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Biomedical subjects

W A Curtin

Publications and source records attributed to W A Curtin.

8 recordsLinked to original sources
PubMed2002

Coupled atomistic and discrete dislocation plasticity.

A computational method for multiscale modeling of plasticity is presented wherein each dislocation is treated as either an atomistic or continuum entity within a single computational framework. The method divides space into atomistic and continuum regions that communicate across a coherent boundary, detects dislocations as they approach the boundary, and seamlessly converts them from one description to another. The method permits the study of problems that are too large for fully atomistic simulation while preserving accurate atomistic details where necessary, but is currently limited to a 2D implementation. A validation test is performed by comparing the method against full atomistic simulations for a 2D nanoindentation problem.

Journal Article↗
PubMed2001

Traumatic posterior dislocation of hip in children.

Traumatic posterior dislocation of the hip joint in children is an uncommon injury. It constitutes a true orthopedic emergency. It makes up over 80% of pediatric hip dislocations. In children, it can occur as a result of minimal trauma, which is attributed to a soft pliable acetabulum and ligamentous laxity. In skeletally mature adolescents, a greater force is required to dislocate the hip joint. Delay in reduction is associated with long-term complications such as avascular necrosis and degenerative arthritis. Avascular necrosis is related to the duration of dislocation. A poorer prognosis is associated with delay in reduction beyond 6 hours, advanced skeletal maturity, or multiple traumas. Prompt reduction minimizes complications. We report two cases of traumatic posterior dislocation of hip in children aged 3 and 14 years. Both were reduced within 6 hours of dislocation, and review at 6 months revealed normal examination and no evidence of any post-traumatic changes. Post-reduction treatment remains without a consensus. This review highlights the clinical presentation, management, and time-sensitive complications of the injury.

Adolescent↗
PubMed1999

Reduction of hemorrhage after knee arthroplasty using cryo-based fibrin sealant.

The spray application of cryo-based fibrin sealant was evaluated for reducing hemorrhage in a complex, anticoagulated canine model of knee joint arthroplasty. Nine heparinized dogs underwent bilateral knee arthroplasty under tourniquet control with each animal having 3 mL of fibrin sealant sprayed onto one joint and the other joint serving as control. The fibrin sealant significantly reduced total and incremental bleeding as compared to the control side (P < .05). In addition, the hemostatic effectiveness of the fibrin sealant increased as bleeding propensity increased (P < .05). This study suggests that fibrin sealant may reduce bleeding from orthopedic joint replacement in human patients undergoing routine operations as well as those receiving forms of anticoagulation to reduce the incidence of deep venous thrombosis and pulmonary embolus.

Animals↗
PubMed1995

Ultrastructural observations on fibril profiles in normal and degenerative human articular cartilage.

Ultrastructural changes in collagen fibril morphology in human osteoarthritis have not been critically analyzed. In this study, fibril profiles in healthy and fibrillated articular cartilage samples obtained from specimens resected during prosthetic arthroplasty were examined by transmission electron microscopy. Collagen fibrils were deposited parallel to the articular surface in the tangential zone, but were aligned radially to the surface in the deeper layers. In the 3 zones studied, fibril volume density was similar despite interzonal variation in mean fibril diameter values. The pattern of collagen deposition in degenerative samples correlated to some extent with the severity of surface fibrillation seen by light microscopy. Samples in which fibrillation was confined to the superficial zone contained fibril profiles similar in size and orientation to those seen in control samples. Where fibrillation extended to the deeper zones, volume density and mean fibril diameter values decreased accordingly. The data suggest that fibril profile differences may reflect variations in matrix proteoglycan levels between normal and degenerative samples.

Cartilage, Articular↗
PubMed1993

Pancreatitis after alar-transverse fusion for spondylolisthesis. A case report.

Acute pancreatitis complicated the postoperative care of a 16-year-old girl treated by alar-transverse fusion for spondylolisthesis. Pancreatitis was diagnosed by a marked increase in plasma amylase in conjunction with abdominal ultrasonography. Symptoms resolved with conservative treatment. Pancreatitis should be suspected when unusual abdominal symptoms persist after spinal surgery.

Acute Disease↗
PubMed1992

Quantitative and morphological observations on the ultrastructure of articular tissue generated from free periosteal grafts.

This study investigates the ultrastructure of articular tissue generated on osteochondral defects in skeletally immature rabbits from free reversed periosteal allografts after 50 and 100 days of post-operative intermittent active motion. Tissue samples prepared for transmission electron microscopy were compared with normal cartilage and periosteum in terms of cell morphology and the pattern of intercellular collagen deposition. Well-differentiated tissue demonstrated many ultrastructural features of normal articular cartilage while poorly differentiated samples contained cells and intercellular collagen profiles which were somewhat similar to those observed in periosteum.

Animals↗