An adjustable opening jack that incorporates a novel locking hinge mechanism and adjustable separation arms to achieve broader scopes of application, bone plate specificity, and variable bone size capability during various osteotomy procedures. The locking hinge mechanism constrains the upper body from moving in either the vertical plane or anterior-posterior (AP) slope trajectory depending on the mode of application. The opening jack has a configuration that allows for a straight and/or sloped opening.
