Biomedical subjects
Publications and source records attributed to A A DeSmet.
Prior to 1972, polymethylmethacrylate, or PMMA, did not contain barium sulfate and was, therefore, radiolucent. We describe a technique using magnetic resonance imaging that is very useful in imaging barium-free PMMA.
OBJECTIVE: To determine how the appearance of fracture line bridging and graft incorporation changed on sequential plain films obtained during the healing of successful grafts for scaphoid nonunion. DESIGN: We identified 50 patients who had healed Russe bone grafts for nonunited scaphoid fractures. These patients had 214 sets of wrist radiographs obtained 1-36 months after surgery. Each set of radiographs was reviewed in random order by two observers who were blinded as to the patient's name and the time interval since surgery. Closure of the fracture line and the presence of a linear lucency in each of six zones surrounding the graft were assessed using a three-point grading scale. PATIENTS: Forty-six men and four women were included in the study. Their mean age was 30 years with a range from 21-43 years. RESULTS AND CONCLUSIONS: With increasing time after surgery, there was progressive fracture line closing and disappearance of linear lucencies at the interfaces between the scaphoid and the graft. However, a 20% of the patients had a well-defined lucency in at least one of the six zones around the graft on their last film. Even 1 year after surgery, the fracture line showed no bridging on the radial side in 22% of patients and on the ulnar side in 11%. We conclude that after grafting, most scaphoid nonunions show progressive fracture line closure and graft incorporation. However, the fracture line may not completely close and lucencies may persist in several zones around the graft for more than 1 year. These radiographic appearances should be recognized as part of the normal spectrum of healing.
Most magnetic resonance (MR) studies evaluating the rotator cuff for tears have used T2-weighted imaging in the coronal oblique and sagittal oblique planes. T2*-weighted gradient echo imaging, however, has advantages over spin echo imaging, including contiguous slices without cross-talk, high contrast around the cuff, and intrinsically shorter imaging times which can be used to increase the number of signals averaged and thus improve the signal-to-noise ratio. We reviewed the shoulder MR scans of 87 consecutive patients who underwent both a MR scan and a shoulder arthroscopy during which the size of tears, if present, was graded. The reviewers were blinded as to the history and arthroscopic results. The MR scans included oblique coronal T2*-weighted gradient echo and oblique sagittal T2-weighted spin echo images. MR cuff grades were correlated with arthroscopic findings. For complete tears, the sensitivity of MR was 0.91 and the specificity 0.95. For partial tears, the sensitivity was 0.74 and the specificity 0.87. This accuracy is similar to two-plane T2-weighted imaging as previously reported in the literature. There was a statistically significant correlation (p < 0.0005) between the cuff grade as determined by MR and the arthroscopic findings.
This article discusses three selected areas of sports medicine in which MRI is useful. The first is muscle injuries and includes the MRI findings in muscle tears, contusions, and myositis ossificans. The second section discusses the usefulness of MRI in imaging the athlete with groin pain, which is a difficult clinical problem for the orthopedist. The ability of MRI to differentiate between such causes of groin pain as osteitis pubis, bursitis, and stress fractures is shown. The final section covers plain radiographic and MRI findings in osteochondritis dissecans. Also discussed is the MRI staging of osteochondritis dissecans, which is important in treatment decisions and surgical planning.
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We studied bone mineral density (BMD) of the spine using dual photon absorptiometry, as well as standard anterior-posterior and lateral lumbar spine X-ray film in 113 ambulatory elderly male volunteers with a mean age of 72 years (range 66-91 years). Each subject had three measurements taken for lumbar vertebrae 1 through 4: BMD, length of aortic calcification (AC), and degenerative facet sclerosis graded 0-3. A separate statistical model was fit to BMD for each vertebra using analysis of covariance. AC did not contribute significantly to BMD. BMD was increased by 0.28-0.03 g/cm2 (L1-L4) with a sclerosis score of 2, and by 0.47-0.25 g/cm2 with a sclerosis score of 3, P less than 0.001. The association between increased BMD and overlying facet sclerosis may be related to the bone density within the sclerosis itself or to an association between degenerative joint disease and a generalized increase in subchondral bone.
Previous radiographic studies have suggested a positive relationship between two degenerative processes associated with aging: calcification of the abdominal aorta and osteoporosis. Such a relationship has not been studied using modern quantitative densitometry. Aortic calcification was quantified on spinal radiographs from 112 elderly men. Bone mineral density was determined at six scanning sites using photon densitometry. There was no significant correlation between aortic calcification and bone mineral density at any of the scanning sites when the effect of age was held constant in the statistical analysis.
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Little information is available on the prevalence of vertebral wedge deformities in elderly males; therefore, 116 ambulatory male volunteers age 65 and over were studied with lumbar and thoracic radiographs. Each patient was questioned concerning a history of high-energy spinal trauma. Those having 25% or greater anterior vertebral wedging were identified. Eleven percent of the males had at least one 25% atraumatic wedge deformity, and 2% had two or more such vertebra. These results are discussed in relation to the few published studies on this topic.
The advantages and limitations of magnification techniques are presented. Optical and geometrical techniques each have their proponents. The geometrical technique has proven valuable in the assessment of trauma, metabolic bone disease, arthritis, osteomyelitis, and neoplasm. It often shows pathology inapparent on conventional radiographs.
The purpose of this paper is to introduce new methodology for the evaluation of diagnostic imaging systems based on the assessment of diagnostic features by human observers. This methodology is intended to supplement the usual receiver operating characteristic (ROC) curve approach to imaging system evaluation. The approach is based on measuring the experimental evidence of a priori scientific propositions. The methodology requires simple calculations that can be implemented by clinical investigators. An example, based on diagnosis of sacroiliitis, is given to illustrate the method's usefulness in a diagnostic situation.
The scoliotic angles of 128 curves in seventy-eight patients were measured on paired anteroposterior and posteroanterior upright radiographs that had been made on the same day. The association between the difference in the measured angles and the various clinical and curve parameters was examined. The angles on the anteroposterior and posteroanterior radiographs were highly correlated (r = 0.96). The angles on the posteroanterior radiographs were larger than those on the anteroposterior radiographs by a mean of 2.4 degrees for the thoracic curves and 1.7 degrees for the lumbar curves. Only the thoracolumbar scoliotic angles measured essentially the same on the two radiographic projections. The magnitude of the difference between the two measured angles was not correlated with the age of the patient, the direction of the curve, the magnitude of the curve, or the degree of deformity in the sagittal plane.
This paper discusses some of the problems encountered in the diagnosis and treatment of 371 ankle fractures treated at the University of Kansas Medical Center over a 14-year period, 1965-1979. Seven of these injuries required major reconstructive procedures after failure of initial treatment and 11 fractures required eventual ankle arthrodesis. The causes of failures of the initial treatment of these 18 cases are discussed. The extent of involvement of the articular surface of the tibia as seen on the original post-injury roentgenogram correlated closely with the extent of subsequent ankle arthrosis. The second most important prognostic feature was recognition or failure to recognize rupture of the distal tibio-fibular syndesmosis, its reduction, and maintenance of reduction until complete healing had occurred. The importance of stabilization of the fibula, maintaining its anatomic length, is emphasized. Closed reductions were as successful as open reductions and internal fixation only when reduction was accurate and maintained until healing was complete. Extensive injuries, particularly the Dupuytren and pilon fractures, are best treated by open reduction and internal fixation. The surgical techniques are demanding and technical errors must be avoided if optimal results are to be achieved.
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We describe a family in which many persons have generalized joint laxity frequently complicated by dislocation of major joints. The condition is an autosomal dominant trait, with high penetrance. The disorder observed in this family and in others from the literature appears to be a specific syndrome that can be distinguished from other familial forms of joint laxity such as simple familial joint laxity and the Ehlers-Danlos syndromes. It has been designated the familial joint instability syndrome.
A prospective study tested the hypothesis of Bell and Loop (1971) that 21 high yield findings are significantly associated with the presence of a skull fracture and can be used to decide which patients need skull radiography. In our study, 17 fractures were detected in 594 patients who had skull radiography because of trauma to the head. Six of these fractures occurred in children who had none of the 21 Bell and Loop high yield findings. These six patients were asymptomatic except for superficial injury at the site of trauma. Had the Bell and Loop criteria been used to decide which patients had skull radiography, 35% (all in children) of the fractures would have gone undetected. Thus, in our study population, the Bell and Loop high yield findings were not satisfactory criteria for the decision about obtaining skull films in children.
An endodermal sinus tumor presenting as a lobulated anterior mediastinal mass in a 20-year-old white man is reported. The clinical implications, histology, and origin of this rare germ cell tumor are discussed. The invasive nature of this highly malignant neoplasm prevented complete surgical resection.
Serial radiographs of 101 total hip arthroplasties were reviewed to evaluate the clinical significance of lucent zones at the femoral metal-cement interface. Such lucent zones were identified in 19 hip prostheses, but only in four was there clinical evidence of infection loosening of the prosthesis. The remaining 14 patients (15 prostheses) were followed for periods ranging from 18 months to 5 years; none had complications despite the development of these lucent zones. Microdensitometry confirmed the existence of a true lucent zone in most cases, but in several the apparent lucency was due to the Mach effect. While progressive widening of the lucent zone or a lucency measuring greater than 2 mm in width should prompt careful clinical evaluation for evidence of infection or loosening, our data indicate that such complications need not necessarily be present.