AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
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• Medication
• Follow-up
• Miscellaneous
• Multimedia
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Background

Transient synovitis (TS) is the most common cause of acute hip pain in children aged 3-10 years. The disease causes arthralgia and arthritis secondary to a transient inflammation of the synovium of the hip.

Pathophysiology

Biopsy reveals only nonspecific inflammation and hypertrophy of the synovial membrane. Ultrasonography demonstrates an effusion that causes bulging of the anterior joint capsule. Synovial fluid has increased proteoglycans.

Frequency

United States

Little data are available regarding the frequency of this illness. However, excluding infections and trauma, TS is one of the most common causes of joint pain in the pediatric age group.

Mortality/Morbidity

• Controversy exists regarding a possible etiologic relationship between TS and Legg-Calvé-Perthes disease (LCP). Although some children with TS may develop LCP, whether persistence of increased intraarticular pressure eventually causes avascular necrosis or whether patients may have a synovitis that occurs before detection of femoral head collapse is not fully known. Approximately 1.5% of patients with TS develop LCP. Coxa magna, osteoarthritis, or recurrences may occur.

Sex

• TS affects boys twice as often as girls.

Age

• TS most frequently occurs when individuals are aged 3-10 years; however, TS has been reported in a 3-month-old infant and in adults. Nonetheless, children outside the typical age group are unlikely to have TS. Some teenagers with enthesitis-associated arthritis are initially diagnosed erroneously with toxic synovitis when they first present with hip pain.

CLINICAL

Section 3 of 11  

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History

• Hip pain: Unilateral hip or groin pain is the most common report; however, some patients with transient synovitis (TS) may report medial thigh or knee pain.
• Crying at night: Very young children with TS may have no symptoms other than crying at night; however, a careful examination should reveal some degree of an antalgic limp.
• Recent infection: Recent history of an upper respiratory tract infection, pharyngitis, bronchitis, or otitis media is elicited from approximately half of patients with TS.
• Limp: Some patients with TS may not report pain and may present with only a limp.
• Fever: Children with TS are usually afebrile or have a mildly elevated temperature; high fever is rare.

Physical

• Hip
• • During physical examination, hold the hip in flexion with slight abduction and external rotation.
  • Examination of the individual with TS usually reveals mild restriction of motion, especially to abduction and internal rotation, although one third of patients with TS demonstrate no limitation of motion.
  • The hip may be painful even with passive movement.
  • The hip may be tender to palpation.
  • The most sensitive test for TS is the log roll, in which the patient lies supine and the examiner gently rolls the involved limb from side to side. This may detect involuntary muscle guarding of one side when compared to the other side.
• Knee
• • The knee of the individual with TS may have decreased range of motion only as it may include hip motion.
  • Any effusion or joint abnormality within the knee should suggest another disease process.

Causes

• No definitive cause of TS is known, although the following have been suggested:
• • Patients with TS often have histories of trauma, which may be a cause or predisposing factor.
  • One study found an increase in viral antibody titers in 67 of 80 patients with TS.
  • Postvaccine or drug-mediated reactions and an allergic disposition have been cited as possible causes.

DIFFERENTIALS

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Other Problems to be Considered

Avascular necrosis
Fracture
Gonococcal arthritis
Lyme arthritis
Rheumatic arthralgias
Soft tissue injury
Tumor or malignancy

WORKUP

Section 5 of 11  

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Lab Studies

• Complete blood count: The white blood cell (WBC) count may be elevated slightly.
• Erythrocyte sedimentation rate
  • The erythrocyte sedimentation rate (ESR) may be elevated slightly. One study found that the combination of an ESR greater than 20 mm/h and/or a temperature greater than 37.5°C identified 97% of individuals with septic hip.
  • Another study by Kocher et al used 4 independent predictors of septic arthritis to distinguish it from transient synovitis and the need for further workup. They concluded that patients who were nonweightbearing and had history of fever, an ESR greater than 40 mm/h, and a WBC count greater than 12,000 cells/mm had a high predicted probability of 99.6% of having septic arthritis.
  • Luhmann et al applied these 4 criteria to their patient population and discovered a 59% predicted probability. However, when they applied the 3 criteria of history of fever, a serum WBC count of greater than 12,000 cells/mm, and a previous health-care visit, they found a predicted probability of 71% that the patient had septic arthritis.
• Urinalysis and culture: Both of these tests should be normal.
• Urine glycosaminoglycans: One study found a decreased level of urine glycosaminoglycans in patients who were diagnosed with Perthe disease, compared with those with transient synovitis and a control group.

Imaging Studies

• Anteroposterior and lateral radiographs of the pelvis
• • Radiographs exclude bony lesions (eg, occult fracture, osteoid osteoma) unless the child had onset of symptoms within 3 days, has no fever, appears well, and has only mildly restricted abduction without guarding against movement in other planes.
  • Plain films may be normal for months after onset of symptoms.
  • Medial joint space may be slightly wider in the affected hip (see Image 1).
  • If excess fluid is present or the patient has early LCP disease, plain films may demonstrate an increase in the teardrop distance (ie, distance between the medial acetabulum and ossified part of the femoral head). Compared to the other side, this distance should be the same or within 1 mm.
  • One half to two thirds of patients with transient synovitis (TS) may have an accentuated pericapsular shadow.
  • In one study, as many as 58% of patients with TS had the Waldenström sign (ie, lateral displacement of the femoral epiphyses with surface flattening).
  • Other studies have reported a positive obturator sign in established incidents of TS. This is a prominent shadow caused by the soft tissues that overlie the interpelvic aspect of the acetabulum.
  • Radiographs may demonstrate diminution of the definition of soft tissue planes around the hip joint or slight demineralization of the bone of the proximal femur, particularly in the metaphyseal region.
• Ultrasound
• • Although extremely accurate for detecting an intracapsular effusion, ultrasound does not assist in determining the cause and is used best to guide hip aspiration. An effusion is present if ultrasound demonstrates capsular distension greater than 2 mm.
  • Occasionally, the radiologist can differentiate between TS and early LCP on the basis of effusion rather than synovial membrane thickening.
• Magnetic resonance imaging
• • A study by Lee et al proposed that the physician may differentiate TS from septic arthritis by considering the results of an MRI. This study found that septic arthritis demonstrated signal intensity alterations in the bone marrow of the affected hip. More studies are needed to confirm this noninvasive means of making the diagnosis of TS before MRI can be applied clinically.

Other Tests

• Bone scintigraphy
• • This test demonstrates mildly elevated uptake; however, bone scintigraphy may also demonstrate a transient decrease in uptake of technetium 99m phosphate.
  • Bone scintigraphy does not help the physician differentiate etiologies.

Procedures

• Aspiration with ultrasound guidance
• • Perform this procedure in all individuals in whom the ultrasound has exhibited evidence of an effusion and any of the following predictive criteria are present:
    • Temperature greater than 99.5°F
    • ESR greater than or equal to 20
    • Severe hip pain and spasm with movement
  • The aspirate should assist the physician in differentiating TS from septic arthritis. The physician can confirm 30-50% of septic arthritis incidents with Gram stain. In individuals with septic arthritis, the WBC count varies (25,000-250,000 mm³); however, in these individuals, the WBC count consistently demonstrates 90% polymorphonuclear cells. Also, in persons with septic arthritis, the glucose is often less than 40 mg/dL or is markedly different from the serum glucose.
  • In one study, 36 children with an effusion underwent aspiration with ultrasound guidance. The Gram stain identified 1 child with an acute infection. The 35 children with a negative Gram stain were sent home with no further complications.
  • In another study published by Skinner et al, 25 children with a clinical diagnosis of transient synovitis were observed. They all had a joint effusion by ultrasound, but no aspiration was performed. The mean age of the patient population was 6 years, the average size of the effusions was 9 mm, and the distribution between the sides affected was equal. They found that by 2 weeks postdiagnosis, all patients were pain and limp free. The effusions, although still present in some, were decreasing in size. They concluded that transient synovitis is benign and can be treated with supportive therapy.

TREATMENT

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Medical Care

• Apply heat and massage to individuals with transient synovitis (TS).
• If the diagnosis of TS is equivocal or the patient is uncomfortable, hospitalize for observation and traction. Home treatment also can include traction. Skin traction of the hip in 45° of flexion minimizes intracapsular pressure.

Activity

• Advise bedrest for 7-10 days, allowing the patient to rest in a position of comfort.
• Advise the patient with TS not to bear weight on the affected limb.
• Advise the patient with TS to avoid full unrestricted activity until the limp and pain have resolved.

MEDICATION

Section 7 of 11  

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Drug Category: Nonsteroidal anti-inflammatory drugs (NSAIDs)

These agents have analgesic, antiinflammatory, and antipyretic activities. They act by inhibiting cyclooxygenase activity, which results in decreased prostaglandin synthesis. Other mechanisms, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell-membrane functions, may also exist.

Naproxen and ibuprofen are the most frequently prescribed NSAIDs in children, with a suspension form and safety and efficacy studies available. The COX-2 inhibitors have not yet been studied adequately in the pediatric population.

FOLLOW-UP

Section 8 of 11  

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Further Outpatient Care

• Advise patients with transient synovitis (TS) to return in 12-24 hours for a repeat examination.
• If significant symptoms persist for 7-10 days after the initial presentation, consider other diagnoses.
• Advise that all patients with TS have repeat radiographs within 6 months to exclude LCP disease.

In/Out Patient Meds

• Recommend NSAIDs (eg, ibuprofen, naproxen). NSAIDs may shorten the duration of symptoms. A study performed on 36 children with transient synovitis showed that those who took ibuprofen had a median duration of symptoms for 2 days. The control group taking a placebo had a mean duration of symptoms for 4.5 days.

Complications

• Sequelae include coxa magna and mild degenerative changes of the femoral neck.
• • Coxa magna is observed radiographically as an overgrowth of the femoral head and broadening of the femoral neck.
  • Coxa magna leads to dysplasia of the acetabular roof and subluxation.
  • An incidence rate of coxa magna of 32.1% has been reported in the first year following TS.
• LCP disease develops in 1-3% of individuals with TS.

Prognosis

• Patients with TS usually experience marked improvement within 24-48 hours.
• Two thirds to three fourths of patients with TS have complete resolution within 2 weeks. The remainder may have less-severe symptoms for several weeks.
• The recurrence rate is 4-17%; most recurrences develop within 6 months.
• No increased risk of juvenile chronic arthritis is known; however, a slightly increased risk for later development of osteoarthritis may exist.

Patient Education

• Advise parents and/or caregivers to initially check the temperature of the patient with TS regularly and inform the physician of any fever.
• For excellent patient education resources, visit eMedicine's Foot, Ankle, Knee, and Hip Center and Arthritis Center.

MISCELLANEOUS

Section 9 of 11  

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Medical/Legal Pitfalls

• Misdiagnosis of toxic synovitis and the resulting delay in treatment of an infectious etiology or malignancy can be disastrous.
• Early use of NSAIDs can mask disease progression in septic joints.

MULTIMEDIA

Section 10 of 11  

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• Multimedia
• References

Media file 1:  Widening of the joint space. Note that the space is wider on the left side. Discrepancies greater than 1 mm indicate the presence of fluid.
	View Full Size Image
Media type:  X-RAY

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Clinical
• Differentials
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• Cassidy JT, Petty RE. Textbook of Pediatric Rheumatology. 3rd edition:1995: 505.
• Chung SM. Diseases of the developing hip joint. Pediatr Clin North Am. Dec 1986;33(6):1457-73. [Medline].
• Connolly LP, Connolly SA. Skeletal scintigraphy in the multimodality assessment of young children with acute skeletal symptoms. Clin Nucl Med. Sep 2003;28(9):746-54. [Medline].
• Del Beccaro MA, Champoux AN, Bockers T, Mendelman PM. Septic arthritis versus transient synovitis of the hip: the value of screening laboratory tests. Ann Emerg Med. Dec 1992;21(12):1418-22. [Medline].
• Eggl H, Drekonja T, Kaiser B, Dorn U. Ultrasonography in the diagnosis of transient synovitis of the hip and Legg-Calve-Perthes disease. J Pediatr Orthop B. Jul 1999;8(3):177-80. [Medline].
• Fink PC, Dufort JE, Smith-Wright D. Orthopedic disorders. In: Pediatric Emergency Medicine. 1996: 937.
• Hart JJ. Transient synovitis of the hip in children. Am Fam Physician. Oct 1996;54(5):1587-91, 1595-6. [Medline].
• Haueisen DC, Weiner DS, Weiner SD. The characterization of "transient synovitis of the hip" in children. J Pediatr Orthop. Jan-Feb 1986;6(1):11-7. [Medline].
• Keenan GF. Transient synovitis. In: The Five Minute Pediatric Consult. 1997: 736.
• Kermond S, Fink M, Graham K. A Randomized Clinical Trial: Should the Child with Transient Synovitis of the Hip be Treated with Nonsteroidal Anti-inflammatory Drugs?. Annals of Emergency Medicine. 2002;40:294-9. [Medline].
• 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. Aug 2004;86-A(8):1629-35. [Medline].
• Koop S, Quanbeck D. Three common causes of childhood hip pain. Pediatr Clin North Am. Oct 1996;43(5):1053-66. [Medline].
• Lee SK, Suh KJ, Kim YW, et al. Septic arthritis versus transient synovitis at MR imaging: preliminary assessment with signal intensity alterations in bone marrow. Radiology. May 1999;211(2):459-65. [Medline].
• Luhmann SJ, Jones A, Schootman M, et al. Differentiation between septic arthritis and transient synovitis of the hip in children with clinical prediction algorithms. J Bone Joint Surg Am. May 2004;86-A(5):956-62. [Medline].
• Robben SG, Lequin MH, Diepstraten AF, et al. Anterior joint capsule of the normal hip and in children with transient synovitis: US study with anatomic and histologic correlation. Radiology. Feb 1999;210(2):499-507. [Medline].
• Simon RR, Koenigsknecht SJ. Hip, pelvis, and thigh. In: Emergency Orthopedics: The Extremities. 1995: 421.
• Skinner J, Glancy S, Beattie TF, Hendry GM. Transient Synovitis: is there a need to aspirate hip joint effusions?. European Journal of Emergency Medicine. 2002;9:15-8. [Medline].
• Snider RK. Transient synovitis of the hip. In: Essentials of Musculoskeletal Care. 1998: 667-68.
• Wingstrand H. Transient synovitis of the hip in the child. Acta Orthop Scand Suppl. 1986;219:1-61. [Medline].

Article Last Updated: Jun 14, 2006