[Simultaneous pseudodynamic MR evaluation of bilateral temporomandibular joints]

Coordination of bilateral temporomandibular joints (TMJs) was evaluated using bilateral simultaneous pseudodynamic magnetic resonance (MR) imaging. Seven patients (6 patients with internal derangement and one with osteoarthritis) were examined by multiplanar gradient echo technique in closed-loop cine fashion on both sagittal and coronal planes. Incoordination of bilateral TMJ motion was observed in 2 of 7 patients. This technique might be suitable for evaluation of TMJ disorders.

Ewing's sarcoma. Radiographic pattern of healing and bony complications in patients with long-term survival

The radiographic appearance of Ewing's sarcoma was studied retrospectively in 22 patients who survived 5 years or longer after diagnosis and treatment. Expected changes from treatment, including regression of the extraosseous soft tissue mass, periostitis, and reconstitution of the cortex, occurred in all patients. Local recurrence occurred in one patient 10 years after complete remission whereas secondary osteosarcoma occurred more than 5 years after complete remission in two other cases. Both recurrent and secondary tumors presented as new lytic foci at the site of the original primary lesion. Lytic changes from radiation (radiation osteitis) may develop more than 2 years after treatment and in this sample; such findings were widely distributed in the radiation port. The authors conclude that bone remodeling and postradiation changes occur slowly over 2 years after treatment, and that any localized lysis at the primary site is suspicious for recurrence or secondary neoplasm. Knowledge of the expected changes and patterns of local recurrence and secondary neoplasms helps one to detect any significant change in its early phase.

[MRI and arthrography in the evaluation of TMJ disorders]

Arthrosis of the temporomandibular joint (TMJ) is a noninfectious, noninflammatory condition characterized by joint pain, noise (clicking) and abnormal motion. It contains various disease processes, such as abnormalities in the menisci or masticating muscles, subluxation of the condyle and degenerative joint disease. Analysis of the morphology and dynamics of TMJ by means of imaging modalities has become highly advanced since the development of arthrography in the late 1970s. Magnetic resonance imaging (MRI) has become the modality of choice in the evaluation of TMJ owing to the development of surface coils. We retrospectively studied MRI and inferior joint compartment arthrography in the evaluation of TMJ disorders. Nineteen joints of 14 patients included 15 with internal derangement, two with osteoarthrosis and two normal joints. Sagittal MR images were routinely obtained in a resting position and in positions with the mouth half open, and also with the mouth fully open on balanced images. Although perforation of the menisci was difficult to evaluate, MRI and arthrography were equally useful in identifying the shape and position of the meniscus. However, MRI was more reliable in depicting TMJ abnormalities than arthrography. MR is considered to be the modality of choice in screening arthrosis of TMJ, making the definitive diagnosis of internal derangement and monitoring conservative therapy for arthrosis.

Malignancy supervening on an intramedullary nail

A primary, malignant, fibrous histiocytoma of bone occurring in association with a Hansen Street intramedullary nail occurred in a 39-year-old man. The physical and chemical characteristics of materials, in relation to the generation of secondary neoplasia are reviewed, but the problem of coincidence is difficult to exclude.

Case report 675: Lipoblastoma of knee

Lipoblastoma in the prepatellar region was observed in a 7-month-old girl. The diffuse (lipoblastomatosis) and circumscribed forms have different radiological appearances. Lobular proliferation of fatty tissue with fibrous septae is characteristic of the circumscribed form.

MRI of myositis ossificans circumscripta

Myositis ossificans circumscripta (or pseudomalignant osseous tumor of soft tissue) may be confused with malignant neoplasms if there is no clear history of trauma. Two cases are presented in which magnetic resonance imaging (MRI) clearly demonstrates disproportionally extensive abnormal signal intensity along the course of muscle fibers. Although the specificity of this finding is uncertain, MRI enhances the level of confidence in diagnosing myositis ossificans.

[Ewing sarcoma: changes after radiation and chemotherapy]

We retrospectively studied 52 cases of Ewing sarcoma to elucidate the pattern of healing and/or recurrence after radiation and chemotherapy. Persistent soft tissue mass was a sign of failure to respond to therapy. Repair or healing of lytic or blastic bone changes were slow and often minimal, and usually bone changes became gradually stable over 3 years. After bone changes became stable, localized new bone changes represented recurrence or secondary malignant neoplasms.

[Insufficiency fracture of the sacrum]

Three cases of insufficiency fracture of the sacrum are reported. Cortical disruption and linear sclerosis with or without linear fracture line at the upper sacral segment parallel to the sacroiliac joint are characteristic. Bone scintigram is suitable for screening, but plain radiographic and CT findings are diagnostic. Insufficiency fracture of the sacrum should not be confused with other conditions, such as metastatic disease.

Case report 619. Intraosseous lipoma of the sacrum

A case of intraosseous lipoma of the sacrum with dystrophic calcification and cystic degeneration is presented. The differential diagnosis of fat-containing bone tumors is considered.

Target pedicle of T-12: radiologic-anatomic correlation

The authors prospectively studied 250 consecutive thoracic and lumbar spinal radiographic examinations and 56 dried skeletons to elucidate the peculiar target appearance in the pedicle of T-12 and occasionally T-11. Target pedicles were seen in 13 of the spines (23%) and in 85 of the 250 radiographic examinations (34%). Similar target pedicles were observed at T-11 in two radiographic examinations and in one spine. Anatomic correlation revealed that the inferior and lateral tubercles contribute to the ring shadow within the pedicle.

Porous-coated anatomic total hip prostheses: radiographic analysis and clinical correlation

The radiographic changes of 46 bone-ingrowth, porous-coated anatomic total hip prostheses were reviewed and compared to the clinical outcome. The average postoperative follow-up was 32 months. The radiographic features that were assessed included subsidence; periprosthetic lucencies; periosteal, endosteal, and heterotopic new bone; loose beads; implant position; and tightness of fit. Clinical results were based on the Harris hip score. All acetabular components fared well. Three of the femoral stem components needed revision. The radiographic finding that correlated best with outcome was subsidence of more than 10 mm, especially if it continued to increase more than 1 year after surgery. Other findings related to failure were loosely placed femoral stems and the presence of loose beads. However, subsidence was such a powerful predictor of clinical outcome, and the other features were so weak, that combinations of variables did not improve the assessment of outcome. Close attention should be paid to subsidence in follow-up studies.

Sacral cysts with exophytic components. A report of two cases

Sacral cysts are rare lesions. Two cases are presented, an aneurysmal bone cyst and a simple cyst. Simple cysts have not previously been described in the sacrum. Both cysts were asymptomatic, had similar radiographic appearances, and displayed significant exophytic components.

[Arthrography of temporomandibular joint; a practical approach]

A practical approach to the arthrography of the temporomandibular joint is presented. More than 80 cases have been performed in one year in our institution with the failure rate of less than 10% and very low complication rate. Advantages and disadvantages of arthrography compared to MR are discussed.

Hemophiliac pseudotumor of the sacrum

Although the pelvis is a common site for hemophiliac pseudotumors, involvement of the axial skeleton, such as the spine and sacrum, is rare. A rare case of hemophiliac pseudotumor arising from a healed fracture of the sacrum is reported. Findings of plain radiographs, CT, and radionuclide bone scan may simulate tumors of neural origin, but the heterogeneity of MRI is suggestive of hemophiliac pseudotumor.

Giant bone island. Computed tomography findings

Although bone island is a well-known benign skeletal entity, it may stimulate an aggressive bone forming neoplasm when it is large. Spiculated margin intermingling with thickened trabeculae together with the lack of bone destruction and soft tissue mass on computed tomography scan is diagnostic.

Pyogenic vertebral osteomyelitis of the posterior elements

Three cases of pyogenic vertebral osteomyelitis involving only the posterior elements are presented. This unusual location creates difficulty in distinguishing vertebral osteomyelitis from neoplasms and arthridites. All three patients had involvement of the articular facet, a helpful indication against neoplasms. However, vertebral osteomyelitis should be differentiated from erosive arthridites.

Aggressive posttraumatic osteoporosis of the humerus simulating a malignant neoplasm

Eleven patients with an unusual, moth-eaten, destructive lesion in the humerus simulating a malignant neoplasm are presented. The radiographic changes developed over an extended period after trauma. This pattern of posttraumatic osteoporosis can easily be mistaken for a malignancy. An awareness of the entity helps one to make the correct diagnosis. Also, certain helpful hints are pointed out.

Scaphotrapezial dislocation: a case report

Traumatic dislocation of either trapezium or trapezoid is rare. We found less than 20 cases of each reported in the literature. We describe a case of traumatic dislocation of the scaphotrapezial joint associated with subluxation of the scaphotrapezoidal joint, which to our knowledge has not been reported.

Bilateral stress fracture of the navicular in a non-athlete

Stress fracture of the navicular is usually seen in physically active individuals. A case of bilateral involvement in a non-athlete with multiple medical problems is reported. Diagnosis is often delayed because routine radiographs are usually normal at the onset of symptoms.