Surgery – Instruments – Stereotaxic device
Reexamination Certificate
2002-02-27
2004-12-07
Shaver, Kevin (Department: 3732)
Surgery
Instruments
Stereotaxic device
Reexamination Certificate
active
06827723
ABSTRACT:
FIELD OF THE INVENTION
This invention generally relates to unicompartmental knee arthroplasty surgical operations using systems and processes for tracking anatomy, implements, instrumentation, trial implants, implant components and virtual constructs or references, and rendering images and data related to them. Anatomical structures and such items may be attached to or otherwise associated with fiducial functionality, and constructs may be registered in position using fiducial functionality whose position and orientation can be sensed and tracked by systems and according to processes of the present invention in three dimensions in order to perform unicompartmental knee arthroplasty. Such structures, items and constructs can be rendered onscreen properly positioned and oriented relative to each other using associated image files, data files, image input, other sensory input, based on the tracking. Such systems and processes, among other things, allow surgeons to navigate and perform unicompartmental knee arthroplasty using images that reveal interior portions of the body combined with computer generated or transmitted images that show surgical implements, instruments, trials, implants, and/or other devices located and oriented properly relative to the body part. Such systems and processes allow, among other things, more accurate and effective resection of bone, placement and assessment of trial implants and joint performance, and placement and assessment of performance of actual implants and joint performance.
BACKGROUND
Knee arthroplasty is a surgical procedure in which the articular surfaces of the femur, tibia and patella are cut away and replaced by metal and/or plastic prosthetic components. The goals of knee arthroplasty include resurfacing the bones in the knee joint and repositioning the joint center on the mechanical axis of the leg. Knee arthroplasty is generally recommended for patients with severe knee pain and disability caused by damage to cartilage from rheumatoid arthritis, osteoarthritis or trauma. It can be highly successful in relieving pain and restoring joint function.
More than 95% of knee arthroplasties performed in the United States are tricompartmental knee arthroplasties (“TKA”), which involves the replacement of all the articular surfaces of the knee joint. TKA is performed when arthritis or trauma has affected two or more of the three compartments of the knee: medial compartment (toward the body's central axis), lateral compartment (away from the body's central axis), and patello-femoral compartment (toward the front of the knee).
The remaining knee arthroplasties are unicompartmental knee arthroplasties (“UKA”). UKA involves the replacement of the articular surfaces of only one knee compartment, usually the medial compartment. UKA is an attractive surgical treatment for patients with arthritis in only one compartment and with a healthy patella.
UKA has several advantages over TKA. UKA allows the preservation of both cruciate ligaments, while the anterior cruciate ligament is usually removed in TKA. Preservation of the ligaments provides greater stability to the joint after surgery. UKA also allows for preservation of more bone stock at the joint, which will be beneficial if revision components must be placed. Finally, UKA is less invasive than TKA because UKA requires smaller resections and components.
In spite of these advantages, there continue to be problems in UKA performance. A leading cause of wear and revision in prosthetics such as knee implants, hip implants and shoulder implants is less than optimum implant alignment. In a UKA, for example, current instrument design for resection of bone limits the alignment of the femoral and tibial resections to average values for varus/valgus flexion/extension, and external/internal rotation. Additionally, surgeons often use visual landmarks or “rules of thumb” for alignment which can be misleading due to anatomical variability. Intramedullary referencing instruments also violate the femoral and tibial canal. This intrusion increases the risk of fat embolism and unnecessary blood loss in the patient. Surgeons also rely on instrumentation to predict the appropriate implant size for the femur and tibia instead of the ability to intraoperatively template the appropriate size of the implants for optimal performance. Another challenge for surgeons is soft tissue or ligament balancing after the bone resections have been made. Releasing some of the soft tissue points can change the balance of the knee; however, the multiple options can be confusing for many surgeons. Although much of the bone stock remains after UKA, if a revision is necessary, many of the visual landmarks are no longer present, making alignment and restoration of the joint line difficult.
SUMMARY
The present invention is applicable not only for knee repair, reconstruction or replacement surgery, but also repair, reconstruction or replacement surgery in connection with any other joint of the body as well as any other surgical or other operation where it is useful to track position and orientation of body parts, non-body components and/or virtual references such as rotational axes, and to display and output data regarding positioning and orientation of them relative to each other for use in navigation and performance of the operation.
Systems and processes according to one embodiment of the present invention use position and/or orientation tracking sensors such as infrared sensors acting stereoscopically or otherwise to track positions of body parts, surgery-related items such as implements, instrumentation, trial prosthetics, prosthetic components, and virtual constructs or references such as rotational axes which have been calculated and stored based on designation of bone landmarks. Processing capability such as any desired form of computer functionality, whether standalone, networked, or otherwise, takes into account the position and orientation information as to various items in the position sensing field (which may correspond generally or specifically to all or portions or more than all of the surgical field) based on sensed position and orientation of their associated fiducials or based on stored position and/or orientation information. The processing functionality correlates this position and orientation information for each object with stored information regarding the items, such as a computerized fluoroscopic imaged file of a femur or tibia, a wire frame data file for rendering a representation of an instrumentation component, trial prosthesis or actual prosthesis, or a computer generated file relating to a rotational axis or other virtual construct or reference. The processing functionality then displays position and orientation of these objects on a screen or monitor, or otherwise. Thus, systems and processes according to one embodiment of the invention can display and otherwise output useful data relating to predicted or actual position and orientation of body parts, surgically related items, implants, and virtual constructs for use in navigation, assessment, and otherwise performing surgery or other operations.
As one example, images such as fluoroscopy images showing internal aspects of the femur and tibia can be displayed on the monitor in combination with actual or predicted shape, position and orientation of surgical implements, instrumentation components, trial implants, actual prosthetic components, and rotational axes in order to allow the surgeon to properly position and assess performance of various aspects of the knee joint being repaired, reconstructed or replaced. The surgeon may navigate tools, instrumentation, trial prostheses, actual prostheses and other items relative to the femur and tibia in order to perform UKA's more accurately, efficiently, and with better alignment and stability.
Systems and processes according to the present invention can also use the position tracking information and, if desired, data relating to shape and configuration of surgical related items and virtual constructs or ref
Kilpatrick & Stockton LLP
Priddy Michael B.
Shaver Kevin
Smith & Nephew Inc.
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