Abstract A bone compression plate is provided with several sliding slits for countersunk bone screws having ball heads in the longitudinal dimension of the plate. Each sliding slit is countersunk in its end area opposite the fracture, the depth of which countersinking in the plate determines the final axial position of the screwhead. That depth is greater than that of the rest of the sliding slit. The bearing surface of the countersinking for the screwhead extends over an area which is included within an angle of more than 180°. It is thus possible, on the one hand, to move the plate with respect to the pieces of fractured bone to obtain a pressing together of the two pieces of bone when the bone screw has not been screwed tight. On the other hand, it is possible to fasten the plate immovably to one piece of the fractured bone by inserting a bone screw into the countersink slit. Pressing of the pieces of bone fragment together can be accomplished automatically by means of chamfering provided on the ball head of the countersunk bone screw in the area at the opposite end of the sliding slit. Deeper countersinking provided in the end area containing the original countersunk depression makes possible the positioning of the countersunk bone screw at an oblique angle.
An elongated bone compression plate having a longitudinal centerline and a transverse centerline, said plate being formed with a plurality of slitlike holes each adapted to receive a countersunk bone screw having a ball head, each said slitlike hole being located in said plate substantially along the longitudinal centerline thereof and on both sides of the transverse centerline thereof with one end of said slitlike holes being distal thereto, each said slitlike hole being a compound countersink and having a portion of substantially uniform depth forming a first countersunk depression extending from said one end of said slitlike hole and having a tapered second countersunk depression extending from its other end, the depth of said second countersunk depression being greater than the depth of said first countersunk depression, a bearing surface formed in said second depression cooperating with said ball head of a said bone screw, said bearing surface being formed in the area of said other end of said slitlike hole, and said bearing surface being provided over an angular zone which is symmetrical with respect to said longitudinal centerline and extending in total over an angle of more than 180° when seen in the plane defined by said longitudinal and transverse centerlines.
Claim 2
Dependent Claim
204 words
An elongated bone compression plate having a longitudinal centerline and a transverse centerline, said plate being formed with a plurality of slitlike holes each adapted to receive a countersunk bone screw having a ball head, each said slitlike hole being located in said plate substantially along the longitudinal centerline thereof and on both sides of the transverse centerline thereof with one end of said slitlike holes being distal thereto, each said slitlike hole being a compound countersink and having a portion of substantially uniform depth forming a first countersunk depression extending from said one end of said slitlike hole and having a tapered second countersunk depression extending from its other end, the depth of said second countersunk depression being greater than the depth of said first countersunk depression, a bearing surface formed in said second depression cooperating with said ball head of a said bone screw, said bearing surface being formed in the area of said other end of said slitlike hole, and said bearing surface being provided over an angular zone which is symmetrical with respect to said longitudinal centerline and extending in total over an angle of more than 180° when seen in the plane defined by said longitudinal and transverse centerlines.
Claim 3
Dependent Claim
43 words
Compression plate as claimed in claim 1, wherein the countersunk slitlike hole at the end area of the compression plate has a chamfered end surface running longitudinally thus making possible the oblique positioning of the countersunk bone screw within the countersunk slitlike hole.