Biomedical subjects
Publications and source records attributed to D Resnick.
We discuss several less well recognized disorders of articular cartilage which may affect pediatric patients, including relapsing polychondritis, idiopathic chondrolysis of the hip and chondrolysis after slipped capital femoral epiphysis. Idiopathic osteolysis is not considered in our review because it has been well described previously.
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The advent of computed tomographic (CT) scanning has initiated a revolutionary approach to the evaluation of articular disease. CT affords the opportunity to noninvasively evaluate both osseous and soft tissue structures during a single diagnostic examination. An optimal CT study demands proper technique, including a localization image, appropriate slice thickness and spacing, and window/level manipulation. The examination must be tailored to the specific indication for the study, which may include degenerative processes, inflammatory disease, or unexplained clinical symptomatology.
Infectious arthritis is a commonly encountered clinical problem which may result from articular contamination by a wide variety of organisms. Involvement of an articulation may occur by one of four mechanisms: hematogenous spread, spread from a contiguous source of infection, direct implantation, or postoperative contamination. Distribution is typically monoarticular with a swollen, erythematous, and painful joint. The radiographic differential diagnosis includes limited rheumatoid arthritis, gout, synovial osteochondromatosis, and pigmented villonodular synovitis. In order to prevent complications, including growth disturbances, articular destruction with ankylosis, osteomyelitis, or soft tissue extension, early diagnostic arthrocentesis is important. Radiographic abnormalities, which include soft tissue swelling, joint space loss, periarticular osteopenia, and central or marginal osseous erosions, may be delayed following clinical onset of infection. Advanced imaging techniques such as scintigraphy, CT, or MRI may allow accurate diagnosis of the infectious process at an earlier stage.
Many tumor and tumor-like lesions may involve bone. Bone tumors in the foot are, however, very rare. An accurate diagnosis relies on a cooperative clinical and imaging effort. The patient's age, sex, history, clinical findings, and presentation, in addition to the radiographic features, allow for proper diagnosis. Specialized imaging techniques may be helpful in certain instances. Aside from a biopsy, the radiograph is clearly the most important single approach to the diagnosis of bone tumors affecting the foot.
A brief description of normal anatomy and common arthrographic, tenographic, and bursographic procedures is presented. The described procedures are important diagnostic tools and do not carry major risk. Therefore, these procedures can be performed on an outpatient basis.
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In this article, the numerous proven applications of diagnostic ultrasound to the assessment of disease processes affecting the popliteal fossa and lower extremities have been discussed. Popliteal cysts and aneurysms, hematomas, cellulitis, abscesses, soft tissue neoplasms, and other space-occupying fluid collections are readily identified using this technique. In addition, post-traumatic and inflammatory disorders affecting tendons, synovial thickening and effusion, derangement of articular cartilage, meniscal tears, and alterations in soft tissue thickness as well as foreign bodies are amenable to detection by sonography. With future technologic improvements in transducer design and computerized image reconstruction, diagnostic capabilities of this method in the lower extremities should continue to expand.
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Methods have been developed that permit repetitive radiographic measurement of the lumbar L4-5 intervertebral disc space area in the laboratory rat. In using this approach, the coefficient of variation in repetitive determinations was 7.6 +/- 0.7%. Normal rats have been shown to manifest statistically significant increase in disc space area size between 2.5 and 5 months of age.
Through the application of oblique planes and flexible surface coil techniques, magnetic resonance imaging (MRI) promises to be of great clinical value in the evaluation of a variety of pathologic conditions affecting the shoulder. In patients with joint effusions, the tendinous portion of the rotator cuff, glenoid labrum, and bicipital tendon can be readily visualized. This capability has particular relevance in patients with inflammatory disease and traumatic conditions. Rotator cuff atrophy and impingement of the coracoacromial arc upon the supraspinatus muscle and tendon can also be demonstrated. MRI is also useful in the evaluation of shoulder instability.
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Magnetic resonance imaging (MRI) provided adequate depiction of carpal soft tissue structures in normal volunteers, as well as accurate anatomic correlation with cadaveric specimens. Using a high field strength system and surface coil techniques, the intricate anatomy of the wrist was best defined on long TR short TE images. However, from a practical view, T1 weighted images (TR 600 ms, TE 25 ms) were most useful because of short imaging times, satisfactory image quality, and the absence of motion artifacts. The coronal plane provided the clearest definition of important structures. Potential diagnostic limitations exist due to the inability of MRI to clearly delineate articular cartilage, joint capsules, and small interosseous ligaments. The presence of intra-articular fluid in both living subjects and cadaveric specimens, however, allowed for fine depiction of these structures on T2 weighted images.
Fluid-fluid levels have been described in association with aneurysmal bone cysts, telangiectatic osteosarcoma, and a chondroblastoma. We report two cases of giant cell tumors of bone with fluid-fluid levels identified by computed tomography and, in one case, by magnetic resonance imaging. This finding has not previously been associated with giant cell tumors. The radiographic features of the fluid-fluid levels cannot be distinguished from those reported in other osseous neoplasms.
The feasibility of creating plastic models of the spinal canal derived from computed tomography data was investigated in six patients with suspected spinal stenosis. The plastic models correlated well with the information provided on the axial scans and with documented stenosis of the central canal or neural foramina in four of the six patients.