Torque limiting device for use with bone penetrating pins
First Claim
1. In combination with a bone penetrating pin, a device for anchoring said pin in bone material comprising separable cap means adapted for engagement with an elongated shank, said cap means including torque applying means and means for transferring torque to said elongated shank;
- said means for transferring torque to said elongated shaft including torque limiting means designed to fail upon application of torque exceeding a predetermined maximum, said pin further including means for facilitating removal of said pin from the bone whether or not said torque limiting means has failed.
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Accused Products
Abstract
A bone penetrating pin for medical use includes, in one embodiment, a shank provided at one end with a bone penetrating element of titanium or single crystal alumina ceramic material, and a driving head at the other end. A removable cap is applied to the driving end, the cap including upper and lower cylindrical portions of substantially identical diameters interconnected by an intermediate portion of substantially smaller diameter. The upper portion is formed with oppositely extending arms for application of torque through the cap to the shank and bone penetrating element. The intermediate portion of the cap is designed to fail in shear upon the application of torque in excess of a predetermined maximum; that is, it provides a torque limiting function. In another embodiment, the torque applying and limiting means are in the form of a tool assembly comprising a shank engageable with one end of a bone penetrating pin, and a cap slidable with respect to the shank, wherein a torque limiting insert is receivable between the cap and the shank to drivingly couple the two. More specifically, the tool of this second embodiment includes an elongated shank provided with a pin fastener engaging tip at one end and a first socket formed at the other end. A torque applying device is slidably mounted with respect to the shank, and includes a second socket substanially aligned with the first socket. A torque limiting insert is receivable within the first and second sockets to couple the torque applying device and the pin engaging shank.
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Citations
30 Claims
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1. In combination with a bone penetrating pin, a device for anchoring said pin in bone material comprising separable cap means adapted for engagement with an elongated shank, said cap means including torque applying means and means for transferring torque to said elongated shank;
- said means for transferring torque to said elongated shaft including torque limiting means designed to fail upon application of torque exceeding a predetermined maximum, said pin further including means for facilitating removal of said pin from the bone whether or not said torque limiting means has failed.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A skull pin and removable cap comprising:
an externally threaded shank having a first skull engaging end and a second driving end, said threaded shank and said skull engaging end formed of different materials, said driving end receiving said removable cap provided with torque applying and torque limiting means, and wherein said driving end is further provided with means for receiving a tool by which said skull pin may be removed in the event of failure of said torque limiting means. - View Dependent Claims (23, 24, 25, 26)
- 27. In combination with a halo crown for immobilizing a patient'"'"'s skull during medical treatment or operative procedure, wherein said halo crown comprises a generally ring-shaped rigid member having interior cross-dimensions larger than the diameter of the patient'"'"'s head, and means defining a plurality of threaded openings extending through said generally ring-shaped rigid member, a plurality of skull pins adjustably received in said openings to adjust the extent of penetration of each of said skull pins into an interior volume defined by said generally ring-shaped rigid member, wherein each of said skull pins comprises an exteriorly threaded elongated shank having first and second ends, a skull engaging portion rigidly connected to one of said shank ends and terminating in a pointed tip, and a removable cap engageable with the other of said shank ends, said cap comprising both torque application and torque limiting means, said other of said shank ends provided with tool engaging means for permitting removal of said in in the event of failure of said torque limiting means.
Specification