Malalignment of implant components is a root cause for knee prosthesis failure. Patient Specific Surgical Guides (PSSGs) are used to improve the postoperative position of the implant relative to a preoperative planned position. The PSSGs are tailor made to match the patient’s bony anatomy and align drill holes and saw slots relative to the bone. However, correct PSSG alignment (and thus prosthesis alignment) is heavily dependent on the geometric fit with the matching anatomy. This thesis provides methods for preoperative optimization of the matched contact and intraoperative adjustments for improved alignment.@en