**6. Procedures**

the need for repeating the surgery. Increased marrow intensity with surrounding inflamma‐ tion are the most suggestive signs of OM. MRI of the spine is useful in children not responding to therapy and/or to detect complications, such as extradural and paraspinal collections that will require surgical treatment because of causing spinal cord compression. The enhanced uptake of the radioisotope, distinguishes OM from deep cellulitis Gadolinium‐enhanced fat‐ saturated T1‐weighted sequences increase the confidence of the diagnosis of OM and may help also to distinguish edema from an abscess [33] and allows one to see the isolated involve‐ ment of the epiphyseal growth cartilage that is occult on radiographs and bone scintigraphy because of the paucity of growth cartilage ossification. The finding of hypo‐enhancing foci in the growth cartilage suggests cartilage ischemia, necrosis or abscess as a consequence of infectious chondritis or septic thrombosis [34]. MRI may not be appropriate for monitoring the evolution of the lesions. Technetium bone scanning has a false‐negative rate of as much as 20%, particularly in the first few days of illness. Indium‐labeled leukocytes have limitations in newborns. Gallium scanning is not recommended because of lower specificity and expo‐ sure to higher levels of radiation. Ultrasonography: Although ultrasonography is an operator dependant technique with an inability to differentiate infectious fluid from traumatic ones, in able hands, it allows the detection of changes of acute OM as early as 48 h after the onset of infection. In the early stages ultrasound document deep soft tissue swelling (1–3 d), then the elevation of the periosteum by a thin layer of fluid, a definite subperiosteal collection, joint effusion and finally cortical erosion (2–4 w). In this last case it is used to guide needle drain‐ age aspiration if necessary. Ultrasound images normalize by 4 weeks in the case of response to treatment [35]. Doppler venous ultrasonography is the first imaging study indicated in the case of clinical suspicion for deep vein thrombosis in patients with OM caused by CA‐MRSA. A normal ultrasound scan does not exclude OM. Radiography is usually the first radiological investigation in a neonate with suspected OM, although it is reported that only 20% of the radiographs are abnormal at 10–14 days [36, 37]. Despite the low prevalence of abnormal fea‐ tures at presentation, it allows the exclusion of fractures and is useful to show long‐term fol‐ low‐up of complications. Initially it may reveal normal results, after 10–15 days signs of bone destruction, osteopenia, lytic lesions, and periosteal changes. Metaphyseal irregularities and periostitis (both non‐specific) may be documented [37]. It has low sensitivity toward detec‐ tion of a joint effusion or deep soft tissue swelling; the diagnosis of suspicion may include widening of the joint space with or without subluxation and soft tissues protruding that can be detected as early as 48 h after the onset of infection. Radiography may detect bone destruc‐ tion when at least one‐third of the matrix has been involved. Findings related to the spine may be limited to a loss of the normal lumbar lordosis, disc space narrowing, end plate ero‐ sions, pressure erosion of the superior and inferior margins of the adjacent vertebral body if the infection prolonged. Normally, other imaging tests are required. A bone scan is reserved for the cases in which radiographs and/or ultrasound are unclear, for suspected multifocal infection, chronic multifocal OM, and discitis. Bone scintigraphy is highly sensitive to the detection of OM in the early stages of the disease. In the first week of the disease, techne‐ tium (99mTc)‐labeled bone scans revealed positive in 87% of the cases as compared with 42% diagnosed with radiography. Scintigraphy is useful for detecting multifocal diseases that are more common in neonates. A 99mTc‐labeled phosphonate complex is the most used isotope. Scintigraphic study, even if non‐specific, is useful to document through increased uptake of

100 Selected Topics in Neonatal Care

If signs and symptoms do not begin to resolve within 48–72 h of initiation of appropriate antimicrobial treatment, bone aspiration may be necessary to identify the pathogen and to drain the pus in accordance with the orthopedic surgeon. Bone and/or joint fluid aspirate for culture, can be bactericidal. Bone biopsy is necessary in the suspicion of tumors.
