Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/38—Joints for elbows or knees
  • A61F2/3859—Femoral components

Definitions

• the present invention relates to a femoral implant of a knee prosthesis, comprising two condyles integral with a trochlea and a central medullary keel adapted to be fixed on a support base formed between the condyles.
• a femoral implant of a knee prosthesis comprising two condyles integral with a trochlea and a central medullary keel adapted to be fixed on a support base formed between the condyles. 5
• the central medullary keel of an implant must be oriented correctly in the frontal plane, to respect the patient's femoral valgus, and on the other hand in the sagittal plane in order to be well positioned relative to the wall inside of the trochlea, to obtain a good primary fixation of the implant, the keel having to be properly placed in relation to
• the femoral valgus is the angle, located in the frontal plane, between the anatomical axis of the femur and its mechanical axis, this angle generally having a value between 3 and 11 degrees.
• patent US-A-5,152,796 and the patent EP-A-0 714 645 describe femoral implants comprising an intermediate part forming a wedge or "pre-leg", interposed between the base or one-piece support boss with the condyles, and the keel itself which is secured to the wedge by means of a screw.
• the preload of patent EP-0 714 645 is symmetrical - with respect to a frontal plane, and has a lower face inclined with respect to the surface of the base, which makes it possible to adapt it to the valgus of the femur, indifferently for the right femur or for the left femur by inversion of 180 degrees .
• this same patent EP 0 714 645 provides for positioning a screw for fixing the pre-rod in the immediate vicinity of the trochlea, in the axis of the keel, which has the consequence of considerably restricting the femoro-patellar surface of support for the patella.
• the femoro-patellar zone of contact of the patella on the trochlea necessarily stops at the level of the recess of passage of the screw. . Therefore, when the ball joint exceeds the corresponding interruption of its support surface, its support is reduced to two points instead of a contact line. This results in an increase in the stresses on the ball joint, therefore in the wear of the polyethylene of the ball joint, which can be replaced prematurely. In the aforementioned patent, the contact line is thus replaced by two contact points after a bending of only about 65 degrees.
• the object of the invention is to propose a femoral implant arranged so as to satisfy the requirements set out above and in particular to provide the patella with an increased femoro-patellar sliding surface, by means of a reduced number of parts compared to to known prior embodiments, by making a set of less expensive orthopedic equipment and more convenient for use by surgeons.
• the femoral implant for knee prosthesis comprises a connecting leg between the base and the keel, and this leg as well as the base, are provided with means allowing an appropriate angular positioning of the leg and the keel.
• the implant also includes fixing means of the shank made to provide the patella with a line of contact with the femoro-patellar surface up to a flexion angle close to 90 degrees.
• the pre-piece has opposite distal and proximal flat faces, in contact respectively with the surface of the base and with a distal end of the keel, these two opposite faces delimit between themselves in a frontal plane a determined angle;
• the surface of the base receiving the pre-leg is planar and inclined in a frontal plane by an angle determined on a horizontal plane, so that when the pre-leg is fixed on the base its proximal face forms with the horizontal plane and in the frontal plane a different valgus angle depending on whether the leg is fixed on a right condyle or a left condyle; in the sagittal plane the pre-stem is profiled so that its proximal part, close to the keel, is distant from a determined interval from the frontal reference plane passing through the proximal end of the trochlea.
• a pre-wedge or wedge thus produced, associated with a right or left implant can offer two angular possibilities of femoral valgus for the keel. If, for example, the support surface of the base forms an angle of 6 ° with the horizontal plane, and the two opposite faces of the leg form an angle of 1 ° between them, the angle of the valgus of the leg and consequently of the keel fixed on it will be 5 ° or 7 ° depending on the side where the pre-keel is fixed.
• two or more pre-legs can have as many different profiles in the sagittal plane. It is thus possible, for example, to produce a set of four pre-legs offering a total of eight possibilities, including four angular possibilities in femoral valgus and four possibilities in the sagittal plane relative to the frontal reference plane, which is the anterior plane, parallel to the anterior aspect of the femur.
• the surgeon can therefore have an orthopedic set consisting of a left femoral implant, a right femoral implant with their bowling pins and a set of a number of bow pins, offering a wide range of possibilities adapting to practically any anatomical case.
• the femoro-patellar area of support of the patella can be notably increased compared to the prior art recalled above, up to a bending angle close to 90 degrees. This results in a reduction of the stresses on the ball joint and therefore of the wear it undergoes.
• Figure 1 is a side elevational view, in a sagittal plane, of a first embodiment of a femoral implant for knee prosthesis according to the invention.
• FIG. 2 is a partial sectional view along 2/2 of the femoral implant of FIG. 1 without the pre-leg, of a femoral implant for a left knee corresponding to FIG. 1.
• Figures 2A and 2B are partial schematic elevational views of the implant base and the shank illustrating how the angle of inclination of the base surface and the angle between the opposite faces of the shank can be added to orient a central medullary keel in valgus as shown in Figure 2.
• FIG. 3 is a view similar to FIG. 2 showing a different valgus obtained with another pre-leg.
• FIGS. 3A and 3B are diagrams similar to FIGS. 2A and 2B illustrating how a valgus different from that of FIGS. 2 and 2B can be obtained with the same pre-frame by orienting it differently.
• Figure 4 is a view similar to Figure 2 for a femoral implant intended for a patient's right femur.
• Diagrams 4A and 4B are similar to the diagrams according to FIGS. 2A and 2B and illustrate the manner in which the pre-leg can be positioned on its base to obtain a femoral valgus according to FIG. 4.
• FIG. 5 is a view similar to FIG. 4 showing a second value of the valgus with another preequille.
• FIGS. 5A and 5B are diagrams similar to FIGS. 4A and 4B showing the manner in which the pre-position can be positioned on the base of the implant to obtain a femoral valgus according to FIG. 5.
• FIG. 6 is a side elevation view of 'a first embodiment of the pre-fitting equipping the implants of Figures 1 to 5.
• Figure 7 is a sectional view along 7/7 of Figure 6.
• Figure 8 is a bottom view of the pre-fitting of Figures 6 and 7.
• FIG. 9 is a side elevation view of a second embodiment of the leg which can be fitted to the implants of FIGS. 1 to 5.
• FIG. 10 is a sectional view along 10/10 of FIG. 9.
• FIG. 11 is a bottom view of the shank of FIGS. 9 and 10.
• Figure 12 is an elevational view in a sagittal plane of the implant and its patella, shown in its two extreme flexion positions on the trochlea.
• FIG. 13 is a bottom view corresponding to FIG. 12.
• Figure 14 is a sectional view in a sagittal plane along 14-14 of Figure 15, of an implant provided with a pre-keel according to the embodiment of Figure 6.
• Figure 15 is a top view corresponding to the figure 14.
• FIG. 16 is a sectional view along 16-16 of FIG. 17 of an implant provided with a pre-form according to the embodiment of FIG. 9.
• FIG. 17 is a top view corresponding to FIG. 16.
• the femoral implant 1 of FIG. 1 is intended to be part of a knee prosthesis, the associated tibial implant not being shown.
• the femoral implant 1 can correspond either to a left knee or to a right knee.
• Figures 2 and 3 show a femoral implant 2 intended for a left knee and Figures 4 and 5 show a femoral implant 3 intended for a right femur.
• the implant 1, 2 or 1, 3 comprises two condyles 4, 5 secured to a trochlea 6, a central medullary keel 7 adapted to be introduced into the medullary canal of a femur not shown, and a "pre-keel" 8 for supporting the keel 7.
• the pre-leg 8 is fixed on a base 9 for support formed between the condyles 4, 5 and in one piece with the latter as well as with the trochlea 6.
• the proximal face 11 of the base 9, on which the leg 8 rests, is planar (FIGS. 2A to 3B) and forms in the frontal plane an angle ⁇ with the horizontal plane P, for example 6 ° (FIG. 2A).
• the pre-leg 8 (FIGS. 2, 2A and 2B) has opposite plane faces 12, 13 proximal and distal respectively, in respective contact with the distal end of the keel 7 and with the surface 11 of the base 9.
• the opposite plane faces 12 , 13 delimit between them a determined angle ⁇ , for example 1 °, these faces 12, 13 being divergent to the right in FIGS. 2A and 2B.
• the pre-leg 8d (Fig.3A and 3B) has a distal face 13 inclined at an angle ⁇ opposite to the angle ⁇ of Fig.2A with respect to its proximal face 12.
• the upper planar surface 11 of the base 9 is inclined, in the frontal plane, in the direction opposite to that of the surface 11 of the base 9 of an implant 2 for an left femur, as seen in the figures 4, 5 and 5A to 5B.
• This surface 11 can form with the horizontal plane P the same angle ⁇ as previously, and similarly the opposite faces 12, 13 of the pre-leg 8b, 8d form between them an angle + ⁇ .
• a shank 8, 8a, 8b, 8d can also have a variable profile in the sagittal plane, as illustrated in the two embodiments of FIGS. 6 to 8, 14, 15 and 9 to 11, 16, 17.
• the shank 8 ( Figures 6 to 8 and 14, 15) consists of a tubular part 16 of axis XX, for receiving the lower end of the keel 7 in a hole 17, and of an enlarged base whose flat lower face 13 bears on the surface 11 of the base 9.
• the base In the anteroposterior direction, towards the condyles 4, 5 the base is enlarged with respect to the upper part 16 by a boss 18 in which a hole 19 is formed intended to receive a not shown fixing element, such as a bolt 50 (Fig.12) passing through the wall of the base 9.
• the femoro-patellar surface 60 of support of the ball joint 61 is notably increased.
• the ball 61 can remain in abutment on a contact line of this surface 60 up to a bending angle A which can reach approximately 80 degrees (FIG. 12).
• Means for complementary attachment of the shank 8 to the base 9 are also provided, for example on the side close to the trochlea 6, a lug 21 projecting below the base and adapted to be introduced into a complementary hole in the base 9 Opposite the anterior wall 6a of the trochlea 6, the wall 21a of the leg 8 is rectilinear.
• the shank 8 is profiled so that its upper part 16 and more precisely the upper end of its side 21 close to the trochlea 6, is distant by a determined interval d from the frontal reference plane F passing through the end superior of the trochlea 6 (figure 1) and which is the anterior plane, corresponding to the anterior face of the femur.
• This distance determines the interval between the axis XX of the pre-leg 7 and the frontal reference plane F, which must be appropriate to the anatomy of the patient in order to contribute to a good fixation of the pre-leg 7 in the medullary canal. and respect for the anterior cortex.
• this distance d can for example be 4mm with the pre-leg 8.
• the shank 22 is profiled so that the distance d with the reference plane F is greater than the corresponding distance with the shank 8 (for example 18.8mm instead 14.8mm).
• This result is obtained by shifting the axis XX of the tubular part 16 (which is also that of the keel 7) relative to the side 21a closest to the trochlea 6, this shift being located in the sagittal plane.
• the lower part of the pre-leg 22 has in the anteroposterior plane an additional boss 23 facing the trochlea 6 and the outer face of which is separated from a distance e2 from the axis XX of the tubular part 16, with e2 greater than e1 (FIG. 6).
• the corresponding interval d is therefore increased with respect to the interval resulting from the use of the pre-frame 8.
• a set of orthopedic equipment comprising two femoral implants 2, 3, the corresponding pins 7 and a set of several pre-legs 8, 22 offering a whole range of possibilities for obtaining a femoral valgus and an interval d determined between the upper end of the pre-leg and the frontal reference plane F of the trochlea 6.
• two pre-legs can be produced, the opposite faces 12, 13 of which diverge from one another by an angle ⁇ , for example 1 °, and one of which presents in the sagittal plane the profile of the pre-leg 8 while the other corresponds to the profile of the pre-leg 22.
• these two pre-legs are associated with a femoral implant, left or right, of which the base 9 has a surface 11 inclined by a determined angle ⁇ , for example 6 °; the game may include two other legs, the opposite faces 12, 13 of which form a determined angle ⁇ , which may or may not be the same as for the previous legs; one of these legs has the profile of the leg 8 and the other that of the leg 22, these two legs being intended for the second femoral implant, right or left.
• the implant according to the invention provides an increased support area 60 for the ball joint 61 by virtue of the distance between the fixing element 50 of the pre-leg (8, 22) and the trochlea 6, which increases the life of the patella.
• the pre-leg can present in the sagittal plane a profile different from those represented.
• the angles ⁇ and ⁇ can vary appreciably in order to allow obtaining of femoral valgus suitable for the anatomical cases which may arise.

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• Health & Medical Sciences (AREA)
• Orthopedic Medicine & Surgery (AREA)
• Physical Education & Sports Medicine (AREA)
• Cardiology (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Transplantation (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Vascular Medicine (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Prostheses (AREA)

Applications Claiming Priority (3)

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• 1997
  • 1997-12-22 FR FR9716271A patent/FR2772593B1/fr not_active Expired - Fee Related
• 1998
  • 1998-12-10 EP EP98959955A patent/EP1041944A1/de not_active Withdrawn
  • 1998-12-10 US US09/582,095 patent/US6423096B1/en not_active Expired - Fee Related
  • 1998-12-10 WO PCT/FR1998/002692 patent/WO1999032053A1/fr not_active Application Discontinuation
  • 1998-12-10 AU AU15674/99A patent/AU1567499A/en not_active Abandoned
  • 1998-12-18 ZA ZA9811633A patent/ZA9811633B/xx unknown

Non-Patent Citations (1)

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