An osteotomy instrument includes a handle, a first arm assembly, a second arm assembly, a displacement mechanism, and a tuning mechanism. The first arm assembly is pivotably mounted to the handle. The first arm assembly includes a first fastener support configured to hold a fastener. The second arm assembly is pivotably mounted to the handle. The second arm assembly includes a second fastener support configured to hold a fastener. The displacing mechanism includes a dial disposed on the handle. The displacing mechanism is configured to laterally displace a distal end of the first arm assembly and second arm assembly away and towards each other. The dial actuates the displacing mechanism. The tuning mechanism is configured to change an angular position of the first fastener support with respect to the second fastener support.