Abstract: A method for producing a customized surgical instrument or prosthesis for a specific patient is described. At least one x-ray image of a body part of the patient is captured. A statistical model having a dense set of anatomical correspondence points across the model is instantiated using image data derived from the at least one x-ray image to generate a patient specific model of the body part having a high accuracy surface. Patient specific data from the patient specific model is used to generate a design of the customized surgical instrument or prosthesis for use in a surgical procedure to be carried out on the body part. The surgical instrument or prosthesis is then manufactured using the design. A computer implemented method for generating the patient specific model of the body part is also described.

Abstract: A patient specific instrument for use in a ball and socket joint arthroplasty procedure, method of manufacture and method of use are described. The instrument comprises an attachment mechanism for attaching the instrument to the socket of the patient, which has at least first and second parts which can engage the rim of the socket of the patient. Each part is shaped, or can transform to a shape, to match the shape of a respective portion of the rim of the socket. A body bears at least one guide formation for guiding a component to be used in the arthroplasty procedure. The instrument includes a locking mechanism by which the body and attachment mechanism can be assembled in a unique configuration into the patient specific instrument. The patient specific instrument is attachable to the socket of the patient only at a single pre-planned position.

Abstract: A device and methods for use in determining the trajectory of a patella of a patient during a navigated knee replacement surgical procedure are described. The device includes a first component including a mounting for attachment to a posterior surface of the patient's patella and a second component having an outer surface presenting a formation adapted to engage with a femoral part of the patient's knee. A slider mechanism allows the second component to translate relative to the first component in a substantially medial-lateral direction of the patient when the first component is attached to the patient's patella. The device can be used in a method to help determine the medial-lateral position for a patella implant.

Abstract: A system and computer implemented method for use in determining the deviation-of an intra-operative position of an orthopaedic implant from a planned position is described. The position of the orthopaedic implant in the bone is defined by a plurality of implant position parameters. The distance of a plurality of anatomical features in a three dimensional model of the surface of the bone relative to a model of the implant at a first position is calculated. The first position corresponds to a first set of values for the implant position parameters. The distance of the plurality of anatomical features to a model of the implant at a second position in the bone is calculated. The second position corresponds to a second set of values for the implant position parameters, and the second position is different to the first position.

Abstract: Patient specific surgical instruments, and in particular cutting guides, and methods of use and manufacture are described. The surgical instrument can be used in an orthopaedic arthroplasty procedure to be carried out on a joint of a patient and can allowing soft tissue balancing for the joint. The instrument comprises a body having an attachment area configured using data specific to a bone of the joint of the patient so as to attach to the bone in a unique position. The instrument includes at least a first cutting guide and an adjustment mechanism operable to change the position of the cutting guide relative to the bone.

Abstract: An orthopaedic cutting guide assembly and method of cutting a bone are described. A component has a guide for guiding a cutting instrument and at least a first mechanism for securing the component to a bone. A movement indicator has a mechanism for securing the movement indicator to the bone independently of the component. The component includes at least one indicium by which movement of the component relative to the bone can be indicated by relative movement of the movement indicator and the indicium.

Abstract: A computer assisted surgery method and apparatus for determining a change in a property of a joint of a patient caused by an arthroplasty procedure is described. The relative position of a first bone and a second bone of the joint is determined with the joint in a first position. The position of a pre-operative center of motion of the joint relative to the first bone is determined. The position of the second bone relative to the pre-operative center of motion is determined using the relative position of the first and second bones. The position of a post-operative center of motion resulting from a prosthetic component to be used in the joint is determined. The position of the second bone relative to the post-operative center of motion is determined. Any change in the property of the joint. is determined from the difference between the position of the second bone relative to the pre-operative center of motion and the position of the second bone relative to the post-operative center of motion.

Abstract: An alignment guide for guiding the positioning of an acetabular cup implant includes a body having a first end and a second end. A flange extends from the first end and is adapted to rest on a labrum of an acetabulum. At least a first formation is provided at the second end which is adapted to engage with a transverse acetabular ligament of the acetabulum. A formation for accepting a trackable instrument is provided to allow a tracking system to determine the orientation of the guide.

Abstract: A method for producing a customised surgical instrument or prosthesis for a specific patient is described. At least one x-ray image of a body part of the patient is captured. A statistical model having a dense set of anatomical correspondence points across the model is instantiated using image data derived from the at least one x-ray image to generate a patient specific model of the body part having a high accuracy surface. Patient specific data from the patient specific model is used to generate a design of the customised surgical instrument or prosthesis for use in a surgical procedure to be carried out on the body part. The surgical instrument or prosthesis is then manufactured using the design. A computer implemented method for generating the patient specific model of the body part is also described.