What are key findings from history of a child with Transient synovitis of the hip?
Refusing to walk, fall from height, acute onset, current URI, no fever, no constitutional symptoms.
What are key findings from physical exam in a child with transient synovitis of the hip?
Low-grade fever, rhinorrhea, appears well, decreased passive range of motion of hip
What is on the differential diagnosis for transient synovitis of the hip?
Trauma, osteomyelitis, reactive arthritis, leukemia, septic arthritis, juvenile idiopathic arthritis.
What are key findings from testing for transient synovitis of the hip?
Results do not show a degree of inflammation consistent with septic hip. Leukocyte count not sig. elevated. Erythrocyte sed. rate below level expected in septic arthritis.
Full examination of a young child with musculoskeletal pain:
- Observe child’s natural movements and position: Is she sitting still? What is the position of her legs and hips?
- Observe skin: Any obvious bruising or rashes? Evidence of wound?
- Slowly approach patient and try to determine origin of pain. Start with unaffected limbs. May be helpful to initially examine patient while on caretaker’s lap.
- Examina all of joints, distal and proximal, first plating for evidence of tenderness, warmth or effusion. Meanwhile, distract patient with a toy.
- Examine patient’s fingers, wrists, elbows, shoulders, toes, ankles, and knees.
- Examine patient on exam table. Perform passive range of motion of each joint, ending with what might hurt the most. Examine toes, ankles, and knees. Complete exam of hips (observation, palpation, passive and active range of motion).
What are the most likely differential diagnosis in a patient with transient synovitis of the hip?
Septic arthritis, Reactive (post-infectious) arthritis, Trauma, Osteomyelitis, Leukemia
What are less likely diagnosis in a patient with transient synovitis of the hip?
JIA, Slipped capital femoral epiphysis (SCFE)
What is transient synovitis of the hip?
Acute, self-limited inflammation of synovial lining of hip often occurring during or following an URI. This inflammatory process most commonly affects the hip or knee and is one of the most common causes of hip pain in children. Usually completely resolves within three to four days with no known serious, long-lasting sequelae.
Infection of joint space, usually bacterial in origin. Causes severe inflammation, often with erythema, warmth or swelling. Patient with septic arthritis typically appear quite ill. A septic hip is a medical emergency that requires urgent attention - pus in the joint space can lead to irreversible damage of the cartilage. Synovial fluid aspirated from a septic hip is turbid, has an increased WBC (predominantly polymorphonuclear cells), and a low glucose. Bacteria will be present on gram stain.
Reactive (post-infectious) arthritis:
This inflammatory process typically follows an infection outside the joint - most often in the GI or GU tract - presenting two to four weeks after the infection. Children are frequently afebrile at presentation. The classic association with urethritis and conjunctivitis is uncommon in children. the condition may be clinically indistinguishable from septic arthritis except that aspiration of an affect joint reveals inflammatory cells, but is sterile (the culture is negative). The arthritis may last a few weeks and require anti-inflammatory treatment. Antibiotics may need to be used to treat the underlying infection if it is still present.
Minor accidental trauma such as a sprain or occult fracture is possible after a fall. Many infectious, inflammatory, an other conditions causing limp are often initially incorrectly diagnosed as due to trauma. Hip or leg radiographs would be indicated to definitively rule out this cause.
Infection of bone, usually bacterial in origin (most often Staph aureus and - before routine immunization - Haemophilus influenza, type B). Usually indolent presentation, so diagnosis can be delayed. In toddlers, usually presents as pain and refusal to bear weight (when affecting a leg bone). Fever, often high, is present in about half of cases.
Replacement of bone marrow by leukemic cells can cause bone pain that presents as limp, refusal to walk or localized discomfort of the jaw, long bones, vertebral column, hip, scapula or ribs. These symptoms may precede systemic signs such as fever and weight loss. The pain of leukemic infiltration would not be affected by position or movement and would be more chronic in nature. Also, additional findings such as lymphadenopathy, hepatosplenomegaly, fever, or other constitutional symptoms would be expected in a systemic disease like leukemia.
Juvenile idiopathic arthritis (JIA):
A group of disorders characterized by chronic inflammation of the joints in a child under 16 years of age. Symptoms must be present in at least one joint for six weeks before the diagnosis can be made. There are seven subtypes of JIA, including:
-Systemic (additional constitutional sx such as fever and rash)
-Oligoarthritis (previously called pauciarticular)
-Polyarthritis (rheumatoid factor positive)
-Polyarthritis (rheumatoid factor negative)
-Other arthritis (has overlapping features or does not meet full criteria for one category)
May be associated with an evanescent salmon-colored macular rash on trunk and extremities.
Slipped capital femoral epiphysis (SCFE):
The most common hip disorder in adolescents, characterized by posterior displacement of the capital femoral epiphysis from the femoral neck through the cartilage growth plate, resulting in limp and impaired internal rotation. Etiology has not been clearly defined. Patients present most commonly with months of vague hip or knee symptoms and limp with or without an acute exacerbation. Occurs more commonly in obese adolescents, suggesting that mechanical strain on the growth plate could be at least partially responsible for the slip. Endocrine factors also may be important.
Will confirm absence of fracture.
This study can demonstrate whether or not an effusion is present in the hip joint as well as guide arthrocentesis, if needed.
The leukocyte count is a measure of inflammation. The more serious condition of septic arthritis should be associated with a greater increase than that seen in transient synovitis.
Will determine bacterial organism if there is septic arthritis due to bacteria entering the joint space via the blood.
Erythrocyte sedimentation rate (ESR) and Creactive protein (CRP):
Both are nonspecific measures inflammation and will be elevated in many conditions, including infections and malignancies. Transient synovitis and septic arthritis are both inflammatory processes; however,e the more serious condition of septic arthritis should be associated with greater increases in ESR and CRP.
There are two studies that assist in differentiating between septic arthritis and transient synovitis:
- Four independent predictors of septic arthritis of the hip (Fever, non-weightbearing, ESR greater than 40 mm/hr, WBC greater than 12 cells x103/uL)
- Five independent predictors of septic arthritis of the hip (Fever, elevated CRP, elevated ESR, refusal to bear weight, elevated WBC)
Study found four independent predictors of septic arthritis of the hip:
-ESR greater than 40 mm/hr
-WBC greater than 12 cells x 103/uL
Predictors and risk: 0-2p, 1-9.5p, 2-35p, 3-72.8p, 4-93
Study found five independent predictors of septic arthritis of the hip:
-Refusal to bear weight
-Elevated WBC count
Predictors and risk: 0-16.9p, 1-36.7p, 2-62.4p, 3-82.6p, 4-93.1p, 5-97.5p
How do you treat transient synovitis?
- Treat with rest and ibuprofen
- Pain resolves in 3-10 days
- Chance of recurrent episode
- No serious or long-lasting consequences
- Instruct parents to call if child develops a high fever, becomes increasingly irritable or uncomfortable in spite of the ibuprofen, or if develops redness, swelling or warmth of the joint.
- Schedule close follow-up