Osteosynthetic pressure plate construction

• US RE31,628 E
• Filed: 04/06/1979
• Issued: 07/10/1984
• Est. Priority Date: 06/22/1966
• Status: Expired due to Term

• Current Assignee: Synthes USA LLC (Johnson & Johnson)
• Original Assignee: Synthes AG
• Inventors: Allgower, Martin, Perren, Stefan, Russenberger, Max E.
• Primary Examiner(s): FRINKS, RONALD
• Application Number:
  US06/027,921
• Time in Patent Office: 1,922 Days
• Field of Search: 128/92 D, 128/92 R, 128/92 B, 128/92 BA, 128/92 E, 128/92 G
• US Class Current: 606/282
• CPC Class Codes: A61B 17/8014 the extension or compression force being caused by interaction of the plate hole and the screws
• CPC Class Codes: A61B 2017/00526 Methods of manufacturing

Abstract

An osteosynthetic pressure plate includes a slot formation for receiving a bone-fixing screw which is adapted to be secured to a bone part which is to be mended. The slot is formed with an edge which includes an oblique portion or ramp having an inclination such that when it is engaged by the underside of a head portion of a bone-fixing screw there will be a displacement of the pressure plate in a direction to move the ramp portion away from the fixing screw and to cause the plate to apply a pressure to hold the bone parts in tight engagement. The plate is advantageously useable with screws having heads of spherical form or conical form, for example. The inclination of the ramp and the configuration of the walls bounding the slot of the pressure plate are such that there will be a uniform and even shifting of the plate having the slot when the ramp of the walls bounding the slot is engaged by the screw head to cause the desired displacement of the pressure plate in order to displace the bone fragment toward tighter engagement with the adjacent bone fragment and into pressure engagement therewith.

Claims

1. We claim:

1. An apparatus for securing bone fragments together in pressure contact using screws at least one of which has a head with an inwardly tapered undersurface, comprising a plate having a top side and a bottom side and at least two spaced .[.longitudinally elongated.]. slot openings extending therethrough for receiving the screws which are adapted to pass through the slot openings to engage into respective bone fragments, .Iadd.at least one of said openings being longitudinally elongated, and .Iaddend.said plate having a wall bounding at least one of said openings which is inclined at an angle .Iadd.to .Iaddend.said top side toward said bottom side to cause shifting of the plate in a direction to move the bone fragments together when engaged by the tapered undersurface of the head of the screw as said plate is being secured to its respective bone fragment, said inclined wall of said slot extending from said top surface inwardly and downwardly towards said bottom surface and defining an inclined planar surface from one end of the slot to the other which is displaceable by the tapered undersurface of the screw head when it is advanced into its respective bone fragment. 2. An apparatus, according to claim 1, including a threaded screw engaged through each slot opening adapted for insertion into a respective bone fragment. 3. An apparatus according to claim 1, wherein the wall of said plate bounding said slot opening which is inclined includes a portion opposite the inclined portion forming an abutment stop shaped to the configuration of the screw head. 4. An apparatus according to claim 1, including a threaded securing screw engaged through each slot opening adapted for insertion into a respective bone fragment and havng a hemispherical countersunk head, said inclined wall portion comprising a surface complementary to said screw head and having an axis inclined to the plane of said plate. 5. An apparatus, according to claim 1, including a securing screw adapted to extend through each of said slot openings and to be threaded into the respective bone fragments and having a conically-shaped countersunk head, the inclined wall portion of said plate being formed as a conical surface. 6. An apparatus, according to claim 1, including at least one slot adapted to be located on each side of the fracture line of said bone fragments, and a threaded securing screw engaged through at least one of the slots adapted to be located on each side of the fracture line and adapted to be threaded into the respective bone fragment. 7. An apparatus, according to claim 6, wherein at least one of said slots is elongated sufficiently to permit an initial shifting of the plate upon contact of the inclined surface by the securing screw and an additional movement, and wherein at least one other slot is provided with an inclined wall portion engageable by a threaded securing screw for effecting additional movement of said plate. 8. An apparatus, according to claim 1, wherein said pressure plate includes at least two slot openings adjacent each end adapted to be oriented over the respective bone fragments adjacent each end, the slots having walls at the ends adjacent the respective ends of said plate inclined at an angle to cause shifting of the plate in the direction to move the bone fragments together when contacted by a securing screw and having at their opposite ends formed with an abutment complementary to the configuration of the bone-securing screw which is to be employed. 9. An apparatus, according to claim 1, including at least one slot adjacent one end of said plate and at least two additional slots adjacent the opposite end of said plate which are each elongated in a direction parallel to the longitudinal axis of said plate end which form an inclined portion arranged at an angle to cause relative shifting of the plate in directions toward the associated adjacent end, at least one of said slots adjacent one of said plate ends being elongated sufficiently to permit a shifting of said plate after it is threadedly secured by the associated screw after the tightening of the threaded securing screw in the other of said slots. 10. An apparatus, according to claim 1, wherein said inclined wall begins at one end of said slot which is inclined from said top surface inwardly and downwardly towards said bottom by a lesser distance than the remaining portions of said inclined wall bounding said slot. .Iadd. 11. In a bone compression plate .Iaddend..Badd.assembly .Baddend.for moving adjacent bone sections relative to each other;

(a) an elongated plate of a length to span adjacent bone sections, (b) there being at least one elongated opening through said plate extending longitudinally thereof and disposed to overlie one bone section and there being another opening through said plate disposed to overlie the other bone section, (c) a first screw of a length to extend through said elongated opening and penetrate said one bone section, (d) a head adjacent one end of said first screw with the under surface of said screw head tapering inwardly toward the other end of said screw, (e) a second screw of a length to extend through said another opening and penetrate said other bone section, and (f) an inclined cam surface on said plate adjacent said elongated opening extending in a direction of the longitudinal axis of said plate and engaging said inwardly tapered under surface of the head of said first screw to move said first screw relative to said elongated opening upon tightening said screw so that said one bone section is moved relative to said plate and said other bone section. .Iadd. 12. A bone compression plate .Iaddend..Badd.assembly .Baddend.as defined in claim 11 in which said another opening is also an elongated opening and an inclined cam surface is provided on said plate adjacent said another opening extending in a direction of the longitudinal axis of said plate and engaging an inwardly tapered under surface of a head of a screw which is adapted to penetrate said other bone section and move the screw longitudinally of said another opening upon tightening the screw so that said other bone section is moved relative to said plate and said one bone section. .Iadd. 13. A bone compression plate .Iaddend..Badd.assembly .Baddend.as defined in claim 12 in which said inclined cam surfaces adjacent said elongated openings slope downwardly and inwardly toward each other so that upon tightening said screws the screws and the bone sections connected thereto move toward each other. .Iadd. 14. A device for securing broken bone fragments together in pressure contact using screws, at least one screw having a head with an inwardly tapered undersurface, comprising a plate adapted to engage over the bone fragments and bridge the break, said plate having a top side and a bottom side and having at least two sets of longitudinally spaced slot openings, said sets being spaced apart longitudinally and defining a central area therebetween which is adapted to overlie the break, said slot openings extending through said plate for receiving the screws which are adapted to pass through the slot openings to engage into respective bone fragments, a slot of at least one of said sets which is nearest to said central area comprising a control slot which is longitudinally elongated, said plate having a wall bounding the longitudinally elongated control slot which is inclined at an angle from said top side toward said bottom side to cause shifting of the plate in the direction to move the bone fragments together when engaged by the tapered undersurface of the head of the screw as said plate is being secured to its respective bone fragment, said inclined wall of said slot extending from said top surface inwardly and downwardly toward said bottom surface and defining an inclined planar surface from one end of the slot to the other which is displaceable by the tapered undersurface of the screw head when it is advanced into its respective bone fragment. .Iaddend..Iadd. 15. A device according to claim 14, wherein all of said slots of each of said sets are longitudinally elongated. .Iaddend.