Abstract: The invention includes a method and system for intra-operative navigation of a joint replacement operation, without recourse to pre-operative imagery of pre-operative computerized simulations. Trackable markers and a locating system are employed to track first and second bones. A computer receives positional information regarding the trackable markers and calculates (predicts) at least one suggested combination of components of a modular implant system to produce a desired post-operative skeletal relationship.

Abstract: The invention includes: a locating system; a computer, interfaced to the locating system and interpreting the positions of tracked objects in a generic computer model of a patient's hip geometry; a software module, executable on the computer, which defines the patient's pelvic plane without reference to previously obtained radiological data, by locating at least three pelvic landmarks; and a pelvic tracking marker, fixable to the pelvic bone and trackable by the locating system, to track in real time the orientation of the defined pelvic plane. Preferably, the system also includes a femoral tracking marker, securely attachable to a femur of the patient by a non-penetrating ligature and trackable by the locating system to detect changes in leg length and femoral offset.

Abstract: The invention includes: a locating system; a computer, interfaced to the locating system and interpreting the positions of tracked objects in a generic computer model of a patient's hip geometry; a software module, executable on the computer, which defines the patient's pelvic plane without reference to previously obtained radiological data, by locating at least three pelvic landmarks; and a pelvic tracking marker, fixable to the pelvic bone and trackable by the locating system, to track in real time the orientation of the defined pelvic plane. Preferably, the system also includes a femoral tracking marker, securely attachable to a femur of the patient by a non-penetrating ligature and trackable by the locating system to detect changes in leg length and femoral offset.

Abstract: An actuator (13) device for a disc brake (4) is provided comprising a rotary actuator (13) operable, via a force transmission device (17, 18), to move a friction element (2) of the brake, in use, into engagement with a rotary brake disc (4), and a thrust member (17A, 18A) arranged to transmit force from the actuator (13) to the force transmission device (17, 18), the actuator (13) being arranged to engage the thrust member (17A, 18A) in a manner such as to prevent rotation of the latter.