DESC:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10 and Rule 13)

1. TITLE OF THE INVENTION:
FEMORAL IMPACTOR EXTRACTOR
2. APPLICANT:
Meril Corporation (I) Private Limited, an Indian company of the address Survey No. 135/139, Muktanand Marg, Bilakhia House, Pardi, Vapi, Valsad-396191 Gujarat, India.

The following specification particularly describes the invention and the manner in which it is to be performed:

FILED OF THE INVENTION
[001] The present disclosure relates to a medical device. More particularly, the present disclosure relates to a femoral impactor extractor.
BACKGROUND OF THE INVENTION
[002] Knee replacement or knee arthroplasty is a surgical procedure intended to replace the affected portion of the knee. Knee joint is the engagement between the femur bone and the tibia bone. Knee replacement mainly includes two types of surgical procedures partial knee replacement and full knee replacement. In total knee replacement, weight bearing surfaces such as femur, tibia and patella are resurfaced with implants. In partial knee replacement, a prosthetic is implanted after removing the damaged portion of the knee.
[003] To implant the prosthetic (or implant), an operator requires a combination of instruments to perform the said procedure. For example, an impactor extractor instrument is used to place a femoral component of the knee implant inside the knee portion and extract it. Such an instrument, assists in providing a smooth passage to the implant inside the knee and retrieving the implant from the knee.
[004] The conventional impactor extractor instrument includes a holding mechanism (such as arms) for securing the femoral component with the instrument. However, the conventional holding mechanisms are prone to dislodge or de-engage from the femoral component due to accidental touches by the operator. This may lead to dislocation of the femoral component from the target area, which may cause injury to the patient. Further, the disengagement of the femoral component may result in dropping of the femoral component during the surgical procedure. Because of sterilization requirements, such a femoral component becomes unusable, which leads to the wastage for the healthcare providers and/or increases the patient’s medical costs.
[005] Therefore, there arises a need for an instrument with improved holding mechanism to overcome the problems associated with a conventional instrument.
SUMMARY OF THE INVENTION
[006] The present invention relates to an instrument for impacting and extracting a femoral component in a joint replacement procedure. The instrument includes a body and a pair of arms. The arms are coupled to the body and include a claw, a gripping member and two protruding portions. The claws are provided at a distal end of the arm and configured to engage with a femoral component. The gripping portions are provided at a proximal end of the arm. The protruding portions are disposed between the claw and the gripping portion and extends towards the body. Each protruding portion of each arm is pivotably coupled to the body at a pivot point. In an embodiment, the pivot point is located between a longitudinal axis of the body, and an axis parallel to the longitudinal axis of the body and passing through a distal end of the respective claw.
[007] The foregoing features and other features as well as the advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.
BRIEF DESCRIPTION OF DRAWINGS
[008] The summary above and the detailed description of descriptive embodiments, is better understood when read in conjunction with the apportioned drawings. For illustration of the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the disclosure is not limited to specific methods and instrumentality disclosed herein. Moreover, those in the art will understand that the drawings are not to scale.
[009] Fig. 1a depicts a cross-sectional view of a femoral impactor extractor instrument 100, according to an embodiment of the present disclosure.
[0010] Fig. 1b depicts an exploded view of the femoral impactor extractor instrument 100, according to an embodiment of the present disclosure.
[0011] Fig. 2a depicts a perspective view of a head 101, according to an embodiment of the present disclosure.
[0012] Fig. 2b depicts another perspective view of the head 101, according to an embodiment of the present disclosure.
[0013] Fig. 3 depicts a perspective view of an adaptor 106, according to an embodiment of the present disclosure.
[0014] Fig. 3a depicts a front view of the adaptor 106, according to an embodiment of the present disclosure.
[0015] Fig. 4 depicts a perspective view of a body 102, in according to an embodiment of the present disclosure.
[0016] Fig. 5 depicts a cross-sectional view of the body 102 along with an adaptor 106, according to an embodiment of the present disclosure.
[0017] Fig. 6 depicts a side perspective view of an arm 107, according to an embodiment of the present disclosure.
[0018] Fig. 7 depicts an exploded view of the coupling between the arms 107 and the body 102, according to an embodiment of the present disclosure.
[0019] Fig. 8 depicts an illustrated view of the femoral impactor extractor instrument 100 showing arcs of rotation of the claws 107a, in accordance with an embodiment of the present disclosure.
[0020] Fig. 9 depicts a top perspective view of the body 102 along with a plurality of torsion springs 115, according to an embodiment of the present disclosure.
[0021] Fig. 10 depicts a side perspective view showing the body 102 coupled to the arm 107, according to an embodiment of the present disclosure.
[0022] Fig. 11 depicts a perspective view of an elongated shaft 104 and a handle 110, according to an embodiment of the present disclosure.
[0023] Fig. 12 depicts a perspective view of a proximal portion of the handle 110, according to an embodiment of the present disclosure.
[0024] Fig. 13 depicts a femoral component 300 mounted on the femoral impactor extractor instrument 100, according to an embodiment of the present discourse.
DETAILED DESCRIPTION OF DRAWINGS
[0025] Prior to describing the disclosure in detail, definitions of certain words or phrases used throughout this patent document will be defined: the terms "include" and "comprise", as well as derivatives thereof, mean inclusion without limitation; the term "or" is inclusive, meaning and/or; the phrases "coupled with" and "associated therewith", as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have a property of, or the like. Definitions of certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art will understand that such definitions apply in many, if not most, instances to prior as well as future uses of such defined words and phrases.
[0026] Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all embodiments” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise.
[0027] Although the operations of exemplary embodiments of the disclosed method may be described in a particular, sequential order for convenient presentation, it should be understood that the disclosed embodiments can encompass an order of operations other than the particular, sequential order disclosed. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Further, descriptions and disclosures provided in association with one particular embodiment are not limited to that embodiment, and may be applied to any embodiment disclosed herein. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed system, method, and apparatus can be used in combination with other systems, methods, and apparatuses.
[0028] Furthermore, the described features, advantages, and characteristics of the embodiments may be combined in any suitable manner. One skilled in the relevant art will recognize that the embodiments may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments. These features and advantages of the embodiments will become more fully apparent from the following description and apportioned claims, or may be learned by the practice of embodiments as set forth hereinafter.
[0029] The present disclosure relates to a femoral impactor extractor instrument (hereinafter instrument) for use during knee replacement procedures. According to an embodiment, the instrument includes a holding mechanism configured to engage with a femoral component. The holding mechanism securely grips the femoral component and prevents unwanted movements. As a result, disengagement of the femoral component from the instrument by accidental touches is avoided, thereby improving the overall safety and effectiveness of the knee replacement procedures. This leads to a better patient outcome.
[0030] Now referring to the figures, Fig. 1a depicts a cross-sectional view of a femoral impactor extractor instrument 100 or (an instrument 100) for impacting and extracting a femoral component in a joint replacement procedure and Fig. 1b depicts an exploded view of the instrument 100, according to an embodiment of the present disclosure. The instrument 100 can be used during knee replacement procedures. For example, the instrument 100 is used to grip a femoral component while implanting the femoral component during a knee replacement procedure (either initial implantation and/or a revision procedure) as well as while extracting a previously implanted femoral component during a revision procedure. In other words, the instrument 100 can function both as an impactor and as a retractor (extractor) during the implantation procedure. The femoral component may include a trial femoral component used during a trial phase of the knee replacement surgery or a final femoral component to be implanted in a patient’s body. The instrument 100 has a proximal end 100a and a distal end 100b. In an embodiment, the instrument 100 includes a head 101, a body 102, an adaptor 106, a plurality of arms 107, and an elongated shaft 104.
[0031] The head 101 is provided towards the distal end 100b of the instrument 100. The head 101 serves as a platform for a femoral component during the implantation procedure. Figs. 2a and 2b depict the head 101 according to an embodiment. The head 101 may have any suitable shape such as, without limitation, a pyramid, cube, cuboid, sphere, cylindrical, hemisphere, frustum, etc. In an embodiment, the head 101 has an inverted frustum shape. The head 101 may be made of a biocompatible material, for example, bio-compatible plastic. In an embodiment, the head 101 has a top surface 101b towards the distal end 100b of the instrument 100. The top surface 101b of the head 101 contacts a bottom surface of a femoral component and provides support and stability to the femoral component. The top surface 101b of the head 101 can be flat, convex or concave complementing the bottom surface of the femoral component. The head 101 may include one or more grooves 101a on an outer surface of the head 101. In an embodiment, the head 101 includes two grooves 101a. The grooves 101a extend longitudinally for at least a length of the head 101 and are provided on opposite sides of the head 101. The grooves 101a provide clearance between the arms 107 and the adaptor 106 to minimize interference between the arms 107 and the head 101 and facilitate smooth movement of the arms 107 without any obstruction. In an embodiment, the head 101 includes an opening 101c provided on the top surface 101b of the head 101 and extending longitudinally for partial length of the head 101. The opening 101c is configured to receive at least a portion of a fastener 105 (e.g., a screw). In an embodiment, the opening 101c includes a threaded portion provided towards a proximal end of the head 101. The threaded portion includes threads configured to engage with corresponding threads of the fastener 105 to couple the head 101 with the adaptor 106. Although the coupling of the head 101 and the adaptor 106 has been explained using a threaded mechanism, any other suitable coupling mechanism or fastener including, but not limited to, a nut-bolt, rivets, etc., can be used without deviating from the scope of the present disclosure. The head 101 has a bottom surface 101f towards the proximal end 100a of the instrument 100. The bottom surface 101f of the head 101 can be flat, concave or convex. In an embodiment the bottom surface 101f of the head 101 is flat complementing a corresponding surface of the adaptor 106. In an embodiment, the head 101 includes a cavity 101d configured to receive a portion of the adaptor 106 as explained later. The opening 101c extends to the cavity 101d.
[0032] The adaptor 106 (shown in Figs. 3 and 3a) is at least partially disposed within the body 102 towards the distal end 100b of the instrument 100. The adaptor 106 is configured to couple the head 101 to the body 102 which is explained later. The adaptor 106 has a proximal portion 106d towards the proximal end 100a of the instrument 100 and a distal portion 106e extending away from the proximal portion 106d towards the distal end 100b of the instrument 100. In an embodiment, the proximal portion 106d of the adaptor 106 has a cylindrical shape, though the proximal portion 106d of the adaptor 106 may have any other suitable shape. The distal portion 106e of the adaptor 106 is configured to reside in the cavity 101d of the head 101. The distal portion 106e of the adaptor 106 has a shape and dimensions corresponding to those of the cavity 101d of the head 101. In an embodiment, the distal portion 106e of the adaptor 106 and the cavity 101d of the head 101 are generally cylindrical having a D-shaped cross-section. This reduces the chances of rotational motion between the head 101 and the adaptor 106. In an embodiment, the adaptor 106 includes an aperture 106a extending from the distal portion 106e into the proximal portion 106d for at least a partial length. The aperture 106a is configured to receive at least a portion of the fastener 105, thereby coupling the head 101 and the adaptor 106. In the depicted embodiment, the fastener 105 is a screw, though any other suitable fastener (e.g., a bolt, a rivet, etc.) can be used. In an embodiment, the aperture 106a is provided with threads 106a1 on its inner surface configured to engage with the corresponding threads on the fastener 105. The threads on the fastener 105 are complementary to the threads of the threaded portion of the opening 101c and the threads 106a1 of the aperture 106a. The adaptor 106 is configured to transmit the force from and/or on the elongated shaft 104 to the head 101 (explained later). In an embodiment, the adaptor 106 includes a pair of first longitudinal slots 106b provided on the proximal portion 106d and extending longitudinally for at least a partial length of the adaptor 106. The first longitudinal slots 106b are disposed adjacent to each other, on either side of a longitudinal axis of the adaptor 106. The first longitudinal slots 106b extend from a front side 106f to a back side (not shown) of the adaptor 106. According to an embodiment, the adaptor 106 includes a pair of second longitudinal slots 106c provided on the proximal portion 106d. The second longitudinal slots 106c extend longitudinally for a partial length of the adaptor 106. The pair of second longitudinal slots 106c are situated diametrically opposite to each other. Each second longitudinal slot 106c of the pair of second longitudinal slots 106c is provided on a lateral side of the adaptor 106. The adaptor 106 may be made from a material such as, without limitation, stainless steel, titanium, Co-Cr, etc. or any biocompatible material. In an example implementation, the adaptor 106 is made of 17-4PH stainless steel.
[0033] Referring to Fig. 4, the body 102 has a proximal end 102a and a distal end 102b. The body 102 may be made of a material such as, without limitation, stainless steel, titanium, Co-Cr, etc. or any biocompatible material. In an embodiment, the body 102 is made of 17-4PH stainless steel. In an embodiment, the body 102 has a tubular structure defining a passage 102c extending from the proximal end 102a to the distal end 102b. The passage 102c is configured to receive the elongated shaft 104. The passage 102c has a proximal section 102c1 and a distal section 102c2 (depicted in Fig. 5). The distal section 102c2 of the passage 102c receives at least a portion of the proximal portion 106d of the adaptor 106. The body 102 and the adaptor 106 are coupled, for example, using a pair of second pins 113 (shown in Fig. 5), though any other suitable mechanism may be used, instead of, or in addition, to the second pins 113 without deviating from the scope of the present disclosure. In an embodiment, a pair of orifices 102e are provided on the body 102 towards the distal end 102b. The pair of orifices 102e are diametrically opposite to each other and are disposed on lateral sides of the body 102 (shown in Fig. 5). Each orifice 102e of the pair of orifices 102e is configured to receive a corresponding second pin 113 of the pair of second pins 113. Each second pin 113 extends from a respective orifices 102e of the pair of orifices 102e into a corresponding second longitudinal slot 106c of the adaptor 106, thereby coupling the adaptor 106 to the body 102 (shown in Fig. 5). The pair of second pins 113 have enough length to penetrate through the corresponding pair of orifices 102e and slidably engage with the corresponding pair of second longitudinal slots 106c. Each second pin 113 is configured to move within the corresponding second longitudinal slot 106c when the adaptor 106 moves. The coupling of the body 102 with the adaptor 106 via the pair of second pins 113 as explained herein enables relative longitudinal motion between the adaptor 106 and the body 102, while preventing de-coupling of the adaptor 106 from the body 102 during the operation of the instrument 100.
[0034] In an embodiment, the proximal section 102c1 is provided with internal threads 102c3 towards the proximal end 102a of the body 102. The internal threads 102c3 are used to couple the body 102 with the elongated shaft 104. The proximal section 102c1 and the distal section 102c2 of passage 102c may have a uniform diameter or non-uniform diameter. In an embodiment, the proximal section 102c1 and the distal section 102c2 of the passage 102c have different diameters. In an embodiment, the diameter of proximal section 102c1 of the passage 102c smaller than the diameter of the distal section 102c2 of the passage 102c as depicted in Fig. 5. In another embodiment, the diameter of the proximal section 102c1 of the passage 102c is larger than the diameter of the distal section 102c2. The diameters of the proximal section 102c1 and the distal section 102c2 are designed such that the elongated shaft 104 is able to move linearly within the passage 102c during the operation of the instrument 100.
[0035] Referring back to Fig. 4, the body 102 includes a pair of flanges 102d extending outwards from each lateral side of the body 102 at the distal end 102b of the body 102. The flanges 102d of each pair of flanges 102d are positioned at a distance from each other such that there is a gap therebetween. The body 102 may include one or more extensions 102f at the proximal end 102a. The one or more extensions 102f facilitate in extraction of the femoral component from the surgical area, e.g., a proximal face of any of the one or more extensions 102f may be impacted by a slap hammer to extract the femoral component. The pair of flanges 102d and the extensions 102f may be integrally formed with the body 102 or may be fixedly coupled to the body 102 using any coupling method known in the art. In an embodiment, the pair of flanges 102d and the extensions 102f are integrally formed with the body 102.
[0036] The instrument 100 includes a pair of arms 107 (or arms 107) coupled to the body 102. The arms 107 may be made of a material including, but not limited to, precipitation hardened stainless steel, titanium, CoCr, nitinol or any other medical grade, biocompatible metal. In an embodiment, the arms 107 are made of stainless steel. Fig. 6 depicts one of the arms 107, according to an embodiment. Each arm 107 includes a claw 107a, a gripping portion 107b and at least one protruding portion 107c. In the depicted embodiment, each arm 107 includes two protruding portions 107c. The claws 107a are provided towards the distal end 100b and are configured to grip the femoral component (e.g., a trial femoral component) during the implantation procedure. The gripping portions 107b are provided towards the proximal end 100a. The gripping portions 107b enable the user to manipulate the arms 107 to cause the claws 107a to grip and/or release the femoral component as needed during the implantation procedure. In an embodiment, the gripping portion 107b is provided with ridges 107e on at least a partial a length of the gripping portion 107b to improve the grip on the arm 107. A portion of the claws 107a of the arms 107 extends over the head 101 (depicted in Fig. 1). In an embodiment, a distal end of the claw 107a has a curved portion 107a1 having a pre-defined shape (e.g., J shape, L shape, etc.) to provide a better grip to the femoral component.
[0037] The protruding portions 107c are disposed between the claw 107a and the gripping portion 107b. Each protruding portion 107c extends from a first end 107f1 disposed towards the gripping portion 107b to a second end 107f2 disposed towards a longitudinal axis of the body 102. The length of the protruding portion 107c is designed such that the protruding portions 107c of each arm 107 partially encircle a portion of the body 102. The protruding portions 107c of each arm 107 are pivotably coupled to the body 102 towards the second end 107f2 of the protruding portions 107c at a pivot point such that the claw 107a and the gripping portion 107b of that arm 107 rotate around the pivot point. For example, in response to the gripping portion 107b of an arm 107 rotating towards the longitudinal axis of the body 102, the claw 107a of the arm 107 moves away from the longitudinal axis of the body 102 around the pivot. Similarly, in response to the gripping portion 107b of the arm 107 rotating away from the longitudinal axis of the body 102, the claw 107a of the arm 107 rotates towards the longitudinal axis of the body 102. The position of the pivot point vis-à-vis the distal end of the claw 107a defines a turning radius and a turning arc followed by the claw 107a when the corresponding gripping portion 107b is manipulated. The position of the pivot points for the arms 107 are designed such that when the claws 107a are coupled to a femoral component, the turning arc of the claws 107a provides a locking action, preventing detachment of the claws 107a from the femoral component even when the gripping portions 107b are accidentally pressed. In an embodiment, the protruding portions 107c of each arm 107 are coupled to the body 102 at a pivot point located between the longitudinal axis of the body 102 and an axis, which is parallel to the longitudinal axis of the body 102 and passes through the distal end of the claw 107a. In an embodiment, the protruding portions 107c of each arm 107 are pivotably coupled with the body 102 at the second end 107f2 of the protruding portions 107c using any suitable coupling mechanism. In an example implementation, the protruding portions 107c of each arm 107 are coupled to the body 102 using a fastener, for example, a first pin 109, though any other suitable fastener (e.g., a screw) may be used without deviating from the scope of the present disclosure. Fig. 7 depicts an exploded view of the coupling between the body 102 and the arms 107 using the first pins 109, according to an embodiment. An aperture 107c1 is provided on each protruding portions 107c at the second end 107f2 and a corresponding pair of apertures 103 is provided on each of a front and a back side of the body 102. The apertures 107c1 align with the apertures 103 and are configured to receive the first pin 109, thereby pivotably coupling the arms 107 to the body 102. The first pin 109 is introduced inside the respective aperture 107c1 of the protruding portions 107c and the respective apertures 103 on the body 102, thereby coupling the arm 107 and the body 102. The first pins 109 pivotably couple the arm 107 to the body 102 allowing the arms 107 to rotate around the body as described above.
[0038] In an embodiment, the first pins 109 passes through the first longitudinal slots 106b of the adaptor 106 thereby coupling the adaptor 106 and the body 102. Since the first pins 109 extend through the first longitudinal slots 106b of the adaptor 106, the linear movement of the adaptor 106 is restricted to the length of the slots 106b. This ensures secure coupling of the adaptor 106 and the body 102.
[0039] The first pins 109 may be made from any suitable material such as, without limitation, stainless steel, CoCr, titanium, etc., or any suitable biocompatible material. In an example, implementation, the first pins 109 are made of 17-4PH stainless steel.
[0040] Fig. 8 illustrates the locking action due to the coupling between the arms 107 and the body 102 as described herein. In Fig. 8, axis A represents the longitudinal axis of the body 102. Further, as shown, axis B passes through the distal end of the claw 107a and is parallel to the longitudinal axis of the body 102, i.e., parallel to the axis A. As seen from Fig. 8, a pivot point P at which the protruding portion 107c is coupled to the body 102 (as defined by the position of the apertures 107c1 and the first pin 109 is located between the axes A and B. Fig. 8 also illustrates the turning arcs followed by the claws 107a when the gripping portions 107b are manipulated. As can be seen, the claws 107a rotate away from the body 102 in a downward trajectory when the gripping portions 107b are pressed towards the body 102. As a result, when the claws 107a are coupled to corresponding coupling grove provided in the femoral component, the claws 107a press against the coupling grooves in a downward direction and prevent the claws 107a from disengaging from the coupling grooves, thus, effectively locking the claws 107a with the femoral component. In contrast, in a conventional instrument, the pivot points at which arms (hereinafter, conventional arms) of a conventional instrument are coupled to a body (hereinafter, conventional body) of the conventional instrument are located further away from a longitudinal axis of the conventional body than an axis passing through a distal end of claws (hereinafter, conventional claws) of the conventional instrument and consequently, a turning arc followed by the conventional claws define an upward trajectory. In such an arrangement, when the conventional claws are engaged with the femoral component and gripping portions (hereinafter, conventional gripping portions) of the conventional instrument are pressed towards each other, even if accidentally, the claws rotate upward and away from the femoral component, thereby, increasing a risk of disengaging them from the femoral component. Thus, the proposed coupling between the arms 107 and the body 102 of the instrument 100 eliminates the risk of disengagement of the femoral component from the instrument 100 and provides an effective, secure locking mechanism.
[0041] Referring back to Fig. 6, each of the arms 107 may include a projection 107d extending away from the arm 107 towards the body 102. The projection 107d sits against the body 102 at the distal end 102b of the body 102 (shown in Fig. 1a). The projections 107d keep the claws 107a at a pre-defined distance from each other in a default state (also, referred to as a rest position), i.e., when there is no force applied on the arms 107. The distance between the claws 107a may be chosen based upon the size of femoral component to be coupled to the instrument 100.
[0042] In an embodiment, each arm 107 includes a torsion spring 115(shown in Fig. 9). The torsion spring 115 provides a controlled force and resistance when operating the respective arm 107. When the gripping portions 107b of the arms 107 are pressed, the claws 107a move away from each other. This movement compresses the torsion spring 115. Further, when the gripping portions 107b are released, the torsion springs 115 returns to a normal (or rest state), exerting force on the claws 107a, returning them to their default position. The torsion spring 115 is coupled to the body 102 using any suitable coupling mechanism, for example, using a fastener. In an example implementation, each torsion spring 115 is coupled to the flanges 102d of the body 102 using a third pin 111 as depicted in Figs. 9 and 10. An aperture 102d1 is provided on each flange 102d of the body 102 to receive the third pin 111. The third pins 111 provides additional stability and reinforcement to a joint where the torsion springs 115 are coupled to the pairs of flanges 102d. Each torsion springs 115 include a first end 115a, a second end (not shown) and coils 115b disposed therebetween. The coils 115b define an opening (not shown). The first end 115a rests within a grove 107e (shown in Fig. 10) which is provided on an inner surface of the arm 107. The second end rests against the lateral side of the body 102. The opening aligns with the apertures 102d1 and receives the corresponding third pin 111. The arms 107 may be made of a material such as, without limitation, stainless steel, Co-Cr, titanium, etc. or any other suitable biocompatible material. In an exemplary implementation, the arms 107 are made of 17-4PH stainless steel. The torsion springs 115 and the third pins 111 may be made of a material such as, without limitation, stainless steel, Co-Cr, titanium etc. or any other suitable biocompatible material. In an exemplary embodiment, the torsion springs 115 and the third pins 111 are made of 17-4PH stainless steel.
[0043] Fig. 11 depicts a handle 110 and the elongated shaft 104 of the instrument 100. The elongated shaft 104 resides in the passage 102c of the body 102. The elongated shaft 104 includes a non-threaded portion 104a provided towards a distal end of the elongated shaft 104 and a threaded portion 104b provided towards a proximal end of the elongated shaft 104. The diameter of the elongated shaft 104 and the diameter of the passage 102c of the body 102 are designed to allow the elongated shaft 104 to move longitudinally. In an embodiment, the elongated shaft 104 is coupled to the adaptor 106 thus, the adaptor 106 moves longitudinally, in response to the longitudinal motion of the elongated shaft 104. The elongated shaft 104 is generally cylindrical. The elongated shaft 104 is coupled to the body 102 at the proximal end 102a using any suitable coupling mechanism. In an embodiment, the elongated shaft 104 and the body 102 are coupled using a threaded mechanism. For example, threads 104c are provided on the threaded portion 104b of the elongated shaft 104 and are configured to engage with corresponding internal threads 102c3 provided on an inner surface of the passage 102c of the body 102 towards the proximal end 102a.
[0044] The handle 110 is provided at the proximal end 100a. The handle 110 is coupled to the elongated shaft 104 at a proximal end of the elongated shaft 104 using any suitable coupling mechanism such as welding, fastening, etc. In an embodiment, the handle 110 and the elongated shaft 104 are integrally coupled, forming an integrated structure. The handle 110 provides a convenient way to operate the instrument 100. The handle 110 is rotatable in clockwise and anticlockwise direction resulting in linear movement of the elongated shaft 104 due to its threaded coupling with the body 102. For example, in response to rotating the handle 110 in the clockwise direction, the elongated shaft 104 is configured to move in the distal direction and in response to rotating the handle 110 in the anticlockwise direction, the elongated shaft 104 is configured to move in the proximal direction. The handle 110 is ergonomically designed to provide a secure and comfortable grip to the user. Referring to Fig. 10, the handle 110 may have a flat surface 110d at the proximal end of the handle 110. The user can impact on the flat surface 110d using, for example, a mallet or a slap hammer, when inserting the femoral component. Optionally, the handle 110 may be removably coupled with an impacting component. The handle 110 may include a cavity 110b at the proximal end of the handle 110. The cavity 110b is configured to couple with the impacting component (not shown), such as, without limitation, a mallet or a slap hammer. In an embodiment, the cavity 110b is configured to couple with a slap hammer. The cavity 110b is configured to receive a corresponding coupling portion of the slap hammer. The cavity 110b may have a shape corresponding to the coupling portion of the slap hammer coupled to the handle 110. In an embodiment, the cavity 110b has ‘T’ shape. Further, the handle 110 may be provided with a slot 110c (shown in Fig. 12) configured to receive a projection (not shown) of the slap hammer to secure the coupling between the slap hammer and the handle 110. The handle 110 and the elongated shaft 104 may be made from a material such as, without limitation, stainless steel, CoCr, titanium, etc., or any suitable bio-compatible material. In an example implementation, the elongated shaft 104 and the handle 110 are made of 17-4PH stainless steel.
[0045] The instrument 100 includes a compression spring 108 (shown in Fig. 1b). The compression spring 108 is coiled over an outer surface of the elongated shaft 104. The compression spring 108 resides in the distal section 102c2 of the passage 102c. At least a portion of the compression spring 108 resides within the adaptor 106. The compression spring 108 facilitates relative movement between the adaptor 106 and the body 102. The compression spring 108 also provides a resilient force to help returning the elongated shaft 104 to its original position during the operation of the instrument 100. The diameter of the coil may correspond to the outer diameter of the non-threaded portion 104a of the elongated shaft 104. The proximal end of the compression spring 108 sits against a groove (not shown) provided on the inner surface of the passage 102c. The compression spring 108 remains in a compressed state between the adaptor 106 and the body 102.
[0046] An exemplary method for assembling the instrument 100 is now described. The elongated shaft 104 is coupled to body 102 by disposing the non-threaded portion 104a of the elongated shaft 104, inside the passage 102c and engaging the threads 104c of the threaded portion 104b of the elongated shaft 104 with the corresponding internal threads 102c3 of the body 102 by rotating the handle 110. The compression spring 108 is introduced inside the distal section 102c2 of the passage 102c such that a proximal end of the compression spring 108 is at a proximal end of the distal section 102c2 of the passage 102c. The compression spring 108 is wrapped around the elongated shaft 104.
[0047] Then, the adaptor 106 is inserted into the distal section 102c2 of the passage 102c of the body 102. At least a portion of the compression spring 108 resides within the adaptor 106 as explained above. The second pins 113 are introduced inside the orifices 102e of the body 102 until the second pins 113 reside into the respective second longitudinal slot 106c of the adaptor 106, thereby, coupling the body 102 and the adaptor 106.
[0048] The pair of arms 107 are placed towards the distal end 102b of the body 102 such that the apertures 103 of the body 102 come in coalition with the apertures 107c1 of the protruding portions 107c of the arms 107. The torsion springs 115 are disposed such that the first end 115a of the torsion springs 115 resides within and coupled with the corresponding groove 107e on the gripping portions 107b. The torsion springs 115 are coupled to the pair of flanges 102d by introducing the third pins 111 through the respective apertures 102d1. Then, the first pin 109 is introduced inside the respective apertures 107c1 of the protruding portions 107c and the respective apertures 103 on the body 102, thereby pivotably coupling the arms 107 and the body 102 as described earlier. The first pins 109 pass through the compression spring 108 towards a distal end of the compression spring 108, thereby coupling the compression spring 108 with the adaptor 106 via the first pins 109. Further, the adaptor 106 and the head 101 are coupled by fastening the fastener 105 inside the opening 101c and the threaded aperture 106a, respectively.
[0049] An embodiment of the operation of the instrument 100 is now explained. During the implantation procedure, a surgical incision is made over an affected compartment of the patient’s knee joint. Soft tissues are dissected to expose the compartment. Any remaining articular cartilage in the compartment is removed to create a smooth surface for the implantation. The femoral condyle of the compartment is prepared to receive a trial femoral component 300 (or femoral component 300). Though the operation of the instrument 100 has been explained using the trial femoral component 300, it can be used to impact and extract an actual femoral component of the implant too.
[0050] The femoral component 300 is coupled to the instrument 100. To couple the femoral component 300 with the instrument 100, first the handle 110 is turned in the clockwise direction. Due to the rotation of the handle 110, the elongated shaft 104 moves in the proximal direction releasing the force applied by the compression spring 108 on the adaptor 106. The adaptor 106 and the head 101 (and therefore, the top surface 101b of the head 101) move a little in the proximal direction due to the compression action of the compression spring 108.
[0051] The arms 107 are pressed at the griping portion 107b, towards the body 102 which opens the claws 107a. The femoral component 300 is then placed on top of the head 101. A bottom surface of the femoral component 300 contacts the top surface 101b of the head 101. The gripping portion 107b are manipulated such that the claws 107a engage with respective coupling grooves (not shown) provided on either side of the femoral component 300. The gripping portions 107b are then released. The coupling of the arms 107 with the body 102 as explained earlier prevents disengagement of the claws 107a from the coupling grooves of the femoral component 300 irrespective of a force applied on the gripping portions 107b as explained earlier. Thus, the instrument 100 ensures a secure grip with the femoral component 300 and eliminates disengagement even when the gripping portions 107b are accidentally pressed. The elongated shaft 104 is then rotated in the anti-clockwise direction using the handle 110 so that elongated shaft 104 moves in a distal direction and the distal end of the elongated shaft 104 contacts a distal end of the cavity 101d of the head 101. Fig. 13 depicts the femoral component 300 coupled with the instrument 100.
[0052] Now the femoral component 300 is ready to be placed inside the compartment. The femoral component 300 is then inserted into the compartment at a desired position. The instrument 100 is then impacted at the flat surface 110d of the handle 110 using a hammer or on the impacting component coupled to the handle 110 The elongated shaft 104 transmits the force to the head 101 via the adaptor 106. To de-couple the instrument 100 from the femoral component 300, first the handle 110 is rotated in anticlockwise direction. Due to the rotation of the handle 110, the elongated shaft 104 moves in the proximal direction releasing the force applied on the adaptor 106 which further allows the adaptor 106 to be moved in the proximal direction. The head 101 is gently pressed downwards and the gripping portions 107b are pressed towards each other to release the claws 107a from the femoral component 300. The instrument 100 is then withdrawn. A trial reduction of the knee joint is then performed using the femoral component 300 to assess fit, alignment, stability and a range of motion for an actual femoral implant to be implanted.
[0053] Once the surgeon is satisfied with the trial reduction, the femoral component 300 can be retracted using the instrument 100 as follows. The head 101 is aligned with the femoral component 300 such that the bottom surface of the femoral component 300 contacts the top surface 101b of the head 101. The handle 110 is rotated in anticlockwise direction to allow manipulative movements of the gripping portion 107b. The gripping portion 107b is manipulated such that the claws 107a grip the coupling grooves of the femoral component 300. The handle 110 is then rotated in anti-clockwise direction to tighten the grip of the instrument 100 over the femoral component 300 and lock any further movement of the claws 107a. Now, the femoral component 300 can be pulled from the knee.
[0054] Thus, the proposed instrument prevents any movement of the claws once the claws grip the femoral component, thereby avoiding any disengagement of the femoral component by accidental touches. This improves the overall safety and effectiveness of the knee replacement procedures and leads to a better patient outcome.
[0055] The scope of the invention is only limited by the appended patent claims. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. ,CLAIMS:WE CLAIM
1. An instrument (100) for impacting and extracting a femoral component in a joint replacement procedure, the instrument (100) comprising:
a. a body (102); and
b. a pair of arms (107) coupled to the body (102), each arm (107) comprising:
i. a claw (107a) provided at a distal end of the arm (107) and configured to engage with a femoral component;
ii. a gripping portion (107b) provided at a proximal end of the arm (107); and
iii. two protruding portions (107c) disposed between the claw (107a) and the gripping portion (107b), and extending towards the body (102);
c. wherein each protruding portion (107c) of each arm (107) is pivotably coupled to the body (102) at a pivot point;
d. wherein the pivot point is located between a longitudinal axis of the body (102), and an axis parallel to the longitudinal axis of the body (102) and passing through a distal end of the respective claw (107a).
2. The instrument (100) as claimed in claim 1, wherein each protruding portions (107c) of the arm (107) comprises an aperture (107c1), and the body (102) comprises a corresponding pair of apertures (103) aligned with the aperture (107c1), wherein the apertures (107c1) and the pair of apertures (103) are configured to receive a first pin (109), wherein the aperture (107c1) of each the protruding portion (107c) defining a respective pivot point.
3. The instrument (100) as claimed in claim 1, wherein the instrument (100) comprises:
a. a handle (110) provided at a proximal end (100a) of the instrument (100);
b. an elongated shaft (104) coupled to the handle (110) at a proximal end of the elongated shaft (104) and residing in a passage (102c) of the body (102);
c. an adaptor (106) coupled to a distal end of the elongated shaft (104); and
d. a head (101) provided at a distal end (100b) of the instrument (100) and coupled to the adaptor (106), the head (101) having a top surface (101b) configured to couple with the femoral component.
4. The instrument (100) as claimed in claim 3, wherein the elongated shaft (104) comprises threads (104c) configured to engage with internal threads (102c3) provided on an inner surface of the body (102).
5. The instrument (100) as claimed in claim 3, wherein in response to the rotation of the handle (110), the elongated shaft (104) is configured to move longitudinally.
6. The instrument (100) as claimed in claim 3, wherein the head (101) comprises a cavity (101d) configured to receive a distal portion (106e) of the adaptor (106).
7. The instrument (100) as claimed in claim 3, wherein the head (101) comprises an opening (101c) and the adaptor (106) comprises an aperture (106a) corresponding to the opening (101c) of the head (101), wherein the opening (101c) of the head (101) and the aperture (106a) of the adaptor (106) are configured to receive a fastener (105).
8. The instrument (100) as claimed in claim 3, wherein a proximal portion (106d) of the adaptor (106) is at least partially disposed within the passage (102c) of the body (102), wherein the body (102) comprises a pair of orifices (102e) and the adaptor (106) comprise a pair of second longitudinal slots (106c), wherein each orifice (102e) of the body (102) and a corresponding second longitudinal slot (106c) of the adaptor (106) are configured to receive a second pin (113).
9. The instrument (100) as claimed in claim 3, wherein the instrument (100) comprises a compression spring (108) residing in a distal section (102c2) of the passage (102c) of the body (102) and coiled over an outer surface of the elongated shaft (104).
10. The instrument (100) as claimed in claim 3, wherein the handle (110) is removably coupled with an impacting component, wherein the handle (110) comprises a cavity (110b) configured to receive a coupling portion of the impacting component and a slot (110c) configured to receive a projection of the coupling portion of the impacting component.
11. The instrument (100) as claimed in claim 3, wherein each first pin (109) passes through a corresponding first longitudinal slot (106b) provided on the adaptor (106).
12. The instrument (100) as claimed in claim 1, wherein each arm (107) comprises a torsion spring (115) coupled to the body (102).
13. The instrument (100) as claimed in claim 12, wherein each torsion spring (115) is coupled to a pair of flanges (102d) of the body (102) using a third pin (111), wherein each torsion spring (115) comprises a first end (115a) configured to reside within a groove (107e) of the corresponding arm (107), a second end resting against a lateral side of the body (102).