Abstract: An apparatus for removably attaching a sleeve to a stem of a femoral prosthesis. The stem has a tapered portion midway along the stem rather than along the complete length of the stem or near the tip of the stem. There is a corresponding tapered portion on an inside surface of the sleeve near one end of the sleeve only.

Abstract: A pneumatically driven orthopedic broach inserter comprising a continuously reciprocating piston which strikes a proximal anvil during each cycle. The impact of the piston with the proximal anvil drives the broach out of a bone. To drive the broach into the bone, a surgeon pushes on the power broach inserter, bringing a distal anvil into the path of the piston, and creating a forward action which dominates over the on-going reverse action produced by the piston striking the proximal anvil. The piston is provided with a low-friction sleeve so that completely oilless operation is possible. A fast-acting chuck having a key and a wedge is provided whereby broaches of different size can be quickly attached to the power broach inserter.

Abstract: A method and apparatus for performing an upper tibia osteotomy comprising cutting a wedge from the bone using a first guide assembly to cut a first slot partially through a bone and a second guide assembly to cut a second intersecting slot to define a wedge shaped bone segment. An external compressor device draws the osteotomy closed by plastic deformation of the unsevered portion of the bone. The bone is secured by a plate and screws.

Abstract: An o-ring attachment system with opposed convex circumferential surfaces for removable dentures to be attached to a natural or an implanted fixed root system. The o-ring attachment system can be screwed into an implanted root using a manipulating means interposed between o-ring abutment and an attachment screw. In connection therewith, a tool is provided for implanting the o-ring attachment system, the tool having a captured toroidal spring for gripping the attachment system.

Abstract: A bioprosthetic heart valve comprising first and second mechanisms for supporting leaflets to provide multiple effective spring constants. An inner frame supporting commissures of the valve is elastic, permitting the commissures to bend in toward the center of the prosthetic heart valve at very low loads. A relatively rigid annular support ring supports the elastic frame and provides the second spring constant mechanism. An attachment system for sewing bioprosthetic leaflets to the frame and clamping the leaflets between the frame and the annular ring minimizes stress risers in the leaflets. The leaflets have an uncoupled mating edge where the leaflets meet in the center of the valve. The uncoupled portions of the leaflets permit the leaflets to roll by each other.

Abstract: An invasive prosthesis device is disclosed which includes an electrical circuit having a cathode and an anode for mounting on opposing sides of body tissue requiring healing. The cathode is connected to a source of power for transmitting electrical stimulating signals to the anode as target. The invasive device includes a constant current circuit which may include either a battery source of power or a power source iductively coupled to the constant current source circuit. If the power source is inductively coupled to the constant current source a diode rectifier can be coupled between the inductive coil and constant current source for rectifying the induced ac to dc. The prosthesis device includes a porous surface area located to maximize the bonding strength between the device and the body tissue. The cathode is located in the porous area and powered to limit tissue growth to ingrowth substantially within the porous area only.

Abstract: Apparatus and a method for providing a micro-computer based expert system having a knowledge base of failure analysis, as it pertains to metallic components. The apparatus and method includes interactive initialization procedure which includes communications between the user and the knowledge base. The system and method incorporates automated visual aids for the analysis of metal failure.

Abstract: A patellar clamp and saw guide for preparing a patella to receive a prosthetic articulating surface on the patella's posterior side. A guide plate supports a saw block. The guide plate can be swiveled so that a sagittal saw can be presented to the patella from any desired angle. The saw block can be advanced or retracted axially so that more or less of the patella will be cut away by the saggittal saw. A scale enables the location of the proposed cut to be quickly and accurately determined. Storage apparatus in a handle of the clamp holds different specialized for use during surgery.

Abstract: A method and apparatus for performing an upper tibia osteotomy comprising cutting a wedge from the bone using a first guide assembly to cut a first slot partially through a bone and a second guide assembly to cut a second intersecting slot to define a wedge shaped bone segment. An external compressor device draws the osteotomy closed by plastic deformation of the unsevered portion of the bone. The bone is secured by a plate and screws.

Abstract: A method for detecting and treating ventricular tachyrhythmias of a patient's heart includes the steps of selectively dividing the heart rate continuum into regions including at least two classes of tachycardia, contiguous to each other and of progressively higher heart rate ranges, the lowest and highest of the tachycardia classes being bounded respectively by a sinus rate region and a fibrillation region of the continuum; selectively adjusting the boundaries between the tachycardia classes and between the lowest and highest of those classes and the respective sinus rate and fibrillation regions, to correspondingly adjust the rate ranges of the classes; selectively detecting cardiac events anywhere within the continuum and distinguishing between normal and abnormal tachycardias among the detected events; selectively treating a detected abnormal tachycardia with any of a multiplicity of therapy regimens of differing degrees of aggressiveness, toward terminating the detected tachycardia; with the improvement o

Abstract: A bone induction tray which acts as a structural support intimate contact with a bone to be repaired and participates directly in the reconstruction of a bone defect by providing direct chemical bonding with the bone and in the repair thereof. A suitable dimensionally formable fabric is selected which comprises a woven or non-woven mesh of fibers having pores between the fibers primarily for carrying an appropriate ceramic material therein. The fabric acts as a substrate support for a calcium phosphate biomaterial which is coated onto the fabric mesh such that the individual fibers of the mesh are completely coated and the pores in the mesh are completely impregnated therewith. Preferred bioresorbable fiber materials are the alpha-hydroxyacids such as lactic acid or glutaric acid. Preferred non-bioresorbable fabrics are typically polyamides, polyesters, or polyacrylics.

Abstract: An implantable endocardial lead with retractable fixation apparatus. The fixation apparatus comprises a sharpened helix which can be repeatedly both retracted within an electrode at a distal end of the lead and displaced outside the electrode by action of a flexible, tubular lanyard. The lanyard passes through a lumen from a proximal end of the lead to the distal end of the lead, where the lanyard is attached to a piston supporting the helix. At the proximal end of the lead, a jig moves the lanyard with respect to a longitudinal axis of the lead. When the helix is in an exposed position, torque can be transmitted from the proximal end of the lead to the distal end thereof, through the electrode to the piston and then to the helix to screw the helix into the endocardial tissue. To stiffen the lead during implantation, a stylet can be inserted into a lumen in the lanyard.

Abstract: A dual chamber pacemaker with variable V-A delay based on detection of multiple criteria before lengthening the V-A delay period. Before the V-A delay period can be extended, the pacemaker must be stimulating the ventricle at a maximum ventricular rate, and an atrial event must be sensed in a relative atrial refractory period. During this interval the pacemaker would not respond to an atrial event that was sensed, but the occurrence of the event would be detected. To optimize a ventricular blanking period, in each cardiac cycle, the energy level of the atrial output pulse and the sensitivity of the ventricular sense amplifier are sampled. Based on these dynamic parameters, the duration of the ventricle blanking period is adjusted for each cycle so that a minimum ventricular blanking period can be maintained without cross-talk.

Abstract: A glenoid prosthesis and method for affixing the same. The glenoid prosthesis has a lateral surface for articulating with a humeral head and a flat medial surface which engages a flat resected surface on the scapula head. In a first embodiment, an integral plastic prosthesis has a pair of pegs extending from a flat medial surface which are positioned in a pair of holes drilled in the bone. The mating flat surfaces and pegs and holes are bonded with cement. The flat mating surfaces resist rocking under applied superior-inferior loading and resection is simplified by providing a flat resected surface and holes drilled substantially perpendicular thereto. Grooves are provided in the pegs to provide an increased area for bonding and the grooves are of graduated depth to provide greater strength at the proximal end of the pegs where the highest stresses occur.

Abstract: A series of test signals are generated by a microprocessor of a pacemaker to determine whether a bipolar or unipolar lead is attached to an implanted cardiac pacemaker restricting programming of said pacemaker to only an unipolar pacing mode unless the presence of an operational bipolar lead is detected. Detection is accomplished by generating a series of low frequency high impedance pulses, applying them to lead contacts and sensing a return signal. If a return signal is detected, then that indicates either a unipolar lead is connected to the pacemaker or that the ring conductor of a bipolar lead is open and bipolar pacing must be inhibited.

Abstract: A surgeon-assemblable asymmetric tibial prosthesis with a snap-in tibial insert for surface replacement of the proximal tibia. The tibial prosthesis, consisting of two parts, a baseplate and a right or left knee specific insert, is used in conjunction with prosthetic femoral and patellar components. Asymmetry is created by having the radius which describes the medial condyle slightly greater, preferably 1/8", than the radius describing the lateral surface. The baseplate exhibits symmetry about an anterior/posterior centerline, allowing it to be used on right or left proximal tibias by rotation of the component 180.degree. about the centerline. The insert is contoured to provide an anatomically correct surface which articulates with the condyles of the femoral prosthesis. The anatomic fit contributes to normal range of motion since there is less chance of lateral overhang to cause soft tissue impingement. The increased cortical rim contact permits direct load transfer to the stronger cortical bone.

Abstract: Apparatus and a method for providing a micro-computer based expert system having a knowledge base of failure analysis, as it pertains to metallic components. The apparatus and method includes interactive initialization procedure which includes communications between the user and the knowledge base. The sytem and method incorporates automated visual aids for the analysis of metal failure.

Abstract: A replacement connector for implanted leads. The proximal end of the implanted lead is cut away and discarded. A slip-on seal is placed on the remaining end of the lead. The replacement connector is connected to the implanted lead using an eccentric locking mechanism both to secure the implanted lead and the replacement connector together and to achieve a positive electrical connection. A boot mates with the slip-on seal to protect the connection from body fluids.

Abstract: A shield to selectively surround a needle or other sharp protrusion on a medical device, such as a syringe, to inhibit accidental injury.

Abstract: A prosthetic implant for use in replacing the ball end of a biological joint includes a cup member for insertion into the natural socket, an insert received in the cup member defining a ball receiving cavity with a stepped entry, and a split locking ring received in the stepped entry. A ball shaped portion of a prosthesis introduced into the entry will displace the locking ring inwardly to a larger stepped portion of the entry where the locking ring can expand to allow passage of the ball after which the ring contracts and slides over the ball to a locking position in a smaller stepped entry portion.