Table. Commonest diseases of the hip in children.

	Age	Prevalence	Etiology	Clinical features	Diagnosis	Therapy
Septic coxitis	0–4 years	1–4/ 100 000	Hematogenous bacterial infection of the hip joint	Guarding and protective behavior, general unwellness, fever	Laboratory tests (blood count, CRP, ESR), ultrasound, arthrocentesis (cell count), blood cultures	Joint irrigation, antibiotics, mobilization
Transient synovitis	2–10 years	76/100 000	Transient hip joint effusion, often virus-related	Protective limp, limited range of motion in the hip joint	Ultrasound, laboratory tests as indicated	Physical rest, pain relief if required
Perthes disease	5–7 years	0.4–29.0/ 100 000	Aseptic femoral head necrosis	Protective limp, limited range of motion	Positive „figure 4“ sign, ultrasound, pelvic and axial hip radiographs	Physiotherapy, rest during periods of acute pain, avoidance of axial compressive loading
Juvenile rheumatoid arthritis	2–18 years	14.8/ 100 000	Rheumatoid oligo- or polyarthritis of the hip joint	Protective limp, limited range of motion	Laboratory tests (blood count, CRP, ESR, ANA, rheumatoid factors, HLA-B27), ultrasound, AP radiograph, MRI as required	Pain relief (NSAIDs), DMARDs (e.g., MTX), biologics (e.g., etanercept), physiotherapy
Benign and malignant tumors	2–18 years	5% of all tumors	Space-occupying lesion with chondral, osseous or connective tissue components	Uninterrupted pain or nocturnal pain	Radiography in two planes, MRI, CT, bone scintigraphy	No-touch lesion, chemo-/radiotherapy, surgical resection
Slipped capital femoral epiphysis	Adolescence	0.33–24.58/ 100 000	Nontraumatic epiphyseal slippage	Protective limp, limited range of motion, positive Drehmann sign	Ultrasound, pelvic and axial (“true lateral” as described by Imhäuser) hip radiographs	In situ screw fixation, osteotomy, Ganz/modified Dunn osteotomy, contralateral prophylactic screw placement
Hip dysplasia, hip displacement	Adolescence	2–5%	Underdevelopment of the hip joint, impaired ossification of the acetabulum	Pain on movement of the hip	Pelvic radiograph, axial hip radiograph	Triple osteotomy, hip replacement

ANA, antinuclear antibodies; AP, anteroposterior; CRP, C-reactive protein; DMARDs, disease-modifying antirheumatic drugs; ESR, erythrocyte sedimentation rate; MRI, magnetic resonance imaging; NSAIDs, nonsteroidal anti-inflammatory drugs; MTX, methotrexate; OT, osteotomy