Transient synovitis - ankle

Case contributed by Michael Yang


5 year old boy with no past medical history presents with acute left ankle pain with associated swelling started at school. No history of trauma.

Patient Data

Age: 5 years old
Gender: Male

Moderate diffuse fullness and swelling of the "ankle joint" is consistent with an ankle joint effusion.

Mild cortical irregularity of the medial malleolus. No definite acute displaced fracture or dislocation.

Subcentimeter sized irregular density in the ball of the heel with adjoining lucency may represent a foreign body/gravel in a superficial ulceration. 

The bone density is normal.


No acute displaced fracture or dislocation considering limited technique.

No ankle joint effusion.

No abnormal calcifications. 

Case Discussion

5 year old boy presents with acute left ankle pain and associated joint swelling with no history of trauma. ESR and WBC were within normal limits. The patient was placed in a posterior short leg splint and advised to be non-weight bearing. Improved over the course of 2 weeks.

Transient synovitis (TS) is a benign and self-limiting condition that involves inflammation that typically occurs in the hip joint. Although the exact cause of TS remains under investigation, it is commonly associated with a viral infection in children between 3 and 8 years old.

TS of the hip in children presents with pain, refusal to bear weight, fever and limp. A fraction of children presenting with a limp also have ankle and knee joint involvement. TS usually resolves within 3-10 days with RICE treatment, and resolution of joint effusion occurs after 1 week.

It is crucial to differentiate TS from septic arthritis. Fever (temperature >38.0 C) and elevated CRP (>20 mg/L) are the most significant predictors for septic arthritis. Imaging can be very helpful, and plain radiographs typically range from normal to joint space widening.  MRI can be used to distinguish the two conditions in complicated cases. The characteristics findings of TS on MRI include joint effusions and absence of signal intensity abnormalities in bone marrow.

Though the other differential considerations for ankle joint effusions include early-onset Juvenile Rheumatoid Arthritis (JRA), Juvenile Idiopathic Arthritis (JIA), traumatic hemarthrosis and much less likely leukemia or metastatic disease. An easy mnemonic for causes of pediatric joint effusion is: "TIM" (Trauma, Infection/Inflammation, Malignancy/Miscellaneous).

This case was submitted with supervision and input from:

Soni C. Chawla, M.D.
Associate Professor
Department of Radiological Sciences
David Geffen School of Medicine at UCLA
Olive View - UCLA Medical Center  

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Case information

rID: 63801
Published: 20th Oct 2018
Last edited: 14th Aug 2019
Inclusion in quiz mode: Included
Institution: Olive View - UCLA Medical Center

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