Abstract: An implant having a joint facing surface and a bone facing surface forming a body member and a dorsal member therebetween. The implant further having a ring member extending out from the bone facing surface to a free end disposed for insertion into a bone recess. The body member and the dorsal member include a concave curvature on the bone facing surface and a convex curvature on the joint facing surface.

Abstract: Stemless components and fracture stems for joint arthroplasty, such as shoulder arthroplasty, are disclosed. Also, methods and devices are disclosed for the optimization of shoulder arthroplasty component design through the use of medical imaging data, such as computed tomography scan data.

Abstract: A system and method facilitating replacement of comminuted bone fractures or portions thereof adjacent bone joints. The system and method employs a prosthesis to replace at least a portion of the comminuted bone fractures. The prosthesis serves in reproducing the articular surface of the portion or portions of the comminuted bone fractures that are replaced. In doing so, the prosthesis serves in restoring joint viability and corresponding articulation thereof.

Abstract: A tooling system and method is disclosed for removing a head portion of a modular implant from a stem portion of the implant. The tooling system can include first and second tools configured to releasably mate together when the upper and lower tools are in an assembled position, and a holder configured to releasably secure the first and second tools in the assembled position. The first and second tools can be inserted between the head portion and an adaptor of the stem portion. When the first and second tools are rotated in opposite directions, the first tool can exert pressure on the head portion of the implant sufficient to release the head portion from locked engagement with the adaptor. The first and second tools can include mating features that disengage from each other as the tools are rotated in opposite directions.

Abstract: An implant assembly comprising an implant having a load bearing surface with a contour corresponding to a patient's articular surface, and a bone facing surface including a fixation element, an anchor configured to be secured to bone beneath said patient's articular surface, said anchor including a second fixation element, and wherein said first fixation element is configured to be secured to said second fixation element.

Abstract: Authenticating issues involving the re-authenticating of a first device that was previously authenticated are resolved by use of a second device which receives a notification of the failed authentication. The second device sends a response to the notification which is operable to facilitate re-authentication of the primary device and without requiring the user to provide credentials at the first device prior to obtaining the re-authentication at the primary device and/or without requiring the primary device to obtain a code to be entered into the secondary device and/or prior to the primary device being notified of a failure condition associated with the primary device.

Abstract: A stemless humeral component for replacing the humeral head of a patient's humerus includes a support flange having a number of cantilevered legs extending distally away from a bottom surface thereof. Instruments and methods for surgically installing the stemless humeral component are also disclosed.

Abstract: A stemless humeral component for replacing the humeral head of a patient's humerus includes a support flange having a number of cantilevered legs extending distally away from a bottom surface thereof. Instruments and methods for surgically installing the stemless humeral component are also disclosed.

Abstract: A system for dynamic stabilization of the spine includes a bone engaging fastener configured to be anchored in a vertebra and a deflectable element mounted on the fastener. The deflectable element or bumper is configured and arranged to contact a portion of an adjacent vertebra, such as the facet, during extension of the spine, while offering no resistance during flexion. In certain embodiments, a cable may be fastened to the bone engaging fastener and arranged to contact a portion of the adjacent vertebra, such as the spinous process, during flexion of the spine. In one surgical technique of the invention, a contralateral approach is used to introduce the bone engaging fastener through the deflectable element and into the vertebra.

Abstract: An artificial joint comprising a first base element and a second base element that are pivotally connected to an intermediate body. A first protrusion extends from the first base element and is configured to be press-fitted into a screw device that is anchored to a first bone member, and a second protrusion extends from the second base element and is configured to be press-fitted into a screw device that is anchored to a second bone member. A related kit-of-parts is also described.

Abstract: An orthopaedic implant comprises an articulation head comprising a bearing surface and a reverse surface and a securement disk. The securement disk comprises an attachment surface attached to at least a portion of the reverse surface of the articulation head, a securement surface opposite the attachment surface and adapted for coupling to a fixation plate secured to a bone, and at least one opening formed in the securement surface of the securement disk and adapted to accept fasteners therein. The securement disk comprises a porous material.

Abstract: Photodynamic devices for stabilizing a joint are provided. In some embodiments, a photodynamic joint spacer is provided that includes an expandable member configured for attachment to a bone having an excised region; a formable bar configured for attachment to the bone along at least a portion of the expandable member; and a light-sensitive liquid passed into the expandable member to expand the expandable member, wherein the expandable member is shaped by the formable bar to a shape resembling the excised region of the bone, and wherein the light-sensitive liquid is curable upon exposure to light energy to set the expandable member in the shape resembling the excised region to form a photodynamic joint spacer.

Abstract: Joint space interpositional prosthetic devices for positioning between surfaces of a joint in a patient are disclosed. The prosthetic device may have exterior surfaces affixed to the joint surfaces and may have internal surfaces which provide bearing surfaces. In an exemplary embodiment, the bearing surfaces are encapsulated within the device. The exterior surfaces of the device may include bone securement features to facilitate attachment of the prosthetic device to the joint surfaces.

Abstract: The present invention is directed to a prosthesis for an arthroplasty in a long bone and a methods for achieving a press fit of the metaphyseal element of the prosthesis into a metaphysis of the long bone and the extraction of the prosthesis when indicated. The prosthesis includes a metaphyseal element attached at a proximal end of a stem, the metaphyseal element of the prosthesis is configured to optimize placement of bone marrow about, and in some embodiments, within the metaphyseal element to achieve a press-fit in the metaphysis of the long bone. The prosthesis also includes one or more apertures formed in the joint base member of the prosthesis. Preferably each slot includes a frangible wall which is readily penetrated to accommodate passage of an osteotome of other tool to break the metaphyseal element free from bony in-growth that occurs against the metaphyseal element.

Abstract: A joint fluid drainage system provides a solution to the aseptic loosening problem resulting from the utilization of total joint prostheses, lowering the pressure inside the joint capsule and draining the joint fluid comprising particles. The system includes a canal outlet starting from the articulation surface. This high pressure joint fluid with particles causing the loosening is drained from the capsule to the outside of the bone through a drainage path starting from this canal outlet, continuing in the prosthesis and the bone, and opening to the outer surface of the bone. The system also includes a silicone tube mounted to the canal outlet of the prosthesis by using the canal disposed in the bone. The tube is placed inside the fatty porous tissue located between the muscle groups outside the bone and the joint fluid is discharged into this area through this canal system by drainage.

Abstract: An orthopaedic implant including a base portion and first and second transverse portions extending transversely from the base portion to thereby define an inner region of the implant sized for receipt of an end portion of a bone therein. The implant further includes at least one anchor structure projecting from the base portion and sized and configured for receipt within an opening formed in the end portion of the bone. The anchor structure extends along a longitudinal axis and includes a proximal end attached to the base portion and an opposite distal end, and further includes a tapered outer surface that inwardly tapers in a proximal-to-distal direction along the longitudinal axis. In one embodiment, the anchor structure also includes one or more grooves extending into the tapered outer surface, with a flowable material positioned about at least a portion of the tapered outer surface and positioned within the grooves, and with the flowable material configured to cure to a hardened state.

Abstract: Implant devices, and method of using the same, are provided. The implant devices have an articular end and a stem, the stem having an oval-shaped cross-section. The articular end has an upper surface, a side surface, and a lower surface. The upper surface and lower surface each intersect the side surface. The upper surface has a first surface curvature, a central surface curvature, and a second surface curvature. The stem extends from the lower surface in a direction away from the upper surface of the articular end.

Abstract: A method of orienting a femoral head member of an implant relative to an acetabular member positioned in the acetabulum including implanting a femoral stem of an implant within an intramedullary canal of a femur, inserting an acetabular member in the acetabulum, positioning a femoral head member of the implant at least partially in the acetabular member with the femoral head member including a curved articulating surface and a plurality of indicia on the curved articulating surface, and orienting the femoral head member relative to the acetabular member and generally aligning one of the indicia on the curved articulating surface with an alignment feature of the acetabular member to signify an orientation of the femoral head member relative to the acetabular member.

Abstract: An in-bone implantable shaft for prosthetic joints or for direct skeletal attachment of external limb prostheses, comprised of a central body fitted in the zone of the bone's medullary cavity conventionally prepared for implantation, and of side elements attached to the central body and fitted in the slots specially made in the bone's walls surrounding said medullary canal; said side elements have spaces between them, arranged to be filled by bone cells to provide a natural and safe osseolocking of the shaft. A method of preparing the bone for implantation of a prosthetic shaft, comprising the steps of: placing a cylindrical guide with slots made in the longitudinal direction of said guide inside said bone's canal which is conventionally prepared for implantation; cutting said bone's walls by progressing a saw along the edges of the slots of said guide; removing the guide; fitting the shaft in the bone's canal, provided that the side elements are fitted to the slots in the bone's walls.

Abstract: A prosthetic ball for use in a ball and cup joint system includes a spherical cap articulation portion defined by a first radius of curvature, and a toroidal articulation portion defined by a second radius of curvature having a circular origin such that the toroidal articulation portion is defined by a portion of the inner surface of a spindle torus.

Abstract: A bone joint prosthesis can augment or replace a natural bone joint. The prosthesis can include a joint head portion and an elongated stem. The stem can include a proximal end coupled to the joint head portion and a distal end having a sharp edge. A stem body, including a bore, can extend between the proximal end of the elongated stem and the sharp edge at the distal end of the elongated stem. The sharp edge of the elongated stem can be capable of being pressed into a long bone so as to core intact marrow into the bore of the stem body. A method can include preparing a bone for a bone joint prosthesis. A sharp distal end of an elongated stem of the bone joint prosthesis can be pressed into the bone. Intact bone marrow can be cored into a bore of the elongated stem.

Abstract: The present invention is directed to a prosthesis for an arthroplasty in a long bone and a methods for achieving a press fit of the metaphyseal element of the prosthesis into a metaphysis of the long bone and the extraction of the prosthesis when indicated. The prosthesis includes a metaphyseal element attached at a proximal end of a stem, the metaphyseal element of the prosthesis is configured to optimize placement of bone marrow about, and in some embodiments, within the metaphyseal element to achieve a press-fit in the metaphysis of the long bone. The prosthesis also includes one or more apertures formed in the joint base member of the prosthesis. Preferably each slot includes a frangible wall which is readily penetrated to accommodate passage of an osteotome of other tool to break the metaphyseal element free from bony in-growth that occurs against the metaphyseal element.

Abstract: Multi-layered prosthetic constructs, kits, and methods are disclosed. A prosthetic construct can include a first ceramic component having a first surface, the first ceramic component comprising a first ceramic material, and a second ceramic component having a second surface disposed on the first surface of the first ceramic component, the second ceramic component comprising a second ceramic material. The second ceramic material of the second ceramic component can exert a compressive force on the first ceramic material. A ceramic material of the second ceramic component can include a different coefficient of thermal expansion than a ceramic material of the first ceramic component. Optionally, a ceramic construct can include a ceramic component and a membrane disposed onto and bonded to at least a portion of the ceramic component, the membrane configured to provide fracture reinforcement to the ceramic component.

Abstract: A joint prosthesis includes a bone engaging portion, such as a stem, and articulating component, such as a humeral head, and an insert component that supports the articulating component and is removable from the stem. A mating component mates with the humeral head and is configured to engage the insert component at adjustable angles according to the anatomy of the patient's joint. In a revision surgery, the stem remains within the patient's bone while the insert component is removed with the mating component and humeral head fixed to the insert component. A new insert component may be prepared with the mating component and humeral head oriented to replicate the angular orientation of the previous prosthesis. The new insert component is then mounted within an insert cavity in the implanted stem and rigidly fastened to complete the revision.

Abstract: A hip prosthesis includes an acetabular cup and a femoral component comprising a head and a stem, wherein the stem comprises a truss structure, the truss structure comprising a space truss comprising a plurality of planar truss units having a plurality of struts joined at nodes, wherein the web structure is configured to interface with bone tissue.

Abstract: Methods and devices are disclosed relating improved articular models, implant components, and related guide tools and procedures. In addition, methods and devices are disclosed relating articular models, implant components, and/or related guide tools and procedures that include one or more features derived from patient-data, for example, images of the patient's joint. The data can be used to create a model for analyzing a patient's joint and to devise and evaluate a course of corrective action. The data also can be used to create patient-adapted implant components and related tools and procedures.

Abstract: An apparatus for orienting a prosthetic femoral head relative to an acetabulum comprises a femoral stem and a femoral head member. The femoral stem is configured to be received within the intramedullary canal of a femur. The femoral head member is configured to couple to the femoral stem and further configured to be received in the acetabulum. The femoral head member further comprises an indicia configured to orient a relative position of the prosthetic femoral head to the acetabulum such that the indicia signifies proper relative position of the prosthetic femoral head in the acetabulum.

Abstract: A kit for use in a procedure for implantation of an orthopaedic joint prosthesis includes a head component of an orthopaedic joint prosthesis, which comprises a body part having a convex bearing surface, and a reverse face at which the head component can be connected to a mating component of the joint prosthesis, in which the head component has a chamfer surface extending around at least part of its periphery where the bearing and reverse faces come together, and a plurality of markings on the chamfer surface. The kit includes a trial head component which comprises a body part having a convex trial bearing surface and a reverse face, in which the trial head component has a plurality of markings on the trial bearing surface at or towards the interface between it and the reverse face.

Abstract: A prosthesis is provided for replacing a portion of a bone making up a joint. The prosthesis is adapted, intraoperatively, to optimize the anatomical alignment of the prosthesis in the joint. In particular, a jig is used to identify the axis of rotation of the joint intraoperatively and to align a portion of the prosthesis with the identified axis. The angle of the head of the prosthesis is adjusted to optimize contact with the appropriate corresponding portions of the joint, at which point the position of the head is fixed to prevent further rotation of the head relative to the remainder of the prosthesis.

Abstract: An implant assembly having an articulating surface and an axial cavity arranged to receive an end of a bone, the axial cavity being generally circular in cross section in a plane normal to the axis of the implant, and including a spacing element detachable from the implant. At least a portion of the interior surface of the cavity is roughened and is arranged to abrade bone when the end of the bone is received in the cavity. The spacing element is arranged to prevent the implant from fully seating on the end of the bone such that the implant and the end of the bone are in a predetermined spaced apart arrangement.

Abstract: A joint prosthesis includes a bone engaging portion having a first recess portion, and an internal wall defining a second recess portion, an articulating component, an insert component having (i) a first insert portion configured to snugly fit within said second recess portion in contact with the internal wall, and (ii) a projecting portion that fixedly projects from said first insert portion and is configured to snugly fit with the first recess portion so as to rotationally fix the first insert portion within the second recess portion, said insert component also having a first coupling portion, and a mating component configured to mate with said articulating component and having a second coupling portion configured to mate with the first coupling portion to form a fixed male/female couple at variable version and inclination angular orientations with respect to the insert component.

Abstract: A modular humeral head resurfacing implant including a head, an anchoring stem, and a modular extended articulation flange. The head includes an exterior hemispherical articulating surface defining a terminating rim, an interior concave surface opposite to the exterior articulating surface, and a first coupling mechanism proximate to the terminating rim. The anchoring stem is coupled to the interior concave surface and extends along a stem axis that extends through an axial center of the head. The articulation flange includes a second coupling mechanism configured to cooperate with the first coupling mechanism to fasten the articulation flange to the head and an outer articulating surface that is curved along substantially its entire length and is substantially flush with the exterior hemispherical articulating surface when the articulation flange is fastened to the head.

Abstract: A prosthesis may include a stem, an adaptor and a head. The stem may include a longitudinal axis. The adaptor may include a first taper having a first taper axis of symmetry. The head may be rotatably supported by the adaptor and may include a semispherical articulating surface defined by a central axis of symmetry that is angled relative to the first taper axis of symmetry. The head may be coupled to the first taper and may be positionable relative to the stem through relative rotation between the head and the stem about the first taper axis of symmetry to adjust a radial offset of the head relative to the longitudinal axis of the stem. The head may be adapted to be received in a glenoid cavity of a scapula.

Abstract: Orthopedic implants having a bone interface member and a water swellable IPN or semi-IPN with a stiffness, hydration, and/or compositional gradient from one side to the other and physically attached to the bone interface member. The invention also includes an orthopedic implant system including an implant that may conform to a bone surface and a joint capsule. The invention also includes orthopedic implants with water swellable IPN or semi-IPNs including a hydrophobic thermoset or thermoplastic polymer first network and an ionic polymer second network, joint capsules, labral components, and bone interface members. The invention also includes a method of inserting an orthopedic implant having a metal portion and a flexible polymer portion into a joint, including inserting the implant in a joint in a first shape and changing the implant from a first shape to a second shape to conform to a shape of a bone.

Abstract: A proposed treatment of arthrosis/osteoarthritis in a joint of a mammal or human patient involves deposing a liquid material on at least one damaged surface of the joint. To accomplish this, a reservoir (110) is provided, which holds a volume of a biocompatible material in liquid form outside of a body containing the joint (J) to be treated. A proximal end (P) of a tube-shaped instrument (120) is connected to the reservoir (110), and a distal end (D) of the instrument (120) is inserted into the joint (J). The liquid material is fed through the instrument (120) to the distal end (D) for deposition on the at least one damaged joint surface. The material is configured to assume a solid form under predefined conditions (e.g. when cooling off or being exposed to a specific type of radiation). When the material has the solid form, it has a resistance to wear adapted to replace a worn out joint surface.

Abstract: A femoral implant for total hip replacement includes a cage screw, a femoral head and a base plate provided between the cage screw and the femoral head, to minimize the stress transferred from the femoral head to the bone. The femoral implant may optionally include devices for lateral fixation (for example, internal and/or external screws for lateral fixation) and a device for minimizing micro-motion that is integral to, and extends from, the cage screw.

Abstract: Systems for joint arthroplasty include prostheses which are secured to bone with sliding anchors. Examples include unicondylar and bicondylar knee prostheses for hemi-arthroplasty and total arthroplasty. Instruments guide the anchors into proper engagement with the prosthetic components. Methods of using the prostheses and instruments are disclosed.

Abstract: A shoulder joint repair prosthesis (12, 14) comprises a support structure which comprises anchorage points (24) which are in the installed configuration positioned adjacent positions of the anatomical tendinous insertion points of the tendons related to the joint. A securing clamp (30) arrangement connects to the anchorage points with direct rigid connection devices (32), the securing clamp arrangement having a surface area larger than the direct connection devices, the securing clamp arrangement being arranged to clamp the tendons between the securing clamp arrangement and the underlying surface area and providing a fixed gap between clamp and underlying connecting areas to trap any attached bony fragments.

Abstract: A kit for use in performing joint arthroplasty on a head of a long bone is disclosed. The kit includes: a first implant including a first implant articulating surface and an opposed first implant mounting surface having a first implant location feature; and an instrument for preparing a cavity in the head of the long bone. The instrument includes a body and a punch extending from the body. The punch includes a portion thereof having a shape similar to the first implant location surface of the implant. A method for providing joint arthroplasty is also disclosed.

Abstract: A set of surgical components for use in a joint arthroplasty to reconstruct a head of a joint is provided. The set of surgical components can include a head member having a first articulating surface opposite a first fixation surface. The first fixation surface can define a first portion that extends outwardly from the first fixation surface. The set of surgical components can include a base member having a fixation peg with three generally triangular fins and a second fixation surface defined as a recess within a top surface of the fixation peg. The first portion of the head member can be received within the recess of the base member to couple the head member to the base member.

Abstract: A system for positioning an element relative to an articular surface. An embodiment of the system may include a first element having a positional reference relative to an articular surface. The system may further include a second element capable of indicating the positional reference of the first element relative to said articular surface. Of course, many alternatives, variations, and modifications are possible without departing from this embodiment.

Abstract: An orthopaedic implant including a base portion and first and second transverse portions extending transversely from the base portion to thereby define an inner region of the implant sized for receipt of an end portion of a bone therein. The implant further includes at least one anchor structure projecting from the base portion and sized and configured for receipt within an opening formed in the end portion of the bone. The anchor structure extends along a longitudinal axis and includes a proximal end attached to the base portion and an opposite distal end, and further includes a tapered outer surface that inwardly tapers in a proximal-to-distal direction along the longitudinal axis. In one embodiment, the anchor structure also includes one or more grooves extending into the tapered outer surface, with a flowable material positioned about at least a portion of the tapered outer surface and positioned within the grooves, and with the flowable material configured to cure to a hardened state.

Abstract: An orthopedic prosthetic implant comprises a metal alloy stem element (13, 63, 113) which has one end portion (19, 69, 119) constructed to reside in the medullary cavity of a bone and an integral connector (23, 73, 123) at the opposite end, to which a crystalline brittle head (17, 67, 117) preferably made of pyrocarbon-coated graphite is joined. The effective joinder of the head to the stem element is achieved through a polymeric insert (15, 65, 115) which has selected elastic properties. The design and material of the polymeric insert allow it to be securely received within an interior cavity (35, 77, 131) of the pyrocarbon-coated graphite head and mated to the stem connector in an either rigidly or bi-polar arrangement. Such joinder allows the composite implants that utilize the most desirable properties of metallic and brittle crystalline materials.

Abstract: A kit for use in performing revision surgery on a cavity in a canal of extending from a resected plane a long bone is provided. The kit includes a canal component fitted to the cavity. The canal component includes a canal portion having first and second ends. The canal component further includes a sleeve portion having an external periphery and an internal periphery defining an internal cavity. The kit also includes a first joint component having a body portion and a connection portion. The connection portion is fitted into the sleeve portion. A connection portion of a second joint component also may be fitted into the sleeve portion so that the external periphery of the connection portion of the first joint component is spaced inwardly from the external periphery of the sleeve portion of the canal component when the first joint component is fixedly connected to the canal.

Abstract: A prosthetic joint includes: (a) first member having a balanced centroidal axis, and comprising a rigid material and a concave interior defining a cup surface, the cup surface including: (i) a cantilevered first flange defining a wear-resistant protruding first contact rim, the first flange being asymmetric relative to the balanced centroidal axis; and (ii) a cantilevered second flange defining a wear-resistant protruding second contact rim; (b) a second member comprising a rigid material with a wear-resistant, convex contact surface; (c) where the first and second contact rims bear against the contact surface of the second member, to transfer loads between the first and second members, while allowing pivoting motion therebetween; and (d) wherein the flanges are shaped and sized so as to deform elastically and permit the first and second contact rims to conform in an irregular shape to the contact surface, when the joint is under load.

Abstract: A joint prosthesis device comprises a head configured to fit within a cup and in one embodiment includes a first member for attachment to a first bone in a joint and including a first articulation surface portion defined by a first radius of curvature and a second member for attachment to a second bone in the joint and including a second articulation surface portion defined by a second radius of curvature and a third articulation surface defined by a third radius of curvature, wherein each of the second radius of curvature and the third radius of curvature has a length that is different from the length of the first radius of curvature by less than 0.05 millimeters and wherein the origin of the second radius of curvature is not coincident with the origin of the third radius of curvature.

Abstract: An implant for use on a joint-facing end of a bone includes a cap having convex outer surface overlying a concave inner surface and a stem protruding from the inner surface such that an edge of the cap surrounds the stem and overhangs a portion of the stem leading up to the inner surface. The stem may further include a plurality of raised ridges parallel to its length that begin near a tip of the stem and extend onto the portion of the stem overhung by the edge.

Abstract: The invention relates to an articular resurfacing implant which is characterized in that it is composed of a sheet (1) of pyrolytic carbon deposited on a graphite substrate and a layer (8) composed of an adhesive elastomer or polymer material adherent to the inner surface of the sheet (1) on the substrate side. The adhesive elastomer or polymer material layer (8) allows the implant to be adherent to bone (3) and acts as a shock absorber layer. In one embodiment the implant further comprises a hard material, e.g. metallic, sheet (4).

Abstract: A prosthetic joint includes: (a) a first member comprising rigid material including a wear-resistant, concave cup surface; and (b) a second member comprising rigid material with a wear-resistant, convex contact surface; (c) one of the surfaces includes: (i) an annular first flange defining a protruding wear-resistant first contact rim at or near an apex of the member; and (ii) an annular second flange defining a protruding wear-resistant second contact rim, at or near an outer periphery of the member; (d) the first and second contact rims bear directly against the contact surface, so as to transfer loads between the first and second members, while allowing pivoting motion therebetween; and (e) the flanges are shaped and sized so as to deform elastically and permit the contact rims to conform in an irregular shape to the surface of the opposite member, when the joint is placed under a predetermined load.

Abstract: A modular humeral head system includes a housing having an outer surface and an inner surface. A hemispherical socket formed on one end of the inner surface and threads formed on the other end of the inner surface. A cap is attached at the threaded end of the housing. The cap has one or more threaded holes that run from the top surface to bottom surface of the cap. A screw may be inserted in each hole. The modular humeral head system also includes an intermediate piece having a hemispherical head at one end of a tapered shaft. The tapered shaft is inserted in a humeral stem. The hemispherical head and the hemispherical socket form a ball and socket coupling. A trial head may be impacted on the housing. The trial head has one or more holes that are aligned with the screws inserted in the cap.