Abstract: A switched-capacitor sigma-delta modulator includes at least one memory element, at least one comparator, and at least one integrator. The at least one integrator has an input stage including a series circuit of a first switch, a first capacitor and a second switch, a third switch for connecting one of the two terminals of the first capacitor to ground potential, and a fourth switch for connecting the other of the two terminals of the first capacitor to ground potential. A nodal point is connected between the second and fourth switches and the other of the two terminals of the first capacitor. A negative feedback stage includes second and third capacitors each having one terminal connected to the nodal point. A fifth switch connects the other terminal of the second capacitor to a first potential. A sixth switch connects the other terminal of the third capacitor to a second potential. Seventh and eighth series-connected switches connect the other terminal of the second capacitor to the second potential.

Abstract: The bone implant is made of a cobalt-based alloy and can be anchored to a bone through the accretion of tissue. The tissue friendly surface of the implant is provided by a coating and a structural element which is secured to the coating with each of the coating and structural element being made of titanium, tantalum or niobium or an alloy of one or more of these materials.

Abstract: The wire mesh is welded to the metal substrate via step-like protuberances formed on the outer surface of the substrate. The wire mesh is permanently deformed in the regions over the protuberances to facilitate forming of spot welds while the remainder of the mesh outside the zones of the protuberances remains porous for the intake of bone cement or the ingrowth of bone tissue.

Abstract: The metal sleeve which is formed with the slot along a generatrix, comprises zones of relatively large wall thickness (D) and zones of relatively reduced wall thickness (d) in alternative relationship around the periphery. The zones of reduced wall thickness are in the form of annular sectors of finite length having parallel walls and radiused transitions into zones of relatively large wall thickness (D). When an insert is pressed in, the sleeve is expanded very uniformly over the entire periphery.

Abstract: The bone implant is formed of a plastic body having a multi-layer wire fabric secured to the outside surface. A separating layer is disposed between the wire fabric and two wire layers embedded within the plastic body. The separating layer serves to block the ingrowing bone tissue from contact with the plastic body while embedded layers are securely enveloped by the plastic of the body to prevent a break out of the fabric.

Abstract: The metallic intervertebral prosthesis is formed of a kidney-shaped body having fishplates extending upwardly and downwardly from the body. Each fishplate has an opening for passage of a bone screw in order to secure the prosthesis to and between adjacent vertebrae. The body is tapered conically from ventral to dorsal and may be fitted in place in the ventral direction. A metal wire mesh may be provided on opposed surfaces of the body for the ingrowth of tissue and ribs may be provided to enhance lateral stability.

Abstract: The fixing stem is provided with a plurality of projections in the proximal region of the blade. Each projection is in the form of a pyramidal prism directed in a distal direction. The apex of each projection is sharp and is inclined at an acute angle to the surface of the blade. In addition, the projections are staggered along the length of the proximal region of the blade and are of decreasing height in the distal direction.

Abstract: The stem of the femoral head prothesis has a distal zone of cylindrical cross-section and a proximal zone of rectangular cross section which extends from the distal zone. The sides of the stem in the proximal zone are plane with outstanding parallel ribs which can be driven into the spongy tissue of a femur bone. The ribs on the anterior side of the stem are of a lower height than the ribs on the posterior side. The outermost ribs on each side provide for a resilient four-point bearing on the hard cortical shell of the fem>r bone. A pair of trochanter wings are provided on the narrow lateral side to penetrate into the cortical shell of the femur bone in order to preclude rotation of the stem within the bone.

Abstract: The cavity of the stem of the tumor or re-operation prosthesis is subdivided by support elements into sub-cavities filled with bony material. The support elements are formed with central apertures through which the bony material can be supplied and re-vascularized from the living bone tissue of the femur stump. Wire mesh may cover over the apertures in the support elements as well as the slots between the circumferentially disposed webs which define the cavity of the stem.

Abstract: The joint endoprosthesis is formed of a compressible elastic hollow body which is disposed between two anchoring elements. The hollow body defines a closed cavity which is filled with an incompressible fluid medium. Compressive loadings near the edges of the endoprosthesis cause a displacement of the liquid into relieved regions of the prosthesis so as to avoid tensile forces from occurring in the anchoring of the prosthesis to the bones.

Abstract: The hemispherical acetabulum has a pin which projects from the cup of the acetabulum on an angle of 45.degree. relative to the polar axis. A sleeve which closes over the pin is rotatably mounted on the pin to facilitate twisting of the cup into a correct position when implanted in a pelvis. The sleeve is made of metal to preclude direct contact between the pin which may be made of plastic and the pelvis bone tissue.

Abstract: The turns of the self-tapping screwthread formed on the outside surface of the metal hemispherical shell have front portions of constant thickness which extend over one third of the cross sectional length of the thread turn. The remainder of the thread turns is wedge-shaped. The shape of the thread turns facilitates the cutting in of the screw thread when the hemispherical shell is being implanted.

Abstract: The outer shell possesses openings in the polar or apical region which serve to backfill the implanted shell with spongious bone material. The openings are separated by a web which extends through the axis of symmetry of the outer shell and which has a threaded bore to receive an insertion instrument. The instrument is centrally guided on an axial direction to facilitate control and alignment of the outer shell during insertion, especially in the case of outer shells to be screwed in with a self-cutting thread.

Abstract: The intervertebral prosthesis provides a replacement for a damaged disk. The prosthesis is formed as a solid body of kidney-shape and is provided with a metal mesh covering for the ingrowth of tissue. Raised parts are formed on the opposite surfaces of the kidney-shaped body impart lateral stability when in situ.

Abstract: The hip joint acetabulum uses a synthetic ring for snap-fitting the acetabulum body within the outer bowl. The ring is slit to provide for the snap fit connection and is provided with an annular lug which projects into an annular groove within the outer bowl. Recesses are also provided to permit a tool to penetrate into the acetabulum to separate the lug from the remainder of the ring to permit ready detachment of the body from the bowl.

Abstract: A circuit configuration includes a differential operational amplifier having differential input terminals and differential output terminals. A common mode feedback circuit sets a direct voltage operating point of the output terminals. A reference voltage terminal connected to the output terminals supplies a reference voltage. Two pairs of operating point transistors of complementary conductivity types have control terminals and have output circuits connected in series at a respective connection point for each pair. Each of the connection points is connected to a respective one of the output terminals. A reference current source controls the operating point transistors in parallel. First coupling capacitors are each connected between a respective one of the output terminals and a respective one of the control terminals of an associated operating point transistor of one conductivity type. The common mode feedback circuit includes second coupling capacitors and a remainder of the common mode feedback circuit.

Abstract: The implanted is constructed with a metal base element and a plastic part which is elastically mounted on the base element and carries a metal grid structure for the ingrowth of bone tissue. The elastic mounting is provided by a prop which extends from a body portion of the plastic part into a depression in the base element. The prop is received in the depression with lateral play to not only hold the mutually facing surfaces of the base element and plastic part from each other but to permit lateral play. The floating suspension permits inevitable micromovements between the metal implant and the plastic part to be absorbed and not transmitted directly to the bone tissue which grows into the metal grid structure.

Abstract: A switched current source includes at least two branches, at least one MOS current source transistor connected in common to each of the at least two branches, and at least two MOS switching transistors each being connected in a respective one of the branches and simultaneously forming an additional current source transistor, the at least one current source transistor being connected as a respective cascode with each of the at least two switching transistors.

Abstract: The artificial crucial ligament is formed of a plurality of tubes which are disposed in concentric relation to define a stem. Alternating tubes extend from the stem to form two branches. The tubes are made of textile structures to impart flexibility and longitudinal elasticity to the ligament. In one embodiment, the tubes are made of a braided construction.

Abstract: The agraffe is composed of a deformable metal plate having two projections, each of which is provided with a threaded eyelet. In addition, anchored pins are threaded into the respective eyelets and can be selected from a set of pins having different lengths. The deformable plate is arched between the projections and has a plurality of tacks fixably secured in place to increase adhesion of a ligament or tendon to a bone. The instrument for implanting or extracting the agraffe includes a pair of angular sector-shaped grooves of T-shaped cross-sections which are sized to engage with and under the heads of the pins in order to form a connection between the instrument and agraffe.