ES2898124A1 - System for navigation in the implantation of knee review prosthesis (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

System for navigation in the implantation of knee review prosthesis, which has a femoral hook (7) fastening to femur (1) with a first follower adapter (8) (3); A second follower adapter (9) (3) with milling coupling means (4), at least one housing slot (14) of a follower (3) and alignment slots (20) to navigate and optimize the entry of the milling machine (4) in the femur (1); A third follower adapter (10) (3) to a pod holder (15), with at least one follower housing groove (14) and alignment slots (20) to navigate and optimize the entry of the femoral pod (5) in the femur (1); A fourth follower adapter (11) (3) to tibial sheath (6) coupled to a carving instrument (16) of tibial sheath (6), with at least one follower housing groove (14) (3). (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

SYSTEM FOR NAVIGATION IN THE IMPLANTATION OF PROSTHESIS OF

KNEE REVISION

field of invention

The present invention belongs to the health sector, specifically to the area of traumatology and more specifically to knee prostheses. The present invention relates to revision knee prostheses, which are those that are implanted when primary knee prostheses fail, and more specifically to a system for navigation and monitoring for assistance in the implantation of revision knee prostheses, which is mainly formed by a set of adapters for the arrangement of the sensors or "trackers" necessary for the positioning and orientation of both the instruments necessary for the implantation of the prosthesis and each of its elements.

Background of the invention

Currently, primary knee prostheses are implanted to solve severe knee osteoarthritis. These primary knee prostheses essentially consist of a femoral component that is placed on the femur and a tibial component that is placed on the tibia, as well as an insert that goes between the femoral component and the tibial component. For the placement of these components, a series of cuts must be made in the aforementioned bones and these cuts must have an adequate orientation and dimensions in the three planes of space, depending on this the final position and orientation of the prosthesis. Figure 1 schematically shows the components of primary knee prostheses.

Knee prostheses can be placed manually (taking into account a series of anatomical references for their correct orientation in the 3 planes of space) or computer-assisted (browsers, robots, templates...). Through these latest systems and thanks to software, a display indicates the surgeon at all times and with an accuracy of up to 1 degree and 1mm (the accuracy depends of the system used) how the bone cuts are made in which the prosthesis components will then be placed (both the orientation of the cuts in space, and the quantification in millimeters of the cut being made).

In addition to considering the costs incurred, it is essential to properly manage the spaces or "gaps" that remain when making the cuts, which must be filled and "balanced" with the prosthesis. For the prosthesis to function correctly and reproduce the kinematics of the knee as well as possible, it must be well oriented and balanced.

Both the orientation of the cuts and the spaces or "gaps" will depend on the effectiveness of the prosthesis, the patient's satisfaction and the survival of the implant. A poorly placed prosthesis will always last less in a patient, in the same way , a prosthesis in which the spaces are not well "balanced" or filled will also last less in a patient.

Currently there are different computer-assisted systems on the market to perform primary knee prosthesis surgery, it could be said that each commercial house has its own system, in addition to the specific instruments.

manually.

Almost all computer-assisted systems consist of some followers, browsers or "trackers", which are sensors that are placed on the extremity to be intervened by means of pins and that reflect infrared light from an emitter that is then collected by a receiver to know the position of the leg in space at all times.In the same way, another follower, navigator or "tracker" is placed on the instruments used to make the cuts, so that the position of the leg can be known at all times. position and orientation with respect to the leg of those cuts. With robots, it is the robotic arm that brings the cutting slots to their optimal position automatically, and with navigators, it is the surgeon himself who places the cutting slot in its optimal position guided by the information given by the browser or tracker in real time. All this to place the components, balance the prosthesis as accurately as possible and thus extend its useful life. Document ES2203556T3 shows a device for determining the position of a cutting guide.

Figure 2 schematically shows examples of followers, browsers or “trackers”, their layout and connection with the receiver.

The main causes of failure of a primary knee prosthesis are malposition of the implant, instability (caused by a poor balance of spaces), loosening of the implant and infection. When the prosthesis fails, it must be replaced, and a revision prosthesis is placed in its place. This new prosthesis, in addition to the femoral and tibial components and the previously mentioned insert, must include an extra bone anchoring system, which can basically be of two types:

1. - Stems: cylinders of the same alloy as the prosthesis with which the medullary canal of the bone is "threaded", they are attached to the components, which provides added stability to the implant placed, they can be pressed or attached to the bone with a medical cement. Figure 3 shows stems attached to the prosthesis.

Vainas, casquillos, manguitos o conos: extensiones de titanio poroso u otro metal trabecular con formas variadas que se colocan en el fémur o en la tibia, y pueden unirse a los componentes tibial o femoral de la prótesis a presión o mediante cemento médico, lo que aporta un plus de estabilidad. A su vez, el anclaje de estos elementos al hueso puede ser a presión o con el uso de un cemento médico. Las figuras 4a, 4b y 4c muestran vainas, casquillos y conos respectivamente.

Sheaths, Caps, Sleeves, or Cones: Extensions of porous titanium or other trabecular metal in various shapes that are placed on the femur or tibia and can be attached to the tibial or femoral components of the prosthesis under pressure or by medical cement, which which provides added stability. In turn, the anchoring of these elements to the bone can be under pressure or with the use of a medical cement. Figures 4a, 4b and 4c show sheaths, bushings and cones respectively.

Additionally, both systems can currently be combined, as shown in figures 5a (sheath stems) and 5b (cone stems).

The main difference between sheaths and cones, sleeves and sleeves is that sheaths can be attached to the femoral and tibial component under pressure and do not require the use of medical cement for attachment, while cones, sleeves and sleeves require the use of medical cement for bonding. Document ES2544528T3 shows porous titanium femoral sleeves and document ES2455090T3 shows porous titanium tibial sleeves.

In the same way as in the primary knee prosthesis, the revision knee prosthesis must be placed as accurately as possible in the 3 planes of space, both the main components and the anchoring systems mentioned above (rods and/or sheaths, bushings, cones or sleeves), since they are joined together and the position of some conditions the position of the others. In addition, in a revision surgery, the position in the space of the femoral joint interline (place where the femoral component of the prosthesis ends and which will articulate with the insert) is of the utmost importance.

As of today, there are only a couple of navigation systems for revision prosthetics, their navigators are called "Orthopilot" and "Exatech GPS". With both systems, both components and stems can be followed or navigated. However, there is no solution on the market to navigate or follow chainstays, bushings and cones.

Therefore, it is desirable to have a system for navigation in the implantation of revision knee prostheses that can provide a follow-up or navigation of all the instruments and components to achieve an exact, effective and long-lasting implantation, avoiding the inconveniences existing in state-of-the-art systems. technique.

Description of the invention

The present invention solves the existing problems in the state of the art by means of a system for navigation in the implantation of revision knee prostheses, which is made up of the following components:

- A femoral hook that has an adjustable clamp for fastening to the femur of the patient to whom the revision knee prosthesis is going to be implanted, and a first follower or navigator adapter to the femur, which has means for fixing the said follower or navigator to the femoral hook. Thus, this femoral hook allows the placement of the femoral follower, navigator or tracker without invading the medullary canal of the femur, providing a stable hold of the femoral tracker and not impeding the drilling of the canal or the implantation of the femoral sheath as it does not cross the femur with the pins, as is the case in the state of the art.

- A second follower or navigator adapter to the milling machine in charge of making the cuts in the femur and tibia, which has coupling means to couple said second adapter perpendicular to the router shank allowing rotation of the second adapter 360° around the shank. This second adapter also has a locating slot for a follower or navigator, which allows following or navigating the varus/valgus and flexo/extension drilling, and therefore following or navigating the placement of the femoral and tibial stem in the femur and the tibia respectively.

In addition, the second adapter has a plurality of alignment slots arranged on the surface of the second adapter, into which a follower or navigator can be inserted, in order to follow or navigate the entry point of the reamer in the femur.

- A third follower or navigator adapter to the femoral sheath, which has a lateral opening and a shape configured to be coupled longitudinally to a sheath holder, which is the conventional instrument for fixing the femoral sheath in the femur. The third adapter also has at least one tracker or navigator accommodating slot provided on the top and bottom surfaces when considered when the third adapter is in use. By introducing the follower or navigator into the accommodation slot, it is possible to navigate the flexo-extension and varus/valgus of the femoral sheath in a similar way as is done with the follower accommodation slot of the second adapter.

The third adapter furthermore has different alignment slots arranged on the surface of the third adapter, into which a follower or navigator can be inserted, in order to be able to follow or navigate the point of entry of the femoral sheath into the femur.

- A fourth adapter for a follower or navigator to the tibial sheath, which has coupling means to be coupled perpendicularly to the cylindrical body of an instrument for carving the tibial sheath, allowing the rotation of the fourth adapter around said carving instrument. The fourth adapter also has at least one tracker or navigator housing slot disposed on its surface.

In this way, the present invention and its adapters provide the advantage of allowing the use of a free-use navigation system that a priori allows follow or navigate the placement of any primary knee prosthesis system, to follow or navigate a revision system for which it was not initially designed nor did it have specific instruments.

In order to follow or navigate this revision prosthesis, the adapters of this system are used, which allow the conventional followers, navigators or "trackers" to be attached to the instruments of the conventional free-use navigation technique applied to the navigation of primary knee prostheses. With this, navigation software designed for initial use in primary knee prostheses (for which it is not designed) can be applied to a revision prosthesis system, and a revision system designed for placement of manually, navigated through followers, browsers or "trackers". Through these adapters, the most critical and important steps of the revision surgery can be followed or navigated, both the cuts to be made, as well as the placement of the stems, sheaths and GAPs. In short, all the necessary steps for the correct placement of all the parts of the implant in the three planes of space and the management of the GAPs, trying to maximize the useful life of the implant and patient satisfaction.

According to a preferred embodiment of the invention, the femoral hook is formed by a first tubular element in which the first follower or navigator adapter to the femur is arranged, and a second element that can be inserted inside the first tubular element and slides along it. along this, whose lower end considered in the position of use of the femoral hook, together with the lower end of the first element forms the adjustable clamp for fastening to the femur. The upper end of the second insertable element considered in the position of use of the femoral hook protrudes from the first tubular element and is threaded for the graduation of the clamp by means of a wing nut.

In particular, the third adapter of the follower or navigator to the femoral sheath has on its upper and lower surface, considered in the position of use of the adapter, at least one projection for fixing elastic fastening means. Thus, once the third adapter has been coupled to the sheath holder for fixing the femoral sheath to the femur, an elastic fastening means, for example a rubber or elastic band with holes, can be attached to both projections, which embraces the third adapter. and to sheath holder, so that the third adapter is more firmly attached to the sheath holder, thus avoiding a possible decoupling of both elements during use.

According to particular embodiments of the invention, the position and orientation of the housing slot for the follower or navigator of the third adapter in use, that is, during the implantation of the knee revision prosthesis, corresponds to the final position and orientation that it will have. the femoral joint line provided by the femoral component of the prosthesis, which will serve as a guide for the surgeon in charge of performing the operation. That is, it helps to follow or navigate the position of the prosthesis, since the position of the slot coincides with the place where the prosthesis will be.

In addition, according to a particular embodiment of the invention, the position and orientation of the slot for housing the follower or navigator of the fourth adapter in use, that is, during the implantation of the revision prosthesis, corresponds to the final position and orientation that the tibial component of the prosthesis, which will also act as a guide for the surgeon performing the operation. That is, it helps to follow or navigate the position of the prosthesis, since the position of the slot coincides with the place where the prosthesis will remain.

Brief description of the drawings

Next, to facilitate understanding of the invention, by way of illustration but not limitation, an embodiment of the invention will be described with reference to a series of figures.

Figure 1 schematically shows the components of conventional primary knee prostheses.

Figure 2 schematically shows examples of followers, browsers or "trackers" of the state of the art, their arrangement and connection with the receiver.

Figure 3 shows conventional stems attached to the prosthesis

Figures 4a, 4b and 4c show conventional sheaths, bushings and cones respectively.

Figure 5a shows the combination of conventional stems and sheaths, and Figure 5b shows the combination of conventional stems and cones.

Figure 6 shows the different components of a particular embodiment of the femoral hook of the system object of the present invention.

Figure 7a shows the femoral hook of Figure 6 before it is placed on the femur, and Figure 7b shows the femoral hook already placed on the femur.

Figures 8a and 8b show a comparison of the fixation to the femur between the femoral hook of the system object of the present invention and the conventional pin fixation of the state of the art. Figure 8a shows both fixings in side view, and figure 8b shows them in section.

Figure 9 shows a perspective view of one embodiment of a second follower-to-mill adapter.

Figure 10 shows the second adapter of Figure 9 coupled perpendicularly to the shank of a milling cutter.

Figure 11 shows the reamer arranged in the femur, with the second adapter of figure 10, which has a follower or navigator incorporated in a slot.

Figure 12 shows schematically how the alignment slots of the second adapter of Figures 9 to 11 serve to follow or navigate the entry of the milling machine into the femur, given that the final sizes and distances of the components coincide.

Figure 13a shows a perspective view of the third femoral sheath follower adapter of the navigation system object of the present invention. Figure 13b shows a side view of the third adapter of Figure 13a.

Figure 14a shows the third adapter of Figures 13a and 13b just before it is attached to a conventional sheath holder. Figure 14b shows the third adapter already coupled to the sheath holder. Figure 14c shows an embodiment of an elastic band attachable to the projections of the third adapter of Figures 13a to 14b. Figure 14d shows an embodiment in which the third adapter is already coupled to the sheath holder, in a similar way to figure 14b, but including the elastic band of figure 14c coupled to the projections and embracing the assembly.

Figure 15a (front view) and figure 15b (side view) show a particular embodiment of the third adapter in which the follower housing slot has a position and orientation in use that corresponds to the final position and orientation of the joint interline femoral.

Figure 16 shows schematically how the alignment slots of the third adapter of Figures 13a to 15b serve to follow or navigate the entry of the femoral sheath into the femur, given that the final sizes and distances of the components coincide.

Figure 17a shows a perspective view of the fourth adapter from the follower to the tibial sheath of the navigation system object of the present invention. Figure 17b shows a plan view of the third adapter of Figure 17a.

Figure 18a shows the fourth adapter of Figures 17a and 17b just prior to being attached to a conventional tibial sheath carving instrument. Figure 18b shows the fourth adapter already attached to the tibial sheath carving instrument.

Figure 19 shows an embodiment of the fourth adapter of figures 17a to 18b, in which the position and orientation of the housing slot of the follower or navigator in use corresponds to the final position and orientation that the tibial component of the prosthesis will have. .

Figure 20 shows a tibial sheath carving instrument placed on the tibia, with the fourth adapter, which incorporates a follower or navigator in a slot.

These figures refer to a set of elements that are:

1. femur

2. lukewarm

. follower

4. femur and tibia milling machine

5. femoral sheath

6. tibial sheath

7. femoral hook

8. first follower-to-femur adapter

9. Second Follower to Mill Adapter

10. Third Follower Adapter to Femoral Sheath

11. Fourth Tibial Sheath Follower Adapter

12. Adjustable clamp for fastening to the femur

13. router handle

14. follower housing slot

15. pod holder

16. tibial sheath carving instrument

17. first tubular element of the femoral hook

18. second element of the femoral hook

19. femoral hook fixation wing nut

20. alignment slots

21. Shoulder of third follower adapter to femoral sheath

22. lateral opening of the third femoral sheath follower adapter

23. femoral joint line

24. femoral component of the prosthesis

25. tibial component of the prosthesis

26. elastic band

Detailed description of the invention

The object of the present invention is a system for navigation in the implantation of knee revision prostheses.

As can be seen in the figures, the system is made up of a set of four elements that will act as supports for followers, browsers or "trackers" to the various components of the prosthesis, the instruments to perform its implantation and the femur, which will facilitate the positioning and orientation of all the elements involved, orienting and guiding the surgeon precisely during the implantation of the revision knee prosthesis The elements that make up the system are the following:

- A femoral hook (7) that is formed by an adjustable clamp (12) for fastening to the femur (1) and a first adapter (8) from follower (3) to femur (1), which has means of fixing a follower (3). Thus, this femoral hook (7) allows the placement of the follower (3), navigator or femoral tracker without invading the medullary canal of the femur (1), providing a stable hold of the femoral follower (3) and not impeding the drilling of the channel or the implantation of the femoral sheath (5) by not passing through the femur (1) with the pins, as occurs in the systems of the state of the art. Figures 8a and 8b show a comparison of the fixation to the femur (1) between the femoral hook (7) of the system object of the present invention and the conventional pin fixation of the state of the art. Figure 8a shows both fixings in side view, and figure 8b shows them in section.

- A second adapter (9) from follower (3) to femur (1) and tibia (2) milling machine (4), which in turn has coupling means for the second adapter (9) perpendicularly to the handle (13) of the router (4) allowing the rotation of the second adapter (9) around the handle (13). In addition, the second adapter (9) has at least one housing slot (14) for a follower (3), which allows following or navigating the varus/valgus and flexo/extension of the milling, and therefore following or navigating the placement of the femoral and tibial stem in the femur (1) and tibia (2) respectively.

In addition, the second adapter (9) has alignment slots (20) arranged on the surface of the second adapter (9), which in use allow the entry point of the reamer (4) to be followed or navigated into the femur (1). ), since as shown in figure 12, the distance from the center of the drilling instrument to each alignment slot (20) corresponds to the distance from the center of the implant stem to the anterior cut of each femoral size. Furthermore, knowing this information and given that the distance from the femoral stem to the posterior condyles is fixed (with a variation of /-2mm if the offset is used), the GAP in flexion can be followed or navigated, and the entry point can be varied. femoral to optimize it.

The second adapter (9) has a right and left side, preferably marked by an "R" and "L" respectively, so that it can be used on both lower extremities.

- A third adapter (10) from follower (3) to femoral sheath (5), which has a lateral opening (22) and a shape configured to couple longitudinally to a sheath holder (15), of those used conventionally to fix the femoral sheath (5) in the femur (1). As can be seen in figure 14b, the third adapter (10) has the complementary shape of the sheath holder (15) to fit and not move in the anterior-posterior direction. The third adapter (10) also has at least one housing slot (14) for a follower (3) arranged on the upper and lower surface of the third adapter (10) of the follower (3) in use. Introducing the follower (3) or navigator into the accommodation slot (14) it is possible to navigate the flexo-extension and varus/valgus of the femoral sheath (5) in a similar way as is done with the accommodation slot (14). ) of follower (3) of the second adapter (9).

In addition, the third adapter (10) has alignment slots (20) disposed on the surface of the third adapter (10), configured to in use follow or navigate the entry point and rotation of the femoral sheath (5) in the femur. (1), since, as shown in figure 16, the distance from the center of the handle of the femoral sheath holder (15) to each alignment slot (20) corresponds to the distance from the center of the implant stem to the anterior section of each femoral size. Furthermore, knowing this information and given that the distance from the femoral stem to the posterior condyles is fixed (with a variation of /-2mm if offset is used), the GAP can be navigated in flexion, and the femoral entry point can be varied to optimize it.

The third adapter (10) also has a right and left side, preferably marked by an "R" and "L" respectively so that it can be used on both lower extremities, so that the upper and lower faces in use are mirror images.

- A fourth adapter (11) from follower (3) to tibial sheath (6) formed by coupling means to be coupled perpendicularly to the cylindrical body of a carving instrument (16) with tibial sheath (6), of those conventionally used to fix the pod tibial (6) on the tibia (2), allowing the rotation of the fourth adapter (11) around the grinding instrument (16). In addition, the fourth adapter (11) has at least one housing slot (14) for a follower (3). Introducing the follower (3) or navigator into the accommodation slot (14) it is possible to navigate the tibial slope and the varus/valgus of the tibial sheath (6) in a similar way as is done with the accommodation slot (14) follower (3) of the second adapter (9) and the third adapter (10). Figure 20 shows a carving instrument (16) with a tibial sheath (6) arranged in a tibia (2), with the fourth adapter (11), which incorporates a follower (3) or navigator in a housing slot ( 14).

According to a preferred embodiment that can be seen in figures 6, 7a, 7b, 8a and 8b, the femoral hook (7) has a first tubular element (17) in which the first adapter (8) is arranged. from follower (3) to femur (1), and a second element (18) insertable inside the first tubular element (17) and slidable along it, whose lower end, together with the lower end of the first element ( 17) forms the adjustable clamp (12) for fastening to the femur, and whose upper end in use protrudes from the first tubular element (17) and is threaded for the graduation of the clamp (12) by means of a wing nut (19). In this way, as can be seen in figures 7a and 7b, after placing the open femoral hook (7) embracing the femur (1), the wing nut (19) is rotated clockwise, thus the second element ( 18) will move upwards on the first tubular element (17) and the femoral hook (7) will be attached to the femur (1) by means of the clamp (12).

Figures 13a, 13b and 16 show a particular embodiment of the system object of the invention in which the third adapter (10) of the follower (3) to the femoral sheath (5) has on its upper and lower surface in use at least one projection (21) configured for fixing elastic fastening means. In this way, once the third adapter (10) is coupled to the sheath holder (15) for fixing the femoral sheath (5) to the femur (1), a means can be attached to both projections (21). elastic fastening, for example a rubber or elastic band (26) with holes, as can be seen in figures 14c and 14d. Thus, the elastic band (26) embraces the third adapter (10) and the sheath holder (15), so that the third adapter (10) is more firmly attached to the sheath holder (15), thus avoiding possible decoupling. of both elements during use.

Preferably, the position and orientation of the housing slot (14) of the follower (3) of the third adapter (10) from follower to femoral sheath (5) in use corresponds to the final position and orientation that the femoral joint line will have ( 23) provided by the femoral component (24) of the prosthesis, as can be seen in figures 15a and 15b. This will help the surgeon to follow or navigate the femoral interline during the intervention.

In addition, according to another preferred embodiment, as can be seen in Figure 19, the position and orientation of the housing slot (14) of the follower (3) of the fourth adapter (11) from follower to tibial sheath (6) in use corresponds to the final position and orientation that the tibial component (25) of the prosthesis will have. Since the tibial sheath (6) remains integral with the tibial component (25) of the prosthesis, the placement of the former influences the position of the latter, so the position of the tibial cut can be followed or navigated for subsequent placement of the latter. tibial sheath (6).

Claims (5)

1. System for navigation in the implantation of knee revision prostheses, characterized in that it comprises - a femoral hook (7) comprising - an adjustable clamp (12) for fastening to the femur (1) and - a first adapter (8) from follower (3) to femur (1), comprising means for fixing a follower (3), - a second adapter (9) from follower (3) to femur (1) and tibia (2) milling machine (4), comprising - coupling means configured to couple said second adapter (9) perpendicularly to the handle (13) of the milling machine (4) allowing the rotation of the second adapter (9) around the handle (13), - at least one housing slot (14) of a follower (3), and - alignment grooves (20) arranged on the surface of the second adapter (9) configured to navigate and optimize the entry point of the reamer (4) in the femur (1), - a third adapter (10) from follower (3) to femoral sheath (5), comprising - a lateral opening (22) and shape configured to couple said third adapter (10) longitudinally to a sheath holder (15) configured to fix the femoral sheath (5) to the femur (1), and - at least one housing groove (14) of a follower (3) arranged on the upper and lower surface in use of the third adapter (10) of the follower (3), and - alignment grooves (20) arranged on the surface of the third adapter (10) configured to navigate and optimize the entry point of the femoral sheath (5) in the femur (1), - a fourth adapter (11) from follower (3) to tibial sheath (6) comprising - coupling means configured to couple said fourth adapter (11) perpendicularly to the cylindrical body of a carving instrument (16) with tibial sheath (6), allowing rotation of the fourth adapter (11) around the carving instrument (16), and - at least one housing slot (14) of a follower (3), 2. System for navigation in the implantation of knee revision prostheses, according to claim 1, wherein the femoral hook (7) comprises - a first tubular element (17) in which the first adapter (8) from follower (3) to femur (1) is arranged, - a second element (18) insertable inside the first tubular element (17) and slidable along it, - whose lower end, together with the lower end of the first element (17) forms the adjustable clamp (12) for fastening to the femur, - and whose upper end in use protrudes from the first tubular element (17) and is threaded for the graduation of the clamp (12) by means of a wing nut (19). 3. System for navigation in the implantation of knee revision prostheses, according to any of the preceding claims, in which the third adapter (10) from follower (3) to femoral sheath (5) comprises on its upper and lower surface in use at least one projection (21) configured for fixing elastic fastening means. 4. System for navigation in the implantation of knee revision prostheses, according to any of the preceding claims, in which the position and orientation of the housing slot (14) of the follower (3) of the third follower adapter (10) The femoral sheath (5) in use corresponds to the final position and orientation that the femoral joint line (23) will have provided by the femoral component (24) of the prosthesis. 5. System for navigation in the implantation of revision knee prostheses, according to any of the preceding claims, in which the position and orientation of the housing slot (14) of the follower (3) of the fourth adapter (11) of the follower The tibial sheath (6) in use corresponds to the final position and orientation that the tibial component (25) of the prosthesis will have.