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SummaryRotation combined with translation; compose the three-dimensional motion of the knee subluxation in anterior cruciate ligament deficient knee. The worldwide scientists were focused initially on the translation part of this complex 3D motion, but since the beginning of the century there was a large interest on knee rotational laxity study. Lot of paper reported new devices and results with an explosion since the beginning of the decade. The purpose of this review is to provide an extensive critical analysis of the literature and clarify the knowledge on this topic. We will start with a dismemberment of different rotational laxities reported: the rotation coupled with translation in 2D tests such as Lachman test and anterior drawer test; the rotational envelope considering the maximum internal external rotation; and the “active rotation” occurring in 3D Pivot-shift (PS) test. Then we will analyze the knee kinematics and the role of different anterior cruciate ligament (ACL) bundle on rotation. A review of different mechanical and radiological devices used to assess the different rotations on ACL deficient knees will be presented. Two groups will be analyzed, dynamic and static conditions of tests. Navigation will be described precisely; it was the starter of this recent interest in rotation studies. Opto electronic and electromagnetic navigation systems will be presented and analyzed. We will conclude with the last generation of rotational laxity assessment devices, using accelerometers, which are very promising.

Computer assisted orthopaedic surgery (CAOS) was developed to improve the accuracy of surgical procedures. It has improved dramatically over the last years, being transformed from an experimental, laboratory procedure into a routine procedure theoretically available to every orthopaedic surgeon. The first field of application of computer assistance was neurosurgery. After the application of computer guided spinal surgery, the navigation of total hip and knee joints became available. Currently, several applications for computer assisted surgery are available. At the beginning of navigation, a preoperative CT-scan or several fluoroscopic images were necessary. The imageless systems allow the surgeon to digitize patient anatomy at the beginning of surgery without any preoperative imaging. The future of CAOS remains unknown, but there is no doubt that its importance will grow in the next 10 years, and that this technology will probably modify the conventional practice of orthopaedic surgery.

La statistique n’est pas la loi des grands nombres : un effectif important n’est pas indispensable pour tirer une conclusion statistique valable. La statistique n’est pas non plus que du calcul : c’est avant tout de la reflexion methodologique, et le calcul mathematique n’occupe qu’une part infime de la statistique. La statistique est en fait la facon d’exploiter au mieux les donnees dont on dispose.