Bone screws and particular applications to sacroiliac joint fusion

Abstract

Procedures for the fusion of the sacroiliac joint advantageously make use of an implant selected to distract the joint upon insertion and to maintain or increase tension upon insertion. The implant can have a varying structure along its length. In some method described herein for fusing the sacroiliac joint using an implant, an implant is screwed into the sacroiliac joint between the sacrum bone and the iliac bone. The implant comprises a shaft, a tool engagement flange at top end of the shaft, a pointed tip comprising no more than about 20 percent of the length of the screw, and threads spiraling around the shaft. For screws of particular interest, the volume displacement perpendicular to the shaft increases at least about 5 percent from a point adjacent the tip to a point near the top of the shaft. Some of the desirable screw designs can be used in other orthopedic application, especially situations involving varying bone hardness. Useful filler material can be formed from a blend of bone powder and bioactive agents.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of copending U.S. application Ser. No. 11 / 879,536 to Stark, filed on Jul. 17, 2007, entitled “Bone Screws and Particular Applications to Sacroiliac Joint Fusion,” which is hereby incorporated by reference.FIELD OF THE INVENTION[0002]The invention relates to methods for fusing the sacroiliac joint using anchors that distract the joint and immobilize the joint in its distracted position. The invention further relates to bone screw designs that are versatile with respect to firm anchoring in softer or harder bone structures through increasing gripping of the structure as the screw is advanced.BACKGROUND OF THE INVENTION[0003]Lower back pain is a common ailment among the population and results in pain and suffering as well as loss of work time. Thus, approaches for the treatment of back pain can both relieve suffering as well as reduce employee sick time. Since back pain results in considerable employee abse...

AI Technical Summary

Benefits of technology

"The invention is related to a method and implant for fusing the sacroiliac joint, which is a joint between the sacrum bone and iliac bone. The method involves drilling the joint, selecting an implant that can distract the joint and maintain tension, and inserting the implant into the joint to immobilize it. The implant can have a varying structure along its length and can be made of bone or a biocompatible material that promotes bone growth. The invention also includes a method for inducing bone growth for joint fusion or bone repair by placing a blend of bone powder and a bioactive agent that induces bone growth into a joint or bone fracture. The implant can also contain a biologically active agent that stimulates bone growth. The technical effects of the invention include improved joint stability, reduced pain, and improved bone growth."

Problems solved by technology

Lower back pain is a common ailment among the population and results in pain and suffering as well as loss of work time.

While the sacroiliac joint has a limited range of motion, dysfunction of the joint has been identified.

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