Patent ID: 8728128

Claim:
An orthopedic device comprising: an implant member including a thru-bore having an entry diameter, an intermediate diameter, and an exit diameter, wherein said intermediate diameter is larger than said entry diameter and said exit diameter; and a screw assembly configured to be coupled to said thru-bore including a thread portion and a selectively expandable head portion; wherein said selectively expandable head portion includes: an expandable ring that includes an un-expanded state and an expanded state; and a pull-lock pin that contacts said expandable ring and expands said expandable ring from said un-expanded state to said expanded state in said thru-bore as said pull-lock pin is pulled from said screw assembly, wherein said pull-lock pin comprises: a first section including a pull element; and a second section including a lock surface; wherein said first section and said second section are joined at a break taper that fractures upon expansion of said expandable ring when a pull force exerted on the first section is greater than a yield force of the pin.