FIELD OF INVENTION
The present invention relates to intra-capsular patient matched device for use in
arthroplasty surgery.
BACKGROUND
[ There are a number of arthroplasty surgical procedures which refers to joint
replacement including replacement of hip, knee, ankle, elbow etc.. One of such
! procedures is a total hip arthroplasty ("THA"), in which a damaged hip joint is
\ replaced with prosthetic implants. The hip joint may have been damaged by J
arthritis such as in severe osteoarthritis or degenerative arthritis, trauma, : osteoporosis or a rare destructive joint disease. During a THA procedure, a
damaged portion in the proximal region of the femur may be removed and
replaced with a metal stem, and a damaged portion of the acetabular cup in the
pelvis may be removed and replaced with a metal cup having a piece of plastic
articulating with the stem, similar to a ball and a socket joint.
\ Implants that are implanted into a damaged region may provide support and
I structure to the damaged region, and may help to restore the damaged region,
thereby enhancing its functionality and patient mobility. Prior to the !
implantation of an implant into a damaged region, the damaged region is usually
prepared pre-operatively to receive the implant. For example, in a hip
arthroplasty procedure, one or more of the bones in the hip area, such as the
femur and/or the pelvis, may be cut, drilled, reamed, and/or resurfaced to
provide one or more surfaces that can align with the implant and thereby
accurately accommodate the implant.
One of the key goals of a total hip replacement is restoration of the patient
anatomy, specifically some key identified anatomical planes thereby providing
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for completely relaxed movements of the affected parts. This is usually done by
standard mechanical instruments or Computer Navigation systems. I
The disadvantages of using standard mechanical instruments lie with the i
inaccurate alignment because it may not be very intuitive and easy to use, and 5
usually require continuous direct visual monitoring while manually aligning the instruments with the key anatomical landmarks on the body. I
Accuracy in implant alignment is an important factor to the success of aTHA
procedure. Five to ten degrees of angular misalignment may result in J
unbalanced ligaments, and may thereby significantly affect the outcome of the
THA procedure. For e.g., Acetabular cup angle (anteversion and inclination)
misalignment may result in dislocation post operatively resulting in pain and
sometimes revision of surgery. In THA procedure, the initial setup of the patient
position, stability of the patient during the procedure plays a crucial role in the i
outcome of the surgery. The surgeon does not always have the option of stable
and repeatable patient position in the surgery due to many limiting factors such as poor patient holding device, obese patient, size of incision etc. This instability
together with the intensive visual monitoring steps during the surgical *
procedure can result in poor surgical outcome.
To achieve accurate implant alignment, prior to treating any region of a bone
such as cutting, drilling, reaming, and/or resurfacing, it is important to correctly
determine the location at which the treatment will take place and how the
cutting, drilling, reaming and/or resurfacing are positioned during the surgery.
Presently some of the methods used include an arthroplasty jig used to
accurately position and orient a finishing instrument, such as a cutting, drilling,
reaming, or resurfacing instrument on the regions of the bone. The arthroplasty
jig may, for example, include one or more apertures and/or slots that are
configured to accept such an instrument.
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In the existing state of art the process of manufacturing of arthroplasty jigs is a
long-drawn, tedious and costly proposition. Various shapes and sizes of the
patient require that a number of these jigs to be sterilized and made available at
the operation theatre to ensure that the right fit is available by way of trial and error. Moreover, due to the size and shape of the arthroplasty jigs, considerable
amount of material is required to construct the patient specific jigs thereby
adding to the costs. Therefore, there is a need to manufacture jigs cost effectively
so that they can be afforded by the masses.
SUMMARY OF THE INVENTION
The present invention obviates the aforesaid problems and provides a
customized arthroplasty jig for use in joint replacements. The reference clip
easily fits into the slots along with the sliding mechanism such that patient
specific surface can slide on to the bone when the referencing and pre-operative
treatment is required and just as easily slide out during the surgery after the
completion on its referencing or when its use is accomplished.
The present invention provides for an accurate placement of the cutting /
reaming instrument without making any additional surgical step to secure the
cutting / reaming instrument.
Joint replacement includes replacement of hip, knee, ankle, elbow etc. For
example, in the context of hip replacement surgery, the present invention
provides a sliding mechanism for locking the acetabular cup angle position. The
hip joint is scanned using for example, CT scans, MRI etc.
In an embodiment, X-rays or CT scans are used to obtain the image of the joints
of a patient as it is cost effective. Using the scanned images, an arthoplasty jig is
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manufactured to match the bone specifications of a patient. Various existing
technologies can be used for modeling the image on the jig.
. ' . • . ' The jigs are provided with slots such that it can be inserted onto the reaming /
cutting / implant positioning instrument, in such a way that they slide along the
cutting axis of the reamer/ cutter / implant positioner. The slot can be such that
it can be easily snapped on / slided-on/ clipped-on to the reamer / cutter /
implant positioner while providing some clearance between the final contact for
easy sliding. The placement of the snapping, sliding or clipping mechanism can
be based on the calculations using scanned image to accurately replicate the pre- : • operative planned position during the surgery. The position of such mechanism
can be such that it provides a mechanical stop and does not allow the reamer to
go beyond certain depth thereby controlling any over-reaming or other possible j
risk of damage, which may result in poor surgical outcome. The jigs can be
manufactured using plastic or metal blocks available in different shapes and ;
sizes. In an embodiment, the slots may be provided with metal inserts.
The jig are placed on the joints which need replacement during or after the joints f
are prepared for better contact during operation. Using the proposed jig, the i
surgical accuracy is increased. 1
The jigs can be made of polymer or other light weight material. The jigs can be a )
single part or may be a multi-part assembly such that during the deployment it's }
size may be shrunk to allow a smaller surgical incision, . The jigs can be manufactured using a layer manufacturing or any other conventional manufacturing technique
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• • . • • ' . - '*
Thus, the present invention delivers necessary patient surgical planning via clipon/
slide-on /snap-on patient specific sliding blocks which can work together
with other reaming / cutting / positioning instruments.
Dated this 17th day of September 2012 /^V? fSunitaK. Sreedharan
Of SKS Law Associates
Attorney for the Applicant
To
The Controller of Patents
The Patent Office, ...
New Delhi