Vital Protocol for Reliability and Accuracy of PolyWareTM Measurements

Introduction: PolyWareTM software (PW) has been an exclusively used software in most polyethylene wear studies of total hip arthroplasty (THA). We found that PolyWareTM (PW) measurements can be significantly inaccurate and unrepeatable depending on imaging conditions or subjective manipulation choices. In this regard, this study reveals the required conditions to achieve the best accuracy and reliability of the PW measurements. Results: : Among all the imported X-ray images, those with a resolution of 1076×1076 exhibited the best standard deviation in wear measurements as small as 0.01 mm and the least occurrences of blurriness. The edge detection area specified as non-squared and off the femoral head center exhibited the most occurrence of blurriness. At the X-ray scanning moment, an eccentric placement of the femoral head center by 15 cm superior to the X-ray beam center led to an acetabular anteversion measurement error up to 5.3°. Conclusion: Because PW has been an exclusively used polyethylene wear measurement tool, revealing its error sources and making the countermeasure are of great importance. The results request researchers to observe the following conditions; 1) the original X-ray image be 1076×1076 squared X-ray images, 2) the edge detection area be specified as a square with edge lengths of 5 times the diameter of the femoral head centered at the femoral head center, 3) the femoral head center or acetabular center be placed as close to the center line of the X-ray beam as possible, at the X-ray scanning moment.