Apparatus for performing an open wedge, high tibial osteotomy, the apparatus comprising:cutting apparatus for forming an osteotomy cut in the tibia, the cutting apparatus comprising:targeting apparatus for identifying a cutting plane through the tibia and a boundary line for terminating a cut made along the cutting plane, wherein the boundary line is located within the tibia, parallel to the anterior-posterior slope of the tibia and parallel to the sagittal plane of the patient.A method for performing an open wedge, high tibial osteotomy, the method comprising:positioning targeting apparatus for identifying a cutting plane through the tibia and a boundary line for terminating a cut made along the cutting plane, wherein the boundary line is located within the tibia, parallel to the anterior-posterior slope of the tibia and parallel to the sagittal plane of the patient;cutting the bone along the cutting plane, with the cut terminating at the boundary line;moving the bone on either side of the cut apart so as to form the wedge-like opening in the bone; andstabilizing the bone.