Last reviewed: March 2026
Contents
MDM Templates
Limp — Transient Synovitis
Child presents with limp and hip pain following recent viral illness. Well appearing, afebrile or low-grade fever. Hip range of motion maintained with mild guarding. Able to bear weight. No erythema, warmth, or swelling over the joint.
Presentation consistent with transient synovitis, the most common cause of hip pain and limp in children. Kocher criteria reassuring with 0-1 predictors present. Labs show normal or minimally elevated inflammatory markers. Not consistent with septic arthritis, SCFE, Legg-Calvé-Perthes, osteomyelitis, or malignancy.[1]
Plan: NSAIDs for pain. Activity restriction until symptoms resolve (typically 1-2 weeks). Discharge with PCP follow-up. Return for fever, worsening pain, refusal to bear weight, or persistent limp beyond 2 weeks.
Limp — Septic Arthritis Concern
Child presents with acute limp, hip pain, and fever. Ill or toxic appearing. Refuses to bear weight. Hip held in flexion, abduction, and external rotation (position of comfort). Passive range of motion severely limited by pain.
Kocher criteria concerning with multiple predictors present (fever >38.5°C, ESR >40, WBC >12k, non-weight bearing). Presentation most consistent with septic arthritis until proven otherwise. Differential includes osteomyelitis, reactive arthritis, and Lyme arthritis in endemic areas.[1]
Plan: Ultrasound-guided hip aspiration for cell count, Gram stain, and culture. Broad-spectrum antibiotics after aspiration. Orthopedic surgery consulted for possible operative drainage. Admit for IV antibiotics and monitoring.
Limp — Orthopedic Concern (SCFE / LCP / Fracture)
Child presents with hip or knee pain and limp. Afebrile, non-toxic. Exam findings concerning for structural or orthopedic pathology rather than infectious or inflammatory etiology.
If SCFE suspected (obese adolescent, hip/knee pain, obligate external rotation): Non-weight bearing status immediately. Frog-leg lateral radiograph is the critical view. Orthopedic consultation emergent — further weight bearing risks worsening slip and avascular necrosis.[3]
If Legg-Calvé-Perthes suspected (age 4-8, insidious hip pain, limited abduction): AP and frog-leg lateral hip radiographs. MRI if radiographs normal and clinical suspicion persists. Outpatient orthopedic referral.
If toddler fracture suspected (age 1-3, acute refusal to bear weight, minimal or no trauma history): Tibia/fibula radiographs. If negative but clinical suspicion high, treat as fracture with immobilization and orthopedic follow-up in 1-2 weeks for repeat films (callus confirms fracture).
Clinical Education
DDx by Age
| Age | Common Causes |
| 1-3 years | Toddler fracture, septic arthritis, transient synovitis, NAT |
| 4-10 years | Transient synovitis, Legg-Calvé-Perthes, septic arthritis, malignancy |
| 11-16 years | SCFE, Osgood-Schlatter, overuse injuries, malignancy |
Kocher Criteria
The Kocher criteria stratify the risk of septic arthritis in a child with hip pain. Four variables: fever >38.5°C, ESR >40 mm/hr, WBC >12,000, and inability to bear weight.[1]
| Criteria Met | Probability of Septic Arthritis |
| 0 | ~3% |
| 1 | ~7% |
| 2 | ~18% |
| 3 | ~40% |
| 4 | ~99% |
CRP >10 mg/L adds discriminatory power in intermediate-risk cases (2 criteria).[2] Clinical gestalt always supersedes the calculator — a toxic child with 1 Kocher criterion still needs aspiration.
Transient Synovitis vs Septic Joint
This is the central clinical challenge in the limping child. Transient synovitis: well child, low-grade or no fever, some preserved ROM, can bear weight with guarding. Septic arthritis: toxic child, high fever, refuses all ROM, won’t bear weight, holds hip in flexion/abduction/external rotation.[1]
When in doubt, aspirate. Ultrasound-guided hip aspiration is both diagnostic and therapeutic. Joint fluid with >50,000 WBC/mm³, >90% PMNs, and low glucose confirms septic arthritis. Many cases have sterile cultures because antibiotics are started before results return — aspirate data drives the decision, not culture alone.
SCFE
Any adolescent with hip or knee pain must be evaluated for SCFE. Classic patient: obese adolescent with insidious hip pain often referred to the knee. Loss of internal rotation with obligate external rotation on exam. Frog-leg lateral radiograph is the critical view — AP films can appear normal in early disease.[3]
SCFE is a non-weight bearing emergency. Further weight bearing risks worsening slip and avascular necrosis. Non-weight bearing from the moment of clinical suspicion, even during transport to imaging. Orthopedic consultation is emergent for surgical pinning. Contralateral hip at risk in up to one-third of cases.
Legg-Calvé-Perthes
Avascular necrosis of the femoral head, typically age 4-8. Insidious onset hip pain and limp in an otherwise well child. Pain is activity-related and may be referred to the knee. Limited abduction and internal rotation. Boys affected 4-5x more than girls.[3]
Early radiographs may be completely normal. MRI is more sensitive in early disease. If a child age 4-8 has persistent hip pain with normal films, order MRI before clearing them. Outpatient orthopedic referral for long-term management. Prognosis better with younger age at onset.
Toddler Fracture
Occult spiral fracture of the tibia in children age 1-3. Results from minor twisting injury that parents often don’t recall. Presents with acute refusal to bear weight. No swelling or bruising is typical. Initial radiographs may be negative — the fracture line is subtle or invisible.[3]
If clinical suspicion high and films negative, treat as fracture. Immobilize and follow up in 1-2 weeks for repeat radiographs showing callus formation. A spiral tibial fracture with inconsistent history or bruising raises concern for non-accidental trauma — obtain skeletal survey.
Don’t Miss
Malignancy: Bone tumors (osteosarcoma, Ewing sarcoma) present with chronic pain, swelling, and constitutional symptoms. Night pain is a red flag. Imaging showing metaphyseal lesion, cortical destruction, or periosteal reaction warrants urgent oncology referral.
Osteomyelitis: Fever, focal bone tenderness, and refusal to bear weight. MRI is the imaging of choice. Needs IV antibiotics and possible surgical debridement.
Lyme arthritis: In endemic areas, monoarticular arthritis (usually knee) with large effusion. Check Lyme serology. Treat with doxycycline (>8 years) or amoxicillin.
Disposition
Admit / emergent orthopedic consult: Septic arthritis (toxic, febrile, non-weight bearing, high Kocher score). SCFE (non-weight bearing until surgical pinning). Osteomyelitis. Concern for malignancy.
Discharge with follow-up: Transient synovitis (well, low Kocher, improving). Toddler fracture (immobilized, orthopedic follow-up). Suspected LCP (outpatient orthopedic referral and MRI). Return for fever, worsening pain, or refusal to bear weight.
References
- Kocher MS, Zurakowski D, Kasser JR. Differentiating between septic arthritis and transient synovitis of the hip in children. J Bone Joint Surg Am. 1999;81(12):1662-1670. PubMed
- Kocher MS, Mandiga R, Zurakowski D, et al. Validation of a clinical prediction rule for the differentiation between septic arthritis and transient synovitis of the hip in children. J Bone Joint Surg Am. 2004;86(8):1629-1635. PubMed
- Leet AI, Skaggs DL. Evaluation of the acutely limping child. Am Fam Physician. 2000;61(4):1011-1018. PubMed
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