| 主权项 |
1. A headless compression screw comprising:
an elongated shaft including a leading portion, a first intermediate portion, a second intermediate portion and a trailing portion; said leading portion having a single thread defining a first outside diameter and a first pitch; said first intermediate portion being unthreaded; said second intermediate portion having a single thread defining a second outside diameter smaller than said first outside diameter and a second pitch smaller than said first pitch; said trailing portion having a single thread defining a third outside diameter greater than said first outside diameter and a third pitch smaller than or equal to said second pitch; wherein, when said headless compression screw is torqueably inserted through a first bone or bone fragment and a second bone or bone fragment separated by a gap, said second bone or bone fragment is translated longitudinally towards said first bone or bone fragment; wherein, when said bone fragments are adjoining each other, further torqueing of said screw, prior to engagement by said trailing portion of said first bone or bone fragment, will maintain said second bone or bone fragment in contact with said first bone or bone fragment without causing substantial compression to occur between said first bone or bone fragment and said second bone or bone fragment, and, wherein, when further torque is applied to said screw upon engagement by said trailing portion of said first bone or bone fragment, compression will occur between said second bone or bone fragment and said first bone or bone fragment. |
