A combination comprising a guide and a stock instrument, the guide being operable to arrange the stock instrument with respect to a patient tissue, the guide and the stock instrument in combination comprising: the stock instrument having longitudinally spaced upper and lower instrument surfaces (322, 320), the lower instrument surface being configured to contact the patient tissue, and the upper instrument surface being configured to contact the guide, the stock instrument having an instrument shaft extending from the lower instrument surface and configured to be placed into an aperture in the patient tissue to position the stock instrument; the guide comprising: a lower guide surface configured to contact the upper instrument surface of the stock instrument when the lower instrument surface is in contact with the patient tissue with at least a portion of the stock instrument being interposed longitudinally between the lower guide surface and the patient tissue, and the upper instrument surface being longitudinally spaced from the patient tissue, the lower guide surface being contoured to substantially mate with at least a portion of the upper instrument surface; an upper guide surface spaced longitudinally apart from the lower guide surface by a guide body, the upper guide surface being accessible to a user when the lower guide surface is in contact with the upper instrument surface; and an orienting feature comprising an arm extending away from the guide body, a first end of the arm being mounted to the upper guide surface, and a second end of the arm having a notch-shaped landmark engaging portion; wherein the guide is arranged to position the instrument in a predetermined instrument relationship with the patient tissue when: (i) the notch-shaped landmark engaging portion of the orienting feature is in a predetermined orienting relationship with a previously placed landmark; and, (ii) the lower guide surface is in mating contact with at least a portion of the upper instrument surface in a predetermined relative guide/instrument orientation. the stock instrument having longitudinally spaced upper and lower instrument surfaces (322, 320), the lower instrument surface being configured to contact the patient tissue, and the upper instrument surface being configured to contact the guide, the stock instrument having an instrument shaft extending from the lower instrument surface and configured to be placed into an aperture in the patient tissue to position the stock instrument; the guide comprising: a lower guide surface configured to contact the upper instrument surface of the stock instrument when the lower instrument surface is in contact with the patient tissue with at least a portion of the stock instrument being interposed longitudinally between the lower guide surface and the patient tissue, and the upper instrument surface being longitudinally spaced from the patient tissue, the lower guide surface being contoured to substantially mate with at least a portion of the upper instrument surface; an upper guide surface spaced longitudinally apart from the lower guide surface by a guide body, the upper guide surface being accessible to a user when the lower guide surface is in contact with the upper instrument surface; and an orienting feature comprising an arm extending away from the guide body, a first end of the arm being mounted to the upper guide surface, and a second end of the arm having a notch-shaped landmark engaging portion; wherein a lower guide surface configured to contact the upper instrument surface of the stock instrument when the lower instrument surface is in contact with the patient tissue with at least a portion of the stock instrument being interposed longitudinally between the lower guide surface and the patient tissue, and the upper instrument surface being longitudinally spaced from the patient tissue, the lower guide surface being contoured to substantially mate with at least a portion of the upper instrument surface; an upper guide surface spaced longitudinally apart from the lower guide surface by a guide body, the upper guide surface being accessible to a user when the lower guide surface is in contact with the upper instrument surface; and an orienting feature comprising an arm extending away from the guide body, a first end of the arm being mounted to the upper guide surface, and a second end of the arm having a notch-shaped landmark engaging portion; wherein the guide is arranged to position the instrument in a predetermined instrument relationship with the patient tissue when: (i) the notch-shaped landmark engaging portion of the orienting feature is in a predetermined orienting relationship with a previously placed landmark; and, (ii) the lower guide surface is in mating contact with at least a (i) the notch-shaped landmark engaging portion of the orienting feature is in a predetermined orienting relationship with a previously placed landmark; and, (ii) the lower guide surface is in mating contact with at least a portion of the upper instrument surface in a predetermined relative guide/instrument orientation.