The anatomy of the pelvis in the exstrophy complex

We compared computerized tomography scans of the pelvis of twenty-four patients who had exstrophy of the bladder with scans of age-matched controls in order to analyze the pelvic deformity that accompanies the variably severe manifestations of this condition. The patients who had classic exstrophy of the bladder were found to have a mean of 12 degrees of external rotation of the posterior aspect of the pelvis on each side, retroversion of the acetabula, a mean additional 18 degrees of external rotation and 30 per cent shortening of the pubic rami, and progressive diastasis of the symphysis pubis. The foot-progression angle demonstrated 20 to 30 degrees of external rotation beyond the normal limits seen in early childhood, but this improved with age. The patients who had exstrophy of the cloaca and the bladder not only had all of these pelvic deformities to a greater degree but also had asymmetry of measured parameters between the right and left sides of the pelvis, malformation of the sacro-iliac joints, and occasional dislocation of the hip. An understanding of the pelvic anatomy that accompanies exstrophy is essential when corrective approaches are planned. Such an understanding will improve the rate of success of both closure of the bladder and control of urinary continence postoperatively.

Computed tomographic imaging of the musculoskeletal system. Current status

Computed tomography has emerged as the "workhorse" of specialized musculoskeletal imaging. It provides rapid, detailed, clinically relevant studies of bones, joints, and associated soft tissues. Applications in trauma, inflammatory disease, neoplasia, pediatric orthopedics, and joint reconstruction are discussed. Advances in prosthetic design, radiation oncology applications, and data acquisition techniques will also be addressed.

Metastatic adenocarcinoma of the prostate: presentation as a pleural-based mass

We have presented an unusual case of metastatic prostate carcinoma simulating a primary bone tumor. Although previous reports have described periosteal and "pseudosarcomatous" prostate metastases, no report makes reference to rib involvement. Furthermore, the large soft tissue component is highly unusual. This case illustrates that although such lesions are rare, in the older patient, metastases should be included along with primary tumors in the differential diagnosis of a spiculated bone lesion with prominent soft tissue involvement.

Subtle orthopedic fractures: teleradiology workstation versus film interpretation

The purpose of this study was to evaluate whether radiologists perform equally well with plain radiographs or digitized images displayed on a video monitor in interpretation of difficult orthopedic trauma cases. Interpretations with film and those made from a teleradiology system with spatial resolution of 2.35 line pairs per millimeter were compared in 120 difficult cases, 60 with the selected abnormality (ie, fracture or dislocation) and 60 that were control cases. Seven senior radiology residents and one radiology fellow each interpreted 60 randomly ordered cases with the teleradiology system (1,280 x 1,024-pixel monitors) and 60 cases with the original radiographs. The overall accuracy of the readers was 80.6% for film interpretations and 59.6% for teleradiology screen readings (P < .001). Sensitivity was 78.5% for film and 48.8% for on-screen images (P < .001), and specificity was 83.2% for film and 72.3% for on-screen images (P < .025). Receiver operating characteristic analysis showed rejection of the null hypothesis in favor of film interpretation (P < .0049). It was concluded that the teleradiology system was not acceptable for primary diagnostic interpretation of difficult fracture cases.

Two-dimensional and three-dimensional computed tomographic imaging in musculoskeletal tumors

Appropriate treatment of musculoskeletal neoplasms relies on prompt and accurate identification of tumor characteristics and extent. Multiplanar and three-dimensional (3-D) computed tomography (CT) provide rapid, relatively noninvasive imaging for initial assessment and for planning of radiation therapy, en bloc resection, and limb-salvage surgery. An integrated 2-D-3-D CT approach also allows precise tracking of therapeutic response and recurrence.

Parosteal ossifying lipoma: CT and MR findings

Radiologic and imaging findings of parosteal ossifying lipoma along with pathologic correlation are presented in this case report.

Lymphoma of bone, muscle, and skin: CT findings

Lymphoma can involve any part of the musculoskeletal system. Primary musculoskeletal lymphoma is rare but can occur in bone (reticulum cell sarcoma) or in the skin and subcutaneous tissues (mycosis fungoides). Secondary involvement in the musculoskeletal system is more common and can have a variety of radiologic findings. The definitive diagnosis of musculoskeletal lymphoma, however, is difficult to make by using imaging criteria alone. Any part of the musculoskeletal system can be involved and, therefore, a wide variety of primary and secondary neoplasms or inflammatory processes may have similar radiologic findings. The main differential diagnostic considerations, depending on the age of the patient and the clinical presentation, include osteosarcoma, Ewing's tumor, metastatic disease (from breast, lung, thyroid, or renal primary lesions), as well as chronic osteomyelitis or myositis. Primary and secondary bone lymphoma can be indistinguishable radiologically and histologically, but modern imaging techniques allow more accurate differentiation of primary from secondary bone involvement. This pictorial essay illustrates the CT findings of primary and secondary lymphoma involving bone, muscle, and skin and subcutaneous tissues.

Acetabular and pelvic fractures in the pediatric patient: value of two- and three-dimensional imaging

Pediatric trauma is a significant source of morbidity and mortality in pediatric patients. Prompt and accurate assessment of injuries is necessary for the best outcome. Computed tomography (CT) has become a well-accepted, rapid, relatively noninvasive way to assess the trauma patient. In certain cases of pelvic trauma, two- and three-dimensional CT (2D/3D CT) adds detail not otherwise obtainable or appreciated. Although the benefits must be balanced against the slight increase in delivered radiation dose, we believe that 2D/3D CT is often an important part of patient management.

Prevention of Lyme disease after tick bites. A cost-effectiveness analysis

BACKGROUND

In areas of endemic disease, the probability of Lyme disease after a tick bite ranges from about 0.012 to 0.05. Early treatment with oral antibiotics prevents most complications of Lyme disease, but antibiotics are generally not prescribed until rash or other symptoms develop.

METHODS

We used decision analysis to evaluate the outcomes, costs, and cost effectiveness of three alternative strategies to treat patients bitten by ixodes ticks in areas of endemic Lyme disease: empirically treat all patients with two weeks of doxycycline, treat only patients in whom erythema migrans develops, and treat only patients with erythema migrans or a positive serologic test for Lyme disease one month after exposure.

RESULTS

Empirical treatment is the least expensive strategy and results in the fewest cases of Lyme disease and the fewest complications when the probability of Borrelia burgdorferi infection after a tick bite is 0.036 or higher. For probabilities of infection below 0.036, empirical therapy prevents most major complications, sequelae, and adverse events, but it incurs additional minor complications, especially as the probability of infection falls below 0.01.

CONCLUSIONS

Empirical treatment of patients with tick bites is indicated when the probability of B. burgdorferi infection after a bite is 0.036 or higher, and this treatment may be preferred when the probability of infection ranges from 0.01 to 0.035. When the probability of infection after a tick bite is less than 0.01, empirical therapy is not warranted.

Preoperative interactive 2D-3D computed tomography assessment of heterotopic bone

Total hip arthroplasty is a common orthopaedic procedure in this country. Postoperative heterotopic bone formation may be seen in anywhere from 5% to 76% of such procedures. Only a small subgroup of these patients are symptomatic. Approximately 6% of arthroplasty patients require evaluation of heterotopic bone. In such patients, computed tomography may be useful in staging the extent of bone formation and in helping to plan surgical or radiotherapy treatment. Reformatting transaxial data into coronal and sagittal planar images and into simulated three-dimensional images provides the most comprehensive overview and maximizes communication of relevant findings.

Musculoskeletal infections in patients with AIDS: CT findings

The CT appearances of various musculoskeletal infections found in patients with AIDS are illustrated. Recognition of these infections is important for management of patients, but conventional laboratory tests may be inadequate in screening for infection or confirming the response of the host to therapy. As a screening examination for patients with AIDS, CT can suggest or confirm the presence of musculoskeletal infections even when infection has not been suspected.

Cervical fracture in ankylosing spondylitis: value of multidimensional imaging

Ankylosing spondylitis creates a rigid spinal column that cannot easily accommodate to altered or increased forces. Fractures or fracture-subluxation may be seen following apparently trivial injury. Assessment of the lower cervical and cervicothoracic spine can be limited in the kyphotic, ankylosed spine. However, reformatted computed tomography (CT) data can be manipulated to provide true orthogonal (sagittal, coronal) planar images of the obliqued spine, and can be used to provide a three-dimensional overview of anatomy prior to treatment. One such case is presented.

Examination of the pathologic anatomy of ankle fractures

A prospective study of the translational and rotational displacement of the lateral malleolus in ankle fractures was carried out utilizing roentgenographic techniques. Twenty-six ankle fractures in 25 patients were studied using both routine plain films and CT scanning with two- and three-dimensional multiplanar reconstruction. Eighty-one percent were Lauge-Hansen supination-external rotation type injuries. Overall, 21 fractures did not involve the medial malleolus. Initial talar shift was less than or equal to 2 mm in 15 fractures. Although all patients exhibited external rotation deformities of the lateral malleolus on plain films, only one fracture was found to possess any degree of external rotation relative to the talus. The proximal fibula was seen on CT scans to have increased internal rotation with respect to the tibia in 19 cases. One patient had a slightly externally rotated proximal fibula; the remainder appeared normally aligned. The displacements measured by the CT scans at the talofibular articulation were compared with the standard plain film measurements. The displacements at the distal lateral malleolus were consistently overestimated by the plain roentgenograms, presumably because the capsular and ligamentous attachments to the distal fibula limit malleolar displacement. The talocrural angle, determined on both plain films and CT scans, was also not found to be a sensitive measure of fibular shortening nor of the severity of the fracture. The results of this study suggest that, in an isolated lateral malleolar ankle fracture, the apparent external rotation of the fracture fragment is relative only to the proximal fibula and is not associated with derangement of the talofibular articulation. Based on these mechanical considerations, surgical intervention for such fractures may not be necessary. This hypothesis is consistent with previous long-term clinical studies.

Pulmonary Aspergillus chest wall involvement in chronic granulomatous disease: CT and MRI findings

Pulmonary Aspergillus infection in patients with chronic granulomatous disease tends to involve the chest wall and consequently carries a high mortality rate. We report the findings of computed tomography (CT) and magnetic resonance imaging (MRI) in three such cases. One patient underwent both CT and MRI, one, CT only, and one, MRI only. In all three, both CT and MRI demonstrated pulmonary consolidations with direct extension to the adjacent chest wall. In both patients who were examined by CT, scans revealed permeative osteolytic changes of adjacent rib or spine compatible with osteomyelitis. In both patients who were examined by MRI, adjacent chest wall involvement was depicted on T1-weighted images and showed increased signal intensity on T2-weighted images. In one of these patients, the chest wall lesion was well defined on T2-weighted images, an appearance compatible with abscess. Epidural extension was demonstrated on MRI in the other patient, who later developed paraparesis. We suggest that CT and MRI have a complementary role in evaluating chest wall invasion by pulmonary Aspergillus infection in chronic granulomatous disease.