Measurement of knee articulation laxity by videofluoroscopy image analysis: CINARTRO

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. Such evaluation is important in case of Anterior Cruciate Ligament reconstruction or Total Knee Replacement, but unfortunately, it is only available in research settings. We have devised a novel clinical methodology based on serial images of knee movement videofluoroscopy, which are interactively analysed to allow automatic determination of kinematics parameters. The method, called CINARTRO, compares values with the contralateral knee and produces a standard Clinical Document Architecture file ready for Electronic Medical Record systems. To correct the “pin cushion” effect of X ray intensifiers, a 10 mm apart lead spheres phantom was developed. To validate the interactive selection of anatomical points, cadaver limbs were marked with lead markers and compared with points marked on the blind image. Anterior Cruciate Ligament (injured and reconstructed) and contralateral Moment Arms averages of 53mm, 39mm and 43mm respectively were found. Similarly the Total Knee Replacement patient̀ s Moment Arm was reduced to 33mm. These findings justify the use of our methodology to help clinicians during rehabilitation follow-up.