Abstract: A surgical fastener applying device for releasable connection to an end effector is provided. The surgical fastener applying device includes an elongated body portion having an outer tube and an inner shaft assembly. The inner shaft assembly defines a non-circular bore in a distal end thereof. The inner shaft assembly is longitudinally movable through the outer tube. The outer tube and the inner shaft assembly define corresponding openings extending radially therethrough. The surgical fastener applying device includes a detent movable within the openings of the elongated body portion. The detent floats between the end effector and the elongated body portion to enable selective connection between the end effector and the elongated body portion.

Abstract: The present disclosure provides an implant extraction tool for removing either cemented or non-cemented intramedullary stem implants from bones. The tool includes an elongated handle section having proximal and distal end sections with a cap section affixed to the distal end section of the elongated handle section, and cap section has a hole extending therethrough. The tool includes an attachment member having opposed ends, one of these opposed ends is configured to grip a cemented or non-cemented intramedullary implant stem in a bone. The attachment member has a size and shape to be received into the hole and the other of opposed end includes at least one hook feature for gripping the implant. The tool includes an elongated lever having an elongate proximal section and a shorter distal end section with a pivot fulcrum at a transition from the distal end section to the elongate proximal section.

Abstract: A transseptal access stability system (TASS) and method of use thereof is disclosed. The TASS includes a venous sheath for reducing the likelihood of complications that may arise when performing transseptal punctures. The TASS uses either suction force or cryo-based energy for securing the fossa ovale against the rim of the orifice of the venous sheath. A method of performing a transseptal puncture using the presently disclosed TASS also is disclosed.

Abstract: A vapor delivery system and method is provided that includes a number of features. In one embodiment, a method comprises inserting a vapor delivery needle into tissue of a patient, activating a flow of vapor from a vapor generator through vapor delivery ports of the vapor delivery needle to cause condensed liquid to exit vapor delivery ports of the vapor delivery needle, generating vapor in the vapor generator, delivering a dose of vapor through the vapor delivery ports of the vapor delivery needle into the tissue, and after the dose of vapor is delivered, re-activating the flow of vapor from the vapor generator through the vapor delivery ports of the vapor delivery needle to prevent a vacuum from forming in the vapor delivery needle. Vapor therapy systems are also provided.

Abstract: Methods and devices for allowing articulation of an end effector on a surgical instrument are provided. In one embodiment, a surgical device can include a flexible neck portion having an end effector coupled to a distal end thereof. The flexible neck portion is configured to bend to as to allow the end effector to articulate. The flexible neck portion can include a monolithic flexible outer shell defining an inner lumen extending therethrough. At least one flexible divider can be disposed within the inner lumen such that it separates the outer shell into elongate pathways configured to receive articulation members extending through the shaft assembly and the flexible neck and coupled to the end effector to cause articulating movement thereof.

Abstract: Various embodiments are directed to systems and methods for providing segmented power curves to tissue. A surgical generator may receive an indication of a first impedance of tissue to be treated by a surgical end effector. The generator may determine that the first impedance is within an impedance range corresponding to a first power curve segment of the segmented power curve and provide a drive signal to the end effector according to a first power curve. The generator may further receive an indication of a second impedance of the tissue to be treated by the end effector, determine that the second impedance is within an impedance range corresponding to a second power curve segment of the segmented power curve, and provide the drive signal to the end effector according to a second power curve.

Abstract: Various examples are directed to a surgical system comprising an end effector and a generator. The end effector may comprise at least one jaw member having an open position and a closed position. The generator may be programmed to receive a request for an energy cycle routine to the end effector. The generator may determine that the at least one jaw member has not been in the open position since a conclusion of a previous energy cycle. The generator may apply a modified energy cycle routine to the end effector. Applying the modified energy cycle routine may comprise delivering less energy than applying the energy cycle routine.

Abstract: An electrosurgical instrument. The electrosurgical instrument includes an end effector movable between a first position and a second position, a first jaw member which includes first and second electrically conductive members, and a second jaw member which includes a third electrically conductive member. The first jaw member is movable relative to the second jaw member from an open position to a closed position to grasp a tissue positioned between the first and second jaw members. At least one of the first and second jaw members is adapted to connect to an electrosurgical energy source such that electrosurgical energy can be selectively communicated through the tissue positioned between the first and second jaw members to effect a tissue seal. A distance between the first electrically conductive member and the third electrically conductive member is less than a distance between the second electrically conductive member and the third electrically conductive member.

Abstract: An end effector is disclosed. The end effector includes a first jaw member. The first jaw member comprises a first electrode. The first jaw member defines a first aperture at a distal end. The end effector includes a second jaw member. The second jaw member comprises a second electrode. The second jaw member defines a second aperture at a distal end. The second jaw member is operatively coupled to the first jaw member. The first and second apertures are configured to define a single aperture when the first and second jaw members are in a closed position. The first and second electrodes are configured to deliver energy.

Abstract: A device, method, and system for adding mapping functionality to an ablation device without adding electrodes, wiring, or other components to the ablation device. The device includes a treatment catheter including a proximal portion and a distal portion, the distal portion including a longitudinal groove. The device also includes a mapping catheter including a proximal portion and a distal portion, the distal portion of the mapping catheter being coupled to the distal portion of the treatment catheter. For example, the distal portion of the mapping catheter is snapped into the groove of the treatment catheter. Together the treatment and mapping catheters are transitionable between a variety of configurations. In this way, the medical device may be used to both treat and map tissue without complicating the design and manufacture of the treatment catheter.

Abstract: A device, system and method for creating transmural lesions between the coronary sinus and left atrium. The device includes an elongate body that is deflectable in two locations to create a transverse portion that is substantially orthogonal to the longitudinal axis of the elongate body and a distal tip portion that defines a longitudinal axis that is parallel to the longitudinal axis of the elongate body. The device may also include two electrodes, an occlusion balloon, a hemisphere marker, and a magnet in the distal portion. In use, one device may be positioned in the coronary sinus and another device may be placed in the left atrium proximate the mitral valve, the magnets being attracted to each other and magnetically coupling the two devices against tissue, through which a transmural lesion may be created when energy is delivered from at least one of the two electrodes of each device.

Abstract: Medical devices and methods for treating and occluding a female patient's fallopian tubes to provide permanent birth control or sterilization.

Abstract: Methods and apparatus are provided for monopolar neuromodulation, e.g., via a pulsed electric field. Such monopolar neuromodulation may effectuate irreversible electroporation or electrofusion, necrosis and/or inducement of apoptosis, alteration of gene expression, action potential attenuation or blockade, changes in cytokine up-regulation and other conditions in target neural fibers. In some embodiments, monopolar neuromodulation is applied to neural fibers that contribute to renal function. In some embodiments, such monopolar neuromodulation is performed bilaterally.

Abstract: The invention provides a non-invasive device comprising an optical system having a laser light source for generating a light beam, being configured such that, in use, the light beam exits the device and impinges on an outer surface of the skin to be treated; the optical system being configured to focus, in use, the light beam at a position of a treatment location inside the skin, whereby Laser Induced Optical Breakdown is induced at the position of the treatment location; an opening disposed such that, in use, light returning from the skin enters the device as a measurement light beam; and a first and second intensity detection channel configured and arranged to detect the intensity in, respectively, a first and a second bandwidth range of the measurement light beam, wherein the first and the second bandwidth ranges both comprise a wavelength of light produced in the skin as a result of Laser Induced Optical Breakdown, and the first bandwidth range comprises the Second Harmonic Generation wavelength of the la

Abstract: In some embodiments, the instant invention provides for a system that includes at least the following components: (i) an Alexandrite laser pumping subsystem; where the Alexandrite laser pumping subsystem is configured to: 1) produce wavelengths between 700 and 820 nm, and 2) produce a pump pulse having: i) a duration between 1 to 10 milliseconds, and ii) an energy measuring up to 100 Joules; where the Alexandrite laser pumping subsystem includes: 1) an optical fiber, and 2) a Lens system, (ii) a Thulium doped Yttrium Aluminum Garnet (Tm:YAG) laser subsystem; where the Tm:YAG laser subsystem includes: 1) a Tm:YAG gain medium, 2) a rod heat sink, and 3) at least one cooling device, (iii) a wavelength selecting device, where the wavelength selecting device is configured to deliver a wavelength between 1.75 microns to 2.1 microns; and where the system is configured to produce a high energy conversion efficiency.

Abstract: A system and method for performing fractional resurfacing of a target area of skin using electromagnetic radiation are provided. An electromagnetic radiation is generated by an electromagnetic radiation source. The electromagnetic radiation is caused to be applied to a particular portion of a target area of skin. The electromagnetic radiation can be impeded from affecting another portion of the target area of the skin by a mask. Alternatively, the electromagnetic radiation may be applied to portions of the target area of the skin, other than the particular portion.

Abstract: The invention relates to a light application apparatus (1) for applying light to an object (3). A light source (4) generates processing light (2) and sensing light (5), which are coupled into the object (3). A light detector (8) detects the sensing light (5) after having left the object (3), and a control unit (9) controls the light source (4) such that processing light (2) in a processing time interval and sensing light (5) in a sensing time interval are alternately generated. Since processing light and sensing light are generated alternately, the generation of the processing light and of the sensing light is decoupled, i.e. the processing light can be optimized for processing purposes and the sensing light can be optimized for sensing purposes. This allows improving the quality of sensing the object and, thus, the quality of controlling the application of light depending on properties of the object.

Abstract: A method of implanting a hip joint prosthesis into a patient can include obtaining image data of hip joint anatomy of the patient. Physical activities that the patient desires to participate in subsequent to implanting the hip prosthesis can be determined. A size and an initial placement of the hip joint prosthesis based on the image data can be determined. A desired range of motion of the hip joint prosthesis based on the determined physical activities can be determined. A plan can be created comprising a desired implanted location of the hip joint prosthesis and based on the desired range of motion. The plan can be incorporated onto a guide. The plan can be executed with the guide thereby implanting the hip joint prosthesis into the patient at the desired implanted position.

Abstract: The invention relates to a method for planning a surgical intervention comprising the implantation of an implant in a patient's anatomical structure, comprising: computing at least one pseudo-radiographic image from a 3D image of the anatomical structure, said pseudo-radiographic image being a 2D image wherein each pixel integrates the information of the 3D image along a determined direction of integration, said determined direction of integration depending on the planned position of the implant with respect to the anatomical structure; displaying said at least one pseudo-radiographic image on a display unit; displaying a representation of the implant on said pseudo-radiographic image; updating the pseudo-radiographic image and/or the representation of the implant when the position of the implant is modified.

Abstract: Methods, systems and devices for pre-operatively planned shoulder surgery guides and implants. Pre-operative planning methods for designing glenoid implants and prostheses, particularly with patient-specific augmentation, based on considerations of multiple factors affecting the outcome of shoulder surgery. Methods of using surgery guides and implants, including adaptive glenoid implants, in patients undergoing shoulder surgery.

Abstract: Presented is a preoperatively designed guidance tool for intraoperative use during bone or joint surgery wherein the guidance tool is specific to the anatomy of the patient being treated. The guidance tool comprises a body portion, a mating surface provided on the body portion for positioning the guidance tool on a corresponding registration surface of a patient's anatomy. The guidance tool further comprises at least one guide mechanism provided on the body portion for guiding a medical instrument at one or more preoperatively defined trajectories relative to a patient's anatomy. In the event of misalignment, the at least one guide mechanism is adjustable to alter the one or more preoperatively defined trajectories if necessary during intraoperative use. Also presented is a preoperative process for designing the guidance tool.

Abstract: A method of manufacturing an arthroplasty jig is disclosed herein. The method may include the following: generate two dimensional image data of a patient joint to undergo arthroplasty, identify in the two dimensional image data a first point corresponding to an articular surface of a bone forming the joint, identify a second point corresponding to an articular surface of an implant, identify a location of a resection plane when the first point is correlated with the second point, and create the arthroplasty jig with a resection guide located according to the identified location of the resection plane.

Abstract: A method of manufacturing an arthroplasty jig is disclosed herein. The method may include the following: generate two dimensional image data of a patient joint to undergo arthroplasty, identify in the two dimensional image data a first point corresponding to an articular surface of a bone forming the joint, identify a second point corresponding to an articular surface of an implant, identify a location of a resection plane when the first point is correlated with the second point, and create the arthroplasty jig with a resection guide located according to the identified location of the resection plane.

Abstract: A method of manufacturing an arthroplasty jig is disclosed herein. The method may include the following: generate two dimensional image data of a patient joint to undergo arthroplasty, identify in the two dimensional image data a first point corresponding to an articular surface of a bone forming the joint, identify a second point corresponding to an articular surface of an implant, identify a location of a resection plane when the first point is correlated with the second point, and create the arthroplasty jig with a resection guide located according to the identified location of the resection plane.

Abstract: A method of manufacturing an arthroplasty jig is disclosed herein. The method may include the following: generate two dimensional image data of a patient joint to undergo arthroplasty, identify in the two dimensional image data a first point corresponding to an articular surface of a bone forming the joint, identify a second point corresponding to an articular surface of an implant, identify a location of a resection plane when the first point is correlated with the second point, and create the arthroplasty jig with a resection guide located according to the identified location of the resection plane.

Abstract: A tracking system and method using the same is disclosed which is capable of minimizing a restriction of surgical space by achieving a lightweight of the system as well as a reduction of a manufacturing cost through calculating a 3-dimensional coordinates for each maker using one image forming unit. In the tracking system and method using the same, lights emitted from each marker are passed through a lens array unit which includes at least a pair of lens, images of the markers corresponding to the number of the lenses of lens array units are formed on an image forming for each marker, and therefore, it is possible to calculate a spatial position and a direction of the markers attached on the target by using only one image forming unit through a trigonometry.

Abstract: A computer-based method includes receiving a video feed of a surgical procedure; identifying a current step of the surgical procedure using the video feed and an electronic surgical database; and determining an expected next step of the surgical procedure. A similarity of the expected next step with the actual next step of the surgical procedure may be determined, and an alert and/or surgical guidance may be provided based on the similarity (or lack of). A system for surgical-guidance is disclosed, the system having a storage unit with an electronic surgical database; a surgery image identification unit for analyzing a video feed to determine characteristic data; a mapping unit for matching a database record based on the characteristic data; an alignment unit for mapping matched database records with a stored surgical procedure; and a surgery prediction unit for determining a predicted next surgical step.

Abstract: The subject matter described herein includes methods, systems, and computer readable media for image guided ablation. One system for image guided ablation includes an ultrasound transducer for producing a real-time ultrasound image of a target volume and of surrounding tissue. The system further includes an ablation probe for ablating the target volume. The system further includes a display for displaying an image to guide positioning of the ablation probe during ablation of the target volume. The system further includes at least one tracker for tracking position and orientation of the ablation probe during the ablation of the target volume. The system further includes a rendering and display module for receiving a pre-ablation image of the target volume and for displaying a combined image on the display, where the combined image includes a motion tracked, rendered image of the ablation probe and an equally motion tracked real-time ultrasound image registered with the pre-ablation image.

Abstract: Devices, systems and methods for performing image guided interventional and surgical procedures, including various procedures to treat sinusitis and other disorders of the paranasal sinuses, ears, nose or throat.

Abstract: A surgical controlling system comprising: at least one location estimating means to real-time locate the 3D spatial position of at least one surgical tool; at least one movement detection means in communication with a movement database and with the location estimating means; and a controller, which controls the position of at least one surgical tool, in communication with a movement database, a control database and the movement detection means. The movement database stores the 3D spatial position of each surgical tool at the present time and at at least one previous time; a tool has moved if its present position is different from its previous position. The control database stores rules to identify a movement of a tool as either an ALLOWED movement or a RESTRICTED movement.

Abstract: Endoscopic surgical apparatuses and methods are described. An endoscopic apparatus comprises an elongate shaft, an inflatable element, an instrument base, and an imaging source. The elongate shaft comprises a steerable distal tip, locating feature(s) proximal of the steerable distal tip, inflation inlet(s) adjacent the locating feature(s), and a working channel. The inflatable element is slid over the elongate shaft to removably couple to the elongate shaft at the locating feature(s), thereby placing the inflatable element in fluid communication with the inflation inlet(s). The instrument base is coupled to a proximal end of the elongate shaft and can be coupled to a robotic system. The robotic system articulates the steerable distal tip through the instrument base to perform a procedure in an anatomical lumen. The robotic system can also advance and retract the endoscopic apparatus through the anatomical lumen. The imaging source is located at the steerable distal tip.

Abstract: Instrument device with an elongated, flexible shaft that is configured to both roll and articulate in a controllable manner. The claimed system and apparatus provides endoscopic rolling and articulating capabilities with minimal tradeoffs in control, allowing for greater ease of use and clinical efficacy.

Abstract: A robotic system including: a robot arm; a camera for capturing motion of the robot arm; an input mechanism for detecting user input; a display device; and a controller. The controller can operate in (i) a first mode configured to drive the display device to display a video stream captured by the camera in a first format and to drive the robot arm such that motion by the user in a first direction causes the robot arm to move a reference part in a second direction; and (ii) a second mode configured to drive the display device to display the video stream in a second format reflected with respect to the first format and to drive the robot arm such that motion by the user in the first direction causes the robot arm to move the reference part in a direction opposite to the second direction.

Abstract: A surgical instrument including an elongate shaft terminating in an end effector, the end effector including two pairs of opposable jaws, the pairs being spaced apart and independently operable to cause the jaws of that pair to grip or release an object located therebetween, wherein the jaws of each pair are movable to an open configuration in which the most distal point on each of those jaws is less distal than the mid-point of that pair of jaws when that pair of jaws is closed with its jaws in their most distally extended configuration.

Abstract: An electromechanical surgical device includes a motor system configured to drive drive-shafts and a steering cable arrangement. A control system may be provided for controlling the motor system. A remote control unit may also be provided for controlling the motor system via the control system. Optical or Hall-effect devices, may be provided for determining the position of the elements of the surgical instrument based on the detected rotation of the drive-shafts. A memory unit stores a plurality of operating programs or algorithms, each corresponding to a type of surgical instrument attachable to the electro-mechanical surgical device. The control system reads or selects from the plurality of operating programs or algorithms, the operating program or algorithm corresponding to the type of surgical instrument attached to the electromechanical surgical device.

Abstract: What is described is a minimally invasive surgical instrument comprising an elongate flexible body including a proximal portion and a distal portion, a plurality of conduits, and at least one tendon extending through the conduit lumen of at least one of the plurality of conduits from the proximal portion into the distal portion of the elongate flexible body. The elongate flexible body includes a central lumen and a flexible wall having a thickness extending from an inner surface to an outer surface. Each conduit includes a conduit lumen and extends through the wall of the elongate flexible body and terminates within the flexible wall of the elongate flexible body. Each conduit includes a distal end directly secured to the flexible wall. The at least one tendon is actuatable to steer the distal portion.

Abstract: A treatment device rotates a second rotation portion by operating an operation element. The second rotation portion switches between a first rotation position and a second rotation position. A direction of the end effector relative to the distal end of the sheath is changed in the first rotation position. A position of the end effector relative to the distal end of the sheath is maintained in the second rotation position.

Abstract: The present invention generally relates to a medical device including a movable instrument (MI) which is activated only when its movement is within an optimal range of acceleration. More particularly the invention relates to a fetal heart rate monitor (FHRM) having a movable Doppler transducer which transceives ultrasound energy only when found within a certain optimal range of acceleration.

Abstract: The invention relates to a surgical lamp (1) that can be controlled without contact, comprising a control unit and a sensor unit, wherein the control unit is designed to control the surgical lamp (1), wherein the sensor unit is designed to detect a motion of an action element and to convert said motion of the action element into motion data, wherein the control unit is designed to read out the motion data generated by the sensor unit and to control the surgical lamp (1) in dependence on the motion data. The sensor unit is designed in such a way that the sensor unit ensures the detection of the motion of the action element in three dimensions in a measurement space (3), which is arranged below the surgical lamp in an emission direction.

Abstract: The invention relates to a retaining device for an instrument, comprising at least one joint having at least two parts that can be moved relative to each other and at least one drive unit associated with the joint. The drive unit is designed to move the joint by driving at least one of the parts of the joint that can be moved relative to each other. The retaining device also comprises a securing device, which has a locking mechanism associated with the joint and a release unit that can be activated, wherein the locking mechanism interacts with the release unit in such a way that the locking mechanism holds the joint in a locked position as long as the release unit is not activated. The securing device is designed to permit a motion of the joint out of the particular locked position within a specified range of motion even if the release unit is not activated. The invention further relates to a corresponding securing device for a retaining device and to an operating method for said securing device.

Abstract: An all-in-one cleaner is disclosed. An all-in-one cleaner, according to an embodiment of the present invention, comprises: a cleaner body; a soaking unit which is provided on one side of the cleaner body and carries out a soaking step on a subject to be cleaned; a washing unit which is provided near the soaking unit and carries out a washing step on the subject to be cleaned, for which the soaking step has been completed; and a rinsing unit which is provided near the washing unit and carries out a rinsing step on the subject to be cleaned, for which the washing step has been completed.

Abstract: Devices and methods for dispensing material from a dental handpiece. In one example, the method includes receiving an input that indicates that an amount of the material is to be dispensed from the container of the dental handpiece. The method also includes rotating an electric motor to rotate an imbalanced mass to vibrate a vibration transmission element that vibrates the material in the container. The method also includes dispensing the amount of the material from the container with a piston based on the input.

Abstract: Assembly comprising a component and a one-piece axial limit stop device (1) intended to be placed in a bore of said component in order to retain an element therein, comprising an annular ring (2) with symmetry of revolution about a central axis (I-I), and comprising at least one angular portion (3, 4) rigidly connected to the annular ring (2), developing in an arc between a first end (3a, 4a), joined to the distal end (2b) of the annular ring (2), and a second, free end (3b, 4b). The angular portion (3, 4) is in part movable from its first end (3a, 4a), in a transverse plane perpendicular to the central axis (I-I), between a retracted position and at least one protruding position, being elastically returned permanently to the protruding position. In the retracted position, the angular portion (3, 4) is included within the volume of a cylinder continuing the outer cylindrical surface of the annular ring (2).

Abstract: A device for helping maintain a mouth of a patient in an open position during a dental procedure may include a novel suction device that preferentially aspirates fluids and not the tissues of the mouth.

Abstract: A cartridge and a piston for storing and dispensing a two-component dental material. The cartridge and the piston have a cross-section which substantially correspond to a D-shape in which the perimeter of the D-shape is defined by a plurality of circle segments only. At least two of the circle segments are based on different radii. The invention helps maximizing the time period over which a dental material can be stored in the compartment.

Abstract: Provided herein is a retraction device for retracting soft tissue from the dental surfaces in the oral cavity of a patient. The retraction device is comprised of a topology conformable structure, where the topology conformable structure is adaptable to be delivered to the oral cavity in a constrained shape. The device can then undergo a conformation change in the oral cavity, where the device transforms into its unconstrained shape. The unconstrained shape of the device creates a useable working field in the oral cavity. The useable working field can provide increased accessibility to and/or visibility within the oral cavity. Also provided herein are methods for using the device and kits.

Abstract: A method for virtual orthodontic treatment is provided in which a virtual set of orthodontic components is associated, in a virtual space, with a first virtual three-dimensional image of teeth, and then by a set of rules which define the effect of the set of components' teeth, the effect of the virtual treatment can be computed. This virtual treatment can be used to predict the results of a real-life orthodontic treatment as to design such a treatment.

Abstract: An apparatus for removing a dental appliance can include a body having a perimeter and a pry lip extending from the perimeter of the body. The pry lip includes a terminal ridge surface and an inclined surface disposed between the terminal ridge surface and the perimeter of the body. The apparatus for removing a dental appliance can be incorporated in a dental system which includes a dental appliance and the apparatus for removing a dental appliance. The apparatus for removing a dental appliance can be configured such that it fits within an area defined by an outer edge of the dental appliance. Thus, the dental appliance and the apparatus for removing the dental appliance can be stored within a dental appliance container with an internal cavity that closely conforms to the shape and size of the dental appliance.

Abstract: An orthodontic distractor includes two rods connected to rotatable head members. The two rods are couplable to one or more of upper teeth or palatal bones of a patient. The rotatable head members have threaded holes and pairs of the rotatable head members have opposite hand threads. The screw system also includes two twin screws that have threaded ends of opposite hand threads. Each of the two twin screws is engaged to threads of a pair of the rotatable head members. Rotation of one of the twin screws causes the pair of rotatable head members and the ends of the rods to either move together or move apart. The two twin screws are independently rotatable to cause independent expansion or contraction of different portions of the screw system.

Abstract: An orthodontic screw system includes two rods connected to rotatable head members. The two rods are couplable to one or more of lower teeth or mandibular bones of a patient. The rotatable head members have threaded holes and pairs of the rotatable head members have opposite hand threads. The screw system also includes two twin screws that have threaded ends of opposite hand threads. Each of the two twin screws is engaged to threads of a pair of the rotatable head members. Rotation of one of the twin screws causes the pair of rotatable head members and the ends of the rods to either move together or move apart. The two twin screws are independently rotatable to cause independent expansion or contraction of different portions of the screw system.