US 5,480,439 A · Method for periprosthetic bone mineral density measurement

Abstract

A method of evaluating bone density around a radiolucent composite prosthesis establishes an implant boundary by fitting a stored template to radio-opaque reference markers embedded in the prosthesis. The implant boundary is used to create a measurement boundary displaced from the implant boundary toward the bone producing a conformal region of interest. Matched histograms of bone density in a lateral and medial such region of interest may be displayed to evaluate symmetrical stress effects. Alternatively, bone density may be displayed plotted along an axis cutting across the medial and lateral sides. Fiducial points are identified from the bone and implant morphology to ensure that either display will have a repeatable reference and hence that such displays will be directly comparable to later and earlier displays thereby aiding in the detection of bone change.

Claims10

Dependent claims

A method of evaluating bone quality in a patient having a substantially radiolucent prosthesis implanted in a bone, the prosthesis having at least one edge and having radiographically detectable reference markers, the method comprising the steps of:

collecting bone mineral density data over at least two dimensions, including portions of the prosthesis holding the reference markers, by means of a body penetrating digital imaging instrument, to generate a matrix of data values wherein the value of each data element of the matrix is proportional to the mineral content of the bone at the corresponding location in the dimensions;
employing an electronic computer to:
(a) analyze the matrix of data values to identify the location of the reference markers;
(b) determine the best fit of a stored template, having stored reference marker data and at least one stored edge, to the location of the reference markers;
(c) employ the best fit to identify an implant boundary within the matrix of data values based on the stored template edge;
(d) establish a measurement boundary translated from the implant boundary by a predetermined distance along a translation axis;
(e) calculate bone mineral density within a plurality of segments following the path of the measurement boundary to produce a set of segment values;
and
(f) display a plot of segment values versus distance along the implant boundary.

6 more elements

An apparatus to evaluate bone quality in a patient having a substantially radiolucent prosthesis implanted in a bone, the prosthesis having at least one edge and having radiographically detectable reference markers, the apparatus comprising:

a radiation source and detector for collecting bone mineral density data over at least two dimensions, including portions of the prosthesis holding the reference markers to generate a matrix of data values wherein the value of each data element of the matrix is proportional to the mineral content of the bone at the corresponding location in the dimensions;
an electronic computer operating according to a stored program so as to:
(a) analyze the matrix of data values to identify the location of the reference markers;
(b) determine the best fit of a stored template, having stored reference marker data and at least one stored edge, to the location of the reference markers;
(c) employ the best fit to identify an implant boundary within the matrix of data values based on the stored template edge;
(d) establish a measurement boundary translated from the implant boundary by a predetermined distance along a translation axis;
(e) calculate bone mineral density within a plurality of segments following the path of the measurement boundary to produce a set of segment values;
and
(f) display a plot of segment values versus distance along the implant boundary.

6 more elements

Dependencies are inferred from the claim text.

Method for periprosthetic bone mineral density measurement

Life of this patent

Method for periprosthetic bone mineral density measurement

Life of this patent

Abstract

Claims10