Magnetic resonance (MR) images and computed tomographic (CT) scans of histologically characterized soft-tissue masses of the locomotor system in 35 patients were compared for image contrast, demonstration of bone destruction, and display of extent and anatomic relationships of the masses. Subjective criteria for predicting malignancy were tested. T1 measurements were made in a few cases. Intensities of masses relative to those of fat and muscle in spin-echo T1-weighted and highly T2-weighted images were evaluated for correlation with tissue type. Subjective value of using coronal and sagittal images was assessed. Because of its superior inherent image contrast and its ability to provide direct sagittal and coronal images, MR was better than CT in demonstrating size and extent of most tumors and their relationships to vascular and nonvascular structures. However, bone destruction was more difficult to see with MR. Except for fatty tumors, MR was not helpful in identifying tissue type. Subjective criteria were of limited value in distinguishing benign from malignant lesions. Moreover, there is currently no credible evidence that T1 or T2 measurements are helpful in this regard. Study results suggest that MR is superior to CT in evaluating soft-tissue masses of the locomotor system. If an MR examination is performed, CT may not be necessary in certain cases unless bone involvement is suspected.

The authors discuss and illustrate the various complications of total joint prostheses. Criteria for the evaluation of radiographs of total joint prostheses are presented.

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Twenty-three patients with a benign bone lesion grafted with calcium sulfate, with and without demineralized bone matrix, were reviewed. At a minimum of 1 year postoperatively, 21 patients had achieved between 76% and 100% bone repair based on anteroposterior and lateral radiographs. Overall, the mean Enneklng Functional Evaluation System score was 98%. Calcium sulfate is a well-tolerated, biodegradable, osteoconductive bone graft substitute. It is a reasonable alternative to autogenous bone graft for benign bone lesions.

A 7-year study of a patient with tumor (hemangiopericytoma)-induced hypophosphatemic osteomalacia (TIO) is presented, and the findings are in keeping with the depressed tubular reabsorption of phosphate and low 1,25(OH)2 vitamin D levels seen in other studies. Despite normalization of 1,25(OH)2 vitamin D levels with pharmacologic doses of vitamin D2, there was no discernible effect on serum phosphorus levels. Also, despite hypercalcemia induced by pharmacologic doses of vitamin D2, serum parathyroid hormone levels were persistently elevated, and gradually returned to subnormal levels after removal of the tumor. Following removal of the tumor, there was a rapid increase of the 1,25(OH)2 vitamin D levels to supraphysiologic levels, prompt appropriate increase in tubular reabsorption of phosphate levels, and symptomatic improvement in the osteomalacia. Speculations on the physiologic and pathophysiologic role of the putative hormone(s) produced by the tumors associated with this syndrome are presented.