Compression screw with variable pitch thread

Abstract

A bone screw apparatus is provided for threaded engagement with a bone and, optionally, a medical device such as a bone plate. The bone screw has a shaft having a first end, a second end, and a first thread having a first pitch. The screw further includes a head having a proximal end, a distal end adjacent the shaft first end, and a second thread having a second pitch. The second thread has a variable pitch that increases in a proximal direction, but never exceeds the magnitude of any portion of the first pitch. Upon threaded engagement of the head with bone or a medical device, a compression force is generated which continuously decreases as the screw is further inserted.

Dependencies are inferred from the claim text.