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Proceedings Paper

A Stereophotogrammetric System For The Detection Of Prosthesis Loosening In Total Hip Arthroplasty
Author(s): Sheldon Baumrind; Harry K. Genant; John Hunter; David Miller; Francis Moffitt; William R. Murray; Steven E. Ross
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Paper Abstract

Loosening of the prosthetic device occurs in about 5% of cases following placement of total hip prostheses (THP). Early detection of loosening is much desired but is difficult to achieve using conventional methods. Due to errors of projection, it is quite possible to fail to detect mobility of even as much as 5 mm on single x-ray films. We are attempting to develop a simplified photogrammetric system suitable for general hospital use which could detect loosening of 0.8 mm at the 95 % level of confidence without use of complex stereoplotting equipment. Metal reference markers are placed in the shaft of the femur and in the acetabular region of the pelvis at the time of surgery. The distances between these reference markers and certain unambiguous points on the prostheses are computed analytically using an X-Y acoustical digitizer (accuracy ± 0.1 mm) and software developed previously for craniofacial measurement. Separate stereopairs of the joint region are taken under weight-bearing and nonweight-bearing conditions. Differences in the measured distances between the bo-ne markers and the prosthetic components on the two stereopairs are taken as indicators of prosthesis loosening. Measurements on a phantom using ten different x-ray stereopairs taken from as many different perspectives have established that true linear distances between reference points and prostheses can be measured at the desired reliability with the present low precision system. Preliminary in vivo measurements indicate that the main unresolved problem is the movement of the subject between the two exposures of each single stereopair. Two possible solutions to this problem are discussed.

Paper Details

Date Published: 29 July 1980
PDF: 12 pages
Proc. SPIE 0166, NATO Symposium on Applications of Human Biostereometrics, (29 July 1980); doi: 10.1117/12.956935
Show Author Affiliations
Sheldon Baumrind, University of California (United States)
Harry K. Genant, University of California (United States)
John Hunter, University of California (United States)
David Miller, University of California (United States)
Francis Moffitt, University of California (United States)
William R. Murray, University of California (United States)
Steven E. Ross, University of California (United States)

Published in SPIE Proceedings Vol. 0166:
NATO Symposium on Applications of Human Biostereometrics
A. M. Coblentz; Robin E. Herron, Editor(s)

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