WO2012049692A1

WO2012049692A1 - Apparatus and method for orthopedic surgery

Info

Publication number: WO2012049692A1
Application number: PCT/IN2011/000709
Authority: WO
Inventors: Rupesh Ghyar; Manish G. Agarwal; Bhallamudi Ravi
Original assignee: Indian Institute Of Technology, Bombay
Priority date: 2010-10-15
Filing date: 2011-10-12
Publication date: 2012-04-19

Abstract

An apparatus for orthopedic surgery includes a fixture (100) with a supporting plate (102) and a guide bar (106). The supporting plate and the guide bar are held to each other by a holding element. A jig assembly (200) with cutting block (202) having first surface and second surface is provided in the apparatus. The second surface is configured to engage at least two clamps (204a, 204b). The cutting block has slot extending from first surface to second surface. Further, jig assembly is engageable with guide bar of the fixture in a moveable manner. A method of measuring a resection distance on a tumor bone and cutting the tumor bone at the resection distance includes providing, on the tumor bone, the apparatus as briefly described above. The bone is clamped at resection point. The jig assembly is disengaged from guide bar and a saw blade is introduced through the slot to cut bone at the resection point.

Description

APPARATUS AND METHOD FOR ORTHOPEDIC SURGERY

FIELD OF INVENTION

[001] This invention relates to an apparatus and a method for orthopedic surgery, and more particularly but not exclusively to an apparatus and method for measuring resection distance of a bone from the condyle and resection of a segment of the bone, thereby facilitating a proper alignment of the prosthesis.

BACKGROUND OF INVENTION

[002] A bone tumor is an abnormal growth of cells within the bone that may be non cancerous (benign) or cancerous (malignant). The bone tumor arises in areas of rapid growth due to inherited genetic mutations, radiation, trauma etc. There are two types of bone tumors viz, primary tumors and secondary tumors. Primary tumors are ones that originate in the bone, and the secondary tumors are ones that originate from other parts of body such as lungs, breasts or prostate and affect the bone.

[003] Generally, surgery is the primary treatment for bone tumor. During surgery, a segment of the bone that has the tumor is removed and then replaced with prosthesis. For example, in case of tumor at femur or thigh bone, a segment of the femoral bone is removed and replaced with prosthesis. During the process, initially, a length of the segment of the bone having tumor that is to be removed is determined from the femoral condyle. The length of the segment determines the length of the prosthesis to be introduced. Thereafter, the segment is removed. A prosthesis stem is then introduced into the exposed bone canal of the remaining stalk of the bone. Alignment of the prosthesis is governed by the bone canal.

[004] Further, an important factor in proper alignment of the prosthesis is the interface of the prosthesis with that of the exposed bone canal of the remaining stalk. To ensure proper alignment of the prosthesis with the remaining stalk, a face of the prosthesis has to be substantially perpendicular to an axis of the bone canal of the remaining stalk of the bone. In the case where there is no proper alignment of the prosthesis face with that of the axis of the bone canal of the remaining stalk, a stepped or diameter transition part of the prosthesis stem experiences high load thereby causing structural failure of the prosthesis stem. Therefore, the cut made on the femoral bone should be at an appropriate resection distance and perpendicular to the axis of the bone canal of the remaining stalk.

[005] At present, a metric scale is being used for determining a length of the segment of the bone to be removed, and then a point where the bone is to be cut is marked. Thereafter, a power saw is used to cut the bone at the marking. With the aforementioned procedure, possibility of making an error in marking of the resection length from the bone condyle may not be ruled out at least due to lack of proper gripping of the metric scale, which causes the metric scale to move or slide on the surface of the bone or the bone condyle. Additionally, in the event where the bone has a tumor, presence of tumor may obstruct a placement of the scale on the bone and hence makes the process of measuring the resection length a tedious and time consuming task. Further, it should also be noted that if the bone has a curvature, use of the metric scale to measure and mark the length of the segment of the bone to be removed is difficult and will often result in improper or inaccurate marking.

[006] Further, once the distance of the cut is determined, the metric scale is removed and the power saw is used to cut the bone. The cuts which are not perpendicular to the axis of the bone canal may cause misalignment of the prosthesis. Therefore, the power saw has to be appropriately positioned and proper care has to be taken so that a plane in which the saw moves is perpendicular to the axis of the bone canal.

[007] Therefore, there is a need for an apparatus that ensures proper measurement of the length of the bone segment to be cut, and facilitates the cutting of the bone in a direction substantially perpendicular to the bone canal axis.

OBJECT OF INVENTION

[008] The principal object of this invention is to provide an apparatus to correctly measure a resection length of the bone by offsetting a measuring element of the apparatus from the bone and further to facilitate proper positioning and movement of a saw blade to cut the bone.

[009] Another object of the invention is to provide an apparatus to measure a resection length of a curved bone or a straight bone or a bowed bone as well as to facilitate proper positioning and movement of a saw blade to cut the bone so as to obtain perpendicularity of the cut with respect to the bone canal axis. [0010] A further object of the invention is to provide a method for measuring the resection length of the bone, and positioning the saw blade to cut the bone so as to obtain perpendicularity of the cut with respect to the bone canal axis and thereby facilitating proper alignment of the prosthesis.

STATEMENT OF INVENTION

[0011] Accordingly the invention provides an apparatus for orthopedic surgery having a fixture with a supporting plate and a guide bar. The supporting plate and the guide bar are held transversely to each other by a holding element. Further, the apparatus includes a jig assembly having a cutting block with a first surface and a second surface. The second surface of the cutting block is configured to engage at least two clamps moveable relative to each other. The cutting block defines a slot extending from the first surface to the second surface. Further, the jig assembly is engageable with the guide bar of the fixture in a moveable manner.

[0012] There is also provided a method of measuring a resection distance on a tumor bone and cutting the tumor bone at the resection distance. The method includes providing, on the tumor bone, an apparatus having a fixture with a supporting plate and a guide bar with markings to enable measurement. The fixture is engageable with a jig assembly having a cutting block with a slot there through and a plurality of clamps. Further, the supporting plate is provided adjacent to a condyle of the bone and the jig assembly is positioned away from the condyle, along the guide bar and beyond the tumor at a resection point. Thereafter, the bone is clamped at the resection point. The jig assembly is disengaged from the guide bar and a saw blade is introduced through the slot in the cutting block thereby performing cutting of the bone at the resection point. Further, providing circular plate in the jig assembly allows the measurement of resection point on the bone canal axis from medial and lateral condyle.

[0013] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

BRIEF DESCRIPTION OF FIGURES

[0014] This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:;

[0015] FIG. 1 depicts a perspective view of the apparatus used for orthopedic surgery according to an embodiment.;

[0016] FIG. 2 depicts a side view of the apparatus of FIG. 1 ;

[0017] FIG. 3 depicts a top view of of the apparatus of FIG. 1 ; [0018] FIG. 4 shows a tumor femoral bone;

[0019] FIG.5 shows a perspective view of the tumor femoral bone of FIG. 4 being held by the apparatus of FIG. 1 ;

[0020] FIG.6 shows a perspective view of the tumor femoral bone held by a jig assembly of the apparatus of FIG. 1 ; and

[0021 ] FIG. 7 shows a perspective view of the bone after removing the tumor.

DETAILED DESCRIPTION OF INVENTION

[0022] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[0023] The embodiments herein achieve a proper measurement of the resection distance of the bone and appropriate positioning of the saw blade to cut the bone so as to ensure perpendicularity of the cut with respect to the bone canal and thereby facilitating proper alignment of the prosthesis by using the apparatus as described herein below. Referring now to the drawings, and more particularly to FIGS. 1 through 7, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.

[0024] FIGS. 1 , 2 and 3 show a perspective view, a side view and a top view, respectively, of the apparatus 10 used for orthopedic surgery according to an embodiment. The apparatus 10 includes a fixture 100 and a jig assembly 200.

[0025] The fixture 100 further has a supporting plate 102 and a guide bar 106 engaged with the supporting plate 102 through a holding element 104. The supporting plate 102 has a connecting element 102a which is connected to a first part 104a of the holding element 104 via a sleeve 102b in a moveable manner. The sleeve 102b is configured to rotate inside the first part 104a of the holding element 104. The connecting element 102a is configured to move telescopically with respect to the first part 104a of the holding element 104 and the sleeve 102b. The first part 104a of the holding element 104 further has a first locking element 103a engageable with each of a corresponding second locking element 103b (not shown) provided on the connecting element 102a and a corresponding third locking element 103c (not shown) of the sleeve 102b to restrict the movement of the connecting element 102a and thereby restricting the movement of the supporting plate 102. For example, the first locking element 103a may be but not limited to a screw, a bolt or a shaft and each of the corresponding second clocking elements 103b and 103c may be but not limited to an aperture or an indent provided on the surface of the connecting element 102a and the sleeve 102b thereof.

[0026] Further, a second part 104b of the holding element 104 is configured to secure a first end of the guide bar 106. The guide bar 106 is provided with markings M to enable measurement of the resection distance. The holding element 104 is provided with markings Ml and the sleeve 102b is provided with markings M2 to enable measurement of sub condylar angle.

[0027] Further, it should be noted that the holding element 104 having a different structure than the one described above is also within the scope of the invention as long as the structure does not deter the intended function of the holding element as explained in this specification and as is apparent from the accompanying drawings. [0028] The guide bar 106 has a projection P which is in a plane perpendicular to the markings. Further, the second part 104b of the holding element 104 defines two prongs in a horizontal plane to secure the projection P of the guide bar 106. Further, it is also within the scope of the invention to provide a depression on the guide bar 106 as an alternate to projection P, in which case, the second part 104b of the holding element 104 will define two prongs in the vertical plane for securing the depressed portion of the guide bar 106.

[0029] Further, the jig assembly 200 has a shaft S. A cutting block 202 is mounted on the shaft S. The cutting block 202 is adapted to house a first c-clamp 204a and a corresponding second c-clamp 204b on a side thereof. The first c-clamp 204a and the second c-clamp 204b are moveable relative to each other. The movement of the c-clamps 204a and 204b is controlled by an adjusting element 203. The adjusting element 203 may be a threaded screw upon which the c-clamps 204a and 204b are mounted and housed inside the cutting block 202. Further, a slot 206 is provided on the cutting block 202 that extends from a side of the cutting block 202 opposite to the side housing the c-clamps 204a and 204b. The slot 206 is configured to guide a saw blade 300 (as shown in FIGS. 5 and 6 ) therein.

[0030] A circular plate 208 having markings thereupon to enable a measurement of angular displacement of the c-clamps 204a and 204b as well as the cutting block 202 is provided on the shaft S. A rotation of circular plate 208 and the shaft S is controlled by a screw R or the like provided on the circular plate 208.

[0031 ] The jig assembly 200 further has a mounting element 210. The mounting element 210, on one side thereof, is adapted to engage the shaft S in a moveable manner. The shaft S is telescopically moveable with respect to the mounting element 210. The telescopic movement of the shaft S moves the cutting block 202 along with the c-clamps 204a and 204b in upward and downward directions. The movement of the shaft S facilitates positioning of the first c-clamp 204a, the second c-clamp 204b and the cutting block 202 over the bone. The movement of the shaft S is restrained by the shaft locking element L.

[0032] Further, the mounting element 210 has a guiding element 212 which engages the jig assembly 200 with the guide bar 106 in a slidable manner. The guiding element 212 may include a jig locking element (not shown) for locking the jig assembly 200 at a desired position on the guide bar 106. The guide bar 106 further may include a guide locking element (not shown) corresponding to jig locking element (not shown) for facilitating the locking of jig assembly 200. The guide locking element (not shown) may be provided on the projection P of the guide bar 106 or on a surface of the guide bar 106 where the markings are provided. For example, the jig locking element (not shown) may be a screw, a bolt or a shaft and the guide locking element (not shown) may be a corresponding aperture or an indent. Further, if a depression is provided on the guide bar 106 as an alternate to projection P, then the guide locking element (not shown) may be provided inside the depression or on the surface of the guide bar 106 where the markings are provided.

[0033] A method for using the apparatus 10 is described below as a non-limiting example. In operation, a bone having tumor is identified. FIG. 4 shows a femoral bone B having a condyle C with tumor T. The orthopedic surgery in this case involves removing the tumor T along with the condyle C by determining a length of a segment of the bone B to be removed.

[0034] Initially, an approximate length of the segment of the bone B to be removed and a sub condylar angle are determined through the image obtained from employing medical imaging techniques. Thereafter, the apparatus 10 is provided on the bone B as shown in FIG. 5. The jig assembly 200 is positioned away from the supporting plate 102 and on the guide bar 106 at the approximate length determined from the image obtained. The apparatus 10 including the supporting plate 102 is adjusted to define the predetermined sub condylar angle. The supporting plate 102 of the fixture 100 is then made to abut the condyle C of the bone B. Further, the guide bar 106 is offset from the bone B so as not to touch the tumor T. During offsetting, the connecting element 102a along with the sleeve 102b and the first part 104a of the holding element 104 are moved relative to each other so as to attain a position where the guide bar 106 is offset at an appropriate distance away from the bone canal axis of the bone B. The guide bar 106 is thereby disposed in a plane substantially parallel to the axis of the bone canal. Thereafter, the connecting element 102a and the sleeve 102b are locked to the first part 104a of the holding element 104 by engaging the first locking element 103a, the second locking element 103b and the third locking element 103c.

[0035] The position of the jig assembly 200 may further be adjusted by making the jig assembly 200 to slide over the guide bar 106 along an exposed portion of the bone B. .At a point P, which may be referred to as resection point, the jig assembly 200 may be locked. The resection point P is an imaginary point on the axis of the bone canal. A resection distance will be the distance of the resection point P from the bone condyle C.

[0036] Thereafter, the first c-clamp 204a is moved away from the second c-clamp 204b by turning the adjusting element 203. The movement of the first c-clamp 204a away from the second c-clamp 204b defines a space sufficient enough to accommodate the portion of the bone B near the resection point P. Further, the shaft S is moved up or down in order for the first c-clamp 204a and the second c-clamp 204b to be positioned such that the resection point P on the bone B is located inside the space created by the c-clamps 204a and 204b there between. The adjusting element 203 is rotated so that the first c-clamp 204a and the second c-clamp 204b move towards each other thereby gripping the bone B at the resection point P.

[0037] Further, it has to be noted that if the bone B has a curvature, the height of the jig assembly 200 may be altered by moving the shaft S and further, the height of the guide bar 106 may be altered by moving the connecting element 102a. Also, the angular orientation of the cutting block 202, the first c-clamp 204a and the second c-clamp 204b may be adjusted by rotating the circular plate 208 by the screw R.

[0038] Upon gripping of the bone B by the first c-clamp 204a and the second c- clamp 204b, the fixture 100 and the jig assembly 200 are disengaged. Disengaging the fixture 100 and the jig assembly 200 includes sliding the fixture 100 away from the condyle C as well as the jig assembly 200 and moving the fixture 100 along with the circular plate 208, the mounting element 210 and the guiding element 212 away from the cutting block 202 so that the shaft S and the cutting block 202 with the first and second c- clamps 204a and 204b remain on the bone B as shown in FIG. 6. The aforementioned process of disengaging the fixture 100 and the jig assembly 200 may be carried out subsequently or simultaneously.

[0039] Further, the saw blade 300 is introduced through the slot 206 defined in the cutting block 202 to cut the bone B at the resection point RP. FIG. 7 shows remaining stalk of the bone B along with the jig assembly 200 and the saw blade 300 after the segment of the bone B has been removed. Thereafter, a prosthesis having a length equal to the resection distance is provided.

[0040] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Claims

WE CLAIM :-

1. An apparatus for orthopedic surgery comprising:

a fixture having a supporting plate and a guide bar, said supporting plate and said guide bar being held transversely to each other by a holding element; and

a jig assembly having a cutting block with a first surface and a second surface, said second surface configured to engage at least two clamps moveable relative to each other and said cutting block defining a slot extending from the first surface to the second surface,

wherein said jig assembly is engageable with said guide bar of said fixture in a moveable manner.

2. The apparatus as claimed in claim 1 , wherein

said supporting plate is connected to the holding element in a moveable manner through a connecting element and a sleeve;

said guide bar is secured to the holding element by a plurality of prongs defined therein in a direction transverse to the supporting plate; and

said guide bar defines a plurality of markings to enable measurement.

3. The apparatus as claimed in claim 2, wherein a guiding element provided on a mounting element of said jig assembly engages said jig assembly with said guide bar.

4. The apparatus as claimed in claim 3, wherein said cutting block and said mounting element are connected to each other by a shaft having a circular plate with a plurality of markings to enable measurement of angular orientation of the cutting block relative to the mounting element; and

said shaft is telescopically moveable with respect to the mounting element.

5. The apparatus as claimed in claim 3, wherein a jig locking element provided on said guiding element engages a corresponding locking element provided on said guide bar to restrain a movement of said guiding element with respect to said guide bar.

6. A method for measuring a resection distance on a tumor bone and cutting the tumor bone at the resection distance, said method comprising:

providing, on the tumor bone, an apparatus having a fixture with a supporting plate and a guide bar with markings to enable measurement, said fixture being engaged with a jig assembly having a cutting block with a slot there through and a plurality of clamps;

adjusting the apparatus to define a predetermined sub condylar angle;

providing said supporting plate adjacent to a condyle of the bone;

offsetting the guide bar relative to the bone;

adjusting the jig assembly which is positioned away from the condyle,along the guide bar and beyond the tumor to reach a resection point;

clamping the bone at the resection point;

disengaging the guide bar from a shaft provided in the jig assembly; introducing a blade through the slot in the cutting block; and cutting the bone at the resection point.

7. The method as claimed in claim 6, wherein said supporting plate and said guide bar are transverse to each other.

8. The method as claimed in claim 6, wherein a surface of the cutting block on which the slot is provided is perpendicular to an axis of a canal of the bone.

9. An apparatus substantially as herein above described in the specification with reference to the accompanying drawings.

10. A method substantially as herein above described in the specification with reference to the accompanying drawings.