Abstract: Instrumentation for osteofixation including a locking bone plate and a surgical drill guide. The plate has a plurality of fastener holes with inner walls of a preselected hole diameter. The drill guide has a guide member, for guiding a drill bit, and a hollow collet disposed substantially coaxially with the guide member. A radially expandable forward end of the collet comprises a radially expandable neck and an outwardly projecting rim disposed forward of the neck. This rim defines a contracted outer rim diameter that is smaller than the hole diameter in a contracted collet position, and an expanded outer rim diameter that is larger than the hole diameter in an expanded position. Thus, the rim is freely extractable through the plate hole in the contracted position, but is unreceivable through the plate hole in the expanded position. The collet neck is configured and dimensioned to press outwardly against an inner wall of the plate hole when the neck is expanded.