Abstract: A patient-specific surgical guide (10) for use in a minimally invasive procedure in a joint can include: a first contoured surface (60); and a second contoured surface (80). The first and second contoured surfaces (60, 80) are configured for engagement with respective opposing articular bone surfaces in said joint such that the guide is located in a pre-operatively determined position and orientation within the joint relative to both bones (12, 14). The provision of the two contoured surfaces for opposing bone surfaces means that the guide (10) can be securely located and retained within the joint by virtue of passive joint stiffness provided by soft tissue tension from the tissues in and surrounding the joint which is relatively unaffected by the minimally-invasive incision(s).