Apparatus for performing an open wedge, high tibial osteotomy, the apparatus comprising: a wedge-shaped implant for disposition in a wedge-shaped opening created in the tibia, wherein the wedge-shaped implant comprises a hole extending therethrough; a fixation screw for extending through the hole and securing the wedge-shaped implant to the tibia; and a locking mechanism for releasably locking the fixation screw to the wedge-shaped implant. Apparatus for performing an open wedge, high tibial osteotomy, the apparatus comprising: a fixation screw for securing an implant to the tibia, the fixation screw comprising: a shaft having a distal threaded portion and a proximal threaded portion, wherein the distal threaded portion and the proximal threaded portion are characterized by different thread pitches.