Best Practices: Best Imaging Modality for Surveillance of Metal-on-Metal Hip Arthroplasty.

OBJECTIVE. Metal-on-metal hip arthroplasty has been shown to result in soft-tissue complications in some patients, making revision surgery necessary. Imaging is critical in the detection and surveillance of soft-tissue complications, which are collectively termed adverse reaction to metal debris (ARMD) and adverse local tissue reaction. Studies have investigated the use of ultrasound, MRI, and CT for detecting ARMD, and each modality has advantages and disadvantages. This article provides evidence-based recommendations for imaging surveillance of ARMD. CONCLUSION. Compared with ultrasound, MRI has been found to be a better imaging modality for surveillance of ARMD. In addition, MRI is not operator dependent, allows visualization of soft-tissue details, and allows more consistent measurement of fluid collections on follow-up examinations. Limitations of ultrasound include operator skill, the inability to visualize osseous structures, and the challenge of visualizing posterior soft tissues for synovitis and fluid collections in larger patients. Finally, CT is only useful for focused evaluation of osteolysis or periprosthetic fracture.

Radiologic Guide to Surgical Treatment of Kienbock's Disease.

Kienbock's disease, or avascular necrosis of the lunate, is a progressive disease ultimately resulting in end-stage arthrosis of the wrist. Various surgical treatments are available for different Lichtman stages of disease. We review the surgical options and indications, expected radiologic post-operative appearance, as well as detail potential surgical complications, as they relate to Kienbock's disease.

Total elbow arthroplasty: a radiographic outcome study.

OBJECTIVES: Total elbow arthroplasty (TEA) is becoming a popular alternative to arthrodesis for patients with end-stage elbow arthrosis and comminuted distal humeral fractures. Prior outcome studies have primarily focused on surgical findings. Our purpose is to determine the radiographic outcome of TEA and to correlate with clinical symptoms such as pain. MATERIALS AND METHODS: This is an IRB-approved retrospective review from 2005 to 2015 of all patients with semiconstrained TEA. All available elbow radiographs and clinical data were reviewed. Data analysis included descriptive statistics and Kaplan-Meier survival curves for radiographic and clinical survival. RESULTS: A total of 104 total elbow arthroplasties in 102 patients were reviewed; 75 % were in women and the mean patient age was 63.1 years. Mean radiographic follow-up was 826 days with average of four radiographs per patient. Seventy TEAs (67 %) developed radiographic complications, including heterotopic ossification (48 %), perihardware lucency (27 %), periprosthetic fracture (23 %), hardware subluxation/dislocation (7 %), polyethylene wear (3 %), and hardware fracture/dislodgement (3 %); 56 patients (55 %) developed symptoms of elbow pain or instability and 30 patients (30 %) underwent at least one reoperation. In patients with radiographic complications, 66 % developed elbow pain, compared to 19 % of patients with no radiologic complications (p = 0.001). Of the patients with radiographic complications, 39 % had at least one additional surgery compared to 0 % of patients without radiographic complications (p = 0.056). CONCLUSIONS: Radiographic complications are common in patients after total elbow arthroplasty. There is a strong positive association between post-operative radiographic findings and clinical outcome. Knowledge of common postoperative radiographic findings is important for the practicing radiologist.

Imaging findings of adiposis dolorosa vs. massive localized lymphedema.

PURPOSE: Adiposis dolorosa (Dercum's disease) is a condition of benign, painful subcutaneous lipomatous lesions associated with weakness, endocrine and lipid abnormalities, and mental disturbances. There is little information documenting the cross-sectional imaging findings that differentiate it from lipomatous and neoplastic soft tissue masses, or massive localized lymphedema. The purpose of this study was to provide a radiological case series of adiposis dolorosa. METHODS: A 10-year retrospective review of the picture archiving and communications system was performed. Two musculoskeletal radiologists reviewed images to confirm and document imaging features, location, size, and patient demographics. Medical records were reviewed to characterize patients into three groups: one group met at least three of the four criteria of Dercum's syndrome, the second group met less than three criteria, and the third group had clinical diagnosis of cellulitis of the lower extremity. RESULTS: Seventeen cases (25 masses) of adiposis dolorosa were found, nine cases of which met at least three criteria of Dercum's syndrome. All cases in the first two groups demonstrated skin thickening and lymphedema of subcutaneous fat, which was fluid attenuation on CT and low or intermediate T1-weighted and high STIR/T2-weighted MR signal. Two cases with pathology showed mild fatty infiltration with fibrous septa, and the third case showed massive localized lymphedema. The third group of ten cellulitis patients demonstrated non-mass-like subcutaneous edema with similar CT attenuation and MR signal characteristics to the first two groups, but differed by the presence of post-contrast enhancement and non-mass-like appearance in 90%. CONCLUSION: Imaging findings of adiposis dolorosa and massive localized lymphedema overlap, as do the symptoms and pathological features. Due to the mass-like engorgement of the soft tissues and pain, patients will often undergo imaging to exclude neoplasm or infection. Knowledge of these conditions and the characteristic imaging findings is important to prevent unnecessary biopsy and misdiagnosis.

Unlocking the jaw: advanced imaging of the temporomandibular joint.

OBJECTIVE: Temporomandibular joint (TMJ) dysfunction is a common condition, affecting up to 28% of the population. The TMJ can be affected by abnormal dynamics of the disk-condyle complex, degenerative arthritis, inflammatory arthritis, and crystal arthropathy. Less commonly, neoplasms and abnormal morphologic features of the condyle are causes of TMJ symptoms. Cross-sectional imaging is frequently used for diagnosis. CONCLUSION: Knowledge of the normal imaging appearance of the TMJ, its appearance on radiological examination, and interventional techniques are useful for providing a meaningful radiologic contribution. This article will review normal TMJ anatomy; describe the normal ultrasound, CT, and MRI appearances of TMJ; provide imaging examples of abnormal TMJs; and illustrate imaging-guided therapeutic TMJ injection.

Imaging of current spinal hardware: lumbar spine.

OBJECTIVE: The purposes of this article are to review the indications for and the materials and designs of hardware more commonly used in the lumbar spine; to discuss alternatives for each of the types of hardware; to review normal postoperative imaging findings; to describe the appropriateness of different imaging modalities for postoperative evaluation; and to show examples of hardware complications. CONCLUSION: Stabilization and fusion of the lumbar spine with intervertebral disk replacement, artificial ligaments, spinous process distraction devices, plate-and-rod systems, dynamic posterior fusion devices, and newer types of material incorporation are increasingly more common in contemporary surgical practice. These spinal hardware devices will be seen more often in radiology practice. Successful postoperative radiologic evaluation of this spinal hardware necessitates an understanding of fundamental hardware design, physiologic objectives, normal postoperative imaging appearances, and unique complications. Radiologists may have little training and experience with the new and modified types of hardware used in the lumbar spine.

Soft-tissue myxomatous lesions: review of salient imaging features with pathologic comparison.

Myxoid soft-tissue lesions are a heterogeneous group of benign and malignant mesenchymal tumors with an abundance of extracellular mucoid material. These lesions may mimic cysts on radiologic evaluation because of the high water content, and histopathologic features also overlap. Benign myxoid lesions include intramuscular myxoma, synovial cyst, bursa, ganglion, and benign peripheral nerve sheath tumor, including neurofibroma and schwannoma. Malignant entities include myxoid liposarcoma, myxoid leiomyosarcoma, myxoid chondrosarcoma, ossifying fibromyxoid tumor, and myxofibrosarcoma. Some syndromes are associated with myxoid soft-tissue lesions, such as Mazabraud syndrome in patients with soft-tissue myxomas and fibrous dysplasia. Certain discriminating features, such as intralesional fat in a myxoid liposarcoma, perilesional edema and a rim of fat in soft-tissue myxoma, and the swirled T2-weighted signal intensity and enhancement pattern of aggressive angiomyxoma, assist the radiologist in differentiating these lesions. The presence of an internal chondroid matrix or incomplete peripheral ossification may suggest myxoid chondrosarcoma or ossifying fibromyxoid tumor, respectively. The entering-and-exiting-nerve sign is suggestive of a peripheral nerve sheath tumor. Communication with a joint or tendon sheath and peripheral enhancement may indicate a ganglion or synovial cyst. This article (a) reviews the magnetic resonance, computed tomographic, and ultrasonographic imaging characteristics of soft-tissue myxomatous lesions, emphasizing imaging findings that can help differentiate benign and malignant lesions; (b) presents differential diagnoses; and (c) provides pathologic correlation.