Patent Publication Number: US-2020289277-A1

Title: Stemless humeral anchoring component for a shoulder prosthesis humeral implant

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/FR2018/052994, filed on Nov. 27, 2018, which claims priority to and the benefit of FR 17/61299, filed on Nov. 28, 2017. The disclosures of the above applications are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to a stemless humeral anchoring component for a shoulder prosthesis humeral implant. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     A stemless humeral anchoring component, also called “stemless humeral component,” is a component provided for an anchoring in the resected proximal epiphyseal and metaphyseal portions of the humerus without using an anchoring stem implanted in the diaphyseal portion of the humerus, and more specifically in the medullary cavity of the humerus. 
     In order to make such stemless humeral anchoring components, it is known from the documents FR 2 980 685, FR 2 997 290 and EP 2 474 288 to use a conical, cylindrical or dome-shaped anchoring part provided with peripheral teeth around its entire perimeter, and it is also known from the document EP 2 815 726 to use an anchoring cup having flexible lateral segments separated by slots, some of the segments having protruding lugs, and others having recessed notches. 
     The state of the art can also be illustrated by the teaching of the document EP 2 830 541 which describes a stemless humeral anchoring component provided with a circular flange, a hollow sleeve and cantilevered protruding toothed tabs of the circular flange, as well as by the teaching of the document EP 2 663 263 which discloses a stemless humeral anchoring component provided with a crown having a lower face from which a plurality of perforated and sharp blades protrudes. 
     A stemless humeral anchoring component is also known from the document EP 2 965 720, including an anchoring stud secured to four anchoring wings extending radially along the periphery of the anchoring stud and angularly spaced by an angle of 90 degrees, these wings being moreover integral with a proximal crown surrounding the anchoring stud. 
     The state of the art can also be illustrated by the teachings of the documents U.S. Patent Publication No. 2013/0018476 and WO 2013/009407 which discloses a stemless humeral anchoring component including an anchoring stud secured to six anchoring wings distributed radially and symmetrically along the periphery of the anchoring stud. 
     All these stemless humeral anchoring components of the prior art have the drawback of being able to be positioned essentially in a central bone area of the resected epiphyseal and metaphyseal portions of the humerus, which is a cancellous bone area where the bone density does not provide an optimal torsional stability for the stemless humeral anchoring component. 
     SUMMARY 
     This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features. 
     The present disclosure provides a stemless humeral anchoring component which is shaped to provide an increased torsional stability. 
     To this end, the present disclosure provides a stemless humeral anchoring component for a shoulder prosthesis humeral implant, this stemless humeral anchoring component including an anchoring stud secured to anchoring wings extending radially along the periphery of the anchoring stud, where this stemless humeral anchoring component is remarkable in that the anchoring wings are three in number and comprise one lateral anchoring wing and two medial anchoring wings, wherein the anchoring wings are angularly spaced by an angle between 110 and 130 degrees, and wherein the lateral anchoring wing has a radially measured length greater than the radially measured lengths of the medial anchoring wings. 
     Thus, thanks to this shaping, the lateral anchoring wing is provided to extend into the lateral region towards the greater tubercle, while the two medial anchoring wings are provided to extend in the medial region close to Merkel&#39;s spur with high bone density. The Merkel&#39;s spur, also called medial calcar, is a medial region originating from the cortex, that is to say from the peripheral portion of the bone, and extending inwardly, such a medial or Merkel region having an increased bone density which provides a particularly stable support of the two medial anchoring wings and therefore an increased torsional stability. The lateral anchoring wing is intended to extend in the lateral region and it is longer, which allows offsetting the anchoring stud and the medial anchoring wings so that they extend in the medial region (or area) with a higher bone density. Indeed, the longer lateral anchoring wing will promote this offset of the stemless humeral anchoring component in the direction of the medial area with a higher bone density, in other words by bringing the anchoring stud and the medial anchoring wings closer together towards the medial side, which allows having an anchoring of the anchoring stud and the medial anchoring wings in the medial or Merkel area. 
     According to one feature, the anchoring wings are angularly spaced by an angle of 120 degrees ±2 degrees. 
     This symmetrical angular distribution of the anchoring wings further promotes the torsional stability. 
     According to a variant, the ratio between the length of the lateral anchoring wing and the length of a medial anchoring wing is between 1.1 and 1.3, and in particular between 1.1 and 1.2. 
     According to a variant, the anchoring stud is a body of revolution centered on a central axis, and the lengths of the anchoring wings are measured radially from this central axis, and the length of each lateral anchoring wing is between 15 and 25 millimeters, and in particular between 17 and 21 millimeters, and the length of a medial anchoring wing is between 11.5 and 22.5 millimeters, and in particular between 14.5 and 19 millimeters. 
     In one particular form, the two medial anchoring wings have the same radially measured length, for an equivalent symmetrical support of these two medial anchoring wings in the medial area. 
     Advantageously, the anchoring wings are perforated, to promote an osseointegration or bone regeneration inside the perforations of the anchoring wings. 
     According to a variant, the anchoring wings and/or the anchoring stud are covered externally and at least partially with a porous or rough metal surface coating promoting an osseointegration. 
     Advantageously, the porous or rough metal coating is a two-layer coating comprising a layer of porous or rough titanium or of a porous or rough titanium alloy, and a layer of calcium phosphate, such as calcium hydroxyapatite. 
     In another particular form, each anchoring wing comprises: 
     a rectilinear segment extending radially from a peripheral proximal portion of the anchoring stud; and 
     a curved segment connecting a termination of the rectilinear segment to a peripheral distal portion of the anchoring stud. 
     According to one possibility of the present disclosure, the peripheral proximal portion of the anchoring stud, from which the rectilinear segments of the anchoring wings protrude, is formed of a peripheral proximal end edge of the anchoring stud. 
     Thus, the proximal end edge of the anchoring stud and the rectilinear segments of the anchoring wings are coplanar, to provide an increased freedom for the surgeon in positioning the stemless humeral anchoring component. 
     According to another possibility of the present disclosure, the peripheral distal portion of the anchoring stud, from which the curved segments of the anchoring wings protrude, is formed of a peripheral distal end edge of the anchoring stud. 
     Thus, the distal end edge of the anchoring stud is extended radially by the curved segments of the anchoring wings, to promote the insertion or depression of the stemless humeral anchoring component. 
     In accordance with another advantageous feature of the present disclosure, the anchoring stud is hollow by being provided with an inner orifice, to facilitate the manipulation during the anchoring operation and also to facilitate the fastening of the humeral insert on the stemless humeral anchoring component. 
     According to one feature, the inner orifice has a frustoconical proximal hole extended by a tapped hole, optionally followed by a distal through hole, where the frustoconical proximal hole is used for fastening a Morse taper of the humeral insert, the tapped hole is used, if desired, to extract the stemless humeral anchoring component by means of an extraction tool screwed into this tapped hole. 
     According to another feature, the anchoring stud has a generally frustoconical shape. 
     The present disclosure concerns a shoulder prosthesis humeral implant, comprising a stemless humeral anchoring component according to the present disclosure, and a humeral insert fastened on the stemless humeral anchoring component and having: 
     a hemispherical cap shaped for a joint with a glenosphere of a glenoid implant; or 
     a spherical joint head (otherwise called a humeral head) shaped for a joint on a joint body of a glenoid implant. 
     The present disclosure also relates to a shoulder prosthesis comprising a humeral implant as described above, and a glenoid implant comprising: 
     a glenosphere shaped for a joint with the hemispherical cap of the humeral insert; or 
     a joint body shaped for a joint with the spherical joint head of the humeral insert. 
     The present disclosure also concerns a range of stemless humeral anchoring components comprising several stemless humeral anchoring components according to the present disclosure and having distinct sizes. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
         FIG. 1  is a schematic perspective view of a stemless humeral anchoring component according to the present disclosure; 
         FIG. 2  is a schematic top view of the stemless humeral anchoring component of  FIG. 1 ; 
         FIG. 3  is a schematic cross-sectional view of the stemless humeral anchoring component according to the section plane A-A shown in  FIG. 2 ; 
         FIG. 4  is a schematic cross-sectional view of the stemless humeral anchoring component according to the section plane B-B shown in  FIG. 2 ; 
         FIG. 5  is a schematic cross-sectional view of the stemless humeral anchoring component according to the section plane C-C shown in  FIG. 2 ; 
         FIGS. 6 and 7  are schematic views of the stemless humeral anchoring component of  FIG. 1  implanted in a humerus; and 
         FIG. 8  is a schematic cross-sectional view along the section plane C-C and in superposition of three stemless humeral anchoring components belonging to a range according to the present disclosure. 
     
    
    
     The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     With reference to  FIGS. 1 to 5 , a stemless humeral anchoring component  1  according to the present disclosure is a one-piece component made of a metal material and which comprises an anchoring stud  2  secured to three anchoring wings  3 ,  4  extending radially along the periphery of the anchoring stud  2 . 
     The anchoring stud  2  is a body of revolution centered on a central axis  20  and having a peripheral wall  21  of a generally frustoconical shape having two opposite peripheral end edges: 
     a peripheral proximal end edge  22 ; and 
     a peripheral distal end edge  23 . 
     The anchoring stud  2  has a generally frustoconical shape in the direction of a narrowing starting from the peripheral proximal end edge  22  to the peripheral distal end edge  23 . 
     The anchoring stud  2  is hollow and defines an inner orifice  24  of revolution centered on the central axis  20  and opening on the side of the peripheral proximal end edge  22  and having successively a frustoconical proximal hole  25  extended by a tapped hole  26 , and optionally followed by a distal hole  27  (shown in the form of  FIG. 8 ) opening on the side of the peripheral distal end edge  23 . 
     The anchoring wings  3 ,  4  extend radially along radial axes A 1 , A 2 , A 3  intersecting on the central axis  20 . The anchoring wings  3 ,  4  protrude externally from the peripheral wall  21  of the anchoring stud  2  and extend in planes including the central axis  20  and the radial axes A 1 , A 2 , A 3 . 
     The anchoring wings  3 ,  4  are angularly spaced by an angle AN between 110 and 130 degrees, and in one form, by an angle AN of 120 degrees ±2 degrees (that is to say between 118 and 122 degrees). In other words, each anchoring wing  3 ,  4  is angularly spaced from each other anchoring wing  3 ,  4  by such an angle AN. In  FIG. 2 , only one angle AN, of the three angles, is illustrated, for clarity. The angles AN can be measured between the radial axes A 1 , A 2 , A 3 . 
     The anchoring wings  3 ,  4  comprise a lateral anchoring wing  3  and two medial anchoring wings  4 , where the lateral anchoring wing  3  has a radially measured length L 3  greater than the radially measured length L 4  of each medial anchoring wings; the two medial anchoring wings  4  have the same radially measured length L 4 . 
     These lengths L 3  and L 4  are measured starting from the central axis  20  along the respective radial axes A 1 , A 2 , A 3 , as shown in  FIGS. 2 to 4 . 
     The ratio between the length L 3  of the lateral anchoring wing  3  and the length L 4  of a medial anchoring wing  4  among the two medial anchoring wings  4  is between 1.1 and 1.2. The length L 3  of the lateral anchoring wing  3  is between 17 and 21 millimeters, and the length L 4  of a medial anchoring wing  4  is between 14.5 and 19 millimeters. 
     The anchoring wings  3 ,  4  are perforated, to promote an osseointegration and, as such, each anchoring wing  3 ,  4  comprises: 
     a rectilinear segment  30 ;  40  extending radially from the peripheral proximal end edge  22  of the anchoring stud  2 ; and 
     a curved segment  31 ;  41  connecting a termination of the rectilinear segment  30 ;  40  to a peripheral distal end edge  23  of the anchoring stud  2 . 
     Thus, each anchoring wing  3 ,  4  may extend over the entire height (distance measured along the central axis  20 ) of the anchoring stud  2 . 
     The anchoring wings  3 ,  4  and the anchoring stud  2  are externally covered with a porous or rough metal surface coating promoting an osseointegration, such as for example a two-layer coating comprising a layer of porous or rough titanium or of a porous or rough titanium alloy, and a layer of calcium phosphate, such as calcium hydroxyapatite. 
     As shown in  FIGS. 6 and 7 , the stemless humeral anchoring component  1  provides an anchoring in the resected proximal epiphyseal and metaphyseal portions PEM of the humerus HU, without reaching the diaphyseal portion PD of the humerus HU. 
     The stemless humeral anchoring component  1  is positioned such that: 
     the lateral anchoring wing  3  extends in the direction of the lateral side CL of the humerus HU, in the direction of the greater tubercle into the lateral region RL with a lower bone density compared to the medial region RM, 
     the two medial anchoring wings  4  are facing the medial side CM of the humerus HU to extend into the medial region RM of the Merkel&#39;s spur with a high bone density. 
     More specifically, the stemless humeral anchoring component  1  is positioned eccentrically, in the sense that the latter is brought closer towards the medial side CM mainly due to the increased length of the lateral anchoring wing  3  which promotes this eccentricity, and therefore by bringing closer the anchoring stud  2  and the medial anchoring wings  4  towards the medial side CM, which allows having the medial anchoring wings  4  which extend almost integrally in the medial region RM also called medial calcar, thus providing a support mainly in the medial region RM with a high bone density, while the lateral anchoring wing  3  extends almost integrally in the lateral region RL of a cancellous bone. 
     In order to facilitate guiding the stemless humeral anchoring component  1  to its final implantation position, as illustrated in  FIGS. 6 and 7 , the surgeon can use a guide pin which cooperates with the inner orifice  24 , such that the surgeon begins by positioning the guide pin and then slides the anchoring stud  2  on this guide pin to the final implantation position, and the guide pin is then removed. The use of a guide pin leaves the possibility of adjusting the right orientation of the anchoring wings  3 ,  4 , by orienting the lateral anchoring wing  3  in the direction of the lateral side CL, in other words in the direction of the greater tubercle. 
     Thus, thanks to this shaping of the stemless humeral anchoring component  1  and thanks to this implantation, a particularly stable support of the medial anchoring wings  4  in the medial region RM with an increased bone density is provided, and therefore an increased overall stability for the stemless humeral anchoring component  1 . 
     As shown in  FIG. 8 , this stemless humeral anchoring component  1  can be declined within a range GA comprising a plurality of stemless humeral anchoring components  1  having distinct (different) sizes, and in particular having heights (dimensions measured along the central axis), lengths (radially measured dimensions) and thicknesses for the segments of the anchoring wings which increase with the size. However, the dimensions of the inner orifice  24  remain identical from one size to another. 
     Of course, the example of implementation mentioned above is in no way limiting and other improvements and details can be made to the stemless humeral anchoring component according to the present disclosure, without departing from the scope of the present disclosure where other types of porous or rough coating can for example be considered, or else other forms of inner orifice can be provided. 
     Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word “about” or “approximately” in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability. 
     As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.” 
     The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.