Hemicallotasis is a procedure where the bone (usually upper tibia) is cut through half its width and then the two parts are pulled apart using an external fixator frame. This stimulates new bone to fill the gap, which can be angled to change the forces, usually to avoid pressure on a surface damaged by arthritis. (www.kneeguru.co.uk). This manual is a step by step guide to the process of Hemicallotasis. Beginning with an introduction to the procedure, the following chapters discuss preoperative planning, fixator application and postoperative protocols. A DVD is included illustrating the parts of the fixator and the application technique, as well as an audio-visual presentation to assist practitioners in helping osteoarthritis patients understand their condition and the hemicallotasis procedure.