Biomedical subjects

P Podsiadlo

Publications and source records attributed to P Podsiadlo.

4 recordsLinked to original sources

PubMed2002

A rig for acquisition of standardized trabecular bone radiographs.

To assess osteoarthritic changes in knee joints a radiography rig for acquisition of standardized radiographs of trabecular bone has been developed. The rig contains a steel frame on castors, a turntable, a cassette holder frame, calibration Plexiglas sheets, body supports and points. It is used to lock the patient in a standardized position. A film cassette holder frame was also developed to reduce scattering of X-rays, and consequently the amount of noise in the radiographs. Calibration Plexiglas sheets were mounted on ball bearing slides to obtain radiographs without a calibration pattern (suitable for the analysis of trabecular bone texture) and radiographs containing a calibration pattern (suitable for the measurement of leg alignment).

Disease Progression↗

PubMed2002

Analysis of trabecular bone texture by modified Hurst orientation transform method.

There is a growing need for noninvasive and inexpensive methods that can effectively be used on a large scale, to detect an onset of early osteoarthritis in human knee joints. Of many possible options, fractal analysis of two-dimensional projection x-ray images of trabecular bone (TB) texture, appears as one of the best approaches. However, there are some problems associated with the characterization of the roughness and anisotropy of the bone texture. To resolve these problems, a modified Hurst orientation transform (HOT) method, previously developed by the authors, has been used in this study. The advantages of the HOT method over other techniques used to analyze bone texture, are that it calculates a two-dimensional fractal dimension in all possible directions and also provides a measure of anisotropy for both surfaces exhibiting strong anisotropy and surfaces exhibiting weak anisotropy. In this study, the accuracy of the HOT method in measuring the bone texture roughness and anisotropy; together with the effects of image noise, blur, exposure, magnification, and projection angle on its performance were investigated. Computer-generated images of fractal surfaces and x-ray images obtained for a human tibia head were used. Results obtained show that the HOT method can effectively be used to characterize the roughness and anisotropy (isotropy) of TB texture.

Algorithms↗

PubMed1998

Shape of wear particles found in human knee joints and their relationship to osteoarthritis.

OBJECTIVE: To analyse and compare the shape of wear particles found in healthy and osteoarthritic human knee joints for monitoring the progress of osteoarthritis, the long-term prognosis and to evaluate therapeutic regimens. METHOD: Joint particles from seven patients with normal cartilage in all compartments of the knee joint, 12 patients with fibrillation of less than half the cartilage thickness (grade 1), seven patients with fibrillation of more than half the cartilage thickness (grade 2) and four patients with erosions down to bone (grade 3) were analysed. A total of 565 particles were extracted from synovial fluid samples by ferrography and analysed in a scanning electron microscope. A number of numerical descriptors, i.e. boundary fractal dimension, shape factor, convexity and elongation, were calculated for each particle image and correlated to the degree of osteoarthritis using non-parametric tests. RESULTS: Experiments demonstrated that there were significant differences between the numerical descriptors calculated for wear particles from healthy and osteoarthritic knee joints (P < 0.01), suggesting that the particle shape can be used as an indicator of the joint condition. In particular, the fractal dimension of the particle boundary was shown to correlate directly with the degree of osteoarthritis. CONCLUSION: Numerical analysis of the shape of wear particles found in human knee joints may provide a reliable means for the assessment of cartilage repair after surgical or conservative treatment of osteoarthritis.

Adolescent↗

PubMed1997

Analysis of wear particle boundaries found in sheep knee joints during in vitro wear tests without muscle compensation.

Pair of sheep knee joints were used in the experiments. One of the joints was worn in a simulator over different periods of time under carefully simulated physiological forces and kinematic cycles while the other, 'control joint', was kept intact for comparison. Wear particles were extracted from a synovial fluid from both the worn and unworn sheep joints by a ferrography technique and then examined in a scanning electron microscope (SEM). The shape of the particles was characterized by boundary fractal dimension, shape factor and convexity. The shape parameters obtained for particle populations were statistically compared using a Wilcoxon rank test. It has been found that subtle changes in the shape of the particle boundary occur during the wear process. Studying the changes in wear particle boundaries provides important information about the cause and progression of wear in synovial joints.

Adaptation, Physiological↗