Measurement of knee articulation looseness by videofluoroscopy image analysis: CINARTRO

The yearly incidence of injured Anterior Cruciate Ligament is one every 3000 persons. Usual clinical evaluation methods are qualitative and thus of limited value for precise follow-up either after surgical or conservative medical conduct. Additionally, routine Anterior Cruciate Ligament evaluation is static, overlooking any dynamic behavior of the knee. In research settings, several methods are used to evaluate knee articulation during movement, such as the Tibio Femoral Contact Point migration or the Instantaneous Centre of Rotation displacement and even the Moment Arm variations during extension. We have devised a novel instrument based on 30 images extracted from knee extension videofluoroscopy, which are interactively analyzed to allow automatic determination of kinematics parameters. The instrument, called CINARTRO, compares values with the contralateral knee and produces a standard Clinical Document Architecture file ready for Electronic Medical Record systems. Proof of concept of CINARTRO was set up using videofluroscopy and computer devices. To correct the “pin cushion” effect of X ray intensifiers, a 10 mm apart lead sphere phantom was developed to calibrate images. To validate the interactive selection of anatomical points on X ray images, a cadaveric leg was marked with lead markers and compared with points marked on the blind image, giving good precision measurements. Anterior Cruciate Ligament and contralateral parameters are given for a series of 6 patients, otherwise healthy amateur and professional soccer players.