AdultPediatric
Hip pain or limp in a child is a high-stakes complaint. Age stratifies the differential: septic hip and transient synovitis at any age, Legg-Calvé-Perthes in 4–8 y, SCFE in 10–15 y. Knee or thigh pain may be the only symptom of hip pathology.
🚩 Red-flag clues (must not miss)
- •Fever + refusal to bear weight + ↑ ESR/CRP = septic hip until proven otherwise (Kocher)
- •Obese peripubertal child with limp + ↓ internal rotation = SCFE — strict NWB, image BOTH hips frog-leg
- •Painless limp in 4–8 y/o boy with ↓ ROM = Legg-Calvé-Perthes
- •Night pain, weight loss, palpable mass = bone tumor or leukemia
- •Neonate / infant with pseudoparalysis = septic hip or osteomyelitis
History
- Age, onset (acute vs insidious), trauma, recent viral illness
- Fever, weight loss, night sweats, rash
- Weight-bearing status, limp pattern (antalgic vs Trendelenburg)
- Referred pain to knee or thigh — common with hip pathology
Exam
- Gait, leg-length, position at rest (septic hip held flexed/abducted/ER)
- Log-roll test — guarding suggests intra-articular pathology
- ROM — loss of internal rotation = SCFE or Perthes
- Always examine the knee, spine, abdomen (referred pain)
Labs
- CBC, CRP, ESR, blood culture if febrile or atraumatic
- Joint aspiration (US-guided) if septic hip suspected — cell count, Gram, cx
- Kocher: fever > 38.5°C, NWB, ESR > 40, WBC > 12k (3/4 = 93%, 4/4 = 99%)
- Lyme serology in endemic areas
Imaging
- AP pelvis + frog-leg lateral of BOTH hips — first line
- US hip — sensitive for effusion, guides aspiration
- MRI with & without contrast if osteomyelitis or occult fracture
Differential & next step
| Diagnosis | Clue | Next step |
|---|---|---|
| Septic arthritis of hip | Fever, NWB, hip held flexed/abducted/ER, ↑ ESR/CRP | US-guided aspiration, IV abx (vanc + ceftriaxone), urgent ortho I&D |
| Transient synovitis | Recent viral illness, afebrile or low-grade, will bear weight | Rule out septic (Kocher); NSAIDs, follow-up 24–48h |
| SCFE | Obese 10–15 y/o, limp, ↓ internal rotation | STRICT NWB, frog-leg pelvis, urgent ortho pinning |
| Legg-Calvé-Perthes | 4–8 y/o boy, painless limp, ↓ abduction & IR | Pelvis XR (may be normal early), ortho referral |
| Osteomyelitis (proximal femur, pelvis) | Fever, focal bony tenderness, ↑ CRP | MRI with & without contrast, blood cx, IV abx |
| DDH (developmental dysplasia) | Infant with asymmetric thigh folds, + Ortolani/Barlow | US hip < 6 mo; XR > 6 mo; ortho |
| Apophyseal avulsion | Adolescent athlete, sudden pain with sprint/kick (ASIS, AIIS, ischial) | Pelvis XR, rest, ortho if displaced > 2 cm |
| Hip fracture / pelvic ring | High-energy trauma | XR, CT, ortho |
| JIA | Morning stiffness, multiple joints, > 6 wk | Rheumatology, ANA, RF, slit-lamp |
| Bone tumor / leukemia | Night pain, mass, systemic symptoms | XR, MRI, CBC w/ diff, hem/onc |
| Psoas abscess / appendicitis (referred) | Fever, abdominal pain, + psoas sign | CT abdomen/pelvis |
Medications & dosing
| Drug | Dose | Notes |
|---|---|---|
| Ibuprofen | 10 mg/kg PO q6–8h (max 600 mg/dose) | |
| Acetaminophen | 15 mg/kg PO q4–6h (max 1 g/dose) | |
| Ceftriaxone (empiric septic joint) | 50–75 mg/kg IV daily (max 2 g) | |
| Vancomycin (MRSA coverage) | 15 mg/kg IV q6h |
Management / next steps
- Limp + fever → think septic hip; aspirate, do not delay
- Suspected SCFE → strict NWB, wheelchair, urgent ortho — do NOT let the child walk
- Transient synovitis is a diagnosis of exclusion
- Knee pain in adolescent → image the hip
Pearls
- Hip held in flexion/abduction/ER = maximizes joint volume — classic for septic hip.
- Bilateral SCFE in 20–40% — image both hips.
- Perthes XR may be normal for weeks; MRI more sensitive early.