Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
  • A61B17/16—Bone cutting, breaking or removal means other than saws, e.g. Osteoclasts; Drills or chisels for bones; Trepans
  • A61B17/17—Guides or aligning means for drills, mills, pins or wires
  • A61B17/1725—Guides or aligning means for drills, mills, pins or wires for applying transverse screws or pins through intramedullary nails or pins
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
  • A61B17/16—Bone cutting, breaking or removal means other than saws, e.g. Osteoclasts; Drills or chisels for bones; Trepans
  • A61B17/17—Guides or aligning means for drills, mills, pins or wires
  • A61B17/1707—Guides or aligning means for drills, mills, pins or wires using electromagnetic effects, e.g. with magnet and external sensors
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
  • A61B2017/00017—Electrical control of surgical instruments
  • A61B2017/00022—Sensing or detecting at the treatment site
  • A61B2017/00039—Electric or electromagnetic phenomena other than conductivity, e.g. capacity, inductivity, Hall effect

Definitions

• TECHNICAL FIELD Many different techniques are employed in current o ⁇ hopaedic and traumatologic practice according to the bone segment involved and to special surgical indications.
• intramedullary metallic means static, dynamic or mixed (Grosse empf, Kuntscher, A O . etc.). control segmental rotation and mantain the desired limb length.
• the great advantage of intramedullary fixation is demonstrated by the simple technique, by the reducet extension of the skin incision for the nail insertion and by the prevention of fracture site opening. Nevertheless such procedure requires repeated x-ray controls, or image intensifier shots, with exposure of the patient and the O.R. personnel to ionizing radiations.
• the recognition ofthe hole ofthe intramedullary nail and the subsequent aiming of a screw is possible by a simple and harmless device which uses an electromagnetic probe that localizes metallic means and reveals the holes with on-off mechanism 8
• the probe is made by an inductive sensor of proximity which an internal high frequency oscillator that produces an elecromagnetic field in the immediate vicinity ofthe sensor.
• the presence of a metallic object (actioner) in the action field of the sensor reduces the wideness of the oscillation since part of the electromagnetic energy is transferred from the sensor to the actioner on which dissipates for the
• the probe consists of a head (site of the electromagnetic device) and a handle which is guided by the operator sliding along the limb where a nail is present.
• the overall length is 15-20 cm.
• the head has a circular configuration and delimits a central hole; while sliding along the limb indicates the presence of the metallic object; at the level ofthe nail hole the signal fades till a complete interruption once fl the probe hole overlaps the nail hole.
• the skin point where the probe hole lies is the exact point where the incision may be made to drive correctly the interlocking screw.
• an electromagnetic probe with a sensor (sensor of Hall) which reveals the electromagnetic field produced by a small magnet.
• This small i ⁇ magnet is inse ⁇ ed in the hole of the nail inside a small pull-out screw (of metal or teflon).
• the probe contains a stabilized feeder, an hall -effect sensor, a differential amplifier, a Schmitt trigger, a low power transistor with open collector. In resting condition the base of the final transistor is not polarized therefore that transitor does not conduct.
• a magneto-resistive sensor made of special "bridge” resistances with a component sensitive to variations of the magnetic field which crosses them, in order to change the inner conductivity according to such 6 field. Having a bridge connection and feeding them with a continous tension on two opposite sides the bridge, one can obtain a variation ofthe differential tension on the other two sides proportional to the variation of the crossed magnetic field.
• the magnet which stimulates probe is characterized by a tiny cylindrical magnet of few millimeters, able to produce a magnetic field axial to the intramedullary nail 47 hole. It is inserted in the heas of a screw or a rod (metallic, teflon, PVC or other material) which temporality plugs the nail hole.
• a fourth possibility is represented by the electromagnetic signal produced by 2 l ⁇ microelectromagnets fixed to the rod which is introduced along the intramedullary nail: a high frequency signal, betwenn 20 Khz and 1 Mhz, is produced alternatively by the two microelectromagnets and is recorded by the probe on the skin.
• the probe is made of 4 magneto-resistive sensor in crossed position for a more precise and straightforward research in the north, south, west and east directions A
• the probe is contained in a small sterilisable cyiider with the shape of a pen, a few millimeters of diameter, and allows the longitudinal gliding along the limb which hosts the nail. It is introduced in a specific guide which, once the hole has been localized, allow the extracion ofthe probe and
• the screw containing the small magnet that plugs the nail hole will then be extracted with a screwdriver, the whole rod containing the magnet will be directly pulled out or a metallic rod will be used to catch the magnet.
• Electromagnetic probe for the recognition of metallic bodies and the discrimination of their holes durin special internal fixation techniques
• Orthopaedics 3 Fig. 3.
• Intramedullary metallic means in long bone fractures The coil emitts an electromagnetic field with the main magnetic axis corresponding to the hole axis. Blocking system ofthe rod aa ig 7 in long bone fractures the use of intramedullary metallic means.
• the head has a circular configuration and delimits a central hole.
• the 4 (8) magnetic sensor have their sensitive surfaces a plane at 90° to the tube axis.
• the guide-tube allows the way through ofthe drill for the bone hole without losing the co ⁇ ect adjustment against the cortical bone, thanks to the special conformation ofthe head.
• a current generator at 20 Khz sinusoidal frequency, with a rough 200 mA RMS intensity, is alternatively connected to 2 emitting coils in a mettalic or teflon rod (with preprinted circuit) in the medullary nail.
• the coil emitts an electromagnetic field with the main magnetic axis co ⁇ esponding to the hole axis.
• the detecting probe is formed by a teflon handle which supports an holed cylinder, containing 4 coils, each on a magnetic iron "semiolla", with the open side looking toward the head of the probe.
• the metallic guide-tube is inserted in the cylinder hole with the faceted and pointed extremity for the adjustment against the cortical bone.
• the 4 magnetic iron sensor have their sensitive surfaces on a plane at 90° to the tube axis, with at the final phase of the research coincides whith the one of the searched magnetic field.
• the positions on the plane are simmetric and equidistant (crosswise).
• the signals induced by the field itself are equidistant
• Such signal are conditioned, filtered and amplified in tension and cu ⁇ ent by a superficially mounted circuit inserted into the probe handle.
• the 4 amplified signal are transmitted by the connection cable to the instrumend containig the generator where they are received, refiltered and reamplified. Each signal is then revealed in
• the signal in continuos cu ⁇ ent, with a tension equivalent to the wideness of the conesponding in alternating cu ⁇ ent, are measured by a microcomputer containig a digital analogic converter.
• the guide-tube allows the way through ofthe drill for the bone hole without losing the co ⁇ ect adjustment against the cortical bone, thanks to the special conformation ofthe head.
• a metallic sheath, removable from the guide-tube, allows the insertion ofthe scew (wose head has a wider diameter than the body) without removing the handle ofthe probe from its leaning point against the cortical bone (co ⁇ esponding

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• 1995
  • 1995-10-13 IT ITBO950144 patent/ITBO950144U1/it unknown
• 1996
  • 1996-09-24 WO PCT/IT1996/000179 patent/WO1997013467A1/en not_active Application Discontinuation
  • 1996-09-24 EP EP96931968A patent/EP0957783A1/de not_active Withdrawn
  • 1996-09-24 AU AU70788/96A patent/AU7078896A/en not_active Abandoned

Non-Patent Citations (1)

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