Abstract: A pedicle hook for use in treatment of the spine has a bifurcated blade in which one of the legs formed by the bifurcation is longer than the other.

Abstract: A bone rasp for preparing the medullary canal of the femur includes a rasp blade portion shaped and tapered so as to conform to the medullary canal and a handle portion which is designed to be manually attached to the rasp blade and detached from the rasp blade for sterilizing and storing. The handle portion is arranged into two components which are pivotally connected and pinned together. The stationary portion of the handle attaches directly to the rasp blade and the movable or adjustable portion is pinned to the stationary portion at a pivoting location and secured in a selected orientation by a second pin. A series of seven oblong slots are disposed in the stationary portion and arranged on 71/2.degree. intervals so as to give the adjustable portion of the handle an approximate 45.degree. range of adjustment.

Abstract: The method and material of this invention eliminates the necessity of removing imbedded particles remaining after shot blasting by providing a method for surface finishing an orthopaedic implant wherein the blasting medium is bioactive. The surface finishing with bioactive material may also be used to clean the porous surface after sintering or diffusion bonding. Since the particles are made from bioactive material, it is not a concern if particles remain in the porous surface after blasting.

Abstract: The acetabular cup positioner of this invention provides for a sighting guide which is removable connected to the shaft of the cup positioner by a tapered locking configuration. The taper lock provides for a secure connection of the sighting guide to the shaft of the cup positioner which enhances the accuracy of the device. The taper lock provides such a strong lock that in order to provide for its removal, the cup positioner of the invention includes a slaphammer carrier on the shaft of the guide which may be employed by the surgeon to remove the guide from the positioner without undue effort.

Abstract: A cannulated bioabsorbable tack has annular ribs configured to enhance fixation to tissue, such as bone, and is particularly effective for attaching soft tissue to bone, such as ligaments or muscles in the shoulder. Apparatus and method for displaying the tack facilitate arthroscopic surgical procedures for attaching or joining tissue.

Abstract: A one piece item of stainless steel or other material suitable for permanent placement in the human body, forms the eye and shaft of an eyebolt by a combination of two shell-like portions, each having threaded bosses at distal ends thereof. The distal ends are placed around a spinal rod simultaneously with insertion of one of the shell-like portions through the yoke of a spinal column connecting hook device. Then the bosses are brought toward each other and the two bosses combine to form a bolt on which a nut is received and advanced along the threads. As this is done, it forms the eye of the eyebolt and it is brought into cooperation with the hook device to clamp tightly on a spinal rod with which the eyebolt is used. The two threaded bosses have interfitting, and thus mating, rib and groove to establish and maintain alignment of the threads of the two bosses to facilitate reception of the nut on the bosses.

Abstract: An arthroscopic method for debulking tissue and a kit of arthroscopic tools for performing the steps of the method. A protruding piece of tissue that is bearing against a nerve is undermined by the formation of a cavity beneath it, and the cavity is collapsed by heat generated by a laser. When the cavity collapses, the protruding tissue falls into it and separates from the nerve. The kit includes plural dilator tubes that are used to progressively dilate the arthroscopic incision and plural cutter tubes that are used in sequence to cut larger and larger pieces of tissue. Plural forceps are employed to remove the cut tissue to form the cavity, and impactor members in the kit are used to compact the bone that surrounds the cavity just before the laser is introduced into the cavity to collapse it.

Abstract: A system and method for positioning a tool relative to a patient's bone to facilitate the performance of a surgical bone alteration task. The system comprises a bone immobilization device for supporting the bone in a fixed position with respect to the reference structure, and a robot that includes a base fixed in position with respect to the reference structure. The robot also includes a mounting member, and a manipulator connected between the base and the mounting member and permitting relative movement therebetween. The tool to be positioned by the system is mounted to the mounting member. The mounting member is caused to move relative to the reference structure in response to movement commands, so that the tool can be moved to a desired task position to facilitate performance of the task. The system preferably also includes a template attachable to the mounting member, a feature of the template representing a portion of a task.

Abstract: A plurality of arms are successively connected to a fixed arm so that the free end of the connected arms is movable three-dimensionally, a direct-access endoscope is attached to the three-dimensionally movable free end of the arms, and angle sensors are provided in the individual arm joints. Changes in angles between the individual arms due to the movement of the front end of the direct-access endoscope are sensed by the angle sensors, and the size and position of the object are numerically determined according to the changes.

Abstract: A reduction frame according to the present invention is secured to shaft handles extending from the pedicle screws of a Vermont Spinal Fixator type implant. Shaft clamps secure two T-handles of the reduction frame to the shaft handles. A lower-rod assembly joins the two opposite T-frames by means of lower-rod clamps. The shaft clamps are provided with four degrees of freedom. The joint between the lower-rod assembly and T-handle is provided with five degrees of freedom. The lower-rod assembly and the T-handle are provided with power screw threads to allow for precise translational control. The shaft clamps and lower-rod clamps are provided with taper fit joints to allow for infinite rotational adjustment and fixture. An upper-rod assembly is also provided on the T-handles to produce rotation of the T-handles by providing means for changing the distance between the upper ends of the T-handles.

Abstract: A method of performing knee surgery and retractors and a femoral distractor for use in performing such method are provided, said retractors including a PCL tibial retractor, lateral patellar retractor, collateral ligament retractor, posterior cruciate ligament retractor and unicompartmental retractor designed to cooperate with one another in performing such method.

Abstract: A fixation device for securing a prosthetic ligament to a bone and which comprises a bone staple having a head portion by means of which the staple can be driven into the bone, and a pair of legs extending from the head and having ends engageable into the bone, characterized by a stirrup for guiding the driving movement of the staple and arranged also to cooperate with the staple in order to enable the prosthetic ligament to engage the staple and the stirrup and to be securable to the bone upon completion of driving of the staple into the bone, the stirrup comprising two generally parallel side portions which define guides to receive the legs of the staple and to guide the driving movement of the legs, and also defining an aperture through which the ligament can be taken prior to securement of the ligament to the bone.

Abstract: An osteosynthetic force transmitting and positioning apparatus has two force transmitting members one of which is slidably telescoped into the other and each of which or at least one of which is connected or is connectable to one or more connecting components for bone screws, bone pins and/or other types of fasteners which secure the connectors to discrete bones, to fragments of bones or to osteosynthetic plates. The connections between the force transmitting members and the connecting components are such that the orientation of the fasteners can be altered in the direction of any one of three axes which are disposed at right angles to each other. Such connections can include fulcra, hinges, pivots, pin-and-hole couplings or others.

Abstract: A method and apparatus for internal fixation of fractures, which method includes the steps of initially aligning the fractured bone and bone segments, drilling pilot holes in the bone and bone segments to receive non-metallic screws and/or pins, inserting the non-metallic screws and/or pins in the drilled pilot holes to temporarily maintain alignment of the bone and bone fragments, applying one or more metal reconstruction plates to the bone and bone fragments, drilling additional pilot holes in the bone and bone fragments to receive metal screws and/or pins and inserting the metal screws and/or pins through the holes in the metal reconstruction plate into the pilot holes in the bone and bone fragments without regard to the location of the non-metallic pins and/or screws, to permanently fix the bone fragments and bone in correct anatomical configuration.

Abstract: A system is disclosed for measuring dynamically forces applied to a prosthetic joint. The system comprises a first support member attached to an outer surface of a first bone, a second support member attached to an outer surface of a second bone and a transducer secured to the second support member and engaging the first support member. The transducer measures forces applied to the first and second support member as the prosthetic joint is articulated and provides a representative force output signal. In the preferred embodiment, the transducer comprises a central body having plurality of integrally formed flexure members, each flexure member defined by a corresponding cavity in the body and defining a force responsive flexure section. A plate is secured to the transducer with support posts to localize forces onto the flexure members. Although the assembly forms components for implementation of a knee prosthetic, the present invention can be adapted to any particular joint of the body.

Abstract: A locking surgical tool handle system. The invention includes a surgical tool handle that has an elongated body portion with a pistol-type grip. The front end of the handle body has a tool retaining structure comprising a contoured engagement face and a movable tension bar with an engagement end. Projections on the engagement end of the tension bar fit within a receiving channel of a surgical tool, such as a broach or rasp. A locking mechanism is provided within the handle body, and is implemented with pivotable links attached to the tension bar. The locking mechanism has an unlocked position in which the engagement end of the tension bar is spaced away from the engagement face of the handle body, and an over-center locked position in which the engagement end of the tension bar is retracted toward the handle body. When the tool handle is placed in its locked position, the engagement end of the tension bar pulls an attached tool into tight contact with the engagement face of the handle body.

Abstract: An orthopaedic device is disclosed for mechanical intercoupling between selected vertebrae of the human spine and an elongated surgical rod. The device includes a block-shaped member having upper and lower surfaces, front and rear surfaces, and left and right side surfaces. A central cylindrical bore extends through the block-shaped member between the upper and lower surfaces. A longitudinal slot extends between the upper and lower surfaces, and from the front and one side surface of the block member into the central bore. The central bore and longitudinal slot serve as a yoke into which a section of the surgical rod may be placed, the width of the slot being slightly larger than the diameter of the rod. A short, hollow, cylindrical sleeve member, with internal diameter slightly larger than the diameter of the rod, is adapted for slidable movement over the rod and into the central bore of the block-shaped member to provide capture of the surgical rod.

Abstract: The bone saw guide of this invention allows precise perpendicular or angular cutting of a bone with a conventional bone saw. An inverted U-shaped blade guide portion positions the blade and an upstanding saw guide portion guides the neck of the saw. A plate connects the two portions. The invention allows a bone segment to be removed and the cut ends to be compressed together to shorten the bone.

Abstract: Surgical apparatus in which a locking device is provided for releasably securing a surgical tool in a sleeve. A lock housing is movable on the sleeve, the lock housing having a through opening through which the tool is insertable to be received into the sleeve. A lock member on said lock housing has a push button actuable for opening the lock housing to reception of the tool through the through opening and into the sleeve. The lock member has means for automatically locking the tool against removal from said lock housing upon release of the push button. A tapered part on the sleeve receives a correspondingly tapered portion of the tool to thereby assure a snug fitting connection of said sleeve with the tool.

Abstract: Ultrasonic blade coupler comprising a blade element composed of a material selected from aluminum and titanium rendered sharpenable by a surface hardening treatment. The blade coupler exhibits improved acoustical properties with reduced energy consumption.

Abstract: A system and method for positioning a tool relative to a patient's bone to facilitate the performance of a surgical bone alteration task. The system comprises a bone immobilization device for supporting the bone in a fixed position with respect to a reference structure, and a robot that includes a base fixed in position with respect to the reference structure. The robot also includes a mounting member, and a manipulator connected between the base and the mounting member and permitting relative movement therebetween. The tool to be positioned by the system is mounted to the mounting member. The mounting member is caused to move relative to the reference structure in response to movement commands, so that the tool can be moved to a desired task position to facilitate performance of the task. The system preferably also includes a template attachable to the mounting member, a feature of the template representing a portion of a task.

Abstract: Disclosed herein is a surgical template including a base having a plurality of openings, including first and second slots. The template further includes a plurality of guides for guiding placement pins. The guides include first and second primary guides which are slidably and removably connected to the base through the first and second slots, respectively. The base further includes a secondary guide removably connected to the base. Each of the primary and secondary guides sized and shaped to cause the placement pins to be parallel to one another when inserted into the guides.

Abstract: A device for use in open reduction of a bone fracture includes a first member for affixing to a first portion of a fractured bone; a second member for affixing to a second portion of the fractured bone separated from the first portion thereof as a result of the fracture; and a retaining element for retaining the first and second elements in a predetermined spaced relation such that the first and second portions of the fractured bone are thereby held together in their normal anatomical positions, the retaining element including a clamping device for clamping to at least one of the first and second elements for retaining the same in the predetermined spaced relation.

Abstract: Apparatus for making a precise cut in a bone comprising a cutting block having at least one saw-guiding slot therein. A screw is carried by the block and is adapted to secure the block to the bone so that the block is held in compression against the bone.

Abstract: An orthopaedic device is disclosed for secure mechanical coupling to an elongated surgical rod. The device consists of a T-shaped member having a short, hollow, cylindrical sleeve portion and a threaded rod portion extending perpendicularly midway between the ends of the hollow sleeve portion. The hollow sleeve portion is adapted for slidable positioning over the cylindrical surface of the surgical rod. A narrow slot is provided through the center of the threaded rod portion, bisecting this rod portion, and through the wall of the hollow sleeve portion. The device further includes a block-shaped member having a central cylindrical bore extending between upper and lower surface and at least one U-shaped cutout extending from the middle of one side through the block into the central bore. A longitudinal slot extends between the upper and lower surfaces and from the front surface through the block into the central bore.

Abstract: An improved orthopedic pin for an external fixator has an enlarged diameter axial region wherein its diameter selected to be larger than a diameter of an osteal bore through which the pin is adapted to be disposed. A frustoconical section is adjacent each side of the enlarged region to form a bevelled surface on each side thereof which is at an angle sufficient to minimize insertion into the osteal bore while simultaneously reducing trauma to the soft tissue during insertion and removal of the pin.

Abstract: An implantable fixing device for extraoral applications includes a basic structure implantable in the bone and having either a thread-pressing or a thread-cutting helix, and an implant post being connectible to the basic structure by being inserted in an axial bore therein.

Abstract: Modular surgical instrumentation and a method of using same is provided, according to the invention. The instrumentation comprises a first bracket defining a generally U-shaped structure having an internal surface adapted to be seated on the distal aspect of a resected femur bone and an elongated central opening appointed to expose a selected area of the resected femur, including a curved track for guiding a first shaping tool along a predetermined path for controlled shaping of a curved patellar groove in a portion of the selected area exposed through the opening. A second bracket defines a linear slotted bore extending generally parallel to the long axis of the femur for guiding a second shaping tool to form a relatively deep recess accommodating an intercondylar stabilizing housing of a knee implant.

Abstract: A rasp tool including a handle member, a cutter member, and a releasable locking mechanism for selectively coupling the handle and cutter members. The locking mechanism includes a locking post on the cutter member and a corresponding post-receiving bore in the handle member. A spring-biased locking key is disposed within a guide bore that intersects the post-receiving bore such that the locking key extends partially into the post-receiving bore. As the locking post is axially introduced into the post-receiving bore, the locking post contacts the locking key and causes it to retract until the locking post is fully received within the bore, at which point the spring-biased locking key engages a transverse notch in the locking post, thereby preventing axial removal of the post from the bore. The locking key is disengaged from the locking post by a manually-actuable trigger coupled to the locking key.

Abstract: A robotic surgical system (10) includes a multiple degree of freedom manipulator arm (14) having a surgical tool (22). The arm is coupled to a controller (24) for controllably positioning the surgical tool within a three dimensional coordinate system. The system further includes a safety monitoring processor (38) for determining the position of the surgical tool in the three dimensional coordinate system relative to a volumetric model. The volumetric model may be represented as a constructive solid geometry (CSG) tree data structure. The system further includes an optical tracking camera system (28, 32) disposed for imaging a region of space that includes at least a portion of the manipulator arm. An output of the camera system is coupled to the processor (38) that processes the volumetric model for determining if the surgical tool is positioned outside of the volumetric model.

Abstract: A fracture reducing apparatus for achieving and maintaining fracture reduction having three side arms which are threadedly connected to two main arms. A knob pivotally connects the two main arms and maintains their relative position with respect to one another. The side arms of the apparatus distribute the surgeon's manipulating force to three points along the surface of the fractured limb and when the reduction is achieved, the knob is tightened to maintain the reduction, thus freeing surgeon's hands to apply the fixation, or to completely move out of the field of x-ray exposure.

Abstract: An external fixation pin entry site dressing, and the method of its application, in which an elongate body of soft, tearable, and compressible absorbent material has a longitudinal primary slit extending inwardly from one side of the body to about the longitudinal midline thereof and a plurality of pairs of transverse slits extending inwardly from opposite sides of the body and partially dividing the body into a multiplicity of separable segments.

Abstract: A system and related method for ankle arthroscopy distraction includes both non-invasive external and invasive skeletal distractors which may be individually applied in a serial manner to provide ever increasing distraction forces as may be dictated by the required arthroscopic procedure. The angle of the distracted ankle may be selectively varied at anytime during any of the non-invasive or invasive distraction techniques without the need to halt the procedure, thereby obviating the need to reprep or to reposition or redrape the patient. The non-invasive distractor is of relatively simple and compact construction and is easily repositionable with changes in the angle of the ankle to allow ready and complete access for all surgical procedures.

Abstract: A fixation screw for securing a bone graft of a tendon section in place in a ligament tunnel is formed from a biocompatible plastic or bioabsorbable material. The tendon section is used to replace a ligament and has a tendon section attached at each end to bone grafts. The fixation screw is tightened between the bone graft and bone surrounding the ligament tunnel to secure the bone graft in place by forcing it against the bone surrounding the ligament tunnel. The material is soft compared to bone so that threads of the fixation screw do not cut into the bone graft or bone graft or bone surrounding the ligament tunnel when the fixation screw is tightened. The fixation screw is formed to have integral instrumentation. A body is molded or fabricated as one piece from the material and has a threaded end, formed as an interference screw, and relatively thicker handle portion connected to each other. The handle portion forms the integral instrument in that it is grasped to turn the fixation screw to tighten it.

Abstract: Power assisted gripping structure and method comprising a surgeon's rongeur including two elongated relatively axially moveable members having at one end thereof structure for gripping, cutting or crushing material, handle means for manually moving the elongated members axially relative to each other, electrically actuated power assist cylinder structure connected between the elongated members for assisting in producing relative movement between the elongated members on actuation thereof and switch structure for actuating the power cylinders in multiple stages. In different modifications, the structure for gripping, cutting or crushing material may be a Kerrison or Leksell rongeur tip. Alternatively, the structure for gripping, cutting or crushing may be adjustable wrench, spreader, prier suction cup or lifter structure and the power assisted gripping structure may be used in industry such as in robotics as well as in medical applications.

Abstract: An improved four-legged distractor with multiplanar adjustability facilitates intervertebral bone grafting. The legs are slidably fixed to a rectangular frame so that the space between opposing legs and the space between adjacent legs may be varied. The bottom portion of each leg is offset so that a large space is created between the top portion of the legs to permit easy access to the operating space.

Abstract: A surface treatment process for stainless steel orthopedic implant devices and an orthopedic implant device surface treated in accordance with the disclosed process are disclosed. A rough ground or machined stainless steel part is shot blasted with stainless steel shot. The device is then shot blasted with glass beads having a nominal size of between one-tenth and one-half that of the stainless steel shot. Electropolishing and passivation follow the shot blasting steps. A part thus treated includes a heavily cold-worked outer layer that enhances the fatigue properties of the stainless steel orthopedic implant device.

Abstract: Apparatus particularly suited for implantation and/or extraction of osteal prostheses, comprising an ultrasonic power generator, regulator means for regulating the ultrasonic power generator in accordance with a predetermined algorithm, at least one transducer connected to the output line for converting said electrical energy to a linear mechanical motion, an acoustic transformer for increasing or decreasing peak-to-peak motion of the transducer and means for connecting the acoustic transformer to a surgical tool or a prosthetic device. The system suitably comprises a pair of transducers, one operating at each of 20 KHz and 40 KHz frequencies. Novel adapters for the four major types of osteal prosthesis are also provided.

Abstract: The bone saw guide of this invention allows precise perpendicular or angular cutting of a bone with a conventional bone saw. An inverted U-shaped blade guide portion positions the blade and an upstanding saw guide portion guides the neck of the saw. A plate connects the two portions. The invention allows a bone segment to be removed and the cut ends to be compressed together to shorten the bone.

Abstract: The present invention relates to instruments for preparing a glenoid surface of a scapula to receive a prosthetic glenoid component to replace the natural socket of a shoulder. More particularly, the present invention relates to a drill guide assembly for aligning and guiding a drill bit to form holes in the glenoid surface at predetermined locations to secure the glenoid component to the glenoid surface. A reamer assembly including a ratchet drive mechanism is also included to facilitate preparation of the glenoid surface prior to installation of the glenoid component.

Abstract: A prosthesis holding system is provided for holding and positioning a prosthetic cup during surgery. The rim of the cup includes opposed inwardly and outwardly facing recesses. A holder includes an elongated rod having a shoe at one end. The shoe includes a tab for engaging the inwardly facing recess in the rim of the cup. The shoe further includes a threaded aperture alignable with the outwardly facing recess in the rim of the cup. A clamping screw is engageable with the threaded aperture and is further engageable with the outwardly facing recess in the rim of the cup. Tightening of the clamping screw securely holds the cup without interfering with either the interior concave surface of the cup or the exterior convex surface of the cup, to enable efficient implantation of the cup in a patient during surgery.

Abstract: A surgical retractor is disclosed for use when surgery is performed adjacent a bone and remains in place for an appropriate duration without requiring manual assistance. A barrier member includes a plurality of cannulated fixation posts for its temporary placement on, and attached to, the bone and a soft tissue engaging surface which extends transverse of a surface of the bone. Guides, including the cannulated fixation posts, slidably receive mounting pins which supplement the fixation posts for temporarily attaching the barrier member to the bone. The barrier member is also provided with bottom and top flanges which extend transversely of the soft tissue engaging surface and cooperate therewith to prevent entry of the soft tissue into an adjacent surgical site.

Abstract: In an external fixation device for osteosynthesis, pins inserted into a bone are joined to a support rod by a clamp which leaves the end of the pin free to move in an arcuate direction under load, thus avoiding angulation of the pin in the bone and the resulting stress on the bone.

Abstract: This invention relates to a new prosthetic ligament and a set of surgical instruments for use in the surgical replacement of a ligament and in particular for inserting a prosthetic ligament into the body.The ligament in accordance with the invention comprises an elongate foraminous flexible strip, having at one end a pouch portion capable of receiving a bone plug and including an opening through which the bone plug may be inserted into the end portion, the pouch portion also including a closure or the like to prevent escape of the bone plug in a direction away from the center of the ligament.The set of surgical instruments includes a new bone plug extractor which is adapted to sever the base of the bone plug from a host bone to allow complete separation of the bone plug.

Abstract: A device for gauging the size of a bone socket comprising a hemispherical member having a pole on its axis at the distal end and having a bore on its axis at its proximal end; a handle releasably attached to the bore of the hemispherical member; and a pressure responsive surface on the hemispherical member to constitute a pressure responsive surface for changing characteristics when brought in contact with a bone socket to be gauged. The change in characteristics may be in color or shape. Also disclosed is the method for using the device.

Abstract: A system and method for positioning a tool relative to a patient's bone to facilitate the performance of a surgical bone alteration task. The system comprises a bone immobilization device for supporting the bone in a fixed position with respect to a reference structure, and a robot that includes a base fixed in position with respect to the reference structure. The robot also includes a mounting member, and a manipulator connected between the base and the mounting member and permitting relative movement therebetween. The tool to be positioned by the system is mounted to the mounting member. The mounting member is caused to move relative to the reference structure in response to movement commands, so that the tool can be moved to a desired task position to facilitate performance of the task. The system preferably also includes a template attachable to the mounting member, a feature of the template representing a portion of a task.

Abstract: A surgical instrument to aid in maneuvering a slideable member along a rod or other base member. The instrument has a distal tip which straddles the slideable member to provide for longitudinal movement of the slideable member in either longitudinal direction. The instrument also allows downward force to be applied to the slideable member. The instrument also may be used to assist in introducing the slideable member into an opening of another device.

Abstract: A pliers-like clamping device having offset bone gripping plates temporarily grips and clamps together two bone segments above and below as diagonal cut at an osteotomy site. The device includes a pair of handle members having distal ends which are turned at substantially right angles to the handle arms and parallel to each other and offset both vertically and horizontally from each other. The distal ends form bone-gripping plates which may be serrated or ribbed on their inwardly facing surfaces. A ratcheting mechanism is provided near the proximal end of the device so that the clamping force may be set and maintained at a desired level.

Abstract: A bone compression and distraction device for compressing and distracting the ends of a bone and affixing a splint plate thereacross. The device comprises a pair of blocks interconnected by an adjustment assembly. The blocks are each seated on the ends of the splint plate and connected to the respective ends of the bone by a long bone screw positioned through a transverse hole in the block and through aligned holes in the splint plate. One of the holes in the splint plate is slotted to allow the compression or distraction of the bone ends whereupon short bone screws are positioned through other holes in the splint plate into the bone ends allowing the blocks to be removed and its screws replaced by short bone screws positioned through the same holes in the plate and into the bone ends.

Abstract: Any external fixture for bone synthesis is provided with at least one bridge member, a plurality of holders are orientable and screw clampable on this bridge member by clamping surfaces. The holders have cylindrical holder openings which are closable by an operating screw and thereby serve as clamp holders, each for one bone nail and/or one bone screw.The cylindrical holder openings are bounded by a one piece connected wall surface and are closable individual or jointly with adjacent holder clamp jaw surfaces on the clamp side, on tightening the operating screw. Thus the cylindrical holder openings are each elastically or plastically deformable by a drill and/or screw guide receiving a bone drill with play, from a layer width - down to a smaller width for clamping.The external fixture affords a simple structure, easy to manufacture and at the same time simple handling during operation.