Biomedical subjects

D Budney

Publications and source records attributed to D Budney.

5 recordsLinked to original sources

PubMed1995

A transpedicularly implanted anterior spinal support.

This article describes a device that has been developed to augment posterior spinal fracture fixation by providing support for the anterior column of the spine. The device is contracted for insertion through the limited opening provided by the transpedicular approach to the vertebral body. Once in situ it is configured to support physiological loads. In this way the structural limitations of posterior instrumentation and the surgical difficulties of anterior spinal fixation instrumentation are overcome. A preliminary investigation of the new device together with in vitro studies of a prototype are described in this report. In vitro tests to determine the expansion characteristics and structural performance of the device were performed together with tests to determine the efficacy of the support to reduce loading on the posterior fixation device. It is shown that the device has the necessary expansion characteristics and can support physiological loads without failure. Tests using porcine vertebral columns with a simulated vertebral fracture showed a significant reduction in load carried by the posterior fixation plates (44 +/- 16%) when the anterior support was included in the construct. In addition, the difference in loading between the left and right plates was significantly reduced (81 +/- 12%).

Bone Cements↗

PubMed1992

A reproducible porcine vertebral fracture for biomechanical testing of spinal fixation devices.

To evaluate vertebral fracture fixation devices in the laboratory, it is necessary to produce identical and unstable fractures either in anatomic specimen or animal models. Consistent achievement of this goal has not been reported in the literature. This report presents a technique for the study of reproducibility for a particular vertebral fracture model. A precise anterior defect was created in a vertebra of each specimen drawn from a homogeneous population of mature sow spines. The spines were loaded to failure. Fracture reproducibility was shown by measurement of load and displacement, and confirmed by roentgenographic evaluation. The technique is easily applied to human specimens. Because there is a plethora of fracture fixation devices based on hooks, wires, or, more recently, plates and pedicle screws, the reliability of comparative testing of these devices in the laboratory requires an appropriate and reproducible fracture.

Animals↗

PubMed1990

Vertebral end-plate failure in porcine and bovine models of spinal fracture instrumentation.

The use of mature porcine and immature bovine spines as models for the assessment of spinal fracture instrumentation is commonplace. By comparing the load-displacement characteristics of these spine segments and observing the fracture type, this study investigated the tendency of immature bovine spines to fail prematurely at the vertebral physis, disrupting biomechanical evaluation of spinal fracture fixation devices. Load to failure of the spines was determined using the Instron Universal Testing Machine and a specially designed endcap. In axial compression, the 10-16-week-old calf spines failed at 12,845 +/- 1,466 N, compared with mature pig spines at 17,300 +/- 5,170 N (p less than 0.05). Axial compression with flexion caused consistent failure through an end-plate in both species: 995 +/- 156 N for the calf spines and 2,025 +/- 575 N for the porcine spines (p less than 0.005). It was concluded that the tendency for immature bovine spines to fail more readily at the cartilaginous end-plate makes the calf spine a less desirable model.

Aging↗

PubMed1990

End-cap for the biomechanical testing of spinal segments.

Precise mechanical loading is essential in the in vitro evaluation of spinal fixation instrumentation, but the control of experimental variables is difficult because of variations in specimen morphology, size and end conditions, and gross specimen flexibility. This paper describes an end-cap which is simple in design, time efficient in its attachment to the spine and which provides precise positioning and rigid control of the end fixation points, resulting in excellent experimental control. It is easily adapted to human or animal specimens and provides a reliable load application unit, which permits specific physiological end conditions to be applied.

Animals↗

PubMed1990

A transducer for measuring motion within a vertebra.

Accurate in vitro evaluation of the efficacy of spinal instrumentation devices requires specialized equipment. A displacement transducer that directly measures motion at the fracture site has been designed. Data are processed on-line by computer. Tests using an earlier photographic technique simultaneously with the transducer show the new method to be more accurate and reliable and the results more readily available. Application of the transducer for monitoring fracture creation and end-cap purchase is also shown.

Animals↗