Radiographic wear measurements in a cementless metal-backed modular cobalt-chromium acetabular component

Linear polyethylene wear was measured radiographically and correlated with direct measurements of wear from 21 of 24 liners retrieved at revision. An optical comparator was used to assess linear wear using the shadowgraph technique. Postoperative and prerevision radiographs were reviewed to measure the amount of linear wear radiographically. Seven radiographic methods described in the literature were used: 5 were manual techniques, and 2 techniques used a computer-assisted digitizer. Linear regression analysis showed that there was a statistically significant correlation between the radiographic measurements compared with the direct measurement for 4 of the 5 manual techniques but only 1 of the 2 computerized techniques. Based on these results, radiographic wear measurements of cementless, modular components should be considered qualitative rather than quantitative. There is a significant difference in the measurements obtained among various published techniques. The addition of computer digitization to enhance manual methodology does not improve accuracy.

Virtual reality computer animation of the effect of component position and design on stability after total hip arthroplasty

Virtual reality technology was utilized to assess the effect of component orientation and component design on the range of motion prior to impingement following total hip arthroplasty. Components were digitized, oriented in the pelvis, and computer animations were performed to assess the likelihood of dislocation with different combinations of component orientation.

The short-term economic implications of prosthetic selection in hemiarthroplasty of the hip

This retrospective study assessed the economic impact of prosthetic selection in the treatment of displaced intracapsular fractures. The records of 28 patients were divided into two groups: 16 patients who received an Austin-Moore, nonmodular device and 12 patients (6 men and 6 women; mean age, 77 years) who received a modular, bipolar device. The bipolar group had significantly greater mean operative times, total charges for the device, and total charges for supplies. Surgeons treating hip fractures should consider implant cost, functional outcome, and patient demands when selecting a prosthesis for hemiarthroplasty care.

Ice-cream truck-related injuries to children

Few studies exist on the cause and nature of injuries to children from ice-cream truck-related accidents. We reviewed the medical records of 11 children with orthopedic injuries treated at Children's Hospital-San Diego from 1985 to 1995 for injuries in such accidents. Of nine children on their way to or from an ice-cream truck who were struck by an oncoming vehicle, all were girls; eight had pelvic or lower-extremity fractures. When ice-cream trucks park on the street, they pose a danger to children, because children are drawn to them, and the trucks' large size blocks the vision of oncoming drivers.

Intramedullary plugs in cemented hip arthroplasty

The use of intramedullary plugs in cemented total joint arthroplasty is currently considered standard practice by most surgeons. In this in vitro study, the authors evaluated the holding power, migration, and leakage of four commonly used plug types--bone, acrylic bone cement, and two polymeric plugs from different manufacturers. Only acrylic bone cement plugs prevented distal leakage of cement and did not migrate under the influences of pressurized cement injection.

The effects of intramedullary implants on bone strains and remodeling in the femur

Bone remodeling and strain distribution in the femur was studied after implantation of LTI pyrolytic carbon, bioglass coated Co-Cr-Mo alloy, and carbon coated porous Co-Cr-Mo alloy intramedullary plugs. Mechanical testing and finite element analysis has shown that the intramedullary stems significantly alter the strain pattern in the femur. However, no statistically significant differences were observed among the implant groups. The analytical and experimental results were found to be in good agreement. Radiographically, differences were observed in the bone remodeling around the carbon implant compared to either of the Co-Cr-Mo based implants. Both internal and external bone remodeling takes place when an intramedullary implant is present.