Within the triangle (Paediatric) | Acute transient synovitis | Male. Refusal to weight bear. Poorly localised pain. Viral precipitant. | 3–6 years | Well, non-toxic, variable range of motion. | Diagnosis of exclusion, to be monitored to exclude septic arthritis.22 |
Apophysitis/avulsion fracture | Associated injury/event. | <18 years23 | Point tenderness.24 | Plain film x-ray,25 computerised tomography (CT).26 |
Perthes’ disease | Male, associated knee pain. | 4–9 years | Decreased range of movement of hip, abduction and internal rotation ↓ | Plain film x-ray, antero/posterior (AP), lateral, and comparative views.27 |
Joint effusion.27 |
Slipped capital femoral epiphysis | Overweight, male, 30% cases bilateral.28 | 12–15 years | Decreased range of motion of hip, abduction and internal rotation ↓. | Plain film x-ray, antero/posterior (AP), lateral, and comparative views. |
Limb shortening, external rotation of hip.29 |
Septic arthritis | Refusal to weight bear. Systemically unwell. | All | Unwell, toxic, variable range of motion. | Temp >38.5, CRP >20, ESR >40, refusal to weight bear, leucocytosis >12.22 |
Plain film x-ray, joint aspiration, isotope bone scan. |
Congenital dysplasia | Delayed mobilising/limp, walking on tip-toe.30 | All | Limb length discrepancy, unilateral symptoms, limitation of abduction.30 | Ultrasound, x-ray. |
Tumour | Night pain, systemic “red flags”, absence of appropriate physical stressors.20 | All ages | Systemic features, may mimic stress fracture.20 | Plain film x-ray, magnetic resonance imaging.21 |