Bone screw retaining system
First Claim
Patent Images
1. An implant comprising:
- a joining member having a bone contacting surface and an opposite outwardly facing surface and at least one opening extending between said bone contacting surface and said outwardly facing surface, said opening having a first diameter with a groove formed around an inner circumference of the opening, said groove having an axially spaced upper and lower surface, said upper surface inclined toward said outwardly facing surface on moving toward said opening;
a bone anchor capable of being accommodated in the opening between said groove and said bone contacting surface, said bone anchor having a maximum diameter less than said first diameter; and
a resiliently expandable split-ring mounted in said groove, the split-ring sized to expand upon insertion of the anchor element into the opening from the outwardly facing bone plate surface, said split ring having an unexpanded internal diameter smaller than said first diameter and an expanded internal diameter larger than said bone anchor maximum diameter, said split ring in said groove positioned to come into direct contact with the bone anchor to prevent the inserted bone anchor from moving towards said outwardly facing surface beyond said groove, said split-ring having an upper surface and a lower surface for respectively engaging said upper and lower surface of said groove, said upper ring surface inclined toward said outwardly facing surface on moving toward said opening.
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Abstract
An implant, particularly for the spinal column, comprises a plate having openings, bone-anchoring members capable of being accommodated in the openings and at least one split-ring capable of holding the members in the orifices. The split-ring can come into direct contact with the anchoring member or members to hold the member or members in the orifices.
569 Citations
37 Claims
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1. An implant comprising:
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a joining member having a bone contacting surface and an opposite outwardly facing surface and at least one opening extending between said bone contacting surface and said outwardly facing surface, said opening having a first diameter with a groove formed around an inner circumference of the opening, said groove having an axially spaced upper and lower surface, said upper surface inclined toward said outwardly facing surface on moving toward said opening;
a bone anchor capable of being accommodated in the opening between said groove and said bone contacting surface, said bone anchor having a maximum diameter less than said first diameter; and
a resiliently expandable split-ring mounted in said groove, the split-ring sized to expand upon insertion of the anchor element into the opening from the outwardly facing bone plate surface, said split ring having an unexpanded internal diameter smaller than said first diameter and an expanded internal diameter larger than said bone anchor maximum diameter, said split ring in said groove positioned to come into direct contact with the bone anchor to prevent the inserted bone anchor from moving towards said outwardly facing surface beyond said groove, said split-ring having an upper surface and a lower surface for respectively engaging said upper and lower surface of said groove, said upper ring surface inclined toward said outwardly facing surface on moving toward said opening. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A screw retaining system for a bone plate comprising:
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a bone plate having at least one opening therein for receiving the screw, the opening extending along an axis from a top surface to a bottom bone contacting surface of said plate, said opening having a region with a first diameter for receiving a head of the screw, said region including a recessed groove, said groove having a depth greater than said first diameter, said groove having an axially spaced upper and lower surface, said upper surface inclined with respect to said lower surface;
the screw having a head with a diameter smaller than said first diameter and an upwardly facing surface; and
an expandable ring mounted in said groove and having a relaxed unexpanded external diameter greater than said first diameter of said opening but smaller than said groove depth and a relaxed unexpanded internal diameter smaller than said screw head diameters, said ring capable of expanding on contact said screw head in said groove so that when said internal diameter expands to said screw head diameter, said external ring diameter is less than or equal to said groove depth, said split-ring having an upper surface and a lower surface for respectively engaging said upper and lower surface of said groove, said upper ring surface inclined with respect to said lower ring surface. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A retaining system for retaining an anchor in a plate comprising:
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a plate having a top surface and a bottom bone contacting surface with at least one bore therethrough, said bore having a first diameter and a recessed groove intermediate said top and bottom surface;
a locking element with an expandable inner surface is mounted in said groove, said groove having an axially spaced upper and lower surface, said upper surface inclined with respect to said lower surface the inner locking element inner surface resiliently expandable in said groove from a first cross-section to a second larger cross-section, said locking element having an upper surface and a lower surface for respectively engaging said upper and lower surface of said groove, said upper surface of said ring and said groove inclined towards said plate top surface with respect to said lower surface on moving towards said bore;
an anchor for insertion into said bore through said locking element from said top plate surface, said anchor having a portion with a cross-section larger than said first cross-section and smaller than or equal to said second cross-section; and
wherein said locking element inner surface and said anchor portion engage and expand said inner surface as said anchor passes through said locking element. - View Dependent Claims (33, 34, 35, 36, 37)
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Specification