Polyware Digitizing Software

In October, 1997 DDI announced the release of PolyWare^TM Pro 3D. The software determines the volume of polyethylene material that is worn away from the bearing surfaces of orthopedic hip implants, over time.

The amount of wear is determined by precise 3D measurements from standard patient radiographs. This data is extremely useful for determining the longevity of bearing materials, the quality of implant design, and even when future revision surgery may be required.

PolyWare Revision 5

Screenshot of PolyWare Revision 5

AUTOMATED 3-DIMENSIONAL MEASUREMENT OF POLYETHYLENE WEAR USING RADIOGRAPHS.

Product History...

In 1993 Dr. Peter Devane, of Wellington New Zealand, developed a new three-dimensional technique for the measurement of polyethylene wear in metal-backed acetabular components. Using a back-lit digitizing tablet, points from Anteroposterior and Lateral radiographs were input into a personal computer. Using AutoCAD® software, and some custom programming, this data created three-dimensional solid models of the prosthesis. The model was rotated to a standard frontal view, and femoral head displacement and the volume of polyethylene was recorded.

In 1995, Dr. Devane and Dr. Robert Bourne approached DePuy regarding development of a user friendly package that would incorporate Dr. Devane's program into a Microsoft Windows environment. Due to its proximity to the heart of the orthopaedic industry (Warsaw, Indiana) and its ties with the industry, DDI was hired to develop Dr. Devane's software. Within one year, nine centers in U.S. were using the new software to measure polyethylene wear in 950 cases.

In early 1997, Dr. Devane and Dr. G. Horne improved the accuracy of the software by minimizing user input and analyzing digital images of clinical radiographs scanned into a personal computer. In October 1997, DDI announced the official release of the PolyWare Pro 3D product for Microsoft Windows.

The Hip Society recently formed a sub-committee to evaluate methods to measure polyethylene wear in acetabular components and has initially accepted Dr. Devane's technique as the industry standard.

State of The Art Analysis...

Methods:
The new software, PolyWare^TM, including custom built filters and an edge-detector, as well as contemporary image processing software, analyzes digital images of radiographs with minimal user input. Three-dimensional wear of all-polyethylene acetabular cups with a wire marker is also now possible. Accuracy was tested by construction of an acrylic jig into which two 38mm diameter steel balls were mounted. Initially the steel balls were in contact with each other. An accurately calibrated engineering "feeler gauge" was then used to separate the two steel balls from 0.05 to 0.3mm in increments of 0.05mm (six measurements), and anteroposterior and lateral radiographs were taken.

Results:
Accuracy (defined as mean plus standard deviation of the absolute difference between measured and true separations) was 0.028mm for the scanned films analyzed by the new image processing software. This was a threefold improvement over measurements made from the digitizing tablet, where measurement of the same radiographs revealed an accuracy of 0.089mm.

Conclusions:
Contemporary image processing techniques have been developed for application to measure polyethylene wear in scanned images of hip prostheses. The ability to measure very small amounts of wear has been improved by using image processing technology to eliminate the observer as a source of error during input of points. Application of automated routines results in a threefold increase in the accuracy over manual selection of points from a digitizing tablet. Accuracy below the expected polyethylene wear rate per year of most prostheses is possible, and may allow yearly measurement of polyethylene wear in individual patients to be a predictor of osteolysis and prosthesis survival.

Overview

PolyWare software is currently available for the Microsoft Windows 95, 98, 2000 and NT operating systems. There are two basic versions of PolyWare. The Digital Edition uses scanned radiograph images for data input, while the Tablet Edition requires that radiographs be "digitized" into the software manually, with a digitizing tablet.

PolyWare supports the following Total Hip Systems:

Biomet Mallory®

Biomet Mallory® (Asian)

Biomet Universal RingLoc Series®

Biomet Bi-Metric®

DePuy Duraloc®

DePuy Solutions®

DePuy PSR®

Encore®

Howmedica PCA®

Richards Inter-Fit®

Richards Optifix®

Richards Reflection®

Sulzer ACA®

Sulzer Allofit®

Sulzer Fitmore®

Sulzer Weber Cup®

Sulzer Inter-Op®

Zimmer Harris Galante I®

Zimmer Trilogy®

Digital Edition

The PolyWare Digital Edition is the newest and most sophisticated version of PolyWare. The Digital Edition determines the size and location of the implant head and cup by using advanced mathematical curve-fitting techniques. Rather than taping radiographs to a back-lit tablet, the Digital Edition accepts scanned radiograph images in the form of TIFF files. Thus all work is done onscreen.

In addition to ease of use, the Digital Edition produces results which are typically more accurate than the PolyWare Tablet Edition. The curve-fitting routines used by the Digital Edition reduces user input, which ultimately reduces the potential for user errors.

Digital Edition System Requirements:

Typical "minimum" PC/hardware requirements for the Digital Edition are as follows:

System Type: IBM-Compatible PC

Processor Type: Intel, AMD or Cyrix CPU

Processor Speed: 486/66 mhz (minimal); Pentium (recommended)

System RAM: 12mb (minimal); 16mb+ (recommended)

Operating System: Windows 95, 98, 2000 or NT

Other Hardware: 12" x 17" Flatbed Scanner (see recommended scanners below)

Other Software: Scanner software that can create TIFF files

Scanners We Recommend for the PolyWare Digital Edition:

Microtek ScanMaker 9600XL (approximate cost: $500)
Microtek ScanMaker 6400XL (approximate cost: $950)

UMAX Mirage SE II (approximate cost: $1,300)

Tablet Edition

The PolyWare Tablet Edition requires use of a back-lit Numonics digitizing tablet. Radiographs are secured directly to the tablet. The tablet's built-in mouse is then use to digitize the head and cup points. The Tablet Edition determines the size and location of the implant head and cup by using advanced mathematical curve-fitting techniques on the points digitized from the tablet.

Tablet Edition System Requirements:

Typical "minimum" PC/hardware requirements for the Tablet Edition are as follows: