DESC:FIELD OF THE INVENTION
The present invention relates to universal femoral trial system and the preparation for posterior stabilizer (PS) surgeries by using the PS box system during knee replacement surgery. More particularly, the invention relates to a convertible femoral trial/PS Box cutting guide device adapted to perform trialing of a femoral implant and resection the femur for PS Box preparation during an orthopedic surgery.

BACKGROUND OF THE INVENTION
The knee joint is where the distal end of the femur or thigh bone meets with the proximal end of the tibia or the shin bone in a hinge joint. It also comprises of patella (kneecap) which sits in front of the joint. A healthy knee allows for movement of tibia with respect to femur. However a person may suffer debilitating pain when the knee is afflicted with a case of severe arthritis which may be caused due to old age or injury. Usually surgeons recommend knee surgery to the people suffering from acute arthritis to decrease pain and to improve the patient’s ability to walk. Knee replacement is a well-known surgical procedure to treat acute arthritis such as osteoarthritis.

In knee replacement surgery there is knee prosthesis which typically comprises of femoral component, tibial component and a central insert. Generally, the femoral implant provides for the smooth up and down movement over the insert as the knee flexes and extends. The femoral and tibial components are typically made of metal with the insert being made of strong durable plastic, cushioned between them. In order to provide additional stability the metal portion may have a stem that inserts directly into the center of the femur and tibia bone.

Most surgeons begin surgery with a general understanding of the patient’s medical history that defines the type of knee replacement that will be carried out. There are three types of knee replacement namely cruciate ligament retaining knee replacement system, cruciate ligament sacrificing system, or revision knee system. There is large ligament in the back of the knee that gives the knee the normal roll back while bending the knee, called posterior cruciate ligament. In cruciate retaining replacement system, as the name suggest this posterior cruciate ligament is kept intact. This type of surgery is usually recommended for those patients whose cruciate ligament is healthy or capable enough to continue stabilizing the knee joint.

In case of cruciate ligament sacrificing system, which is also called posterior stabilized design as there is no posterior cruciate ligament, posterior stabilizer box (PS box) is created on the femoral component and the cushion of tibial component is raised to form a post which fits or accommodates into the said PS box for the entire range of motion of the knee.

Accurate fitting of femoral implant continues to be one of the challenges in the Knee replacement surgery whether it is PS surgery or cruciate retaining surgery. To achieve it, the surgeon generally uses the femoral trial system to assist them in finding the appropriate type and size of the final femoral implant. In this procedure different femoral and tibial component trial sizes are tried, and the knee is flexed and extended to determine whether the said components fit and placement is appropriate or not. This procedure is repeated until best fit is determined.
For cruciate sacrificing surgical procedure, many system uses separate femoral trial and cutting guide. In this process surgeon secures the cutting guide on to femur bone and prepare PS box using reciprocating saw and/or box chisel/or other available methods. After that for femoral trialing, surgeon removes the cutting guide from the femur bone and places femoral trial with built-in box geometry there. Surgeon also selects tibial trial component and patellar component if required. After selection and fixing them appropriately in the knee joint, surgeon checks the knee for range and stability of motion.

However the practice of using separate left and right femoral trials for each size of knee, as well as separate femoral trial component and cutting guide in cruciate sacrificing surgery lead to significant increase in the number of instruments in the operation theater. Inside Operation Theater (OT), it’s operation theater (OT) space, surgical steps and surgery time may get impacted due to this increase in the number of instruments as it not only increases the surgical steps and surgical costs but also makes their management difficult, especially in the small operation theater (OT) space. In addition to it, outside of Operation Theater, managing checklist, transportation, tray optimization, sterilization cycle, ordering or replacing the old ones and related logistics are directly related to the quantity of instruments. Hence it is advantageous to bring down the number of parts of instruments in and out of the operation theater.

In the existing state of art technology, some implant designers have attempted to solve the problem by providing a femoral trial that has a detachable central portion which could be removed from the trial and then PS Box could be prepared. Later when the trialing is to be done, the central portion is snapped back in place. U.S Patent Application. 20110307067 titled “Trial femoral prosthesis and its use” published on Dec 15, 2011 discloses one such femoral trial system. The drawback of this system is that the supporting surface on which the cutting blade rests during PS Box preparation is too small. Thus there is always a chance of inaccurate cut being made. Moreover, the presence of a detachable central portion inevitable increases the number of instruments present in the Operation Theater (OT).

Object of the invention:
In order to obviate the drawbacks in the current state of art, the main object of the present invention is to provide the universal femoral trial with PS box system which is adapted to perform resection of the femur for PS Box preparation and trialing of a femoral implant during an orthopedic surgery.

Another object of the present invention is to provide the universal femoral trial with PS box system for preparing PS box geometry cuts and perform implant trialing without the need of attaching a third component to the patient’s bone or removing the instrument from the bone thereby decreasing number of surgical instrument and non-productive surgical steps and operating time.

Yet another object of the present invention is to provide the universal femoral trial with PS box system wherein PS box jig is configured to sit on the universal femoral trial body in a manner that it provides sufficient area to the cutting instrument for the preparation of PS box geometry.

Yet another object of the present invention is to provide a universal femoral trial system with PS box system in which only one universal femoral trial is used for both left and right knee for a given size instead of using separate left and right femoral trial sizes during knee replacement surgeries

SUMMARY OF THE INVENTION
Accordingly, the present invention provides a universal femoral trial with PS box system for use in the preparation for posterior stabilizer (PS) surgeries during knee replacement surgery. More particularly, the invention relates to a convertible femoral trial/PS Box cutting guide system adapted to perform trialing of a femoral implant and resection of the femur for PS Box preparation during an orthopedic surgery.

The present invention provides for a universal femoral trial with PS box system jig in which only one universal femoral trial body is used for both left and right knee for a given size instead of using separate left and right femoral trial sizes during knee replacement surgeries.

The said universal femoral trial system has a central flipper which is hinged to the universal femoral trial body through single or multi-point pivoted mechanism.

The present invention provides for a universal femoral trial system comprising of universal femoral trial body, at least one central flipper and at least one posterior stabilizer (PS) box jig. The central flipper is attached to the universal femoral body by at least one pivot mechanism while said posterior stabilizer (PS) box jig is capable of being fitted onto said universal femoral body using peg post , thereby forming convertible universal femoral trial system capable of being used as femoral trial PS box cutting guide to prepare PS Box during an orthopedic surgery when used in open position, or as a femoral trial to perform trialing of a femoral implant when used in closed position.

The present invention also provides PS box jig which is adapted to make PS box cut in case of surgeries where PS implants are to be implanted. The PS box jig is seated on to the universal femoral trial after the central flipper is moved off the place by the pivot mechanism keeping the same essentially two-three pieces construct and some pivot pin(s). This allows quick set-up for trial reduction as soon as PS box is prepared. Once the PS box is prepared, the PS Box jig is removed and hinged central flipper is pivoted back to the original position making it ready for trialing.

Universal femoral trial system is one piece construct for cruciate retaining (CR) surgeries because the pivoting option for central flipper as well as PS box jig are not required for CR surgeries. This is due to the fact that no PS box preparation is done in case of CR surgeries.

The use of universal femoral trial with PS Box system not only leads to nearly 50 percent reduction in the number of instruments required for the femoral trials but also results into significant reduction in the number of non-productive surgical steps. Further it minimizes the chances of a surgical error and less number of instruments to be sterilized. Additionally, this is also helpful in effectively managing the operation theater space, surgical ease and company’s inventory.

Hence the present invention overcomes the drawbacks in the current state of art of technology by providing a femoral trial component that has the central flipper which can be flipped to make room for a box cutting jig. The presence of box cutting jig ensures that sufficient resting surface area is provided to the cutting blade. This system also provides the convenience of trialing after the box preparation without removal of the instrument form the patient’s bone.

BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a perspective view of a universal femoral trial assembled with PS box jig;
FIG. 2 is a perspective view of one embodiment of the tool shown in Fig. 1 in a disassembled form and having a universal femoral trial body, a central flipper, a PS box jig, and a locking pin;
FIG. 3 is a perspective view of the universal femoral trial body member shown in Fig. 2 having central opening adapted to receive the central flipper and PS box jig member;
FIG. 4 is a perspective view of the central flipper shown in Fig. 2. The central flipper has a neck feature adapted to mate with the universal femoral trial body and a pin hole to allow locking using the locking pin;
FIG. 5 is a perspective view of the PS box jig shown in Fig.2. The PS box jig has peg posts adapted to mate with the peg holes of the universal femoral trial body. The PS box jig is adapted to be disposed in the central opening of the universal femoral trial body;
FIG. 6 is a perspective view of the universal femoral trial body disclosed in Fig. 1-2 having the central flipper in the flipped position and adapted to receive the PS box jig in the central opening of the universal femoral trial body;
FIG. 7 is a perspective view of the universal femoral trial body disclosed in Figs. 1 and 2 having the central flipper in the closed position such that it acts as a universal femoral trial for trialing;
FIG. 8 is a cross-sectional illustration of the all of the components of the universal femoral trial with PS box such that the PS box jig is disposed over the universal femoral trial for the PS box resection;
FIG. 9 is a perspective view of the universal femoral trial with PS box disclosed on Fig. 1 showing an alternative version having double flipper and a central bridge in the universal femoral trial body;
FIG. 10 is a perspective view of one embodiment of the tool shown in Fig. 9 in a disassembled form and having a universal femoral trial body, an anterior central flipper, a posterior central flipper, and two locking pins;
FIG. 11 is a perspective view of the central flipper shown in Fig. 10. The central flipper has a posterior central flipper and an anterior central flipper;
FIG. 12 is a perspective view of the universal femoral trial body shown in Fig. 10 having a central bridge;
FIG. 13 is a perspective view of the universal femoral trial disclosed in Figs. 9 and 10 having the central flipper in the flipped position and adapted to receive the PS box jig in the central opening of the universal femoral trial body;
FIG. 14 is a perspective view of the universal femoral trial disclosed in Figs. 9 and 10 having the central flipper in the closed position such that it acts as a universal femoral trial for trialing;
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO DRAWINGS AND ILLUSTRATIVE EXAMPLE:
The present invention provides a universal femoral trial with PS box system that is useful for preparing PS box geometry cuts and perform implant trialing without the need of attaching a third component to the patient’s bone or removing the instrument from the bone. This invention avoids the need of attaching and removing instruments to perform first the PS box resection and then trialing, thereby reducing surgical steps and operating time.
Embodiments of the present invention overcome the drawbacks in the current state of art of technology by providing a universal femoral trial body that has the central flipper which can be flipped to make room for a PS box jig. The presence of PS box jig ensures that sufficient resting surface area is provided to the cutting blade. This system also provides the convenience of trialing after the box preparation without removal of the instrument form the patient’s bone.

Figs 1, 6, 7 and 8 depict universal femoral trial system in which the central flipper is attached to the universal femoral body via single pivot mechanism while Figs 9, 13 and 14 depict universal femoral trial system in which the central flipper is attached to universal femoral body via multi-pivot mechanism.

FIG. 1 and FIG. 2 depict universal femoral trial with PS box system (100) in assembled and dissembled forms respectively. The FIG. 1 illustrates the position and deployment of the PS box jig (500) over the universal femoral trial body (300) while the central flipper (400) is flipped all the way to the anterior side to make room for the PS box jig (500) to be deployed.
As depicted in FIG.1 the PS box jig (500) comprises of anterior resection surface (503), medial resection surface (502), lateral resection surface (501) fixation holes (509) and (510) while universal femoral body (300) comprises of proximal surface (303), elongated slot (301) and fixation holes (308) and (310). Further Fig 1 also depicts central flipper (400) which comprises of cam (403), stop post (402) and central flipper neck (410).
The cam (403) connects the medial surface (404), (FIG. 4) and the lateral surface (405) (FIG. 4) of the central flipper (400). The cam (403) acts as the stopping surface for the post present on the tibial trial component. The post of the tribal trial component goes into the tibial post opening (406) and its excessive posterior movement is restricted by the presence of cam (403).
The proximal surface (303) of the universal femoral trial body (300) rests on the resected patient’s femur during trialing or PS box resection. The universal femoral trial body (300) is fixed onto the patient’s bone using fixations pins passing through fixation hole (308) and fixation pin hole (509, 510) of universal femoral trial body (300) and PS box jig (500) respectively. The central flipper (400) having a cam (403) is flipped to the anterior side by pivoting it in the elongated slot (301) present in the universal femoral trial body (300). A locking pin (600), (FIG. 2) passes through the elongated slot (301) of the universal femoral trial body (300) and the pin hole (401), ( FIG. 2) of the central flipper (400).
The construct shown in FIG. 1 may be used to prepare for the PS box geometry cut either by using a reciprocating saw on the anterior resection surface (503), medial resection surface (502) and lateral resection surface (501) or a milling cutter that passes between medial resection surface (502) and lateral resection surface (501) and is restricted in the anterior direction by the anterior resection surface (503). Any other bone removal tools like, but not restricted to box chisel or notch block may also be used for PS box geometry cut.
The FIG. 2 additionally depicts the components of universal femoral trial with PS box system (100) in disassembled form. The central flipper (400) comprises of a cam (403), a pin hole (401), central flipper neck (410), a medial surface (404), stop post (402, 409) and a tibial post opening (406).
The universal femoral trial body (300) comprises of proximal surface (303), an elongated slot (301), a convex anterior surface (306), a pair of distal femoral condylar surfaces i.e. distal lateral condylar surface (304) and distal medial condylar surface, peg holes (305, 311) and an opening (307) between medial and lateral surface. The PS box jig (500) comprises of a lateral resection surface (501), a medial resection surface (502), peg post stop collar (508), peg post (506), fixation pin hole stop collar (511), a push stop (504) and an anterior resection surface (503). The universal femoral trial with PS box (100) also has locking pin (600).
FIG. 3 illustrates the universal femoral trial body (300) which comprises of two stop grooves (302, 312), two peg holes (305, 311) and two fixation holes (308, 318). The universal femoral trial body (300) also has medial surface (309) and a lateral surface (310) separated by an opening (307). Further the Universal femoral trial body (300) at its anterior end comprises of lateral anterior surface (313), a medial anterior surface (314), concave anterior surface (317), the lateral neck surface (320), medial neck surface (321) and a convex anterior surface (306).
During femoral trial proximal surface (303) of the universal femoral trial body (300) rests on to the patient’s bone while the distal lateral condylar surface (304) and distal medial condylar surface (319) which are articulating surfaces move over patient’s tibial implant, of the prosthesis system. The elongated slot (301) having a proximal end (315) and a distal end (316) passes throughout the medial lateral width of the universal femoral trial body (300). At the anterior end of the universal femoral body (300) the distance between the lateral neck surface (320) and the medial neck surface (321) is width lB1 that accommodates the width lF1 of the central flipper neck (410) (FIG. 4). Similarly, the distance between the lateral surface (310) and the medial surface (309) is of width lB2 that accommodates the width lF2 of the central flipper (400) (FIG. 4). The distance between the convex anterior surface (306) and the concave anterior surface (317) is length lB3 that accommodates the length lF3 of the central flipper (400) (FIG. 4).
FIG. 4 depicts the central flipper (300) in more detailed manner. The central flipper (300) comprises of a cam (403), two stop posts (402, 409), a medial surface (404), a lateral surface (405), a proximal surface (407), a tibial post opening (406), and a patella-femoral groove (408). Further, the anterior side of central flipper has a central flipper neck (410), a pin hole (401), a medial arc surface (415), a lateral arc surface (416), a posterior neck surface (414), a convex anterior surface (413), medial neck corner (411) and lateral neck corner (412). The width of the central flipper neck (410) is lF1. Similarly, the distance between the lateral surface (405) and the medial surface (404) is the width lF2. The distance between the convex anterior surface (306) and lateral/medial neck corner (411, 412) is the length lF3.
FIG. 5 illustrates the PS box jig (500) of the universal femoral trial with PS box (100) disclosed in FIG. 1 and FIG 2, in much detailed manner. PS box jig (500) comprises of two peg post holes (505, 507), two peg posts stop collars (508, 514), two fixation pin holes (509, 510) and two fixation pin holes stop collars (511, 512). It also comprises of peg post (506), a medial resection surface (502), a lateral resection surface (501), an anterior resection surface (503), a proximal surface (513), a push stop (504) and an opening between the lateral and medial resection surface (515).
FIG. 6 shows the universal femoral trial (700) in open position, with the central flipper (400), flipped to the anterior side. To assemble the central flipper (400) to the universal femoral trial body (300), the locking pin (600) (FIG. 2) is passed through the elongated slot (301) and the pin hole (401) (FIG. 4). The width of the central flipper neck lF1 (FIG. 4) fits within the width lB1 (FIG. 3) of the universal femoral trial body (300). Similarly, the width lF2 (FIG. 4) of the central flipper (400), fits within the width lB2 (FIG. 3) of the universal femoral trial body (300). Also, the length of the central flipper neck lF3 (FIG. 4) fits within the length lB3 (FIG. 3) of the universal femoral trial body (300). The difference between corresponding mating widths and lengths (lF1 and lB1;; lF2 and lB2; lF3 and lB3) is generally in the range 0.1 mm to 0.2 mm, and more preferable about 0.125 mm. The stop post (402) goes into the stop groove (302) when the central flipper (400) is in closed position (FIG. 7). The extent to which the central flipper (400) can be flipped in the anterior side is governed by the restriction provided by the distal end of the elongated slot (314) to the locking pin (600) ( FIG. 2) or flushing of medial/lateral neck corner (411, 412) on the medial/lateral anterior surface (314, 313) ( FIG. 3, FIG. 8). In flipped position, the locking pin (600, FIG. 2) along with the pin hole (401) (FIG. 4) moves away from the proximal end of the elongated slot (315) (FIG. 8) towards the distal end of the elongated slot (316) thereby increasing the distance between the stop groove (302) and the stop post (402). When the central flipper (400) is flipped, the opening (307) between the medial and the lateral surface is created, as the cam (403) which had been occupying this position (FIG. 7) makes way. The PS box jig (500) can now be placed (FIG. 1) in the opening (307) between medial and lateral surface with peg post (506) (FIG. 5) mating with peg hole (311). The presence of peg post stop collar (508, 514) (FIG. 2) controls how deep the PS box jig (500) sits on the universal femoral trial body (300). Additional stability of the PS box jig (500), when assembles onto the universal femoral trial body (300) is achieved by passing fixation pin through the fixation pin holes (509, 510) (FIG. 5) and fixation holes (308, 318) of the universal femoral trial body (300).
FIG. 7 shows the universal femoral trial system in closed position (700), with the central flipper (400), flipped back to the posterior side where the cam (403) occupies the location of opening (307) between the medial and lateral surface (FIG. 3). In this position the stop posts (402, 409) goes into the stop grooves (302, 312). This embodiment of the universal femoral trial (700) can be used for trialing the implant. The distal lateral condylar surface (304) and distal medial condylar surface (319) act as the articulating surface of the tibial insert trial. The patella-femoral groove (408) along with the lateral anterior surface (313) and medial anterior surface (314) also acts as an articulating surface of the patella bone of the patient. The presence of minimum clearance between the medial/lateral arc surface (415, 416) (FIG. 4) and the convex anterior surface (306) ensures that the assembled central flipper (400) and universal femoral trial body (300) acts a continuous surface during trialing. In this embodiment, the tibial post opening (406) acts as the site to receive the post of the trial tibial insert. Also, the locking pin (600) (FIG. 2) along with the pin hole (401) (FIG. 4) moves towards the proximal end of the elongated slot (315) against its initial position at the distal end of the elongated slot (316. The elongated slot (301) is provided as it provides additional leverage for the central flipper (400) to move further away on the anterior side of the universal femoral trial body (300). Had there been pin hole instead of the elongated slot (301) in the universal femoral trial body (300), the anterior flipping of the central flipper (400) would have been restricted. In this embodiment, the elongated slot (301) may be in an oval or kidney bean shape or any other shape that instills the functionality of providing additional flipping ability to the central flipper (400) in the anterior direction. Extra flipping of the central flipper (400) in the anterior direction ensures that the PS box jig (500) sits uninterrupted on the universal femoral trial body (300) and provides adequate space for PS box cut geometry to be made.
The universal femoral trial system has the lateral anterior surface (313) and medial anterior surface (314) that simulates the anterior profile of a patient’s left and right femur bone. The presence of patella-femoral groove (408) adds to the articulating surface on the anterior side of the universal femoral trial body (700). By including both the lateral anterior surface (313) and medial anterior surface (314) along with the patella-femoral groove (408) facilitate the use of the universal femoral trial body (700) for trialing and PS box resection for both the left and right leg.
FIG. 8 is a cross-sectional illustration of the all of the components of the universal femoral trial with PS box such that the PS box jig is disposed over the universal femoral trial for the PS box geometry cut. The universal femoral trial system (100) is in open position, with the central flipper (400), flipped to the anterior side. In this embodiment, the universal femoral trial system with PB box sits on the patient’s bone and the proximal surface (303) of the universal femoral trial body (300) flushes with the bone. The proximal surface (513) of the PS box jig (500) may or may not flush with the patient’s bone based on the facts that the peg post stop collar (508, 514) (FIG. 5) allows or restricts the PS box jig to sink deeper into the universal femoral trial body (300). As the central flipper (400) is flipped to the anterior side, its proximal surface (407) no longer touches the patient’s bone. The locking pin (600) acts as the pivot point on which the central flipper (400) flips. The convex anterior surface (413), medial/lateral arc surface (415, 416) and the locking pin (600) share the same arc center. Similarly, the concave anterior surface (317) shares the same arc center as the proximal end of the slot (315). These common arc centers ensure that when the central flipper (400) is flipped, there is a smooth transition between the members.
The lateral neck corner (412) may or may not touch the lateral anterior surface (313). The lateral resection surface (510), anterior resection surface (503) and medial resection surface (502) shown in FIG 1 may be used to prepare for the PS box geometry cut either by using a reciprocating saw or any other compatible bone cutting tool. The lateral surface (310) and stop groove (312) of the universal femoral trial body (300) is also shown in FIG. 8. When the PS box jig (500) is assembled onto the universal femoral trial (700), the push stop (504) pushes down on the posterior neck surface (414) thereby keeping the central flipper (400) in a constrained position.
FIG. 9 and FIG. 10 depict an alternative embodiment having multi-pivot mechanism in which central flipper (1900) is double joint flipper and a central bridge (1320) in the universal femoral trial body (1300) of the universal femoral trial with PS box (100), (FIG. 1 and FIG. 2). In this embodiment the universal femoral trial with PS box (1000) comprises of a universal femoral trial body (1300), a PS box jig (1500), an anterior central flipper (1800), a posterior central flipper (1400), a locking pin (1600) and a flipper pin (2600). The central bridge (1320) connects the medial surface (1309) (FIG. 12) and lateral surface (1310) (FIG. 12) of the universal femoral trial body (1300). The cam (1403) (FIG. 13) along with the central bridge (1320) form the complete cam of the universal femoral trial (1700) (FIG. 14) and acts as the restriction surface for the post of the tibial trial post.
The FIG. 10 additionally depicts the components of universal femoral trial with PS box system (1000) in disassembled form. The flipper pin (2600) connects the anterior central flipper (1800) to the posterior central flipper (1400). The locking pin (1600) connects the entire central flipper (1900) (FIG. 11) to the universal femoral trial (1300). The PS box jig (1500) assembles on to the universal femoral trial body (1300).
FIG. 11 depicts the central flipper (1900) which comprises of an anterior central flipper member (1800) (FIG. 9), a posterior central flipper member (1400) (FIG. 9) and a flipper pin member (2600). The anterior central flipper member (1800) (FIG. 9) comprises of pin hole (1801), anterior concave surface (1815), posterior convex surface (1806) and a dead stop (1803). The posterior central flipper member (1400) (FIG. 9) comprises of dead stop (1411), tibial post opening (1406), medial stop surface (1402), lateral stop surface (1409), cam (1403), anterior dead stop (1414), anterior concave surface (1416) and a posterior concave surface (1415). The posterior central flipper member (1400) (FIG. 9) is pivoted on the anterior central flipper member (1800), (FIG. 9) using the flipper pin (1600). The posterior central flipper member (1400) (FIG. 9) rotates with respect to the anterior central flipper member (1800), FIG. 9) till the dead stop (1803) hits the dead stop (1411) on the posterior side or anterior dead stop (1414) on the anterior side. The presence of double flipper ensures that the entire central flipper assembly is flipped further in the anterior side and the surgeon has sufficient room to prepare the PS box geometry cut.
FIG. 12 illustrates the universal femoral trial body (1300) which comprises of two stop surfaces (1302, 1312) and two peg holes (1305, 1311). There is also a medial surface (1309) and a lateral surface (1310) which is connected by the central bridge (1320). An elongated slot (1301) passes throughout the medial lateral width of the universal femoral trial body (1300).
FIG. 13 shows the universal femoral trial (1700) in open position, with the anterior/posterior central flipper (1400, 1800) (FIG. 9), flipped to the anterior side. To assemble the central flipper (1900) to the universal femoral trial body (1300), the locking pin (1600) (FIG. 10) is passed through the elongated slot (1301) and the pin hole (1801, FIG. 11). The flipper pin (2600) connects the anterior/posterior central flipper (1400, 1800) (FIG. 9) together. As the central flipper (1700) is flipped to the anterior side by pivoting over the locking pin (1600) (FIG. 10) in the elongated slot (1301), the medial stop surface (1402) and lateral stop surface (1409) moves further away from the two stop surfaces (1302, 1312) of the universal femoral trial body (1300). Simultaneously, the cam (1403) also moves away from the central bridge (1320 which makes room for the PS box jig (1500) (FIG. 9) that can then be assembles using the two peg holes (1305, 1311).
FIG. 14 shows the universal femoral trial (1700) in closed position, with the central flipper (1900), flipped back to the posterior side where the cam (1403) occupies the location over the central bridge (1320). In this position the medial stop surface (1402), (FIG. 13) and lateral stop surface (1409), (FIG. 13) flush with the stop surfaces (1302, 1312) (FIG. 13). This embodiment of the universal femoral trial (700) can be used for trialing the implant. The presence of minimum clearance between the posterior convex surface (1806) and anterior concave surface (1416) ensures that the assembled anterior central flipper member (1800, FIG. 9) and posterior central flipper member (1400, FIG. 9) act as a continuous surface during trialing. In this embodiment, the tibial post opening (1406) acts as the site to receive the post of the trial tibial insert. The elongated slot (1301) provides additional leverage for the central flipper (1900) (FIG. 11) to move further away on the anterior side.
The invention is not to be limited by what has been particularly shown and described by way of examples.
Example 1:
The various parts of the universal femoral trial system (100), namely the universal femoral trial body (300), the central flipper (400), the PS-box jig (500) and the lateral and medial condylar surfaces of said universal femoral trial body (300) are configured and made ready to use prior to the commencement of the surgery. The said parts are configured in a manner that the universal femoral trial system (100) is used on either leg of the patient without any further configuration.
The universal femoral trial body (400) has a central flipper pinned to it by at least one pivot mechanism, so that it can be flipped back using the first or second pivot mechanism. The unique arrangement of the first pivot system allows the central flipper to be flipped back to allow space for the placement of the PS-Box jig into the open space between the lateral and medial condylar surfaces. The optional second pivot mechanism on the central flipper (400) allows the central flipper to flip further back giving additional space.
Example 2:
In order to prepare the PS box cut, the universal femoral trial body (300) is placed on the surgical area in a manner that its proximal surface (302) rests on the femoral bone of the patient. After this step surgeon places PS box jig on the opening space (307) between lateral and medial surface of universal femoral body trial (300) which is created due to the flipping of central flipper member (400) by means of pivoting mechanism. The PS box jig provides anterior resection surface (503), medial resection surface (502) and lateral resection surface (501) to the surgeon to make PS box geometry cut. Surgeon uses reciprocating saw blade which passes between medial resection surface (502) and lateral resection surface (501) with restriction in the anterior direction by the anterior resection surface (503). Any other bone removal tools like, but not restricted to box chisel, milling cutter or notch block may also be used for PS box geometry cut.
During femoral trial the surgeon moves the said central flipper (400) to the posterior side of the universal femoral trial body (300) after removing the PS box guide out such that in closed position the cam (403) of central flipper (400) occupies the opening between the medial surface (309) and lateral surface (310) of the universal femoral body trial (300). In this position distal medial condylar surface and distal lateral condylar surface of the universal femoral trial body (300) act as articulating surfaces that move over the tibial insert trial while patella-femoral track acts as articulating surface for the patella inserts, the tibial post opening acts as the site to receive the post of the tibial inserts trial.
Example 3
In other embodiment, said central flipper is double joint flipper (1900). Said double joint flipper comprises of anterior central flipper (1800) and posterior flipper member (2600 which ensure that entire flipping assembly can be flipped further in the anterior side thereby providing the Surgeon sufficient area to prepare PS box.
,CLAIMS:We claim
1. Universal femoral trial system, comprising of universal femoral trial body (300), at least one central flipper (400) and at least one posterior stabilizer (PS) box jig (500),
wherein said central flipper is attached to said universal femoral body (300) by at least one pivot mechanism while said posterior stabilizer (PS) box jig (500) is capable of being fitted onto said universal femoral body using at least one peg post (506), to form convertible universal femoral trial system capable of being used as femoral trial PS box cutting guide to prepare PS Box during an orthopedic surgery when used in open position (Fig 1), or as a femoral trial to perform trialing of a femoral implant when used in closed position (Fig 7).

2. The universal femoral trial system as claimed in claim 1 wherein said universal femoral trial body (300), comprises of
- proximal surface (303) that rests on patient’s bone,
- an elongated slot (301) having proximal end (315) and distal end (316) passing through the medial lateral width of said universal trial body,
- said distal end having a pair of distal femoral condylar surfaces comprising of distal lateral condylar surface (304) and distal medial condylar surface (319) which is the articulating surface, said lateral condylar and medial condylar surfaces (319, 304) being separated by an opening (307),
- said anterior end having lateral anterior surface, medial anterior surface and a concave anterior surface (319)
- lateral neck surface (320), medial neck surface (321) and convex anterior surface (306),

3. The universal femoral trial system as claimed in claim 2 wherein distance between said convex anterior surface and said concave anterior surface is length lB3 capable of accommodating length lF3 of said central flipper (400).

4. The universal femoral trial system as claimed in claim 1 wherein said central flipper (400) comprises of central flipper neck (410) at the anterior end of said central flipper having pin hole (401), cam (403) at posterior end of said central flipper, patella-femoral groove (408) and three surfaces, said three surfaces being proximal surface (407), medial surface (404), and lateral surface (405), said medial and lateral surfaces being separated by tibial post opening (406),
said central flipper (400) being attached to said universal femoral body by means of at least one pivot mechanism.

5. The universal femoral trial system as claimed in claim 4 wherein said pivot mechanism is selected from single pivot mechanism or multi-pivot mechanism.

6. The universal femoral trial system as claimed in claim 5, wherein said single pivot mechanism comprising at least one locking pin (600).

7. The universal femoral trial system as claimed in claim 2, 4 and 6, wherein said locking pin (600) passes through said elongated slot (301) of universal femoral trial body (300) and pin hole (401) of said central flipper (400) in a manner that said central flipper (400) is capable of sliding from distal end (316) to proximal end (315) of said elongated slot (301) of the universal femoral trial body (300) in the anterior direction.

8. The universal femoral trial system as claimed in claim 5 wherein said multi-pivot mechanism comprises the central flipper (1900), said central flipper comprises of at least two members, anterior central flipper member (1800) and posterior central flipper member (1400), said posterior central flipper (1400) is attached to anterior flipper member (1800) via flipper pin member (2600) while said anterior central flipper member (1800) is attached to the universal femoral trial body (1300) via locking pin (1600), thereby providing extra flipping to the central flipper (1900) in anterior direction of the universal femoral trial body in addition to the anterior direction provided by single pivot mechanism.

9. The universal femoral trial system as claimed in claim 8 wherein said anterior central flipper member (1800) comprises of pin hole (1801), anterior concave surface (1815), posterior convex surface (1806) and a dead stop (1803) while posterior central flipper (1400) comprises of dead stop (1411), tibial post opening (1406), medial stop surface (1402), lateral stop surface(1409), cam(1403) , anterior dead stop (1414), anterior concave surface(1416) and posterior concave surface (1415).

10. The universal femoral trial system as claimed in claim 8 or 9, wherein said posterior central flipper member (1400) being pivoted on the anterior central flipper (1800) in a manner that it rotates with respect to the anterior central flipper member till the dead stop (1803) hits the dead-stop (1411) on the posterior side or anterior dead stop (1414) on the anterior side.

11. The universal femoral trial system as claimed in claims 1 or 4, wherein said cam (403) and said tibial post opening (406) occupy said opening (307) of the universal femoral trial body (300) when said universal femoral trial system is in closed position in a manner that said tibial post opening (406) acts as the site to receive the post of the tibial trial insert with cam (403) acting as stopping surface, while patella-femoral groove (408) along with the lateral anterior surface (313) and medial anterior surface (314) of said universal femoral body (300) acts as an articulating surface with the patella bone of the patient.

12. The universal femoral trial system as claimed in claims 1 or 2 wherein said PS box jig (500) comprises of proximal surface (513), medial resection surface (502), a lateral resection surface (501) and anterior resection surface (503), at least one said peg posts (506) bearing peg post holes (505, 507), at least two fixation pin stop collars (511, 512) bearing fixation pin holes (509, 510)
said lateral and medial resection surfaces being separated by opening (515)
said resection surfaces capable of being adapted in a manner that during open position of universal femoral trial system (100), said opening (515) of PS box jig is in alignment with the said opening (307) of universal femoral trial body (300) thereby providing medial resection surface (502), a lateral resection surface (501) and anterior resection surface (503) to make PS box cut during orthopedic surgery .

13. The universal femoral trial system as claimed in claim 12, wherein said PS box jig (500) further comprises of push stop (504) to prevent the flipping of central flipper member (400) in posterior direction during PS box cut procedure.

14. The universal femoral trial system as claimed in claim 2 or 4 wherein said universal femoral trial body (300) further comprises of stop groves (302, 312) on femoral condylar (319) while central flipper comprises of stop posts (402, 409) in a manner that said stop posts mate (402, 409) with stop groves (302, 312) respectively thereby enabling the locking of central flipping member (400) into the universal femoral body (300) so that said femoral trial system is used for femoral trial.

15. The universal femoral trial system as claimed in claim 2, wherein said universal femoral trial body (300) further comprises of at least two peg holes (305, 311) and two fixation holes (308, 318).

16. The universal femoral trial system as claimed in claim 12 or 15, such that said universal femoral system is capable of being fixed on patient along with PS box jig in a manner that said peg posts (506) bearing peg post holes (505, 507) mates with peg holes (305, 311) of universal femoral trial body (300).

17. The universal femoral trial system as claimed in claim 12 or 15 wherein said PS box jig is capable of fixing to said universal femoral body (300) via passing fixation pin through fixation pin holes (509, 510) of said PS box jig (500) and fixation holes (308, 318) of said universal femoral trial body (300).