Abstract: The present invention provides a bearing material that is excellent in durability and is capable of maintaining wear resistance over a long period of time. The bearing material of the present invention is a high wear-resistance bearing material 10 for being used under a humid environment comprising: a base body 12 made of a polymer material having a methylene group; and a polymer layer 30 covering a bearing surface 16 of the substrate 12, the polymer layer 30 comprising polymer chains which have a phosphorylcholine group and are grafted from the bearing surface 16, wherein a phosphoric index of the sliding surface 16 which is calculated by dividing a peak intensity of phosphate group in an infrared spectrum measured on the sliding surface by a peak intensity of the methylene group therein is not less than 0.28.

Abstract: Disclosed herein a prosthetic or orthotic device having a joint portion and a compliant transmission assembly in operational communication with the joint portion. The device restores the normal capabilities and natural dynamics of a healthy joint for common activities. The compliant transmission assembly includes a compliant element. The compliant transmission assembly absorbs energy when a torque is applied. between a prosthetic or orthotic device portion and another adjacent device portion or the adjacent limb segment, of the user. The compliant element of the invention absorbs energy during flexion of a joint for the dampening thereof and releases this energy during extension of the joint for assistance thereof. Also disclosed herein is an actuator assembly, a torque sensor and an actuator locking device as well as a method for determining the torque of such prosthetic and orthotic devices.

Abstract: A prosthetic joint kit, particularly well suited for an elbow, transmits load through the prosthetic joint through a pair of spherically shaped bearing surfaces so as to transmit load over a relatively large area rather than at a point or over a line of contact. The prosthetic joint kit may be configured in a modular manner wherein a plurality of interchangeable stem structures, bearing structures and/or bearing inserts of various types are available. Construction in this manner enables a surgeon to configure the prosthetic joint to best suit the needs of the patient. For example, the surgeon may employ a modular flange for compressing a bone graft, a tissue fastener for securing soft tissue to a portion of the prosthetic joint, a cam for limiting the amount by which the prosthetic joint articulates or a bearing insert for tailoring the degree of varus/valgus constraint.

Abstract: A method for implanting an intra-articular shoulder prosthesis is provided. The method includes removing a proximal portion of a humerus. The proximal portion of the humerus preferably forms a resected portion. The resected portion has a convex outer surface and an inner surface. The method further includes engaging the convex outer surface of the resected portion with a cut surface of the proximal portion of the humerus. The cut surface of the proximal portion of the humerus and/or the inner surface of the resected portion are optionally processed to form a generally concave surface, such as by impacting. In one embodiment, the inner surface of the resected portion is impacted into engagement with the cut surface of the proximal portion of the humerus. The generally concave inner surface of the resected portion forms a concave articular surface to receive an interpositional implant.

Abstract: An implantable device which provides structural support for the skeletal system, such as the spine, coated with hydroxyapatite (HA). This invention provides a mechanically and bioactively functional coating of hydroxyapatite (HA) without altering the biocompatibility profile of the poly-ether-ether-ketone (PEEK) substrate.

Abstract: A ball and socket assembly including a ball component with a notch formed therein. The socket is a one-piece structure including an opening sized to receive the ball component.

Abstract: A shroud for protecting exterior portions of a prosthetic implant from adhesive and a method for utilizing the same. The shroud includes a hub, a rim, and at least one bridge connecting the hub and the rim. The rim of the shroud may be sized to cover substantially the same area as a guard of the implant. The method of utilizing the shroud involves securing the shroud to the prosthetic implant. A quantity of adhesive is provided, and the prosthetic implant is secured thereto. The shroud is removed from the implant, and then the guard is secured to the implant.

Abstract: A disposable articulated spacing device for use as a temporary joint prosthesis includes a first member secured during an implantation procedure to a first articulation end and a separate and independent second member secured separately during the implantation procedure to the other articulation end, both members being pre-formed and made entirely of biological compatible and porous material suitable to be added with pharmaceutical and therapeutical products. The pre-formed members are reciprocally coupled in an articulated manner to maintain a suitable joint space and at least a partial articulation for the time necessary to perform the further implantation of a joint prosthesis.

Abstract: A tightenable joint for use in a surgical retractor system includes a monolithic, unitary joint body which has a top leg and a bottom leg. The top leg provides a top compression surface and the bottom leg provides a bottom compression surface operating on a ball. A handled cam is used between proximal ends of the top leg and the bottom leg. When the handle is thrown to tighten the joint, the proximal ends of the top leg and the bottom leg are driven apart by the cam, and a hinge or fulcrum portion on the joint body flexes between top and bottom leg portion such that the top compression surface and bottom compression surface tighten on the ball. The ball has flats that enable the ball to be positioned into the socket, and then an extension is fixed to the ball to prevent removal of the ball from the socket. The cam is defined with an eccentric surface relative to its pivot pin, which is received in an arcuate recess of a bearing plate.

Abstract: A reinforced joint assembly includes a first implant portion secured to a sectioned end of a first bone. A second implant portion is likewise secured to a sectioned end of a second bone and in opposing fashion relative to the first implant to define a joint zone therebetween. The first implant exhibits a first surface profile, whereas the second implant exhibits a second and mating surface profile. A male projection extends from the first surface profile of the first implant and seats within a recess defined within the second implant.

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 crystalline brittle head (17, 67, 117), preferably made of pyrocarbon-coated graphite, is joined. The head interfaces with human bone, and its effective joinder to the stem element is achieved through a polymeric insert (15, 65, 115) of proportional shape and design 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. The method of joinder allows the construction of composite implants that utilize the most desirable properties of metallic and brittle crystalline materials.

Abstract: A method of attaching an implant to a bone, the implant comprising a hydrated polymer comprising a lubricious hydrated surface and an attachment surface comprising accessible chemical functional groups. The method includes the steps of treating the implant or the bone with an isocyanate-containing compound; placing the attachment surface in apposition to the bone; and allowing the isocyanate-containing compound to cure to bond the implant to the bone. The invention also includes a medical implant having a hydrated polymer comprising an attachment surface comprising a thermoplastic material, the hydrated polymer having an interpenetrating polymer network with at least two polymers, the hydrated polymer having a low coefficient of friction on at least one surface.

Abstract: The present invention relates to implants used for alleviating and/or preventing conditions relating to damaged joints involving articulating surfaces. The implants comprise fibre of polymer and/or metal, and can be used as an artificial joint, as part of an artificial joint or as an artificial joint spacer made to replace the missing cartilage or to improve the slidability between two natural and/or artificial components of the body, or between a natural and artificial component. The product of the invention can be used to partly or entirely coat medical products or to make up implant partly or entirely.

Abstract: Disclosed herein are methods and devices for repairing articular surfaces. The articular surface repairs are customizable or highly selectable by patient and geared toward providing optimal fit and function.

Abstract: In order to improve an implant for insertion into a human or animal body which comprises at least one implant part, wherein the at least one implant part has a base member which is produced from an implant material and has a surface which is designed at least partially in the form of an artificial joint surface, wherein part of or the entire joint surface is covered with a wear-reducing hard material coating, such that a service life of the implant is extended and the compatibility of the implant increased, it is suggested that an intermediate layer be provided between the hard material coating and the at least one joint surface formed from the implant material for the purpose of reducing tension between the hard material coating and the implant material. Furthermore, an improved method for the production of an implant for insertion into a human or animal body is suggested.

Abstract: A system and method for prosthesis fitting in joints comprising an artificial condyle and a spacer which cooperates with the condyle to form an artificial joint. The spacer embedded with at least one sensor which is responsive to a force generated between the condyle and the spacer. The artificial joint is adapted to move between a flexed position and an extended position defining a range of motion. The sensor is responsive to the force and generates an output representative of that force. The output is transmitted, either wirelessly or other, to a processor which utilizes an analysis program to display a representation of the forces applied. A practitioner utilizing the displayed analysis may intraoperatively determine the adjustments and balancing required within the artificial joint. The system may also utilize a ligament tension sensor which generates data representative of tension on a ligament of the artificial joint, and a joint angle sensor responsive to the range of motion of the artificial joint.

Abstract: An artificial knee joint is described that includes a femoral component with a specially shaped bearing surface and a tibial component, whose surface interacts with the femoral surfaces. The interaction provides for the required motion and stability characteristics. The interaction between the femoral and tibial surfaces is such that as the knee is flexed to maximum, the femoral component moves posteriorly on the tibial surface, by an amount similar to that in the anatomic knee. The opposite motion, roll forward of the femur from a fully flexed to a more extended position, is accomplished by varying the outward radii of the lateral and medial femoral bearing surfaces, together with a ramp on the postero-lateral and postero-medial regions of the tibial surfaces.

Abstract: An osteochondral repair assembly and a kit, both include an osteochondral regenerative implant and an associated retracting spacer. A method of osteochondral regeneration includes forming a recipient socket in a chondral area of an articular surface in need of repair, placing a retracting spacer at the recipient socket and removably wedging the retracting spacer between a wall of the recipient socket and an implant.

Abstract: The present invention comprises an apparatus, system and method utilizing a passive electro-magnetically damped joint for prosthetics or orthotics. Such as system may be controlled through changing the resistive nature of the circuit in which a braking or damping mechanism can sufficiently replicate and augment biomechanical movement. This may be accomplished through electronic circuitry means only, or through the use of intelligent control through a microprocessor and dynamic ambulation replication algorithms.

Abstract: A substantially cup-shaped prosthetic device for a joint is provided. The prosthetic device includes an outer surface configured to operatively engage at least one of a first bone of the joint and a component, an inner surface including at least a portion configured to connect to a second bone of the joint, and at least one reservoir having an opening at each of the inner surface and the outer surface and extending therebetween.

Abstract: An artificial joint as an endoprosthesis for a human joint, has at least two joint parts wherein each joint part has two functional surfaces that operatively interact with each other, one associated with the first joint part and the other with the second joint part. The two functional surfaces of each joint part are spheroidal in shape and convex-concave, concave-convex or convex-convex in shape in the proximal-distal arrangement, and the functional surfaces can each pivot around a pivoting axis. In order to create an artificial joint as an endoprosthesis for a human joint, whose motion behavior is perceptibly improved for the patient, the two pivoting axes of the two functional surfaces of each joint part are slanted towards each other.

Abstract: The invention relates to an implant for relieving damaged areas of the surfaces of hip or shoulder joints from stress. Said implant can be introduced into the space between the joint surfaces of the condyle (11) and the socket (13) cooperating in the natural joint. The inventive implant is cup-shaped or cap-shaped, rests in the socket (13) by means of a convex external face, and sits on the condyle (11) by means of a concave internal face in the implanted state. The implant comprises at least two articulation layers (15, 17) which are movable relative to each other and encompass articulation surfaces that face one another in the implanted state.

Abstract: A method for providing joint arthroplasty includes providing a gauge for making a measurement of the contour of a long bone, making a measurement of the contour of a long bone with the gauge, providing a plurality of joint prostheses, selecting one of the plurality of joint prostheses based upon the measurement of the contour, resecting a long bone, and implanting the selected one prosthesis onto the long bone. A kit is also provided for selecting one of a plurality of joint implants for use in joint arthroplasty on a bone. The kit includes a first gauge and a second gauge.

Abstract: Various methods and devices for ligament replacement in the human body, and in particular, the spine are provided. In an exemplary embodiment, a ligament replacement system is provided that has an artificial ligament configured in the form of a closed loop. The artificial ligament is adapted to be coupled between the ligament seating regions of first and second connection members in a connection geometry that results in the artificial ligament having a large motion with a non-linear relationship between the force and displacement, similar to that of a natural ligament.

Abstract: A prosthesis suited for orthopedic implantation possesses a multi-piece stem component that supports an artificial joint surface that can articulate with another artificial joint surface in various ways. The prosthesis can be assembled in a snap fit and/or interlocking fashion that provides positive locking means without the use of screws or other fasteners. The prosthesis can accommodate fitment of a plastic joint surface made, e.g., from ultra high molecular weight polyethylene. The prosthesis is well suited for use in an ankle replacement system that can be installed using minimally invasive intramedullary guidance established with respect to the major axis of the tibia by minimally invasive access through the calcaneus, through an incision in the bottom of the foot. The prosthesis makes possible the installation of a total ankle system using minimally invasive anterior access to the ankle joint for making bony cuts and to install prosthesis components.

Abstract: The invention concerns article having a surface oxide layer up to 20 nm thick, the surface oxide layer comprising chromium and cobalt oxides where the atomic ratio of Cr/Co is more than 3. The invention also concerns methods for treating a chromium containing material, said method comprising contacting said material with a gas plasma under conditions effective to oxidize at least a portion of the material; and contacting said material with an acid. The treated surface is corrosion resistant and can be used in orthopedic implants, especially the wear surface of the orthopedic implant to reduce wear, and other corrosive environment.

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: Disclosed, in one general aspect, is a musculoskeletal imaging system that includes a source of feature data extracted from imaging data resulting from imaging acquisitions from joints of different individuals affected by different diseases, and this feature data includes disease characteristic categorization information for a plurality of disease categories. A comparison module is operative to compare patient imaging data resulting from an imaging acquisition from a joint of a patient with the feature data. The comparison module is also operative to provide at least one categorization indicator for the patient imaging data that indicates a correspondence between spatial information in the patient imaging data and the disease categories for which there is extracted categorization information in the feature data.

Abstract: An assembly, for example for a reconstructive joint of the human body, comprises first and second parts which bear against one another. The first and second parts may both comprise a first polymeric material which is preferably polyetheretherketone in combination with carbon fibre.

Abstract: The present teachings provide a modular articulating cement spacer mold for forming a temporary implant. The modular spacer mold includes a head component mold defining a first opening, a head connector positioned within the first opening of the head component mold, a stem component mold defining a second opening, and a stem connector to fit within the second opening of the stem component mold to mateably engage the head connector. Related kits and methods of forming a temporary implant are provided.

Abstract: The application relates to a process for manufacturing a prosthetic joint with at least one loaded surface which consists at least partially of polyethylene, comprising compressing one or more layers of a woven fabric of drawn gel-spun polyethylene fibres into the desired shape in a hollow mould part using a plug at a pressure of at least 0.05 MPa and at a temperature of between 120 and 165° C. and below the crystalline melting point of the polyethylene at the prevailing temperature and pressure, without a matrix material being present, and at least the woven fabric in a layer situated on a loaded surface comprising at least 90 wt % of fibres with a titre of at most 1000 denier, and to a prosthetic joint with a crease-free surface.

Abstract: A cartilage implant for replacing a portion of the cartilage adjacent to a skeletal joint. In one exemplary embodiment, the cartilage implant includes a bearing portion and a drape. The bearing portion is configured to replace a portion of the cartilage adjacent to a skeletal joint. In one exemplary embodiment, the bearing portion is formed at least partially from a resilient polymer, such as a PVA hydrogel. The drape may be configured to secure the implant to an adjacent bone. Additionally, the drape may be extended over adjacent tissues and connected to the tissues to hold the implant in place while permitting some anatomic movement of the bearing portion.

Abstract: A prosthesis and method for a ball and socket joint. The prosthesis includes a first component including an anchoring shank and a metaphyseal portion. The metaphyseal portion includes a first articular surface configured to move in translation relative to the anchoring shank. An intermediate component includes a first articular surface configured to engage with the first articular surface on the metaphyseal portion, and a second articular surface configured to engage with the ball and socket joint.

Abstract: A trial implant component for use in a surgical procedure for replacement of a joint between a long bone and another bone, comprises a metaphyseal part which can be located so that it extends into a cavity at the resected face of the long bone in contact with the internal wall of the cavity in the metaphyseal region, and a disk which has an essentially flat shape and which can be fitted to the metaphyseal part to provide a gauge as to the appropriate size of a head part which is to be selected according to the location of the axis of the bone relative to the edge of the resected bone.

Abstract: Described herein are peptides having antimicrobial activity (antimicrobial peptides). The antimicrobial peptides, designated LBU, WLBU and WR, are analogs of the Lentivirus Lytic Peptide 1 (LLP1) amino acid sequence. The antimicrobial peptides are monomers or multimers of peptides referred to as the Lytic Base Unit (LBU) peptides, derived from the LLP1 analogs and also having antimicrobial activity. Also described herein are using the peptides in a variety of contexts, including the treatment or prevention of infectious diseases. Methods of killing fungi, such as Candida and Cryptococcus species, and bacteria, such as B. anthracis, are provided herein. Methods of neutralizing enveloped viruses, such as poxvirus, herpesvirus, rhabdovirus, hepadnavirus, baculovirus, orthomyxovirus, paramyxovirus, retrovirus, togavirus, bunyavirus and flavivirus, including influenza virus and HIV-1 also are provided herein. Solid phase substrates and peptide-cargo complexes comprising the peptides also are provided.

Abstract: The invention relates to an implantable device to be fixed to a bone and comprising an electrically conductive base body provided with at least two through holes and at least one pair of shaft-shaped contact means, wherein each contact means passes through a through hole of the base body and penetrates a section of the bone in an implanted state, wherein the surface of each contact means comprises a first and a second electrically conductive surface section as well as an electrically insulating surface section separating the electrically conductive surface sections from each other, wherein the first electrically conductive surface section electrically contacts the base body while the second electrically conductive surface section is electrically insulated with respect to the base body, wherein each contact means contains a coil arrangement in its interior by means of which the electrically conductive surface sections of each contact means are electrically coupled, and wherein the coil arrangements of a pair a

Abstract: A replacement device for resurfacing a joint surface of a femur and a method of making and installing such a device is provided. The custom replacement device is designed to substantially fit the trochlear groove surface, of an individual femur. Thereby creating a “customized” replacement device for that individual femur and maintaining the original kinematics of the joint. The replacement device may be defined by four boundary points, and a first and a second surface. The first of four points is 3 to 5 mm from the point of attachment of the anterior cruciate ligament to the femur. The second point is near the bottom edge of the end of the natural articulatar cartilage. The third point is at the top ridge of the right condyle and the fourth point at the top ridge of the left condyle of the femur.

Abstract: An implantable joint prosthesis configured such that it does not squeak during movements of a subject. The joint prosthesis includes a means to modify the dynamic response of parts of the prosthesis such the response is not audible to the human ear.

Abstract: There is disclosed a gold surface for the catalytic release of hydrogen from an alkane thiol. More specifically, the present disclosure provides a large surface area of gold on a carbon fiber scaffold that does not contain any sublayers of metals that can block the catalytic release of hydrogen from alkane thiols or form other reactions that remove the sulfur moiety from alkane thiol. There is further disclosed a method for forming a gold surface onto woven carbon fiber sheets wherein no sublayer or other intermediate material is used.

Abstract: A method of surface finishing a bone implant comprises the steps of roughening a surface of the implant by blasting with abrasive particles and then pickling the surface-roughened implant in a pickling solution in order to loosen any partially embedded abrasive blasting particles that may be contaminating the surface of the implant. Thereafter the roughened surface of the implant is cleaned by mechanical action to detach the loosened abrasive particles there from. The pickling and cleaning steps are not intended to produce any additional roughening of the treated surface, which should be structured to the required roughness by the initial abrasive blasting, typically such that the Ra and Rt roughness parameters are 3?Ra?7 ?m and 20?Rt?70 ?m respectively.

Abstract: The present invention provides an irradiated crosslinked polyethylene containing reduced free radicals, preferably containing substantially no residual free radical. Disclosed is a process of making irradiated crosslinked polyethylene by irradiating the polyethylene in contact with a sensitizing environment at an elevated temperature that is below the melting point, in order to reduce the concentration of residual free radicals to an undetectable level. A process of making irradiated crosslinked polyethylene composition having reduced free radical content, preferably containing substantially no residual free radicals, by mechanically deforming the polyethylene at a temperature that is below the melting point of the polyethylene, optionally in a sensitizing environment, is also disclosed herein.

Abstract: A joint device for an orthoses or prostheses includes an upper part, a lower part mounted on the upper part in such a way as to turn about a pivot axis, and braking means that brakes or blocks a pivoting movement of the lower part relative to the upper part. The braking means includes a spiral spring arranged between two contact surfaces and is mounted such that it can be braced in the direction of the contact surfaces about a rotation axis parallel to the pivot axis.

Abstract: A ligament incorporated into a prosthetic joint exhibiting a plasticized, elongated and deformable material. A fibrous material is internally disposed within the deformable material, the fibrous material terminating in first and second enlarged bead portions arranged in proximity to enlarged pocket defined ends associated with the deformable materials. First and second bones define a joint region therebetween, the deformable end pockets and bead portions being inserted through associated holes defined in joint proximate locations associated with the bones, so that actuation of a projection location of the fibrous material causes the bead portions to outwardly deflect the end pockets, resulting in the ligaments being anchored in place between the bones.

Abstract: The present invention relates to an apparatus and method for treating inflammation and/or infection within a synovial joint. The invention is comprised of a depot, tether and cap. The depot is comprised of a biodegradable polymer which is impregnated with a biological agent targeted to treat the inflammation and/or infection. The depot is inserted into the synovial joint through an incision or hole in the synovial membrane. A tether that extends from the depot is then thread back through the incision or hole and coupled to a cap such that the depot is coupled to the synovial membrane on an interior side of the synovial joint capsule and the cap is secured to the membrane on an exterior side of the synovial joint capsule. Once secured, the depot degrades and gradually releases the biological agent over a sustained time period. The biological agent then treats the targeted inflammation and/or infection.

Abstract: A system for restoring articular cartilage has a cover, an anchor, and a tether that cooperate to retain graft tissue with respect to a graft site. The cover is attached to the anchor via the tether. The tether passes through a tunnel through a bone to which the articular cartilage is attached. The tunnel connects the graft site to an anchoring side of the bone. The anchor is retained proximate the anchoring side such that tension in the tether keeps the cover in place over the tissue graft to capture the tissue graft at the proper position with respect to the graft site. The cover and/or the anchor may be bioabsorbable. The cover may be perforated to permit fluids to access the tissue graft from outside the cover to enhance incorporation of the graft tissue with the graft site. The cover may be formed of rigid or flexible materials.

Abstract: The tibial component of a prosthetic ankle joint including a tibial component, a talar component, and an intermediate sliding plastic bearing, with the tibial component including a depending peripheral wall that surrounds and is spaced from the plastic bearing and is intended to reduce rubbing of the plastic bearing against tissue which would produce wear particles that lead to the formation of bone cysts. The depending peripheral wall of the tibial component is intended to reduce such possible abrasions by at least partially shielding the plastic bearing from the surrounding tissue.

Abstract: A prosthesis, in particular a shoulder prosthesis, includes a socket part receiving a joint head; an anchoring part anchoring the prosthesis in a bone; and a connecting arrangement securely connecting the socket part to the anchoring part. The socket part is assigned at least one pin and the anchoring part has at least one guide. The guide is designed in such a way that the pin can be held substantially safe from tilting in the guide.

Abstract: A surgical implantation approach for preparing a patient and precisely and effectively placing an energy absorbing apparatus relative to the patient's anatomy. Various surgical implantation apparatus and methods for achieving proper device-to-anatomy juxtapositional relationships are employed in the implantation approach.

Abstract: A system and method is provided in which natural bone removed during a joint surgery is retained along with the natural attachment of the associated soft tissues. For instance, in a hip surgery, a portion of the greater trochanter is removed while retaining the soft tissue attachments. An implant and the bone portion are provided with mating features, such as a keystone configuration. The keystone configuration can include mating male and female dovetail configurations. The bone portion can be engaged to the mating feature of the implant to support the natural bone and its soft tissue attachment in an anatomically appropriate position.

Abstract: A prosthetic implant for securing to bone to form an articulating joint is provided. The implant is prepared by a process which includes the steps of preparing a porous surface on a component to form a prosthetic implant, placing the prosthetic implant including the porous surface in a fixture closely conforming to the porous surface of the implant and having an inlet and an opposed outlet, and directing a biological compound including stem cells into the inlet, through the porous surface of the implant and out of the outlet to form a prosthetic implant having a porous surface coated with a portion of the biological compound.