Preliminary tribological evaluation of nanostructured diamond coatings against ultra-high molecular weight polyethylene.

Background: Some loss of joint prostheses has been attributed to osteolytic loosening associated with debris from wear of polyethylene articulating against metal alloys. Reduced polyethylene wear has been reported with ceramics serving as an alternative counterface.

Methods: Nanostructured Diamond (NSD) coatings were deposited onto Ti6Al4V by microwave plasma-assisted chemical vapor deposition, with both hydrogen-rich (H-NSD) and helium-rich (He-NSD) feedgas mixtures.

A biomechanical study of periacetabular defects and cement filling.

Periacetabular bone metastases cause severe pain and functional disability in cancer patients. Percutaneous acetabuloplasty (PCA) is a minimally invasive, image-guided procedure whereby cement is injected into lesion sites. Pain relief and functional restoration have been observed clinically; however, neither the biomechanical consequences of the lesions nor the effectiveness of the PCA technique are well understood.

Biomechanical response of the pubic symphysis in lateral pelvic impacts: a finite element study.

Automotive side impacts are a leading cause of injuries to the pubic symphysis, yet the mechanisms of those injuries have not been clearly established. Previous mechanical testing of isolated symphyses revealed increased joint laxity following drop tower lateral impacts to isolated pelvic bone structures, which suggested that the joints were damaged by excessive stresses and/or deformations during the impact tests. In the present study, a finite element (FE) model of a female pelvis including a previously validated symphysis sub-model was developed from computed tomography data.

Three-dimensional finite element models of the human pubic symphysis with viscohyperelastic soft tissues.

Three-dimensional finite element (FE) models of human pubic symphyses were constructed from computed tomography image data of one male and one female cadaver pelvis. The pubic bones, interpubic fibrocartilaginous disc and four pubic ligaments were segmented semi-automatically and meshed with hexahedral elements using automatic mesh generation schemes. A two-term viscoelastic Prony series, determined by curve fitting results of compressive creep experiments, was used to model the rate-dependent effects of the interpubic disc and the pubic ligaments.

Effects of trochanteric soft tissues and bone density on fracture of the female pelvis in experimental side impacts.

Pelvic fractures continue to be a source of morbidity and mortality for occupants in motor vehicle side impacts, especially among women. Previous studies have produced fracture tolerances for the female pelvis, yet the roles of soft tissues and bone quality remain unclear. Presently, we studied the influence of trochanteric soft tissue thickness (T) and total hip bone mineral density (BMD) on pelvic fracture of 10 female human pelves subject to lateral impact centered over the greater trochanter.

Contact pressures in the flexed hip joint during lateral trochanteric loading.

Acetabular fractures are an especially problematic outcome of motor vehicle side impacts. While fracture type has been correlated with impact direction and femoral orientation, actual contact pressures in the hip joint have not been quantified for lateral loading conditions. In the present study, we used pressure sensitive film to measure contact areas and pressures in seven hip joints from four cadavers under quasi-static lateral loading through the greater trochanter.