Limp in a Child
Differential Diagnosis
Common Diagnoses
- Trauma, Including Foreign Body in Foot (Especially Toddlers)
- Irritable Hip (Transient Synovitis)
- Acute Viral Infection with Arthralgia
- Pauciarticular Juvenile Chronic Arthritis (JCA: 1 in 1000)
- Slipped Femoral Epiphysis (Usually Over 10 Years Old)
Occasional Diagnoses
- Perthes’s Disease (1 in 2000 between 4 and 10 Years Old)
- Septic arthritis
- Idiopathic Scoliosis
- Congenital Dislocation of the Hip
- Acute Lower Abdominal Pain: Especially Appendicitis
- Unequal Leg Length
- Neurological (e.g. Cerebral Palsy)
Rare Diagnoses
- Acute Osteomyelitis
- Rheumatic Fever
- Autoimmune Disorders (e.g. SLE, Dermatomyositis)
- Rickets
- Genuine Juvenile Rheumatoid Arthritis
- Malignancy Affecting Bone
- Duchenne’s Muscular Dystrophy
Ready Reckoner
Key distinguishing features of the most common diagnoses
| Trauma | Irritable Hip | Viral Infection | JCA | Slipped Epiphysis | |
|---|---|---|---|---|---|
| Fever | No | Possible | Yes | Possible | No |
| Sudden Onset | Yes | Possible | Possible | No | Yes |
| Stiff in Early Morning | No | No | No | Yes | No |
| Usually Over 10 Years Old | No | No | No | No | Yes |
| Many Joints Affected | No | No | Yes | Possible | No |
Possible Investigations
Likely:FBC, ESR/CRP, X-ray.
Possible:Autoimmune screen.
Small Print:Calcium, phosphate, alkaline phosphatase, creatine kinase, ASO titre, blood culture.
- FBC and ESR/CRP: WCC and ESR/CRP elevated in an underlying inflammatory or infective cause.
- Hip X-ray: May reveal fracture, slipped femoral epiphysis, congenital dislocation, Perthes’s and other significant disorders – but may be normal in the presence of serious pathology.
- Rheumatoid factor and autoimmune screen may be helpful if a connective tissue disorder is suspected.
- Serum calcium, phosphate and alkaline phosphatase: Calcium and phosphate low, alkaline phosphatase high in rickets.
- Creatine kinase: Markedly elevated in muscular dystrophy.
- ASO titre is raised in 80% of cases of rheumatic fever.
- In hospital, blood culture may identify the infecting organism in osteomyelitis and septic arthritis.
Top Tips
- Never forget to examine the soles of the feet and between the toes for obvious and potentially simple to treat, non-serious causes of limp.
- It’s worth investing some time gaining the child’s confidence – this will enable you to make a proper assessment and feel positive about your management.
- Parents may try to rationalise the symptom by recalling a recent minor episode of trauma, which is likely to be purely coincidental.
- Don’t forget referred pain. Hip pathology can cause pain in the knee.
Red Flags
- Marked restriction of movement and/or dramatic bony tenderness suggests a significant problem – especially fracture, septic arthritis and osteomyelitis.
- Fever with a limp requires an urgent specialist opinion. Admit to exclude osteomyelitis or septic arthritis.
- Beware the obese pubertal boy with groin pain and a limp – slipped femoral epiphysis is likely.
- Do not confine your assessment to the hip – for example, abdominal pain, especially appendicitis, can make a child limp.