Sonographic Evaluation of Acute Osteomyelitis in Infants

PURPOSE: To analyze the related sonographic findings and to determine the value of sonography in establishing the diagnosis of acute osteomyelitis in infants. MATERIALS AND METHODS: The sonographic findings of eleven infants aged 10 days-4 months (mean, 45 days) with acute osteomyelitis were retrospectively evaluated. The involved bones were the femur (n=5), humerus (n=2), tibia (n=2), rib(n=1), sternum(n=1), and calcaneus(n=1). Discontinuity or destruction of cortical margins, echotexture of the metaphysis and epiphysis, the presence of subperiosteal hypoechoic lesion, adjacent soft tissue swelling, distension of the joint capsule, the echotexture of joint effusion, and dislocation or subluxation of the involved joint were evaluated. The sonographic findings were compared with the plain radiographic (n=12) and MR (n=5) findings, with special attention to the identification of the metaphyseal or epiphyseal bony lesions and the involvement of adjacent joints. RESULTS: The sonographic findings of osteomyelitis were cortical discontinuity or destruction (n=12), hypoechoic lesions with an echogenic rim in the metaphysis (n=12), subperiosteal hypoechoic lesions (n=8), soft tissue swelling (n=9), a distended hip joint, with echogenic fluid (n=5), ill-demarcated echogenic lesions in the capital femoral epiphysis (n=5), and a subluxated hip joint (n=3). Plain radiographs revealed well or ill-defined osteolytic lesions in the metaphysis, accompanied by cortical destruction (n=8), new periosteal bone formation (n=3) and reactive sclerosis (n=2). Abnormality of the femoral epiphyses and joint involvement were not detected on plain radiographs, and in four cases no abnormality was noted. MR imaging showed that at T1WI, affected bony lesions were of low signal intensity and enhanced, with high signal intensity at T2WI. In all cases, both metaphyseal and epiphyseal lesions were demonstrated at MRI, but in one of the three cases in which an epiphyseal lesion was seen at MRI, this was not detected at US. CONCLUSION: Sonography is not only more sensitive than radiography in evaluating metaphyseal bony lesions but also useful in assessing concomitant joint and epiphyseal involvement of acute osteomyelitis in infants. Sonography is, therefore, a useful additional diagnostic tool for the early detection and management of acute osteomyelitis in infants.

Ultrasonographic Evaluation of Ischial Bursitis

PURPOSE: The objective of this study was to evaluate the findings of ultrasonography (US) in patients withis-chial bursitis. MATERIALS AND METHODS: Our study included 27 patients (mean age 62 years) who underwent US fora painful mass or tenderness in the buttock area. In six of these 27, serous fluid was obtained by needleaspiration, and in five cases, bursal excision permitted histologic confirmation. The other sixteen patients werefollowed up for one or two months with only NSAID medication; all showed some improvement or remission of symptoms. Using a 5-10 MHz linear array probe, US examination was performed while the patient was lying facedown. US images were analyzed with regard to location and size of the lesions, thickness of cyst wall, thepres-ence of internal septa or mural nodules, echogenicity of the cyst wall, fluid content, internal septa,compressibility by a probe, and Doppler signals within the cyst wall. RESULTS: In all 27 patients, ischialbursitis was located superficially to ischial tuberosity. Lesion size(maximum diameter) was 1.5-7(mean 3.8)cm, andthe cyst wall was 0.2-0.8cm thick. Internal septa and mural nodules were seen in 12 cases (44%) and 13 cases(48%), respectively. The cyst wall was identifiable in 21 cases (78%), appearing as a single layer with lowechogenicity (n=10) or with high echogenicity (n=1); it also appeared as two (n=6) or three (n=4) layers ofdifferent echogenicities. When internal septa were present, fluid within the cyst was low echoic in 59% of cases,high echoic in 30%, and of mixed echogenicity (so-called compartmentalization) in 15%. In all cases, the cystbecame deformed, when compressed by a probe. In all patients who underwent doppler examination, some vascularitywas found within the cyst wall. CONCLUSION: US helped to detect ischial bursitis; US findings were thin-walled cystic lesion located superficially to ischial tuberosity, with or without internal septa and mural nodules, andeasy compressibility.

Usefulness of Ultrasonography in follow-up evaluation after Ilizarov Procedure: Comparison with PlainRadiography

PURPOSE: To compare the usefulness of ultrasonography in follow up evaluation after the Ilizarov procedurewith that of plain radiography. MATERIALS AND METHODS: We analyzed ultrasound findings in twelve patients who hadundergone the Ilizarov procedure, and retrospectively compared the results with the findings of plain radiography.The procedure was performed due to post-traumatic limb deformity or non-union(nine of twelve patients), congenitalpseudoarthrosis(one case), sequelae of poliomyelitis(one case), and short stature(one case). The patients' meanage was 29 years ; eleven of twelve were male. Ten of twelve procedures were performed on the tibia and two on thefemur. After 7-10 days, distraction was initiated at a rate of 0.25mm four times a day. Ultrasonography wasperformed with a 5-10 MHz linear or convex transducer ; new bone formation was defined as dotted or linearechogenic foci within a hypoechoic distraction gap. Initial ultrasonographic examination was performed 2-4 weeksafter distraction, and the results were compared with those of plain radiography. Color Doppler imaging wasperformed in three cases. RESULTS: On ultrasonograms, new bone formation was initially detected 18-29(mean, 23)days after distraction, and on plain radiographs, 37-58(mean, 45) days after this procedure ; ultrasonography thusdetected new bone formation at least three weeks earlier than did plain radiography. Complication after theIlizarov procedure were four cysts at the distraction site, and one pin site infection, as seen on ultrasonograms.None of these four cysts, the size of which was 12-22mm(mean, 17mm), was visible on plain radiographs. In one casein which a cyst was present, ultrasound-guided aspiration was performed. Color Doppler examination was performedin three of twelve patients, and in all three, periosteal vascularity at the edge of the distracted gap was seento be preserved. CONCLUSION: After the Ilizarov bone lengthening procedure, ultrasound appears to be useful forfollow-up examination. New bone formation, as well as complications, can be detected earlier ; it can indicatewhether ultrasound-guided interventional procedure is required, and if combined with color Doppler study, is ableto detect the periosteal blood supply. Further evaluation of the clinical significance of preserved periostealblood supply seems however, to be needed.