Abstract:
The distal end part of the retractor according to the invention is provided both with terminal tips for abutment on one of the femoral condylar walls which define therebetween the intercondylar space, and with a wing extending laterally in projection from this end part in order to form a frontal surface for thrust, in a medial-lateral direction, of that part of the quadriceps muscle tendon containing the patella when the tips are in abutment in the intercondylar space. By using this retractor as a lever, the wing efficiently reclines the patella, without turning it completely on itself, entirely exposing one of the femoral condyles. This invention is more particularly applicable to a surgical procedure for implanting a unicompartmental knee prosthesis.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a patellar retractor intended to be used when performing knee surgery, particularly when a unicompartmental knee prosthesis is being implanted. The invention also relates to a method of surgical procedure on the knee employing such a retractor.  
       BACKGROUND OF THE INVENTION  
       [0002]     When implanting a knee prosthesis, it is necessary to incise the anterior face of the knee and to recline the corresponding soft parts, i.e. disengage these soft parts rearwardly so as to render the operative field more visible and thus allow the surgeon to access the femoral and tibial epiphyses articulated on each other, particularly the femoral condyles and corresponding tibial articular cavities.  
         [0003]     U.S. Pat. No. 5,380,331 discloses using various retractors intended to facilitate access and treatment of osseous or ligamentary zones of the knee operated on, depending on the stage of operation underway. This type of retractor is in the form of an elongated rigid body of which the distal end is introduced at the level of precise interstitial zones of the knee in order to raise, hold back and/or disengage muscular, osseous or ligamentary parts of the knee. U.S. Pat. No. 5,380,331 thus envisages retractors of the tibia, the posterior ligament, the collateral ligament, etc. . . . as well as patellar retractors of which the distal end, inclined with respect to the rest of the rectilinear body of the retractor, is applied against the outer lateral face of the tibial epiphysis in order to hook on the lower part of the quadriceps muscle tendon and dislocate the patella contained in the upper part of this tendon. Such patellar retractors prove in practice to be inefficient insofar as, by elasticity of the quadriceps muscle tendon, the patella tends to resume its initial place, only a small extent of the lower zone of the tendon being efficiently disengaged towards one of the lateral sides of the knee. The surgeon is in that case often obliged to use these patellar retractors to force on the quadriceps muscle tendon and completely turn the patella round, this risking damage to this tendon and/or the patella. In addition, as these patellar retractors abut against the outer lateral face of the tibia, their use requires a long and deep incision of the soft parts of the knee, even if the purpose of the operation is to implant a unicompartmental prosthesis, i.e. a prosthesis to be implanted only on one of the external or internal sides of the knee.  
         [0004]     In the domain of the implantation of unicompartmental knee prostheses, intramedullary patellar retractors are known, whose distal end in the form of a rod is to be introduced in the medullary cavity of the femur, after having previously bored an access to this cavity through the femoral epiphysis. Although, in practice, this type of retractor limits the stress of the quadriceps muscle tendon and of the patella during reclination of the latter, the necessity of accessing the femoral medullar cavity leads to a long operation, which destroys the patient&#39;s osseous matter and is particularly invasive.  
         [0005]     It is an object of the present invention to propose a patellar retractor which makes it possible to recline the patella efficiently without everting it, i.e. without turning it completely on itself, in order to offer the surgeon a good field of vision for the operation, while limiting the extent and depth of the incision necessary for use thereof, in particular which does not necessitate accessing the medullary cavity of the femur or of the tibia, and which is thus more particularly adapted to the implantation of a unicompartmental prosthesis.  
       SUMMARY OF THE INVENTION  
       [0006]     To that end, the invention relates to a patellar retractor, comprising a globally elongated body, characterized in that the distal end part of the body is provided both with at least one terminal tip for abutment on one of the femoral condylar walls which define therebetween the femoral intercondylar space of the knee, and with a wing extending laterally in projection from this end part in order to form a frontal surface for thrust, in a medial-lateral direction, of the part of the quadriceps muscle tendon containing the patella when the or each tip is in abutment in the intercondylar space.  
         [0007]     The quadriceps muscle tendon contains the patella insofar as the patella is integrated with this tendon.  
         [0008]     The structure of the retractor according to the invention is particularly simple to manufacture and to use. When the surgeon seeks access to one of the femoral condyles, in particular to implant at that level a unicompartmental prosthesis, he inserts the distal end part of the retractor in the femoral intercondylar space, then, by causing the or each tip to abut on the wall of the treated condyle facing the intercondylar space, he makes a lever with the body of the retractor in order, thanks to the lateral wing, to dislocate the patella by pushing it in a medial-lateral direction directed towards the other condyle. This simple gesture allows the surgeon to recline the quadriceps muscle tendon efficiently, by stressing the latter at the level of its current part, i.e. its part containing the patella, and this thanks to the lateral wing from which the frontal surface extends in that case along this current part of the tendon. It will be understood that, in the invention, the term “tip” is understood broadly as a swelling or an element in relief, able to allow a stable abutment of the distal end of the retractor in the intercondylar space during its stress as lever for thrust of the patella.  
         [0009]     As the stress of the quadriceps muscle tendon is applied over a substantial length of the current part of this tendon, no traumatic excess pressure or strain is applied to the tendon, while guaranteeing a sufficient lateral disengagement of the patella without having to turn it completely on itself. During the subsequent steps of the surgical procedure, particularly during osseous cuts of the condyle to be treated, the lateral wing of the retractor efficiently holds the patella in its reclined position, while protecting it from the ancillary instruments used at the level of the treated condyle, for example cutting tools, since this wing is in that case interposed, in the medial-lateral direction, between the front zone of the treated condyle and the current part of the quadriceps muscle tendon. As the patellar retractor is advantageously manipulated in one hand, the operating gesture is simple and easily reproducible.  
         [0010]     As the distal end of the retractor according to the invention may access the intercondylar space by passing through the incision necessary for access to the condyle to be treated, the use of the retractor does not involve any extension of this incision, the surgical approach in that case being able to be considered as mini-invasive. Moreover, no removal of osseous matter is necessary in order to use this retractor.  
         [0011]     According to other advantageous characteristics of this retractor, taken separately or in any technically possible combinations:  
         [0012]     the or each tip extends longitudinally in line with the distal end part;  
         [0013]     in longitudinal section, the or each tip, on the one hand, and the zone of the distal end part connected with the rest of the body, on the other hand, present respective opposite curvatures;  
         [0014]     the frontal thrust surface is concave;  
         [0015]     in frontal view, the wing presents a globally triangular contour of which one of the edges corresponds to the side of the distal end part from which the wing extends;  
         [0016]     a second edge of the triangular contour, facing towards the or each tip, presents a hollowed profile, advantageously corresponding to an arc of circle of which the centre is located in the vicinity of the or each tip;  
         [0017]     a third edge of the triangular contour, facing opposite the or each tip, presents a convex profile directed opposite the distal end part;  
         [0018]     the proximal end part of the body forms or is provided with a handle for manually manipulating the retractor;  
         [0019]     in longitudinal section, the profiles of the two end parts, except at the level of the or each tip, together form a substantially continuous arc;  
         [0020]     the distal end part is further provided with a second wing extending in lateral projection from this end part, on the side opposite that from which the first wing extends.  
         [0021]     The invention also proposes a method of surgical procedure on the knee, which allows the patella to be efficiently reclined without turning completely on itself, in order to offer a wide field of vision for the operation, while limiting the extent and depth of the necessary incisions or the like, in particular which does not necessitate accessing the medullary cavity of the femur or of the tibia.  
         [0022]     To that end, the invention relates to a method of surgical procedure on the knee which comprises the following successive steps of:  
         [0023]     incising an anterior and external or internal zone of the knee,  
         [0024]     holding back the edges of the incision to reveal at least in part the corresponding external or internal femoral condyle,  
         [0025]     introducing a pointed distal end of a patellar retractor into the femoral intercondylar space, passing via the incision,  
         [0026]     using the retractor as lever to dislocate the patella by pushing that part of the quadriceps muscle tendon containing the patella in a medial-lateral direction towards the other condyle, causing said pointed end to abut on the wall of the revealed condyle facing the intercondylar space.  
         [0027]     The method according to the invention leads to accosting one of the external or internal condyles of the femur in mini-invasive manner, since the patellar retractor used, by passing through the incision necessary for access to this condyle in order to treat it, involves no extension of this incision. The method according to the invention is thus more particularly adapted to the implantation of a unicompartmental knee prosthesis.  
         [0028]     In practice, the patellar retractor as defined hereinabove is advantageously used when carrying out the method according to the invention.  
         [0029]     According to other advantageous characteristics of this method:  
         [0030]     in order to introduce the pointed end of the retractor in the intercondylar space, this end is made to slide successively against the front wall and the wall turned towards the intercondylar space of the revealed condyle;  
         [0031]     when that part of the quadriceps muscle tendon containing the patella is pushed, the patella is slid laterally on the anterior face of the lower epiphysis of the femur; and/or  
         [0032]     when that part of the quadriceps muscle tendon containing the patella is pushed, the posterior face of the patella is maintained directed towards the femur. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]     The invention will be more readily understood on reading the following description given solely by way of example and made with reference to the accompanying drawings, in which:  
         [0034]      FIG. 1  is a view in perspective of a patellar retractor according to the invention, illustrated in the course of being used on a knee shown solely schematically.  
         [0035]      FIG. 2  is a view in elevation of the retractor, in the direction of arrow II of  FIG. 1 .  
         [0036]      FIG. 3  is a view in perspective, on a larger scale, of the distal end of the retractor of  FIG. 1 .  
         [0037]      FIG. 4  is a schematic section, along plane IV of  FIG. 3 , of the retractor and of the corresponding osseous parts of the knee in the configuration of use of  FIG. 1 .  
         [0038]     FIGS.  5  to  8  are views in perspective illustrating successive steps of the method of surgical procedure according to the invention; and  
         [0039]      FIG. 9  is a view in perspective of a variant patellar retractor according to the invention. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0040]     Referring now to the drawings, FIGS.  1  to  4  show a patellar retractor  10  adapted to recline the patella  2  of a knee  1 . In  FIGS. 1 and 4 , the knee  1  is shown bent, with the lower epiphysis of the femur  3 , the upper epiphysis of the tibia  4  and the tendon of the quadriceps muscle  5  which, to the rear of its current part  5 A, contains the patella  2 , while its upper ( 5 B) and lower ( 5 C) ends are respectively connected to the front faces of the femur  3  and of the tibia  4 . The knee  1  shown being a right-hand knee, the femoral epiphysis comprises an external condyle  3 A and an internal condyle  3 B, the upper parts of these condyles being connected by an osseous trochlea  3 C while, in their lower part, these condyles are distant from each other in a medial-lateral direction, defining therebetween an intercondylar space  3 D, clearly visible in  FIG. 4 . During the movements of the knee  1 , the condyles  3 A and  3 B are articulated in complementary cavities  4 A and  4 B provided at the upper end of the epiphysis of the tibia  4 .  
         [0041]     The retractor  10  is constituted by a one-piece rigid body  11  made for example of metal or any material sufficiently rigid to hold the patella  2  back when the retractor is used, as described in detail hereinbelow. The body  11  is in the form of a piece elongated in a curved direction X-X, the other two dimensions of this piece being clearly less than its length. In other words, the body  11  is in the form of a curved, flat bar. The thickness of the body  11 , i.e. its dimensions seen in plan view in  FIG. 2 , is substantially constant over the whole of its length, while its width varies as detailed hereinbelow.  
         [0042]     The body  11  comprises a proximal end part  12  which forms a handle for manually manipulating it.  
         [0043]     Opposite, the body  11  comprises a distal end part  13  connected to part  12  by a current part  14  of the body, whose width increases from part  13  to part  12 . Along axis X-X, the parts  12  and  14 , as well as part  13  except for its distal terminal zone  13 A, are each curved in the same direction and join one another in tangential manner, with the result that most of the body  11  presents, in longitudinal section, a continuous arcuate profile.  
         [0044]     At its distal end, the terminal zone  13 A of the part  13  is provided with two tips  15  which extend globally longitudinally in line with the part  13 , the pointed end of each of these tips constituting the distal terminal point of the retractor  10 . As shown in  FIG. 3 , each tip  15  presents a globally pyramidal shape with rectangular base, it being understood that other shapes may be envisaged, for example conical shapes, and that the number of tips provided may, in a variant, be equal to one or be greater than two.  
         [0045]     Each tip  15  is intended to abut firmly against the walls  3 A 1  and  3 B 1  of the condyles  3 A,  3 B, which delimit therebetween the intercondylar space  3 D, as shown in  FIG. 4 . To allow the insertion of the distal end of the retractor  10  in the intercondylar space, the thickness of the tips  15  and that of at least the terminal zone  13 A are less than the medial-lateral dimension of this space, while the width of the terminal zone  13 A is less than the vertical dimension of the intercondylar space considered with the knee bent.  
         [0046]     The tips  15  are connected to part  13  in curved manner. As shown in  FIG. 2 , the tips and the terminal zone  13 A do not, however, extend in a direction joining the direction X-X without change of curvature but, on the contrary, in longitudinal section of the retractor, the tips  15  and the terminal zone  13 A, on the one hand, and the rest  13 B of the part  13 , i.e. the zone of part  13  facing the parts  12  and  14 , on the other hand, present respective opposite curvatures. In this way, on a frontal side of the body  11  seen in the direction of observation of  FIG. 2 , the part  13  presents a concave face at the level of its zone  13 A then convex at the level of its zone  13 B, while, on the other side, it presents a convex frontal face at the level of its zone  13 A then concave at the level of its zone  13 B.  
         [0047]     The zone  13 B of the part  13  is provided with a solid wing  18  rigidly connected to the rest of the body  11 , being for example integral with this body. This wing extends the zone  13 B laterally in projection from the longitudinal edge  13 C of this zone facing upwardly in operation. The wing  18  presents a substantially constant thickness, equal to that of the body  11  and, along axis X-X, a curvature identical to that of zone  13 B, as is visible in  FIG. 2 .  
         [0048]     Consequently, at the level of the two frontal sides of the wing  18  seen in the direction of observation of  FIG. 2 , this wing respectively makes a concave surface  18 A and an opposite, convex surface  18 B. In practice, the curvature of the concave face  18 A is dimensioned to correspond substantially to the geometry of the lateral flanks of the current part  5 A of the tendon of the quadriceps muscle  5 .  
         [0049]     Seen frontally, the wing  18  presents a globally triangular shape of which one of the edges, indicated in broken lines in  FIG. 3  and referenced  18 C, corresponds to the longitudinal edge  13 C of the part  13 . A second edge  18 D of this triangular shape, facing the tips  15 , presents a hollowed profile, corresponding approximately to an arc of circle C centred at a point O located in the vicinity of tips  15 , while the third edge  18 E presents a convex profile.  
         [0050]     The use of the retractor  10  will be described hereinafter, essentially with reference to FIGS.  5  to  8 .  
         [0051]     In  FIG. 5 , it is considered that the knee shown corresponds to the knee  1  of  FIG. 1 , it being noted that, contrary to  FIGS. 1 and 7 , in which none the soft parts of the knee, except for the tendon of the quadriceps muscle  5 , have been shown for reasons of visibility, the flap of outer skin as well as all the surrounding soft parts of the knee are shown in  FIG. 5 , as well as in  FIGS. 6 and 8 .  
         [0052]     The surgical procedure described hereinafter aims at implanting a unicompartmental knee prosthesis at the level of the external compartment of the right-hand knee  1 . To that end, as shown in  FIG. 5 , the surgeon places the knee in configuration of flexion, then incises the soft parts of the right-hand compartment of the knee from the front. The edges of the incision  20 , made substantially vertically, are held back by surgical claws  22 .  
         [0053]     The incision and retraction of the soft parts of the right-hand compartment of the knee  1  are continued until the external condyle  3 A of the femur  3  is rendered accessible to the surgeon by a globally antero-posterior surgical approach, as represented in  FIG. 6 .  
         [0054]     Without incising the soft parts of the knee further, the surgeon manipulates the patellar retractor  10 , gripping it at its proximal end part  12 . To that end, the surgeon introduces the terminal zone  13 A of the part  13  of the retractor in the knee  1 , sliding the concave face of its pointed terminal zone  13 A against the front wall of the external condyle  3 A, in the direction of the intercondylar space  3 D. The concavity of this pointed terminal zone facilitates the positioning and advance of the retractor along the external condyle  3 A, firstly on its front face then on its intercondylar face  3 A 1 , the body  11  of the retractor is thus manipulated so that the wing  18  extends at a distance from the outer flank of the tendon of the quadriceps muscle  5 , as represented in broken lines in  FIG. 7 . In this configuration, the concave frontal face  18 A is turned towards the outer flank of the current part  5 A of the tendon of the quadriceps muscle  5  likewise represented in broken lines, while the opposite convex face  18 B is turned towards the external condyle  3 A.  
         [0055]     The distal end of the part  13  is thus introduced until its tips  15  are received in the intercondylar space  3 D. The length L D  of the distal end of the part  13 , between the tips  15  and the join between the edges  18 C and  18 D of the wing  18 , is provided to guarantee to the surgeon that the tips  15  have attained a sufficient depth in the intercondylar space when the edge  18 D of the wing  18  is in the immediate proximity, or even substantially in contact with the soft parts adjacent the condyle  3 A.  
         [0056]     As indicated by arrow  24  in  FIG. 7 , the surgeon then moves the retractor  10 , still manipulating it at the level of the proximal end part  12 , in a tipping movement in a globally horizontal plane, centred on the intercondylar space  3 D. More precisely, when the retractor  10  is being tipped, the tips  15  come into abutment against the wall  3 A 1  of the external condyle  3 , as shown in  FIG. 4 , this forming stable and resistant points of abutment. The concave face  18 A of the wing is then brought into contact against the outer flank of the current part  5 A of the tendon of the quadriceps muscle  5 , then pushes this part  5 A laterally towards the inside, until the tendon is brought into its offset position shown in  FIG. 7 . The retractor is thus used in the manner of a lever for tipping the tendon  5 . By complementarity of shapes between the face  18 A and the outer flank of the tendon  5 , the effort of drive of this tendon is distributed over substantially the whole length of the current part  5 A, in other words over the length of the tendon at the level of which the patella  2  is located, without the wing  18  coming into pressing contact with the femoral epiphysis since its edge  18 D is arcuate in centred manner on the intercondylar space. The patella is thus reclined.  
         [0057]     As the tipping is globally centred on the intercondylar space  3 D, the patella  2  slides over the anterior face of the epiphysis of the femur  3 , passing from its sagittal position in broken lines in  FIG. 7 , in which it is received in the femoral trochlea  3 C, to a position offset inwardly, without, however, being completely turned round since the posterior face of the patella remains directed towards the femur.  
         [0058]     In its reclined configuration, the patella  2  and the corresponding part  5 A of the tendon  5  clears an antero-posterior access to the whole of the external condyle  3 A, as shown in  FIG. 8 . This condyle  3 A is then completely exposed to the surgeon who, by means of appropriate ancillary tools, such as a saw  26  or the like, effects one or more surgical actions necessary for the implantation of the unicompartmental prosthesis at the level of this condyle. During these actions, the wing  18  protects the patella  2 , particularly thanks to its convex edge  18 E.  
         [0059]     In this way, the patellar retractor  10  is an ancillary tool easy to manipulate and particularly efficient for holding back the current part  5 A of the quadriceps muscle tendon, without subjecting the latter to excessive strains.  
         [0060]     This retractor is easy to manufacture, for example from a substantially planar piece, and machined to present the tips  15  and the wing  18 , which is subsequently curved to give the retractor its definitive curvatures.  
         [0061]     It will be understood that the patellar retractor  10  described hereinabove is specifically intended to recline the patella during a surgical procedure at the level of the external condyle of a knee. If it is desired to operate at the level of the internal condyle, for example condyle  3 B for the knee  1 , another patellar retractor should be used, presenting arrangements similar to the retractor  10  and obtained by symmetry of the retractor  10  with respect to the plane P indicated in  FIG. 1 , which, for the retractor  10  in service, corresponds to a sagittal plane of the knee.  
         [0062]      FIG. 9  shows a variant embodiment of the patellar retractor  10 , which differs from that of the preceding Figures only by the additional presence of a second lateral wing  30  located on the longitudinal side opposite that from which the wing  18  extends. The wing  30  thus extends in projection from the body  1  from the lower longitudinal edge  13 D of the part  13 . This additional wing  30  presents arrangements similar to those of the wing  18 , particularly concerning its curvature, with the result that the wing  30  makes it possible, when the retractor is driven in the manner of a lever described hereinabove, to push the lower end  5 C of the tendon of the quadriceps muscle  5  in a medial-lateral direction.  
         [0063]     Various arrangements and variants of the patellar retractors, and of the method of surgical procedure described hereinabove, may, in addition, be envisaged. By way of example, the proximal end part  12  of the retractor may be equipped with an added handle, presenting in particular a crest/trough profile in order to facilitate manual gripping thereof by the surgeon.