Transient Synovitis of the Hip

Key Points:

  • Self-limited inflammatory joint condition.  
  • Differentiating from septic arthritis is the primary concern.
  • No single laboratory or imaging study will be definitive to confirm or exclude transient synovitis.

Description:

Self-limited inflammatory joint condition of unknown etiology.  The hip joint is most commonly affected.

Evaluation

A thorough history, examination, and published diagnostic criteria should be used in the evaluation and management of patients with acute onset of pain, limp, or inability to walk.  No single laboratory or imaging study will be definitive to confirm or exclude transient synovitis.  Septic arthritis is the primary concern due to the high complication rate with a delay in diagnosis and treatment.
 

 

Epidemiology:

Incidence/Prevalence:

  • Common cause of hip pain in the pediatric population
  • 3% children between ages 3-10 years old
  • Predominance boys ~2:1
  • Right side is more commonly affected

Clinical Findings:

History 

  • Onset of pain is often initially not disabling and gradually worsens over a few days.  However, the onset can be more sudden.
  • A sudden onset of symptoms may cause presentation to emergency or urgent care facility.  Pediatric orthopedic surgeons are frequently called upon to help with diagnosis and treatment.
  • A thorough history to include recent (within 4-5 weeks) viral or bacterial upper respiratory or gastrointestinal illnesses is essential.  There may be a history of trauma. 
  • The main diagnostic dilemma is differentiating between septic arthritis and transient synovitis.


Physical Examination 

  • Afebrile 
  • Nontoxic clinical appearance
    • Young patients may be comfortable sitting in a parent’s lap but become very guarded with any attempt at examination.  Septic arthritis patients may be miserable or ‘toxic’ appearing no matter what position, whether held or sitting/lying down.
  • The child commonly walks with a limp but may refuse to walk. 
  • Assessment of the range of motion (ROM) of the joint is important. There tends to be minimal pain in the middle of the ROM arc with pain mostly at the extremes of motion. In contrast, a septic joint often has pain with any attempted ROM of the joint.

Lab

  • CBC, ESR, CRP are usually normal may be marginally elevated.
  • Synovial Fluid Examination
  • Joint aspiration under ultrasound or fluoroscopic guidance is performed if there is concern for septic arthritis. 

Imaging Studies:

Plain radiographs 

  • Useful to evaluate for other etiologies of pain. Joint space widening is not reliable to detect a joint effusion. 

Ultrasound 

  • Often demonstrates a joint effusion.

MRI 

  • May be considered to evaluate for periarticular pyomyositis or osteomyelitis if suspected, particularly if there is significant lab abnormality.

Etiology:

Essentially unknown.  There is some evidence linking the diagnosis to an antecedent viral infection, usually an upper respiratory infection

Natural History:

  •   Spontaneous resolution with rest

Treatment:

  • Close observation with anti-inflammatories and rest may be appropriate. 
  • Follow-up with orthopedic surgeon or primary care physician helpful several weeks later to confirm resolution of symptoms and return of normal motion.  Usually further studies are not necessary but repeat labs, plain radiographs, and MRI may be indicated if continued symptoms or stiffness.

Outcomes

  • Symptoms usually begins to resolve within 24 – 48 hours.
  • It may take a couple of weeks for joint irritability to completely resolve. This may delayed if there is too much activity too soon.  Follow-up with a primary care physician or an orthopaedic surgeon is recommended to confirm resolution of symptoms and return of normal motion. 

Complications:

  • Generally believed that there are no significant long-term sequelae  
  • 0 – 10% incidence of subsequent Legg-Calve-Perthes Disease has been reported
  • Recurrence in the range of 4 – 26%. This may be related to too much activity too soon. 

Differential Diagnosis:

Septic arthritis, Trauma, Legg-Calve-Perthes, Juvenile Inflammatory Arthritis, Lyme Arthritis, Osteomyelitis, Slipped Capital Femoral Epiphysis 

References:

  1. Caird, MS, et.al., Factors Distinguishing Septic Arthritis from Transient Synovitis of the Hip in Children. A Prospective StudyJ Bone Joint Surg Am, 2006 Jun; 88 (6): 1251 -1257
  2. Heyworth, BE, et.al., Management of Pediatric Patients with Synovial Fluid White Blood-Cell Counts of 25,000 to 75,000 Cells/mm3 After Aspiration of the Hip.  J Bone Joint Surg Am, 2015 Mar 04; 97 (5): 389 -395.
  3. Kocher,MS, et.al., Validation of a Clinical Prediction Rule for the Differentiation Between Septic Arthritis and Transient Synovitis of the Hip in ChildrenJ Bone Joint Surg Am, 2004 Aug; 86 (8): 1629 -1635
  4. Luhmann, SJ, Jones,A, et.al., Differentiation Between Septic Arthritis and Transient Synovitis of the Hip in Children with Clinical Prediction AlgorithmsJ Bone Joint Surg Am, 2004 May; 86 (5): 956 -962.
  5. Nouri A et. al., Transient Synovitis of the hip: a comprehensive review. J Pediatr Orthop B. 2014 Jan;23(1):32-36
  6. Sultan J, Hughes PJ. Septic arthritis or transient synovitis of the hip: the value of clinical prediction algorithyms. J Bone Joint Surg (Br) 2010; 92B(9): 1289-1293

Top Contributors:

Matthew Boyle MD