Evaluation of a stepped, fixed-height magnification marker stand for use with a 100-mm marker in implant sizing prediction in 52 total hip replacement procedures in dogs.

Objective: To describe the use of a 100-millimeter marker placed on a stepped, fixed-height magnification marker stand to measure radiographic magnification on accuracy of implant size prediction when used for canine total hip replacement (THR) implant size selection.

Study Design: Retrospective study.

Animals: Fifty-two hips in 45 dogs.

Methods: This study evaluated 52 consecutive canine total hip replacement surgery pre-planning procedures involving 45 dogs with 7 undergoing staged bilateral THRs. Data collected included demographic information, measured radiographic magnification for magnification recalibration, implant size prediction of the cups (52) and the stems (52) based on digital templates superimposed on digital radiographs, and the actual implant sizes used during surgery.

Results: Use of the magnification marker stand (MMS) and template application system resulted in an accurate prediction of implant size of 98/104 implants (94.2%) implants.

Conclusion: A 100-mm marker placed on a magnification marker stand was a viable method to measure and recalibrate for magnification on digital radiographs during the template process to predict the THR implant sizes that should be available when the surgery begins.

Clinical Significance: This stepped calibration marker stand is helpful in determination of an accurate preoperative THR implant size prediction, lowering implant stock thresholds, operating time, and associated complications. Additionally, the radiographic documentation of the marker's step height allows for indefinite confirmation of the magnification marker height used and for accurate repeatability for all follow-up imaging examinations and contralateral procedure planning.