Screw anchored joint prosthesis
OwnerSlobodan Tepic, W. Andrew Hodgeinventors
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Abstract
Screw-based primary fixation of the prosthetic components within the medullary cavity solves the problem of micro-movements encountered in conventional press-fit cementless fixation. For a total hip prosthesis, the stem is fixed to the medial cortex of the proximal femur by the medial approach alone, obviating the need for drilling of the lateral cortex. The stem may be implanted using special drill guide instrumentation. Anchoring screws are locked into the stem of the femoral component, while self-cutting threads on the screw head engage the pre-drilled medial cortex. This novel fixation principle can also be applied to other joint prostheses, e.g. finger, shoulder, elbow and knee, as well as to dental and spinal implants.
Claims45
An orthopaedic implant system for implantation in a patient's bone, the system comprising:
- an orthopaedic implant comprising an intraosseous portion, the intraosseous portion having:
- a first side
- a second side;
- and
- at least one screw hole, the screw hole having an internally-threaded portion;
- at least one bone screw having:
- an externally-threaded front end for engagement with the internally-threaded portion of the screw hole;
- and
- an externally-threaded head for engagement with the bone.
An orthopaedic implant system for implantation in a patient's bone, the system comprising:
- an orthopaedic implant comprising an intraosseous portion, the intraosseous portion having:
- a first side
- a second side;
- and
- at least one screw hole, the screw hole having:
- an entry opening at the first side,
- a conically-tapered intermediate hole portion decreasing in diameter from the entry opening towards the second side, and
- an internally-threaded portion located between the intermediate hole portion and the second side;
- at least one bone screw having:
- an externally-threaded front end for engagement with the internally-threaded portion of the screw hole, the front end having a first thread diameter;
- an externally-threaded head for engagement with the bone, the head having a second thread diameter;
- and
- a conically-tapered intermediate screw portion between the front end and the head, the intermediate screw portion tapering from a major diameter near the head to a minor diameter near the front end.
A hip joint prosthesis comprising:
- a femoral component having an intramedullary stem, the stem having:
- a medial side;
- a lateral side;
- and
- at least one screw hole, the screw hole having an internally-threaded portion;
- at least one bone screw having:
- an externally-threaded front end for engagement with the internally-threaded portion of the screw hole, the front end having a first thread diameter;
- and
- an externally-threaded head for engagement with the medial cortex of the femur, the head having a second thread diameter.
An improved method for implanting an orthopaedic implant, using screws rather than cement, in a bone having a near cortex, a far cortex, and an intraosseous region, the implant having an intraosseous portion, the improvement comprising:
- inserting the intraosseous portion of the implant into the intraosseous region of the bone;
- inserting a bone screw first through the near cortex and then into the implant;
- engaging the front end of the screw with the intraosseous portion of the implant;
- and
- engaging the head of the screw with the near cortex of the bone;
- thereby coupling the orthopaedic implant to the bone in close apposition to the interior surface of the near cortex.
An improved method for implanting a femoral component of a hip joint prosthesis, using screws rather than cement, in the intramedullary canal of the patient's femur, the femoral component having an intramedullary stem, the improvement comprising:
- inserting the intramedullary stem of the femoral component into the intramedullary canal of the patient's femur;
- and
- inserting a bone screw first through the medial cortex of the femur and then into the stem, such that the front end of the screw engages with the stem of the implant and the head of the screw engages with the medial cortex, coupling the femoral component to the femur in close apposition to the interior surface of the medial cortex.
Dependencies are inferred from the claim text.