Transient Hip Tenosynovitis

Aka: Transient Hip Tenosynovitis, Transient Synovitis, Transient Tenosynovitis of the Hip, Irritable Hip, Toxic Synovitis, Kocher Criteria

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II. Etiology

  1. Idiopathic

III. Epidemiology

  1. Incidence: Common (8x more common than septic hip in children)
    1. Most common cause of limp with Hip Pain under age 10
    2. Peaks ages 3 to 6 years
  2. Boys more commonly affected than girls by a 2:1 to 4:1 ratio
  3. Unilateral involvement in 95% of cases

IV. Pathophysiology

  1. Inflammatory Arthritis of the hip

V. Symptoms

  1. Follows 3-6 days after Upper Respiratory Infection

VI. Signs

  1. Hip Pain
    1. Pain radiates to anteromedial thigh and knee
  2. Reduced Hip Range of Motion
    1. Hip typically held in position of comfort (hip flexed, abducted and externally rotated)
    2. Guarded hip rotation in Transient Synovitis (but will tolerate passive range of motion testing)
    3. Will bear weight on joint enough to demonstrate a limp
    4. Contrast with Septic Arthritis with more pronounced spasm, guarding, and fixed position with a refusal to bear weight
  3. Fever
    1. Low grade fever may be present (under 39 C or 101 F)
    2. Contrast with Septic Arthritis with higher Temperature and associated systemic symptoms (e.g. malaise)

VII. Labs

  1. Complete Blood Count with differential
  2. Acute phase reactants: Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (C-RP)
    1. ESR and C-RP will be normal or only slightly elevated in Transient Synovitis
    2. Contrast with Septic Arthritis in which ESR >25 mm/h (>40 is highly suggestive) and C-RP >20 mg/L
  3. Joint aspirate (typically by orthopedics or radiology)
    1. Hip Synovial Fluid clear

VIII. Imaging

  1. Hip XRay
    1. Bony landmarks normal
      1. No signs of Fracture or defect
      2. Rules out serious hip disease
        1. Aseptic necrosis
        2. Osteomyelitis
    2. Increased space between acetabulum and femoral head
  2. Hip, Pelvis, femur, tibia-fibula and foot XRay
    1. Consider in children where the source of pain and limp is unclear
  3. Hip Ultrasound
    1. Demonstrates joint effusion (>2-5 mm) in >50% of cases
    2. Joint effusion on Ultrasound requires joint aspirate to differentiate from septic hip
  4. Hip MRI
    1. Consider in non-diagnostic Ultrasound (no effusion), but higher suspicion for septic hip

IX. Diagnosis: Kocher's Decision rule - 4 Criteria

  1. Findings suggestive of Septic Arthritis (Mnemonic: Walk FEW)
    1. Fever >38.5 C (101.3 F)
    2. Inability or refusal to bear weight
    3. Erythrocyte Sedimentation Rate >40 mm Hg
    4. White Blood Cell Count >12,000/mm3
  2. Interpretation of 4 critreria rule
    1. All 4 factors absent rules out Septic Arthritis (Test Sensitivity 99.8%)
    2. One predictor present: 3% risk of septic hip
    3. Two predictors present: 40% risk of septic hip
    4. Three predictors present: 93% risk of septic hip
    5. All 4 factors present strongly suggests infection (60-98% likelihood of septic hip)
  3. Modifications
    1. C-Reactive Protein (C-RP) >20 mg/L (or 2 mg/dl) has been included as a fifth factor criteria
  4. References
    1. Kocher (2004) J Bone Joint Surg 86-A:1629-35 [PubMed]
    2. Sultan (2010) J Bone Joint Surg Br 92(9): 1289-93 [PubMed]

X. Diagnosis: Decision rule - 2 Criteria

  1. Findings suggestive of Septic Arthritis
    1. Inability or refusal to bear weight
    2. C-Reactive Protein (C-RP) >20 mg/L (or 2 mg/dl)
  2. Interpretation
    1. Both factors absent: <1% probability of Septic Arthritis
    2. Both factors present: >74% probability of Septic Arthritis
  3. References
    1. Caird (2006) J Bone Joint Surg Am 88(6): 1251-7 +PMID:16757758 [PubMed]
    2. Singhal (2011) J Bone Joint Surg Br 92(9): 1289-93 [PubMed]

XI. Differential Diagnosis

  1. See Pediatric Limp Causes
  2. Septic Arthritis of the hip
    1. Keep high index of suspicion
    2. See Signs and Diagnosis above
  3. Pediatric Osteomyelitis
  4. Pyomyositis
  5. Avascular Necrosis of the Femoral Head (including Legg-Calve-Perthes Disease)
  6. Hip Injury

XII. Evaluation: Red Flags suggestive of Septic Arthritis of the hip

  1. Fever (esp. >101.3 F or 38.5 C)
  2. Toxic appearance
  3. Pain with Hip Range of Motion in any direction
  4. Refusal to bear weight
  5. Erythrocyte Sedimentation Rate >40 mm/hour
  6. C-Reactive Protein >20 ml/L

XIII. Evaluation: Emergency Department Approach

  1. See Limping Child
  2. Obtain initial basic studies (XRay, labs and consider Bedside Ultrasound)
  3. Consider giving NSAIDs in Emergency Department
    1. If child is walking after Ibuprofen and is non-toxic in appearance, may typically disposition home
  4. Toxic appearing, febrile, non-ambulatory child
    1. Obtain formal Ultrasound and if non-diagnostic (no effusion), then obtain MRI
    2. Admit and obtain orthopedic Consultation
  5. Non-toxic, febrile non-ambulatory child
    1. If labs, XRay are reassuring and child is well-appearing, disposition home with follow-up
    2. If labs positive or non-well appearing, obtain Ultrasound (consider MRI if non-diagnostic Ultrasound)
    3. Consider Pediatric Limp Causes
  6. Non-toxic, affebrile, non-ambulatory child
    1. If XRay non-diagnostic, obtain labs and if positive, then obtain Ultrasound
    2. Consider Pediatric Limp Causes
  7. References
    1. Orman and Horezcko in Herbert (2017) EM:Rap 17(5): 13-4

XIV. Precautions

  1. When higher clinical suspicion, fully exclude septic hip (u/s, MRI, hip Joint Aspiration) regardless of Kocher Criteria

XV. Management

  1. Non-weight bearing on affected leg
  2. Bed rest for 2 to 3 days
  3. NSAIDs
    1. May speed up recovery time
    2. Also offers Analgesic effect
    3. Failure to improve with NSAIDs should prompt reconsideration of differential diagnosis
    4. Kermond (2002) Ann Emerg Med 40:294-9 [PubMed]

XVI. Course

  1. Transient Synovitis usually clears within 7 days

XVII. Complications

  1. Legg-Calve-Perthes Disease occurs in 1-3% of Transient Synovitis cases

XVIII. References

  1. Jhun and Raam in Herbert (2016) EM:Rap 16(2):15-6
  2. Claudius and Behar in Majoewsky (2012) EM:RAP-C3 2(8): 1
  3. Sawyer (2009) Am Fam Physician 79(3):215-24 [PubMed]

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