Hip Transient Synovitis

• Transient synovitis is characterized by the acute onset of monarticular hip pain, limp, and restricted hip motion.
• It must be distinguished from septic arthritis.
• Gradual but complete resolution over several days to weeks is the norm.
• Synonyms: Toxic synovitis; Irritable hip

• Transient synovitis is the most common cause of hip pain in children.
• It is a diagnosis of exclusion.
• Transient synovitis of the hip can occur from 9 months of age to adolescence; most cases occur in children 3-8 years old.
• The risk of a child having at least 1 episode of transient synovitis of the hip is 1-3%.
  • This risk is 3 times greater in patients with a stocky or obese physique.
• Right and left involvement is essentially equal; concurrent bilateral involvement has not been reported.
• Male:Female ratio is 2:1.

• Male gender
• Upper respiratory infection or other active infection

• The true cause is unknown; it appears to be an immune-mediated inflammation, not an infection.
• It has been proposed that transient synovitis of the hip may be associated with active infection elsewhere, trauma, or allergic hypersensitivity.
• Nonspecific upper respiratory infection, pharyngitis, and otitis media have been associated with the occurrence of transient synovitis in as many as 70% of cases.
• An association is noted with minor trauma in up to 30%, and with allergic predisposition in up to 25%.

• An acute onset of unilateral hip pain occurs in an otherwise healthy child.
• Pain usually is confined to the ipsilateral groin and hip area, but it may present as anterior thigh and knee pain.
• Limp and antalgic gait are common, with some patients refusing to bear weight on the involved extremity.
• The hip is held in a flexed and externally rotated position and has restricted ROM.
• The patient may have a low-grade fever.
• Laboratory values are nonspecific and are often within normal limits.

Tests

• Transient synovitis of the hip is a diagnosis of exclusion.
• Conditions to rule out include:
  • Pyogenic arthritis
  • Osteomyelitis in the adjacent femoral neck or pelvis
  • Tuberculous arthritis
  • Psoas abscess
  • Other muscle infection about the hip
  • Juvenile rheumatoid arthritis
  • Acute rheumatic fever
  • Legg-Calve-Perthes disease
  • Tumor
  • SCFE
  • Dislocation
  • SI joint infection

• Transient synovitis usually has a limited duration of symptoms, averaging <7 days.
  • Most studies report complete resolution of all signs and symptoms with no immediate residual clinical or radiographic abnormalities.
  • Long-term studies have shown mild radiographic changes in the involved hip.
• Traction and routine joint aspiration are not always needed.
  • If traction is used, it is to promote rest and comfort.
  • The hip should be in ~30° of flexion to avoid increasing intra-articular pressure.
• The important point in management of this condition is to establish the diagnosis: Pyogenic arthritis must be excluded, on clinical grounds or with laboratory tests.
• Treatment is directed at rapidly resolving the underlying inflammatory synovitis with its symptoms.

Special Therapy

• 1 study has reported that Legg-Calve-Perthes disease or AVN of the femoral head may develop several months after an episode of transient synovitis of the hip.
  • This finding probably represents a delay in establishing the correct diagnosis.

• A physician should be available for re-evaluation at all times until the possibility of infection is excluded.
• The child should be re-examined in ~1-2 weeks to determine return of motion before resuming full weightbearing and normal activity.
• Parents should bring the child back if symptoms recur or increase.

Miscellaneous

• Transient hip synovitis is a self-limiting process without major consequences.
• Some authorities have suggested an increased incidence of later Legg-Calve-Perthes disease in such patients, but this finding has not been proven conclusively.

FAQ