FR2522090A1 - IMPROVED SPHERICAL KINETIC JOINT FOR PROSTHETIC - Google Patents

Abstract

IMPROVED SPHERICAL KINETIC JOINT 10 THAT FACILITATES ASSEMBLY AND DISASSEMBLY, ESPECIALLY ASSEMBLY, BY PROVIDING MULTIPLICITY OF BEARING SEGMENTS PHYSICALLY SEPARATE IN A SUBSECTION SO THAT THESE BEARING SEGMENTS ACTUALLY FORM A UNIT STRUCTURE FOR THE PURPOSES ASSEMBLY AND DISASSEMBLY, WHILE EXPANDING EASILY WHILE SUBJECTING TO LOW MANUAL FORCE WHEN ASSEMBLING AND DISASSEMBLING THESE BEARING SEGMENTS FROM THE HEAD 16 AND FROM A CAVITY OR SPHERICAL SEAT IN THE OTHER ELEMENT JOINT AS FOR EXAMPLE WHERE THIS JOINT IS JOINT FOR A PROSTHETIC ACETABULAR CAVITY 30. ALSO, THE FACILITY OF ASSEMBLY AND DISASSEMBLY MAY BE OBTAINED WHILE MAINTAINING A HIGH RESISTANCE TO DEBITMENT AND TO SEPARATION AND CAN BE OBTAINED IN A MANNER THAT DOES NOT PRODUCE A SIGNIFICANT AXIAL GAME.

Description

Improved spherical kinetic joint.

  The present invention generally relates to an improved spherical or ball joint, which, as is well known in the art, provides three rotational degrees of freedom; Kinetic ball joints are commonly used in machines, be they workshop machines or office machines, as well as in various applications in the automotive industry, such as

  example link links typically

  that these joints include an element with a spherical head

  or ball joint, an intermediate bearing constituting a cavity or seat for receiving the spherical head, and a third element constituting another cavity or seat for receiving the bearing in which the ball joint is housed.

  case, it is required that such a seal resist dislocation during

  that it rotates at its maximum speed and that it withstands separation when a tensile force tends to separate the various components of the joint The structure of such joints is well known to those skilled in the art and it is also known that these joints can be

  made up of many different structural elements.

  Moreover, it is often desirable that, in such joints, the axial clearance between the elements of the assembled joint

either zero or minimal.

  Such seals are described in US Pat.

  United States No. 1,891,804, No. 1,894,309, No. 1,985,728, No. 3,220,755 and No. 3,401,965 All the seals described in these Patents have means for minimizing or eliminating axial backlash. further describe two

  different types of spherical kinetic joint structure.

  In the first three patents mentioned above,

  carry separate bearing segments which are assembled on the spherical head or ball and are then introduced into a housing where they are held by various means. The aforesaid Patent No. 3,401,965 discloses a different type of joint structure, which comprises a housing bearing the load and a retaining collar to prevent dislocation

  and the tensile separation of the elements of the assembled joint.

  The aforementioned Patent No. 3,220,755 discloses a unitary structure, in which the bearing has, on the front face near

  an opening, a multiplicity of slots forming a multiple

  tiplicity of fingers or curved segments that move outward when brought into engagement with the ball or spherical head; after assembly, the bearing and the ball are introduced into the cavity of the third element, the latter then preventing any separation to the outside of the fingers and enclosing the bearing on the ball joint Additional means are then provided to maintain the bearing in the cavity of the third element, thereby providing a seal

  which resists traction separation and dislocation.

  Recently, spherical kinetic joints have found

  applications in joint prostheses in humans.

  In these prosthetic applications, the ease of assembly and

  Disassembly of the elements of the joint are of great importance.

  The use of an intermediate bearing constituted by a

  multiplicity of unrelated segments of

  that they are not mounted in the joint is not desirable

  in prosthetic applications, because it is difficult to

  cile to manipulate and maintain the bearing segments on the patella when mounting it and the segments of

  the third element, especially when

  Urgency works inside a surgical cavity.

  Although a bearing having flexible curved fingers or segments reduces the amount of mounting force that would be required if there were no fingers, such flexible fingers may nevertheless present difficulties in

  surgeon during operation; because to provide the

  the fingers must be relatively rigid, which, in turn, requires a considerable amount of assembly force to apply.

by the surgeon.

  As is well known in the prosthetic applications of spherical joints, the assembly force must be low and the assembly must be easy to reduce the time of assembly.

  and also because of the difficulties of such operations.

  Often, the field of view is limited and the

  elements of the joint are slippery because they are

  of blood and fat, which can happen when they fall, which raises another problem because these prosthetic joints must be sterile and

  after falling, they must be re-sterilized or replaced

  placed, while the surgical cavity remains open In addition, due to urgency or other difficulties during

  the operation, it is desirable to be able to dismantle

  joints, preferably in a manner which avoids the same assembly difficulties as those noted above,

  that is, excessive disassembly forces and a multiplicity of

  This is because joints that are satisfactory in machines where conventional assemblies and other tools can be conventionally used to assemble the joint elements require improvements. to be

  actually used as prosthetic joints.

  Such prosthetic joints are described in U.S. Patent Nos. 3,813,699, 3,863,273, 4,044,403 and 4,241,463. The prosthetic seal described in the above-mentioned first patent resists dislocation and separation and partially eliminates the assembly problems noted above by having a unitary structure comprising both the bearing and the cavity coty-

  loid (acetabulum), which reduces the manipulation of

  seals during assembly and disassembly.

  However, the unitary structure of the bearing and the cavity

  cotyloid does not allow to combine an assembly and a disassembly

  easy to handle with high separation resistance, since the opening in the spherical cavity of the bearing which receives the spherical femoral head can not expand or deform appreciably outwardly when it is force-fed in cooperation with this spherical head, therefore the prosthetic joint thus described, either requires extremely high mounting and disassembly forces, or causes a relatively low resistance to disengagement forces

and separation.

  The prosthetic joint described in the patent No. 3,863,273

  partially undermines the problem of the importance of mounting or dismounting forces using, as in the patent

  No 3,220,755, an intermediate tier with a multi-

  of curved segments at the entrance to the Dhé siege.

  receiving the patella, the other curved segments, in

  being forced into the femoral head, require, however,

  With a manual force too high to move outward and allow the head to enter the spherical seat of the intermediate bearing. Furthermore, the prosthetic seal described in this patent No. 3,863,273 uses a tongue on the bearing to prevent the landing of

  separating from the cotyloid cavity However, such a structure

  ture introduces undesirable axial play in said seal.

  Similarly, the prosthetic seal described in Patent No. 4,044,403 proposes only a partial solution to the problem

  above mentioned, in that the mounting forces required

  The joints for joining the seal members are, of course, reduced below those required to assemble the seal members in the prosthesis of Patent No. 3,813,699 for disengagement resistance and predetermined separation; this result is achieved by using flexible lips on the bearing cooperating with the spherical head of the first

  element and / o the cavity of the third element or cavity coty-

  loide However, it is not easy to disassemble such a joint structure without causing some damage to the bearing;

  such a structure does not therefore provide the combination

  of a low manual assembly force and

  resistance to high separation desired by chiropractors

  The prosthetic joint described in US Pat. No. 4,241,463 provides a structure that requires only a small force.

  to mount the bearing on the head, but it uses a solu-

  Similar to that described in US Pat. No. 4,044,403 for mounting the third element or cotyloid cavity to the bearing. Likewise, the inner retaining ring of the prosthetic seal of Patent No. 4,241,463 functions

  which causes end play between the spherical ball joint

  In addition, this prosthetic joint does not allow, during operation, to easily mount the bearing on the third element or cotyloid cavity, nor the disassembly of this bearing on this third element As known well specialists, it is desirable, in prosthetic joint applications, to have cotyloid cavities and physically separated bearings to

  to reduce the cost of storing prostheses of different sizes.

  to reduce the costs of sterilization associated with

these prostheses.

  Furthermore, the bearings described in the aforementioned patents provide a covering which, when the spherical head is housed in the bearing and the bearing with the spherical head housed inside is placed inside the bearing housing, prevents the dislocation of the spherical head of

  bearing during a rotational movement between the spherical head

  and the cavity of the bearing housing.

  The improved spherical kinetic joint of the present invention

  The present invention eliminates previous problems by providing various bearing designs which permit easy assembly and disassembly, including mounting, by providing a plurality of substantially physically separate bearing segments in a subset such that these segments of Bearings effectively form a single structure for mounting and dismounting purposes, but they can easily deviate under the application of a low manual force during assembly and disassembly of these various embodiments of bearings on the head. and / or the cavity or spherical seat of the third element, as for example in the embodiments of joints for prostheses, a cavity

  In addition, one can obtain this ease of

  dismantling and dismantling while maintaining a high resistance

  disengagement and separation and, in some cases,

  case, this is obtained without introducing a significant axial play.

  The invention will be better understood on reading the description of

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS RELATING TO THE JOINT DRAWING FIG.

  the spherical kinetic joint of the present invention, incor-

  pored as a hip prosthetic joint implanted in

  be a pelvis and a femur; Figure 2 is a cross-sectional view of a first embodiment of a split bearing according to the present invention; Figure 2 (a) is a partial front view of a portion of the split bearing of Figure 2; FIG. 3 is a cross-sectional view of a cavity

  cotyloid of the present invention, particularly useful

  when the spherical kinetic joint of the present invention

  vention is used as a prosthetic hip joint; Figures 4 (a) and 4 (b) are cross-sectional views of two variants of retaining rings; FIGS. 5 (a), 5 (b) and 5 (c) are respectively a side view, a top view and a large scale view of a release ring used to disassemble the spherical kinetic seal elements of the present invention. invention; Figs. 6 (a) and 6 (b) are successive cross-sectional views for illustrating the mounting of an embodiment of the present invention; FIGS. 7 (a) to 7 (c) illustrate the utility of the cutouts provided on the split bearings of the present invention to reduce the radial expansion required for mounting the bearings on the femoral head of a femoral spindle when

  uses the spherical kinetic joint of the present invention.

  as a hip prosthetic joint; FIGS. 8 (a) and 8 (b) show schematically in cross-section the advantage of greater cooperation between

  a retaining ring and the outer grooves provided on.

  a bearing between the retaining ring and the circumferential groove

  inner projection provided on an acetabular cavity, when the present invention serves as a hip prosthetic joint and uses a retaining ring; and Figures 9 (a) to 9 (c), Figures 10, 11, 12 (a) to 12 (d) and Figures 13 to 20 show variations of various split bearings of the improved spherical joint of the present invention, especially when used as articulation

prosthetic hip.

  Referring now to Figure 1, we see a first E

  realization of the improved spherical kinetic joint of the pre-

  This invention is used as a hip prosthetic joint 10 which is shown implanted. The hip prosthetic joint 10 comprises the following components

  a femoral component 12 sometimes referred to in the art.

  intramedullary pin or femoral insert; a fetal bearing 20, an acetabular cup or cotyloid 30; and a ring

40.

  The femoral component 12 includes a pin 14 which secures the component into the medial cavity of the femur, preferably but not exclusively with the aid of a fixation grout; a spherical or spherical femoral head 16; and a neck region 18 that transfers the load of the head

  femoral spherical 16 at the spindle 14.

  The split bearing 20, which is best seen in FIGS. 2 and 2 (a), has a plurality of opposed identical split bearing segments in the form of comb shells.

  21-21, a single pair being shown; in this realization

  tion, each split bearing segment 21 is physically dis-

  Each segment has an outer spherical surface 22, an outer cylindrical surface 23, and an outer annular conical surface 24; in addition, each segment 21 has an inner spherical surface 25 and an inner annular conical surface or beveled surface

  In the illustrated embodiment, each segment 21 comprises

  carries a generally U-shaped longitudinal surface 29 which has the same shape as the hatched surface of FIG. 2, but without the gap Each outer spherical surface

  22 is connected to the inner end of the cylindrical surface

  outer jaw 23, and the outer end of each cylindrical surface 23 ends at the inner end

  the outer annular conical surface 24; likewise

  that inner spherical surface 25 connects to its end.

  mounded to the inner annular conical surface 26; and the outer ends of the annular conical surfaces 24 and 26 intersect, as shown, preferably with a slight radius r. When placed in opposition as shown in Fig. 2, the inner spherical surfaces 25-25 of the elements Shape 21-21 cooperatively provides a cavity or spherical seat 27 for receiving the spherical femoral head 16 (Figure 1) of the femoral component 12 (Figure 1); it is thus well understood that the cavity or spherical seat 27 closely matches the shape of the spherical femoral head 16, the diameter of the

  femoral head 16 being superior to the access to the seat 27 pro-

  curved by the bevel 26 Two cuts or bevel surfaces

  28-28 may be provided for each element 21 adja-

  longitudinal surfaces 29 and are connected thereto; these bevelled surfaces 28-28 facilitate the introduction of the spherical femoral head 16 of the femoral component 12 into the spherical cavity 27 by reducing the expansion of the split bearing 20 required for this introduction Finally, an outer circumferential groove 19 is provided in each cylindrical surface 23 to receive, in full or at least partially, the flexible retaining ring 40 shown in Figure 4 (a) The depth and width of the groove 19 are sufficient to allow the retaining ring 40 to accommodate completely inside the

  when the ring is compressed radially towards the

  It is understood that before assembly of the components

  Drothetic Hip Joint for implantation purposes.

  the first function of the retaining ring 40, when

  it is housed in whole, or at least partially, inside the outer circumferential grooves 19, is to hold together the elements 21-21 in the form of comb shells in a subset and vis-à-vis ,

  As can be seen in Figure 2, the longitudinal surfaces

  U-shaped 29 cooperating in a contact plane or

  separator extending through the central line C / L.

  The cotyloid cup 30, which is best seen in FIG. 3, has a smooth outer spherical surface 31 which ends at

  the inner end of an outer annular conical surface

  32; the bowl also has a spherical surface

  Inner 33 which connects to its outer end

  with the inner end of a cylindrical surface

  34, which connects at its outer end

  greater, with the inner end of an inner annular conical surface or bevelled surface 35; the conical surfaces 32 and 35 intersect at their outer ends as seen. An inner circumferential groove 37 is provided adjacent to the outer end of the inner cylindrical surface 34 to receive the retaining ring shown in FIG. The outer spherical surface 31 preferably closely follows the acetabular cartilage or the natural cotyloid cavity (Fig. 1), with acetabular articular cartilage not always present due to degeneration of the joint;

  the inner spherical surface 33 and the cylindrical surface

  Inner diaper 34 cooperatively provides a cavity or seat 38 for receiving the split bearing 20 Preferably, the inner spherical surface 33 and the cylindrical surface

  34 of the acetabular cup 30 closely match the

  the outer spherical surfaces 22-22 and the

  outer cylindrical faces 23-23 respectively of the split bearing 20 As best seen in FIGS. 3 and 3 (a), the acetabular cup 30 has a multiplicity of radial grooves 39 extending axially in the inner annular conical surface 35 and in the outer portion of the inner cylindrical surface 34; when the ring

  40 is housed inside the circumferential grooves

  19 and 37 and when the spherical femoral head 16, the split bearing 20 and the acetabular cup 30 are mounted as shown in FIG. 1, the radial grooves 39 provide access from the outside to the ring

  40 by the radial teeth 44 of the disengagement tool

  46 shown in FIGS. 5 (a) and 5 (c) for disassembling the split bearing 20 and the spherical head 16 of the femoral component 12 of the acetabular cup 30, as shown in FIG.

  it will be explained in detail below.

  The hip spherical prosthetic joint 10, according to the

  The invention is implanted as follows: the femoral component 12 is implanted in the femur as described above and as shown in FIG. 1; the front portion or chamfer 26 of the split bearing 20, with

  the retaining ring 40 housed, in whole or at least

  Actually, in the outer circumferential grooves 19 and now together the segments 21-21 of the split bearing into a subassembly as described above, is pushed (the manual force of the surgeon being more than sufficient) in cooperation with the spherical femoral head 16 which the diameter is larger than the access opening to the cavity 27, whereupon the bearing segments 21-21 deviate radially outwardly (i.e., generally radially pivotally outside) around their rear portions (such spacing is facilitated by the cutouts 28 if there are any) to allow the femoral head to be housed inside the split bearing 20 and to be housed in the housing. interior of the cavity or spherical seat 27; then the acetabular cup 30 is pushed onto the

  split bearing 20 to bring the annular conical surface

  or chamfer 35, as seen in Figure 6 (a),

  engaged with the retaining ring 40 to compress the latter

  radially inwardly to the inside of the outer circumferential grooves 19 on the segments 21-21, allowing the acetabular cup 30 to pass over the retaining ring 40 as shown in FIG. b: the inner spherical surface 33 of the

  acetabular cup then comes into contact with the surfaces

  these outer spherical 22-22, low coefficient of friction, the split bearing 20 At this time, the outer circumferential grooves 1919 formed in the

  segments 21-21 are axially aligned with the circumferential groove

  conferred interior 37 formed in the acetal bowl

  30, on which the retaining ring 40 expands radially outwardly to partially lodge

  in the inner circumferential groove 37 and partially

  in outer circumferential grooves 19-19.

  The retaining ring 40 then performs its second function; it retains the acetabular cup on the split bearing 20, with the spherical femoral head 16 housed therein, which prevents the separation (that is, axial disengagement) between the bearing (with the femoral head lodged inside )

  and the acetabular cup during rotation of the joint.

  The three components of the spherical prosthetic joint of

  10 are then assembled and the acetabular cup 30 can be introduced inside the cotyloid cavity,

  as shown in Figure 6 (b).

  The manner in which bevel cuts or surfaces 28-28 facilitate the introduction of the femoral head 16 into the spherical cavity 27 by reducing the amount of radially outward expansion required for insertion into the split bearing 20 is shown schematically in more detail in FIGS. 7 (a) to 7 (c). As shown in FIG.

  FIG. 7 (b), when the split bearing segment 21 'does not

  28-28, the segment must be expanded radially outwards by a distance L 1 to allow the introduction of the head

  spherical 16 in the spherical cavity 27, whereas,

  that the segment 21 has cutouts or bevel surfaces

  28-28 as shown in FIG. 7 (c), the segment 21 should be expanded radially outward only by a lesser distance L 2 to allow the introduction of the femoral head; we see that the distance L 2 is lower

  at the distance L1 practically from the depth S of the discovery

pure 28-28.

  In the embodiment of the present invention shown in FIG. 6 (b), the lap angle y is about 30 and the allowed pivoting or turning movement is

thus about 60.

  For disassembly, we can introduce the release tool

  46, FIGS. 5 (a) and (b), on the neck region 18 of the

  Femoral Health 12 (Figure 6 (b)), the introduction being

  through the opening 48 in the disengagement tool (fi

  Figure 5 (b)); the radial teeth 44 are introduced into the radial grooves 39 (FIG. 3) formed in the acetabular cup 30 to cause the chamfered edges 47 of the release tool (FIG. 5 (c)) to pass over the retaining ring 40 and to push it completely inside the outer circumferential grooves 19-19 formed on

  the split bearing segments 21-21, which allows

  the acetabular cup 30 of the split bearing 20, and thus to disassemble the acetabular cup of the nalier

  clevis 20 and the spherical femoral head 16 housed in the

  interior of the spherical cavity 27 of the bearing 20

  mount the bearing 20 of the spherical head 16, apply

  a force, which can be supplied by hand

  rurgien, on the split bearing 20 to tear it off the head

  spherical femur 16, whereupon the bearing segments

  21-21 can move radially outward

  This allows the bearing 20 (which is facilitated by the cutouts 28, if any) to be easily removed from the spherical femoral head 16, leaving the femoral component 12 implanted in the femur if desired. that, by providing the opening 48 on the release tool 46 (fifugres 5 (a) and 5 (b)), we have a monobloc release tool that can be used to disassemble the bowl

  acetabulum of the split bearing 20 and the spherical femoral head

  16 housed inside the cavity 27, without removing

  the femoral component 12 of the femur (Figure 1).

  It should also be noted that the characteristics

  bearing 20 by dimensioning the bearing segments 2121 as a function of the size of the femoral head 16 so that when the bearing 20 is mounted on the head 16, a gap is provided between the longitudinal U-shaped surfaces. 29 (Figure 2) to allow a lubricant, which, in the case of a hip joint, is synovial fluid, to reach the bearing surfaces of the spherical joint and to help remove wear debris from the surfaces of the bearing by

  appropriate access to surrounding areas.

  Although, in the preferred embodiments of this

  invention, the retaining ring 40 has a transverse section

  circular, particularly because of a larger

  The lower the cost of this circular section, it is possible, as shown in FIG. 4 (b), to use retaining rings with other cross sections, for example square, rectangular, etc .; of course, the shapes of the outer circumferential grooves 19-19 on the segments 21-21 and the inner circumferential groove 37 on the acetabular cup 30 must have a suitable cross-sectional shape It is not necessary that the retaining ring and the grooves are of complementary shape; it has been found that a circular cross-section ring functions properly in a groove of rectangular cross-section, with side walls generally perpendicular to the surface

  outer cylindrical and a bottom parallel to this surface.

  In addition, as seen in FIG. 4 (b), the retaining ring 40 'has a cross section with a width "w"

  and a height "h" whereas, if the trans-

  of the retaining ring 40 (FIG. 4 (a)) has a circular shape, the width and the height of the retaining ring

  are both equal to the diameter "d".

  It has been found desirable that the penetration "e" (Fig. 8 (a)) of the retaining ring 40 into the outer circumferential grooves 19-19 on the bearing 20 be greater than the penetration of the ring retained 40 in the inner circumferential groove 37 provided on the acetabular cup 30, so that the retaining ring 40

  protrudes as little as possible from the groove 19 during assembly.

  This can be explained in connection with FIGS. 8 (a) and 8 (b). If the ring 40 protrudes less from the groove 19 of the bearing 20, a smaller chamfer 35 can be used.

  the entrance into the spherical cavity 38 of the acetal bowl

  This smaller chamfer 35 causes a lesser interruption in the access face of the acetabular cup 30, which gives it a better appearance and allows the use of a thinner pan wall "t" (Fig. 3); this makes it possible to increase the range of dimensions of the acetabular cuvettes which can be housed on a given level, for example

  example the bearing 20 of Figure 2.

  Returning to Figure 8, it can be seen that the maximum overshoot Pmax occurs when one side of the ring is pushed

  completely in the outer groove 19, which makes it

  to move the other side of the ring to the maximum It is well

  tended that the smallest maximum overshoot "P max" for a

  given penetration "e" of the ring in the throat, is obtained

  when the depth of the inner groove 37 is equal to the diameter of the cross section "d" of the retaining ring 40 In this case, the maximum overshoot is Pma P + C (1) max where P is the exceedance of the retaining ring 40 when its axis coincides with the axis of the bearing and C is the clearance between the ring and the bottom of the outer groove 19 when the ring

restraint is thus aligned.

  Now d P + e or P d -e (2) and C d -e (3) Now, if the ring is placed so that one side is completely inside the groove 19, as one see it in FIG. 8 (b), the excess Pmax is: Pmax = 2 (of) (4)

  We can see that increasing "e" reduces Pmax.

  With circular cross sections so that the

  penetration of the retaining ring 40 into the external groove

  Bearing 19 is larger than the penetration of the retaining ring 40 into the inner groove 37, it is necessary to tilt the rear face of the groove 19 to prevent retraction of the ring. The angle as shown in FIG. 2 can be calculated from the formula e <cos 1 (2 e / d 1) (5) where the "is the penetration of the retaining ring 40 into the groove 19 and". is the cross-sectional diameter of the ring 40 The outer diameter D1 of the retaining ring 40 is substantially equal to the diameter D 2 of the internal groove 37 of the acetabular cup, as

  see it respectively in Figures 4 and 3.

  Figures 9 (a) to (c), 10, 11 and 12 (a) to (d) show spherical kinetic seal variants of the present

  invention, also incorporated into a hip prosthesis.

  These embodiments comprise various bearing variants, having various connections by articulation or pivot of the rear portions of the bearing segments, which reduce or eliminate the possibility of the segments to disengage from each other and the retaining ring during assembly and It is of course also understood that these variants comprise the femoral component 12, the acetabular cup 30 and, in some cases, the retaining ring 40 of FIG. 1; the bearing variants are marked 20A, 20B, etc., to distinguish them from the bearing 20 of the first embodiment; when the structure and the surfaces of these bearing variants are identical to those of the first embodiment, they receive identical numerical designations, but,

  when different, they receive a designation of

  alphanumeric code corresponding to the alphabetical designation

  tick of the bearing variant. The first variant (FIG. 9 (a) to 9 (c)) comprises the split bearing 20 A, which comprises a multiplicity of segments of

  opposite identical bearing 21 A-21 A (one pair is

  1), each of which has an outwardly extending tongue 81 and an inwardly extending cavity 83 at its rear end. At assembly, as seen in FIGS. 9 (b) and 9 (c) , the tongues 81 are housed in the cavities 83 to form a hinge connection around which the segments 21A pivot outwards to allow the introduction of the spherical femoral head 16 into the spherical cavity 27A provided by the surfaces Fig. 10 shows another variant, which comprises split bearing 20 B consisting of a multiplicity of opposite identical segments 21 B; the rear part of each of these segments has a hole 61 extending inwards for

  receiving one end of a flexible pin 63; otherwise

  theirs, this other variant includes the components of the joint

  spherical described above After introduction of the

  flexible lug 63 in the opposite axially aligned holes 61-61, the bearing segments 21 B pivot outwardly about the pivotal connection provided by the cooperation of the holes 61 and the flexible pin 63 to

  expand radially outward the bearing 20 B to

  placing the femoral head 16 within the inner cavity 27 B provided inside the split bearing B by the inner spherical surfaces B. A further variant is shown in Figure 11, in which the split bearing 20 C is practically identical to the bearing 20 of FIG. 2; but, while the bearing segments 21 of FIG. 2 were physically distinct from each other, the segments 21 C of the embodiment of FIG. 11 are connected or articulated together to their rear portions by a relatively thin one-piece portion C This variant comprising the bearing with a low coefficient of friction 20 C of FIG. 11 is assembled and dismounted substantially from the

  same way as in the embodiment comprising the

  20 of FIG. 2, except that, when the bearing 20 C of FIG. 11 is expanded radially outward to allow the introduction of the femoral head 16 into the spherical cavity 27, the bearing segments 21 C rotate.

  radial outward around the thin monotone

* Flexible block C. A variant of the bearing 20 C shown in Figure 11 is shown in Figures 12 (a) to 12 (d), the bearing being marked in this figure at 20 D In this embodiment, the element of Articulation D is sufficiently thick to deform plastically as the bearing segments 21 D pivot radially outward, as seen in FIG. 12 (a), to allow insertion of the femoral head.

  16 of the femoral component 12 in the split bearing 20 D

  the inner spherical cavity 27 D formed in the interior

  20 of the split bearing 20 D is wide enough to be slightly larger than the spherical head 16 of the femoral component 12, thereby providing a clearance, indicated at 46, between the spherical cavity 27 D and the femoral head 16 when 14 acetabular cup 30 is partially mounted on the

  plastic bearing 20 D as shown in Figure 12 (b).

  A partial outer circumferential rib 43 is

  formed in one piece on the outer cylindrical surface

  23 D of each landing segment 21 D and corresponds to

  the inner circumferential groove 37 on the acetabulum

  when the bowl and the landing are complete-

  The assembly of this embodiment is as follows: The femoral component 12 is implanted in the femur (FIG. 1) and the split bearing 20 D and the femoral head 16 are assembled as shown in FIG. 12 (a) by deforming somewhat the hinge member D, which slightly separates the anterior portions of the bearing segments 21 D as seen in Figure 12 (a) The acetabular cup 30 is then partially mounted

  on stage 20 D as shown in Fig. 12 (b), re-

  pushing the 21 D segments towards each other against the resistance

  As the assembly progresses, the chamfers or inner conical annular surfaces engage the partial circumferential ribs 43 and press the anterior portions of the segments 21 D together as shown on FIG. FIG. 12 (c) This is allowed by the clearance 46 between the femoral head 16 and the inner spherical surface 25 D of the split bearing 20 D and the spacing between the longitudinal shaped surfaces.

  U 29 At the end of the assembly, the circumferential ribs

  the outer 43 formed on the outside of the split bearing

  D are axially aligned with the internal groove 37

  on the front portion of the inside of the bowl

  acetabulum 30, thereby allowing the ribs 43 to penetrate

  in the groove 37 by the spreading action of the hinge segment D The disassembly or separation of the acetabular cup 30 of the split bearing 20 D can not take place because of the wedge action of the femoral head 16 against the anterior portion of the inner spherical surfaces 25 D of the bearing 20 D and this separation is prevented when the tangent of contact q 1, as we see it on the

  Figure 12 (d) is greater than the contact tangent t 2.

  Disassembly is carried out in the manner already described in use.

  reading the disengagement tool 46 of FIG.

  Figures 13 to 20 show another variant of the seal

  spherical kinetics of the present invention, also used

  As a hip prosthesis

  carries another split bearing 20 E having a plurality of physically distinct bearing segments, namely

  the main bearing segment of generally spherical shape

  51 of Figure 13 and that is the segment of generic form

  the annular groove of the radially or circumferentially split bearing, or the collar 61 of FIG. 14 with the outer circumferential groove 19, ie the generally annular segment or collar 71 for the radially or circumferentially split bearing of FIG. 16 with the rib

  partial or complete circumferential outer circumference 43.

  As can be seen in Figure 13, the main bearing segment

  cipal 51 has an outer spherical surface 52, an outer cylindrical surface 53 and an inner spherical surface

  ; it also has, in its front portion, a protuberance

  annular bearing extending radially outward

  58 and an annular groove extending radially inwardly

59.

  The collar 61 of FIG. 14 comprises a cylindrical surface

  63, in which the circumferential groove is formed.

  outer casing 19 for receiving the retaining ring, an outer annular conical surface 24, a surface

  tapered inner or chamfered cone 26 and one

  inner spherical face 65; in addition, the collar 61 pre-

  at its rear portion a ring protuberance

  extending radially inward 68 and an annular groove

  Similarly, the collar 71 of Fig. 16 has an outer cylindrical surface 73, an outer annular conical surface 24 and an inner or chamfered annular tapered surface 26, and an inner spherical surface 75; in addition, it has in its rear part a radially inwardly extending annular protuberance 78 and an annular groove extending radially outwardly 79 It should be noted that the collars 61 and 71 are made of a flexible material

  appropriate and are split radially, or circumferentially

  64 and 74 respectively to allow the collars to expand radially outward or circumferentially to be assembled

with the main segment 51.

  Before assembly on the spherical femoral head 16 of the joint

  femoral position 12 (Figure 1), the main bearing segment

  51 and either the collar 61 of Figure 14, or the collar

  71 of FIG. 16, are assembled together in a sub-section

  together for ease of manipulation by the surgeon, for the reasons noted above. More particularly, as shown in FIG.

  collar 61 (it is understood that the collar 71 is also

  wheat in the same way), the collar 61 is expanded radially outwardly or circumferentially (preferably before the operation and before sterilization or packaging), to allow the protrusion 68 to pass over the protrusion 58 and, when the collar 61 contracts, the protrusion 68 is housed inside the groove 59 and the protrusion 58 is housed inside the groove 69, on which the

  main bearing segment 51 and collar 61 are assembled

  in a subassembly shown in Figure 18.

  It should also be noted that during this assembly to obtain

  While holding the split bearing 20 E, the flexible retaining ring 4C is also used which is housed inside the groove 19 as seen in FIGS. 17 and 18. In this embodiment, the retaining ring 40 serves to maintain in a subassembly the main bearing segment 51 and the collar 61 However, it is understood that this

  The invention also contemplates providing a necklace in a

  The collar is then formed by a multiplicity of annular segments having on their outer surfaces a groove (for example a groove 19) for receiving the flexible retaining ring 40 which holds the annular segments together and on the bearing segment.

  main 51 to obtain the bearing subassembly.

  Thus, as can be seen in FIG. 18, it should be noted that, when assembled with the primary bearing segment 51, either of the collar 61 or of the collar 71, the same external bearing configuration as that described is obtained. In the same way, it should be noted that the inner spherical surface 55 of the main bearing segment 51 and either the inner spherical surface 65 of the collar 61 or the inner spherical surface 75 of the collar 71 cooperatively provides a cavity or seat spherical wedding

  the shape of the spherical femoral head 16 (FIG.

  1) of the femoral component 12 (FIG. 1), this spherical seat being identified in FIG. 18 in 57 E.

  note that, as in the case of the achievements described above,

  above bearings, the access opening to the spherical seat 57 E provided by the bevel 26 of the collars 61 and 71 is more

  small as the diameter of the spherical head 16 of Figure 1.

  The fitting of the split bearing 20 E on the spherical femoral head 16 of the femoral component 12 (FIG. 1) will now be described with reference to FIGS. 19 (a) to 19 (d), in the case of the split bearing E shown here. and having the collar 61 of Fig. 14; it should be noted, however, that in the case of the split bearing 20 E having the collar 71

  of Figure 16, the installation is carried out in a

Milaire.

  As seen in FIG. 19 (a), when the bevel 26 of the collar 61 (FIG. 14) is forced on the spherical femoral head 16 (the manual force exerted by the surgeon is more than sufficient and this force is indicated by the arrows 81 and 83), the collar 61 expands radially outwardly to the slot 64 and against the action of the retaining ring 40, as seen in Fig. 19 (b), to allow the collar 61 to pass over the spherical femoral head 16 and allow the latter to be housed inside the spherical cavity 57 E (Figure 18) of the split bearing; the acetabular cuvette 30 is then pushed, as in the case of the split bearing 20 described above and shown in FIGS. 6 (a) and 6 (b), on the bearing

  split 20 E to bring the annular conical surface into

  upper or bevel 35 of the acetabular cup 30 (FIG. 6 (a)) to cooperate with the retaining ring 40 and compress it radially inwards completely inside the outer circumferential groove 19 formed on the collar 61, thereby allowing the acetabular cup 30 to pass over the retaining ring 40; the bearing 20 E with

  the femoral head 16 housed inside is then complete-

  housed inside the spherical cavity 38 (FIG. 3) and the elements constituting this embodiment of the present invention.

  invention occupy the position shown in cross section.

  in FIG. 20, with the retaining ring 40 being housed partially inside the outer groove 19 of the collar 61 and partially inside the internal groove of the acetabular cup 30, whereby the ring 40 retains the bearing 20 E inside

  acetabular cup 30 during the rotation of the ar-

reticulation.

  When assembling the collar 71 of FIG. 16 on the primary bearing segment 51 to obtain the subassembly

  indicated above, and when mounting this sub-

  together on the spherical femoral head 16 in the manner shown in Figs. 19 (a) to 19 (d) with respect to the collar 61, the rib 43 penetrates the inner groove

  37 of the acetabular cup 30, whereby this last

  is retained on the split bearing and the bearing (with

  the femoral head lodged inside) and the acetabular cup.

  It should be noted that, as in the case of the split bearing 20 D (FIG. 12 (d)), a clearance, for example the

  46 of Figure 12 (d), shall be provided between the

  inner spherical face 75 and the spherical femoral head 16 to allow the collar 71 to contract as the rib 43 enters the cylindrical surface 33 of the

  acetabular cup 30 (Figure 3).

  Disassembly of the bearing 20 E, that it is assembled in

  together with the collar 61 or with the collar 71, can be performed with the clearance ring 46 described above with regard to the bearing 20 and the retaining ring 40 or with respect to the bearing 20 D with the

circumferential rib 43.

  In the embodiment of the present invention shown in Fig. 20, the lap angle y is about and the rotational or pivotal movement allowed

is thus about 600.

  Referring again generally to the present invention, it should be noted that the split bearing variants shown in FIGS. 2, 9, 10, 11 and 12 are slit in a plane (for example a plane coinciding with the centerline C / L of FIG. 2) perpendicular to the plane 85-85 of FIG. 2 defined by the access opening to the spherical cavity 27 provided by the bevel 26 and that the bearing variant 20 E of FIGS. 13 and 14 is split along a plane represented by the line 87-87 of Figure 13, which is parallel to the plane indicated by the line 85-85 defined by the access opening to the spherical cavity 57 E provided by the bevel 26 of the collar 61 of Figure 14; in each

  realization, the split bearing is constituted by a multiplicity

  cited of bearing segments and by a multiplicity of

split bearing segments.

  Referring generally to all bearing variants of the present invention, it will be appreciated that in the

  embodiments of Figures 2, 9, 10 and 18, the steps correspond to

  are constituted by a multiplicity of bearing segments that are in fact physically distinct and that the steps of Figures 11 and 12 (a) to 12 (d) are constituted

  by a multiplicity of landing segments that are physically

  separately except for single-piece flexible elements C and D respectively to their parts

  back; therefore, it will be used in the claims

  attached the expression "consisting of a multiplicity of substantially physically distinct bearing segments" to describe both the bearing embodiments in which the bearing segments are in fact physically distinct and the bearing embodiments in which the bearing segments are physically except for flexible monoblock elements C and D. Referring now generally to the variants

  described above of the spherical joint of the present invention.

  It will be appreciated that this seal provides a large overlap angle y, as shown in FIGS. 6 (b) and 20, providing high resistance to disengagement with very low assembly and disassembly forces.

  allow radial expansion towards the outside of the

  variants of split bearings in order to be able to

  the head in the shape of a ball joint, for example the head of

  spherical, in the seat or spherical cavity provided by the various variants, it is sufficient to expand radially outwardly a thin retaining ring, or to bend a relatively thin one-piece spherical plastic bridge or opposite tabs or a flexible pin,

  or to expand radially outwardly an annular collar

  In the same way, it is easy to assemble an acetabular cup 30 with the various variants of split bearings and the ball-shaped head, for example

  a spherical femoral head, housed inside, and effected

  kill their disassembly, deforming slightly thin radially inward or radially outward a thin retaining ring while providing great resistance to separation In addition, in the implementations using

  the retaining ring 40, because there is no deformation

  different split bearings during assembly, none of the

  axial play is introduced and the result is a very good

landing stage.

  The femoral component 12 and the acetabular cup 30 may be made of an implantable rigid metal, such as stainless steel, titanium or a cobalt-chromium alloy, as well as

  in certain appropriate ceramics.

  Split bearing arrangements may be of any material suitable for articulation with the spherical head 16 providing sufficient strength to resist dislocation and separation; in the case of the split bearing 20 E (FIGS. 13 to 20), any sufficiently flexible material can be used to provide the desired function of the collars 61 and 71. A satisfactory material for these split bearings is ultra-high molecular weight polyethylene. and some ceramics can also give

  satisfaction for the realization of split bearings not

  not reading a bridge or a flexible joint or a

flexible ring collar.

  Returning again to the split bearings 20 E of FIGS. 13 to 20, it will be noted that the subassembly comprising the main bearing bore 51 and either the collar 61 or the collar 71 can be disassembled from the acetabular cup 30 other than by using the clearance ring 46 of FIGS. 5 (a) to 5 (c) and that the radial slots or grooves 39 of the bowl

  acetabular 30 (FIG. 3), for example the anterior portions

  collars 61 and 71 adjacent to the slots

  64 and 74, can be provided by inwardly extending holes or slots in which conventional flange ends commonly encountered in operating theaters can be introduced to compress the collar, thereby reducing the circumference of the collars to the radial slot, whereby either the retaining ring 40 of the collar 61 or the rib 43 of the collar 71 is released from the groove 37 of the acetabular cup 30 and the bearing 20 E with the head Femoral 16 housed inside can be separated from the acetabular cup 30, the force

  manual surgeon being more than enough.

at

Claims (22)

Claims.   1 spherical kinetic seal (10) providing three degrees   movement in rotation between two elements, of the type com-   carrying: (a) a first component (30) cooperating with one of the two elements and providing a first seat   (38); (b) a second comnosant (12) cooperating with the   be of the two elements and having a neck (18) and a head (16); (c) a bearing (20) consisting of a multiplicity of substantially physically distinct bearing segments (21) and providing a second seat (27) having an opening, the head (16) being accommodated during assembly of the joint, inside the second seat (27) with the neck (18) passing through the opening, the bearing (20) being housed at   inside the first seat (38), the first component   the bearing to expand outwardly and thus confining the head within the second seat, whereby rotational movement is allowed between the two elements, the bearing providing a recovery angle for   prevent the head from dislodging the nierier during this movement.   rotation member, characterized in that it comprises means (40) for holding together said plurality of substantially physically separate bearing segments into a subassembly, thereby facilitating assembly of the joint   spherical kinetics, this subset expanding towards the former   to allow the head to be housed in the first seat.   Kinetic seal according to Claim 1, characterized in that the opening defines generally a first plane (85-85) and in that the bearing (20) is split in at least one second plane oriented in a predetermined manner. compared to the foreground to provide the multiplicity   of bearing segments (21) practically physically tincts.   Kinetic seal according to Claim 2, characterized in that the second plane C / L is substantially perpendicular in the foreground (85-85).   Kinetic seal according to Claim 2, characterized in that the second plane (87-87) is practically parallel. in the foreground (85-85).   Kinetic seal according to claim 3, characterized in that the plurality of substantially physically distinct bearing segments has front portions and posterior portions, the anterior portions delimiting the opening and, when these anterior portions are forcibly brought into engagement with the head, the bearing segments pivot outward around their rear portions to expand the subassembly and allow the head to pass through the opening and be introduced and housed in the second seat.   Kinetic seal according to claim 5, characterized in that   what each bearing segment (21 A) has in its por-   an outwardly extending tongue (81) and an inwardly extending cavity (83), the tongue of each bearing segment being housed in the cavity of a   other bearing segment, the tongues and cavities pro-   co-operating means by which the bearing segments pivot outwards and also prevents the shear separation of these bearing segments by preventing relative movement between them in the second shot.   Kinetic seal according to claim 5, characterized in that it further comprises a flexible pin (63) and in that each bearing segment comprises, in its portion   rearwardly, a hole (61) extending inwardly, the gou-   flexible lug being housed inside these holes when   that they are axially aligned, the pin and the holes cooperatively providing means by which the bearing segments pivot outwardly and also prevent the shear separation of these bearing segments by preventing relative movement between them in the second plane.   Kinetic seal according to Claim 5, characterized   in that the multiplicity of bearing segments practically   physically separate parts has a hinge in their rear portions connecting these bearing segments and that they pivot outwards around this   articulation to dilate the bearing.   9 kinetic seal according to claim 8, characterized in that the hinge is a flexible element (C) formed integrally with the rear portions of these segments. bearings (21 C).   Kinetic seal according to Claim 4, characterized in that the multiplicity of bearing segments substantially   physically separate components comprise a main bearing segment   (51) and at least one generally shaped bearing segment   annular groove (61, 71) the main bearing segment and the generally annular bearing segment cooperatively providing the second seat (57 E), the generally annular bearing segment defining the opening, and in that, when the generally annular bearing   forced into cooperation with the head, it is   late out to allow the head to move to   through the opening and to be introduced and housed in the inside the second seat.   Kinetic seal according to claim 10, characterized in that the means for holding the bearing segments in a subassembly comprise a groove (59, 69) formed on either the main bearing segment or the bearing bearing segment. generally annular, and a protrusion (58, 68) provided on the other of these two bearing segments, the projections being housed inside the grooves during the assembly of the two segments.   Kinetic seal according to claim 10, characterized in that the generally annular bearing segment is   a flexible unitary ring bearing segment.   Kinetic seal according to claim 1, characterized in that it comprises means for preventing the separation first component and bearing.   Kinetic seal according to claim 13, characterized in that the means for preventing the separation of the first   component and bearing comprise at least one recess   curé, either on the first component or on the bearing, and a protrusion provided on the other of the first component or the bearing, which projection is provided to enter the recess. Kinematic joint according to Claim 14, characterized   in that said recess comprises a first groove (37) for   curée on the first component (30) and a second groove (19) provided on the bearing (20) and in that the projection is constituted by a retaining ring (40) partially housed in each of the gorges.   Kinetic seal according to Claim 14, characterized   in that the projection is a monobloc rib of general shape annular groove 143).   Kinetic seal according to claim 14, characterized in that one of the first component or the bearing comprises means for providing access from outside to said   protrude from the recess,   thus separating the bearing from the first component.   Kinetic seal according to Claim 15, characterized in that the first component or bearing comprises   least one groove (39) to allow access from outside the   to the retaining ring (40) and allow it to degaaer the first groove, thereby separating the bearing of the first component. Kinetic seal according to claim 1, characterized in   what the means for maintaining the landing segments   seems in a subset also prevent separation first component and bearing.   Kinetic seal according to claim 1 or claim   5, characterized in that the head and the second seat are spherical, 21 kinetic seal according to claim 13, characterized in that the means for preventing separation comprise a retaining ring (40) and in that the bearing segments (21) are physically distinct and have throats   (19) for at least partially receiving the   retaining ring and in that, when the retaining ring is at least partially housed in the outer grooves before the head is introduced into the second seat, this retaining ring holds together in a subset the bearing segments 22 Kinetic seal according to Claim 21, characterized   in that the first component (30) has an integral groove   (37) intended to be aligned with the outer grooves   and at least partially to receive the retaining ring, and in that, when this retaining ring is partially housed inside the outer groove and the inner groove, it also maintains the bearing with the head housed at inside, in the first seat during the rotation movement.   Kinetic seal according to claim 22, characterized in that the cross-sectional shape of the ring of   retained at a predetermined height and that the   melter of the inner groove is less than the   half of this predetermined height.   Kinetic seal according to claim 23, characterized in that the cross-sectional shape of the ring of   retained is circular, in that this predetermined height   completed is the diameter of this cross section   circular, and that the depth of the groove   is less than half the diameter.   Kinetic seal according to Claim 1, characterized in that the bearing segments comprise cutouts   (28) to reduce the value of the outward expansion   subassembly needed to allow the head   to be housed inside the first seat.   Spherical kinetic seal according to claim 5, characterized   in that the multiplicity of bearing segments   There are two such segments and each bearing segment (21) has an outer spherical surface (22), an outer cylindrical surface (23), an outer annular conical surface (24) and an inner spherical surface (25). ), a surface   internal annular cone (26), and a longitudinal surface   generally U-shaped dinal (29), the outer spherical surface (22) being connected to the inner end of   the outer cylindrical surface (23), the outer end   of the cylindrical surface (23) ending in the ex-   inner end of the outer annular conical surface   (24), the inner spherical surface (25) terminates   at the inner end of the annular conical surface   inside (26), the outer ends of the   inner and outer annular conical faces intersecting, and in that the generally U-shaped longitudinal surfaces (29) of each bearing segment are intended to be placed opposite to the longitudinal surface thereof.   general U-shape of the other bearing segment.   Spherical kinetic seal according to claim 26, characterized in that each bearing segment comprises   two cutouts (28) contiguous to the annular conical surface   the inner surface (26) and the U-shaped longitudinal surface (29) and connecting to these surfaces, these cutouts facilitating the introduction of the head (16) into the second   seat (27) by reducing the value of the expansion towards the   inner subassembly necessary to allow the head to pass through the opening and be introduced   and housed inside this second seat.   Spherical kinetic seal according to claim 4, characterized in that the bearing segments comprise a generally spherical main bearing segment (51) having an anterior portion, and a generally annular and radially split collar (61, 71). , having a rear portion, the front and rear portions having   respectively means of cooperation of complementary forms   the collar being expanded radially towards the ex-   interior and contracting means of cooperation so that they come into contact with each other to form   the main bearing segment and the collar into a sub-base   together. Spherical kinetic seal according to Claim 28, characterized in that the main bearing segment (51)   has an outer spherical surface (52), a sur-   outer cylindrical face (53) and inner spherical surface (55), and in that the collar (61) has an outer cylindrical surface (63), an outer annular conical surface (24), an inner annular conical surface (26) and an inner spherical surface (65), the spherical surfaces cooperating to provide the second seat (57 E), and in that the complementary shape engaging means includes a radially outwardly extending annular projection (58) and an annular groove extending radially inwards (59)   in the forward portion of the main bearing segment   cipal (51) and a radially inwardly extending annular projection (68,78) and a radially inwardly extending annular groove (69,79) provided on the   rear portion of the collar (61, 71).   Spherical kinetic seal according to claim 1, characterized in that this seal serves as a joint for a   hip prosthesis and that the elements are respectively the pelvis and femur.   Spherical kinetic seal according to claim 1, characterized in that this seal serves as a hinge for a   shoulder prosthesis and in that the two elements are the rus and collarbone.