in the femoral head
  • As the disease progresses, the femoral head becomes fragmented and irregular

Treatment varies on severity of disease:

  • If caught early and less than half the femoral head is affect, only bed rest and traction is required
  • In later presentations or in severe cases, the femoral head needs to be covered by the acetabulum. The acetabulum acts as a mould for the re-ossifying process. This is achieved by maintaining hip abduction:
    • Conservative treatment – plaster cast or callipers
    • Surgical treatment – femoral or pelvic osteotomy

Although prognosis in most children is good, it is important to note that long-term complications include:

  • Chronic pain
  • Osteoarthritis in later life

Developmental Dysplasia of the Hip (DDH)

Incidence varies from 1.6 to 28.5 cases per 1000 births in the UK

Risk factors include:

  • First born child
  • Female
  • Family history of DDH
  • Breech presentation at birth
  • High birth weight (>4 kg)
  • Oligohydramnios

Will only present as limp if missed during the routine neonatal review

Treatment will vary according to age and will be based on the orthopaedic decision:

  • Conservative measures – Pavlik harness or splint to keep the hip in abduction
  • Surgical treatment – femoral shortening osteotomy

Slipped Upper Femoral Epiphysis

It is a displacement between the head and neck of the femur through the growth plate.

Neck of the femur is normally displaced anteriorly and externally rotates while the head of the femur remains in the acetabulum

Usually affects children over the age of 10 years

Must be diagnosed early! Delayed diagnosis can lead to:

  • Deformity
  • Limb shortening
  • Loss of function

Risk factors:

  • Obesity
  • Male

Can be associated with endocrine abnormalities such as hypothyroidism or in children undergoing treatment for growth hormone deficiency.

Presents with:

  • Limp
  • Thigh atrophy
  • Hip, knee or thigh pain
  • Obligate external rotation on flexion of the hip upon examination

Diagnosis confirmed with bilateral frog leg X-rays as well as anteroposterior and lateral radiographs.

Classification:

  • Stable: can bear weight without crutches
  • Unstable:
    • Unable to weight bear
    • Severe pain
    • Risk of osteonecrosis
    • THIS IS AN ORTHOPAEDIC EMERGENCY

Management:

  • Admission into hospital and bed rest to prevent further slippage of the head and neck of the femur
  • Surgical treatment only – pinning of the neck of the femur back onto the head to allow stabilisation of the growth plate

Assessment of the Child

If there is no history of trauma, age is an important factor when considering the likely aetiology of the limp:

0-3 years 3-10 years 10-15 years
Developmental hip dysplasia Transient synovitis Slipped upper femoral epiphysis
Toddler fracture Perthe's Disease Perthe's Disease
Fracture or soft tissue injury Fracture or soft tissue injury Fracture or soft tissue injury
Septic arthritis or osteomyelitis Septic arthritis or osteomyelitis Septic arthritis or osteomyelitis

Conditions that can occur at any age:

  • Fracture or soft tissue injury
  • Septic arthritis or osteomyelitis
  • Malignancy such as a leukaemia or lymphoma
  • Haematological disease such as sickle cell disease
  • Metabolic disease such as rickets
  • Neuromuscular disease such as cerebral palsy
  • Primary anatomical abnormality such as limb length discrepancy
  • Inflammatory muscle or joint disease

The history should be taken from both the child and the carer and include:

  • Any history of trauma – must identify any possibility of mistreatment.
    • Check medical records for previous injuries or child protection concerns
  • Birth and developmental – this should include:
    • Walking history
    • Neurodevelopmental abnormalities
      • Delay in motor milestones – indicates neuromuscular cause
      • Regression – indicates acquired cause
    • Risk factors for developmental dysplasia of the hip
  • Any other associated factors such as recent fevers, infections or trauma
  • The duration and progression of the limp
  • A full history of any associated pain (SOCRATES)
    • Nature and location particularly important – children can present with referred pain
    • Is the pain bilateral or unilateral?
    • In infants, pain on changing of the nappy causing backing flexion may indicate discitis
  • Any associated muscle weakness – indicative of neuromuscular disease
  • Any family history of rheumatological or neuromuscular disease
  • Exclude any red flags that could indicate serious pathology (see below)

Examination

Perform a general examination:

  • Pyrexia and tachycardia – indicative of sepsis
  • Pallor, irritability or lethargy – indicative of sepsis or systemic disease
  • Unusual bruising – may indicate maltreatment or a bleeding disorder
  • Generalised lymphadenopathy or rash – may indicate infection, inflammatory joint or haematological disease

Perform a musculoskeletal examination – use the pGALS assessment (paediatric Gait, Arms, Legs, Spine):

  • Gait/general
    • Observe the child walking
    • Ask to walk on tiptoes and on heels
  • Arms – not applicable to the limping child
  • Legs
    • Check for effusion of the knee
    • Feel for crepitus of the knee during flexion and extension
    • Examine the hip
    • Apply passive flexion of the hip to 90⁰ with internal rotation
  • Spine
    • Observe the spine from behind – pay particular attention to curve and movement
    • “Can you bend and touch your toes?”

RED FLAGS that might indicate serious pathology include:

  • Pain disturbing sleep at night – sign of malignancy
  • Signs of redness, swelling or stiffness of the joint or limb – sign of infection or inflammatory joint disease
  • Weight loss, anorexia, fever, night sweats or fatigue – can indicate malignancy, infection or inflammation
  • Unexplained rash or bruising – sign of haematological disease or maltreatment
  • Severe pain, anxiety, and agitation after a traumatic injury — may indicate an evolving compartment syndrome

Management

When to Refer for Urgent Assessment?

Arrange urgent assessment for patients who are:

  • Less than 3 years’ old
  • Older than 9 years’ old and are suspected to have a slipped upper femoral epiphysis
  • Unable to weight bear
  • Febrile or have any other red flag symptoms (see above)
  • Has any signs of neurovascular compromise or compartment syndrome – this includes:
    • Severe pain
    • Agitation
    • Reduced peripheral pulses
    • Muscle weakness
  • Suspected of being maltreated

Who to X-Ray?

Same day X-ray for patients where there is a history of trauma and/or focal bony tenderness on examination

X-rays in two or more planes will be required in the majority of cases

Who Should be Referred On?

If urgent assessment is not necessary, refer the child for further investigation/management:

  • Refer to paediatric orthopaedics or orthopaedics if:
    • A well child has a working diagnosis of transient synovitis but the symptoms have failed to resolve after 1 week
    • A child presents with limp on multiple occasions
    • There is uncertainty about the diagnosis
  • Refer to rheumatology if suspect an inflammatory joint condition e.g. juvenile idiopathic arthritis is suspected

Who can be Managed in Primary Care?

If urgent assessment or referral is not indicated, children with an acute limp can be managed in primary care under the following conditions:

  • Working diagnosis of transient synovitis in a child aged 3–9 years
    • If the child is well, afebrile, mobile but limping, and has had the symptoms for under 48 hours:
      • Advise parents or carers to bring the child to an Accident and Emergency department urgently if symptoms deteriorate, the child develops a fever, or becomes systemically unwell
      • Advise rest and analgesia, such as paracetamol and ibuprofen
    • Arrange follow-up at 48 hours — if symptoms are resolving, no investigations are needed
    • Arrange subsequent review 1 week from onset of symptoms to confirm complete resolution of symptoms — if symptoms have not resolved completely or there is any uncertainty about the diagnosis, arrange urgent assessment (see above)
  • Persistent limp with normal initial X-rays
    • Refer to paediatric orthopaedics or rheumatology for further investigation – urgency of referral is based on clinical judgement
  • Diagnosis of sprain or strain
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