Limp is a symptom and not a diagnosis
There are red flag conditions not to be missed. The causes can be broadly divided into acute and chronic and are categorised by age.
Common pitfalls in making a diagnosis of limp include:
- Ascribing limp to trauma and overlooking features that suggest other causes.
- Referred pain (e.g., from the abdomen [and testes in boys], back or chest and hip pathology manifesting as knee pain).
- Think beyond the hip (!) and examine the child comprehensively.
- Assess for proximal muscle weakness; ask the child to get up from the floor (Gower's manoeuvre), jump or climb a step.
- Classical clinical features of sepsis may be masked in the immunosuppressed child.
- Mycobacterial infection can be easily missed.
- Synovial fluid may be sterile in partially treated septic arthritis.
- Labelling children with daytime symptoms as having “growing pains”.
- Medically unexplained limp or physical symptoms warrant specific management and referral (i.e., discharge without a diagnosis and follow up plan is not advised).
- The blood film may be normal in children with malignancy.
- Radiographs are often normal in children with early sepsis or arthritis.
- Acute phase reactants may be normal in children with inflammatory arthritis.
- Rheumatoid factor is usually negative in children with inflammatory arthritis.
- Antinuclear antibody and rheumatoid factor may be false positive in children without inflammatory joint or muscle disease.