Septic Arthritis Versus Transient Synovitis of the Hip: Gadolinium-Enhanced MRI Finding of Decreased Perfusion at the Femoral Epiphysis

Abstract

OBJECTIVE. The purpose of this study was to identify differences in the MRI findings of septic arthritis and transient synovitis in patients with nontraumatic acute hip pain and hip effusion.MATERIALS AND METHODS. The MRI findings in nine patients with septic arthritis and 11 with transient synovitis were reviewed retrospectively. This study was approved by our institutional review board. The diagnoses were based on findings at physical examination, laboratory studies, and joint aspiration and bacteriologic study. The MRI findings were analyzed with emphasis on the grade of joint effusion, alterations in signal intensity in the soft tissues and bone marrow, and the presence of decreased perfusion at the femoral head.RESULTS. Low signal intensity on fat-suppressed gadolinium-enhanced T1-weighted coronal MRI suggesting decreased perfusion at the femoral head of the affected hip joint was seen in eight of nine patients with septic arthritis and in two of 11 patients with transient synovitis. Statistically reliable differences (p = 0.005) were found between the two groups. Alterations in signal intensity in the bone marrow were seen in three patients with septic arthritis but in none of the patients with transient synovitis. Decreased perfusion on fat-suppressed gadolinium-enhanced coronal T1-weighted MRI was seen in the six patients with septic arthritis who did not have alterations in signal intensity involving the bone marrow.CONCLUSION. Decreased perfusion at the femoral epiphysis on fat-suppressed gadolinium-enhanced coronal T1-weighted MRI is useful for differentiating septic arthritis from transient synovitis.

Can early MRI distinguish between Kingella kingae and Gram-positive cocci in osteoarticular infections in young children?

“…This has been suggested to be a sign of septic arthritis and it has recently been also reported as a sign of epiphyseal osteomyelitis in pre-school age children [32,33].…”

Fluxograma diferencial entre a artrite séptica e sinovite transitória do quadril em crianças

“…15 It is also possible to use magnetic nuclear resonance, which is able to detect further details and also the decrease of femoral head perfusion. 16 But it is an exam that requires anesthesia in younger children or sedation, and is not always available, especially in our field. Bone scanning can also be used, with more restricted use, whereas at the beginning of septic arthritis the image appears with a low standardized uptake value due to the decreased blood flow and, afterwards a "hot" standard, due to the result of the vascular response of blood flow increase.…”

Transient synovitis of the hip: Ultrasound appearance. Mini-pictorial essay

“…In transient synovitis of the hip, a 2-view standard x-ray examination (anterioreposterior and frog-leg lateral views) yields a negative outcome or is only indicative of joint effusion [1,5]. According to some authors [2] gadolinium-enhanced magnetic resonance has proven useful in the differential diagnosis between transient synovitis and septic arthritis because septic arthritis presents a reduced perfusion of the femoral head in gadolinium-enhanced images. However, this sign is not always present.…”

“…In 5% of cases the lesion is bilateral and it is sometimes associated with a low-grade fever usually not exceeding 38 C. Diagnosis is essentially by exclusion because imaging is similar to that of other causes of acute hip pain in children. The main differential diagnosis is septic arthritis [2] and juvenile rheumatoid arthritis. Also cases of Lyme arthritis of the hip [3] with clinical and imaging characteristics identical to transient synovitis of the hip are described in the literature.…”