PATIENT MATCHED INSTRUMENT
A patient matched instrument is disclosed. The patient matched instrument includes a body having an interior patient matched surface; a cutting slot extending through at least a portion of the body; a first paddle extending from the body; and a second paddle spaced apart from the first paddle and extending from the body; and wherein at least one of the first paddle and the second paddle further comprises a hook.
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This application is a PCT International Application of U.S. Patent Application No. 61/681,455 filed on Aug. 9, 2012, and U.S. Patent Application No. 61/715,565, filed on Oct. 18, 2012. The disclosure of each application is incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION1. Field of the Invention
Embodiments of the present invention generally relate to surgical instruments and methods for the treatment of bones or joints, in some instances surgical instruments that are matched to a particular patient's anatomy, are described herein. Also described are methods of designing and using such surgical instruments.
2. Related Art
Conventional patient-matched instruments are provided with large surfaces that are configured to conform to a patient's unique anatomy. Successful surgical outcomes depend on the ability of patient-matched instruments to provide a reproducible, “confident” 3D-fit between the patient-matched instrument and the anatomy that they are designed to rest against. If there is any doubt by an end user that a patient-matched instrument fits well upon repeated engagement with a patient's unique anatomy, or if the instrument appears to fit well with the patient's anatomy in multiple spatial orientations with respect to the anatomy, the instrument is typically discarded, and the surgery is carried out with the use of conventional, non-patient specific instruments.
To date, at least some patient-matched surgical instruments for use in total knee arthroplasty have employed anatomy-contacting surfaces that are substantially “negatives” of distal femoral and proximal tibial articular joint surfaces. The anatomy-contacting surfaces are generally large surface areas that conform in a continuous manner to substantial areas of a patient's anatomy. In some instances, the custom surgical instruments are provided by obtaining 3D image data of the patient's anatomy (e.g., via an MRI scan), segmenting the 3D image data to clearly delineate surfaces of the bony and/or cartilegeneous anatomy from surrounding tissues, converting the segmented data to a computer model via CAD or other software, performing one or more optional secondary processes (e.g., smoothing functions), using a computer model to customize one or more surfaces of an instrument to the patient's anatomy, and manufacturing the custom instrument such that it is adapted to conform to the patient's anatomy in a single spatial orientation.
In at least some current practices, substantially all portions of the joint anatomy shown in each 3D image data slice are segmented and conventional patient-matched instruments are provided with anatomy-contacting portions that contact substantially continuous areas of the patient's anatomy. Such anatomy-contacting portions have large continuous surface areas of contact with the patient's bone and cartilage, and therefore, it is critical that the engineers or automated programs creating the patient-matched instruments maintain a high level of accuracy and precision throughout each step of the entire segmentation process. Even if only one or two points on anatomy-contacting surfaces of a patient-matched instrument are inaccurate, misaligned, or otherwise misrepresent the true unique anatomy of the patient, the patient-matched instrument may not fit well, sit proud, teeter, wobble, or may not fit at all. In such instances, an end user is less likely to use the instrument. In many cases, poor patient-matched instrument fit may be attributed to even a few minor errors in the segmentation process.
SUMMARY OF THE INVENTIONThe various embodiments of the present invention described below and shown in the Figures provide a patient matched instrument that is designed to provide improved repeatability and reproducibility over the prior art. The patient matched instrument incorporates design features that encourage consistent placement and accurate placement.
Further areas of applicability of the invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the particular embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the present invention and together with the description, serve to explain the principles of the invention. In the drawings:
The accompanying drawings which is this case is a group of sketches prepared by the inventor and , which are incorporated in and form a part of the specification, illustrate the embodiments of the invention and together with the written description serve to explain the principles, characteristics, and features of the invention. In the drawings:
Referring to the accompanying drawings in which like reference numbers indicate like elements,
In use, the tibia 2 is exposed via surgical incision. The patient matched cutting block 100 is placed on the tibia 2 and located in a home position. Pins (not shown) are inserted into the fixation holes 118. The cutting instrument is reciprocated in the cutting slot 116 to remove bone from a proximal end of the tibia 2.
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One of the paddles 510, 512 may be thinner or thicker than the other paddle. In the depicted embodiment, both paddles have a thickness of about 4 mm. The thickness of the paddles may range from about 2 mm to about 15 mm, and more preferably from about 3 mm to about 5 mm. Moreover, the paddles 510, 512 may be trimmed at different angles to achieve an overall desired height. The overall height of the paddles 510, 512 may be determined by an offset function relative to the proximal tibia bone surface. Paddles with a sufficient minimum thickness may provide an advantage of allowing for tibial placement prior to making posterior femoral resections.
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The patient matched instrument 500 also includes a hook 550. The hook 550 is adapted to contact a posterior surface of the tibia 2. The height and width of the hook 550 may a set size for all patient matched instruments or may be sized based upon a particular patient's anatomy. Although the hook 550 is depicted as being upon the medial paddle, it could also be formed as part of lateral paddle, or both paddles.
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In use, the tibia 2 is exposed via surgical incision. The patient matched cutting block 500 is placed on the tibia 2 and located in a home position. Pins (not shown) are inserted into the fixation holes 518. The cutting instrument is reciprocated in the cutting slot 516 to remove bone from a proximal end of the tibia 2.
In some embodiments, in order to give a user more confidence in placing a patient matched instrument and/or to minimize the chance of false placement, the patient matched instrument may be provided with certain combined features that act in synergy to enhance the patient matched instrument's fit, stability, and/or constraint. As examples, such features may be larger paddles, anterior medial contact, slot contact, and/or the posterior hook. The location, dimensions, and combinations of particular features may be worked into an algorithm based upon the patient's anatomy and/or user preference. For example, to improve varus/valgus constraint, the features may focus on constraint provided by the medial and lateral paddles. Alternatively, to enhance flexion and extension, the features may focus on constraint provided by the hook and the body along the anterior portion. Otherwise, to enhance rotation, the features may focus on constraint provided by the slot contact and the anterior-proximal-lateral tibia body contact.
Any of the features of the embodiments disclosed herein may be combined in various combinations to form alternative embodiments.
As various modifications could be made to the exemplary embodiments, as described above with reference to the corresponding illustrations, without departing from the scope of the invention, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the claims and their equivalents.
In view of the foregoing, it will be seen that the several advantages of the invention are achieved and attained.
The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.
As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. For example, while
Claims
1. A patient matched instrument comprising:
- a. a body having an interior patient matched surface;
- b. a cutting slot extending through at least a portion of the body;
- c. a first paddle extending from the body; and
- d. a second paddle spaced apart from the first paddle and extending from the body; and wherein at least one of the first paddle and the second paddle further comprises a hook.
2. The patient matched instrument of claim 1, wherein the body includes at least one fixation hole.
3. The patient matched instrument of claim 1, wherein one of the first paddle and the second paddle is thinner or thicker than the other paddle.
4. The patient matched instrument of claim 1, wherein the interior patient matched surface has a surface roughness different than the remainder of the body.
5. The patient matched instrument of claim 1, wherein the cutting slot comprises a ledge.
6. The patient matched instrument of claim 1, further comprising an area of the body configured to contact a portion of an anterior of a particular patient's tibia and is matched to the particular patient's anatomy.
7. The patient matched instrument of claim 1, further comprising a first member and a second member, and wherein the first member and the second member intersect to provide a confidence point.
8. The patient matched instrument of claim 1, further comprising a built-in alignment checker.
9. The patient matched instrument of claim 8, wherein the built-in alignment checker has a receiver and a bridge.
10. The patient matched instrument of claim 1, wherein each paddle has a contact surface.
11. The patient matched instrument of claim 10, wherein the interior patient matched surface and the contact surfaces are used to locate the cutting slot.
Type: Application
Filed: Aug 9, 2013
Publication Date: Sep 3, 2015
Applicant: Smith & Newphew, Inc. (Memphis, TN)
Inventors: Eric S. Kennedy (Memphis, TN), Maroun T. Tarsha (Memphis, TN), Zachary C. Wilkinson (Germantown, TN), Randy C. Winebarger (Southaven, MS)
Application Number: 14/420,453