Rosen & Barkin's 5-Minute Emergency Medicine Consult (693 page)

• Nonspecific inflammation and hypertrophy of the synovium with an effusion of the hip joint inchildren
  
• It can affect any joint but most commonly affects the hip.
  
• Disease process is self-limiting.
  
• Most common cause of acute hip pain and a limp in children aged 3–10.
  
• Also referred to as acute transient synovitis and irritable hip syndrome.
  
• Age group most affected is 3–6 yr.
  
• Male > female (2:1)
  
• Right hip > left
  

• Cause of toxic synovitis is unknown.
  
• Infectious etiology is suspected, because an upper respiratory infection precedes the symptoms of transient synovitis in ∼50% of cases.
  

DIAGNOSIS

• Unilateral hip pain
  
• Pain in the anteromedial thigh and knee
  
• Pain with weight bearing
  
• Limp
  
• Low-grade fever
  
• Decreased range of motion (ROM) of the affected hip
  
• Pain with ROM of the affected hip
  

• Acute onset of unilateral hip pain
  
• No history of trauma
  
• Pain with ambulation
  
• Recent upper respiratory infection
  

• Low-grade fever, usually <38.5°C (101.3°F)
  
• High-grade fevers are more concerning for septic arthritis
  
• Nontoxic appearing
  
• Limited hip ROM due to pain
  
• Hip is usually held in the flexed and externally rotated position for maximal comfort.
  

• Hip x-rays
  
• AP pelvis
  
• CBC, C-reactive protein (CRP), ESR if concerned for septic arthritis
  

CBC, CRP, ESR:

• May be normal or elevated
  
• An elevated white blood cell (WBC) count, CRP, or ESR alone does not differentiate toxic synovitis from septic arthritis or osteomyelitis.
  
• If WBC count, CRP, and ESR are normal, more serious causes of hip pain are less likely.
  
• If CRP <2 mg/dL and able to bear weight, more likely to be toxic synovitis
  

• Plain hip films (anteroposterior and frog-leg view):
  
  • Usually normal
    
  • May detect an effusion or other causes of hip pain
    
• US to rule out joint effusion and to guide hip joint aspiration if required
  
• MRI (rarely indicated):
  
  • Very useful in diagnosing Legg–Calvé–Perthes (LCP) disease
    
• Bone scan:
  
  • Used to differentiate LCP disease from toxic synovitis
    
  • Can detect osteomyelitis
    
  • The increased radiation is usually reserved for recurrent cases or cases in which the diagnosis is still in question.
    

Joint aspiration:

• Not necessary if the patient is afebrile with a normal WBC count, CRP, and ESR
  
• Abnormal joint fluid analysis indicates SA (see “Arthritis, Septic”)
  

• SA
  
• Osteomyelitis
  
• Soft tissue infection
  
• LCP disease
  
• Slipped capital femoral epiphysis
  
• Juvenile rheumatoid arthritis
  
• Rheumatic fever
  
• Chondrolysis
  
• Gaucher disease
  
• Osteosarcoma
  
• Ewing sarcoma
  
• Osteoid osteoma
  
• Leukemia
  
• Tuberculosis of the hip
  
• Fracture
  
• Lyme disease
  
• Psoas abscess
  
• Sickle cell crisis
  

• 4–17% of children have a recurrent episode.
  
• 10% of recurrent cases may be the presenting feature of a chronic inflammatory condition.
  
• 2–10% of patients with toxic synovitis later develop LCP disease:
  
  • Suggested that toxic synovitis may represent an early stage of LCP disease.
    

TREATMENT

• Keep leg in position of comfort.
  
• Treat with NSAIDs.
  

• Conservative treatment
  
• Bed rest in position of comfort: Flexion and external rotation
  
• Initiate NSAIDs
  
• Apply heat to the area
  
• Antibiotics and steroids are not indicated
  
• Some authors recommend no weight bearing for 7–10 days following improvement and return of normal hip function, citing increased risk for recurrence.
  
• Close follow-up is essential, with repeat radiographs due to association with LCP.
  

• Ibuprofen: 200–600 mg (peds >6 mo old: 5–10 mg/kg/dose) PO q6h PRN
  
• Naproxen: 250–500 mg (peds >6 mo old: 5–10 mg/kg/dose) PO BID PRN
  

Acetaminophen: 500 mg (peds: 10–15 mg/kg, do not exceed 5 doses/24 h) PO/PR q4–6h, do not exceed 4 g/24 h

FOLLOW-UP

Patients with severe joint pain or a large effusion may require hospitalization for bed rest and analgesics.

All patients who have had more serious causes of hip pain excluded and have been diagnosed with toxic synovitis can be discharged from the hospital with good follow-up.

Follow-up with an orthopedic surgeon in 1–2 wk for repeat evaluation.

• Return to the ED immediately for worsening pain in the hip or increasing fever.
  
• Follow-up with pediatric orthopedic surgeon in 1–2 wk for repeat evaluation.
  
• Patients should have repeat x-rays done in 6 mo to exclude LCP disease.
  

• Most cases are diagnosed by history and physical exam alone with fever and weight bearing as key elements.
  
• ∼50% of children have a history of a preceding viral illness.
  
• NSAIDs help treat the pain and shorten the course of the illness.
  
• Nearly all children recover from toxic synovitis within 2 wk and without sequelae.
  
• ∼2–10% of children with toxic synovitis develop LCP disease.
  

• Caird MS, Flynn JM, Leung YL, et al. Factors distinguishing septic arthritis from transient synovitis of the hip in children. A prospective study.
  J Bone Joint Surg Am
  . 2006;88:1251–1257.
  
• McCarthy JJ, Noonan KJ. Toxic synovitis.
  Skeletal Radiol
  . 2008;37:963–965.
  
• Singhal R, Perry DC, Khan FN, et al. The use of CRP within a clinical prediction algorithm for the differentiation of septic arthritis and transient synovitis in children.
  J Bone Joint Surg Br.
  2011;93(11):1556–1561.
  
• Sultan J, Hughes PJ. Septic arthritis or transient synovitis of the hip in children: The value of clinical prediction algorithms.
  J Bone Joint Surg Br
  . 2010;92(9):1289–1293.
  

See Also (Topic, Algorithm, Electronic Media Element)

• Arthritis, Septic
  
• Hip Injury
  
• Legg–Calvé–Perthes Disease
  

CODES

727.09 Other synovitis and tenosynovitis

BASICS