Quantitative Pivot Shift Technology for Tablets and Smart Phone Devices

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A simple image analysis method for quantifying the translation of the knee during the pivot shift test (Hoshino et al., 2012) has been developed. Therefore, a video camera tracks stickers placed on anatomic landmarks of the lateral knee, which has been found to be correlated to clinical grading of the pivot shift test (Bedi et al., 2010)(Figure 1). Although this image analysis evaluates indirect movement of the lateral knee compartment on the skin, the results of the image analysis are related to the actual tibio-femoral AP translation (Araujo et al., 2012).

An IPad app was then developed to aid in processing of the image capture as well as calculation of translation (Figure 2) (Hoshino et al., 2013). The app was constructed with the assistance of a local, contracted software developer. An invention disclosure was filed with the Office of Technology Management at the University of Pittsburgh in December 2011 (Patent, Dec 2012: “Quantified Injury Diagnostics” 2559/106852.46). The iPad app was designed to serve two purposes, (1) pre-operative assessment of rotatory knee laxity under anaesthesia in an attempt to assist with grading of the injury and (2) postoperative assessment of rotatory knee laxity to judge ACL graft function. We have used the iPad app to quantify the pivot shift test in 34 patients during examination under anaesthesia and published this in a peer-reviewed journal after filing the patent (Hoshino et al., 2013). The technology is also currently being validated using cadaveric experiments.

This material was originally published on the website of the Orthopaedic Robotics Laboratory