The functional morphology of the wrist pertains to a number of important questions in primate evolutionary biology, including that of hominins. Reconstructing locomotor and manipulative capabilities of the wrist in extinct species requires a detailed understanding of wrist biomechanics in extant primates and the relationship between carpal form and function. The kinematics of carpal movement, and the role individual joints play in providing mobility and stability of the wrist, is central to such efforts. However, there have been few detailed biomechanical studies of the nonhuman primate wrist. This is largely because of the complexity of wrist morphology and the considerable technical challenges involved in tracking the movements of the many small bones that compose the carpus. The purpose of this article is to introduce and outline a method adapted from human clinical studies of three-dimensional (3D) carpal kinematics for use in a comparative context. The method employs computed tomography of primate cadaver forelimbs in increments throughout the wrist's range of motion, coupled with markerless registration of 3D polygon models based on inertial properties of each bone. The 3D kinematic principles involved in extracting motion axis parameters that describe bone movement are reviewed. In addition, a set of anatomically based coordinate systems embedded in the radius, capitate, hamate, lunate, and scaphoid is presented for the benefit of other primate functional morphologists interested in studying carpal kinematics. Finally, a brief demonstration of how the application of these methods can elucidate the mechanics of the wrist in primates illustrates the closer-packing of carpals in chimpanzees than in orangutans, which may help to stabilize the midcarpus and produce a more rigid wrist beneficial for efficient hand
Langerhans cell histiocytosis is essentially a pediatric disorder with a large spectrum encompassing focal lytic osseous eosinophilic granuloma, chronic multifocal Hand-Schuller-Christian lesions, and fulminant disseminated Letterer-Siwe syndrome. However, adult involvement is not uncommon. The authors present a case of multifocal Langerhans cell histiocytosis in a 47-year-old woman. The PET/CT-depicted infiltrative features of soft tissue and osseous pelvic lesions with obstructive uropathy are unusual for this disease.
Although PET/CT imaging provides the most comprehensive evaluation of cancer, coexisting hypermetabolic benign processes may interfere with the staging of aggressive malignancy such as melanoma and extranodal non-Hodgkin lymphoma. Acute and subacute skeletal injuries have been reported as false-positive PET findings. The authors present additional mimickers of high metabolic malignancy with a case of stage III recurrent melanoma featuring F-18 FDG accumulation at partially torn medial plantar fascia and tibiocalcaneal ligament of the left foot.
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