A positioning apparatus for guiding resection of a patient tissue and guiding placement of a prosthetic implant component in a desired implant position with respect to the resected patient tissue, the apparatus comprising: a locating block including: a cutting plane indicator providing a physical indication of a desired cutting plane for the resection, the cutting plane indicator being positioned on the locating block to guide a cutting implement in performing the resection of the patient tissue along the desired cutting plane when the mating surface is in mating contact with the patient tissue; a placement indicator, spaced apart from the locating block and including a component-contacting feature; and an elongate spacing arm operative to space the placement indicator apart from the locating block, the spacing arm having oppositely disposed first and second spacing arm ends, the first spacing arm end. being attached to the locating block and the second spacing arm being attached to the placement indicator, the spacing arm being configured to place the component-contacting feature of the placement indicator at a predetermined placement position in three-dimensional space relative to the patient tissue; characterized in that the locating block further comprises a mating surface contoured for mating contact with the patient tissue, the mating surface being custom-configured for the patient tissue responsive to pre-operative imaging of the patient tissue; and in that when the prosthetic implant component is being placed with respect to the resected patient tissue, a preselected surface of the prosthetic implant component is brought into contact with the component-contacting feature to indicate that the prosthetic implant component has achieved the desired implant position. a locating block including: a cutting plane indicator providing a physical indication of a desired cutting plane for the resection, the cutting plane indicator being positioned on the locating block to guide a cutting implement in performing the resection of the patient tissue along the desired cutting plane when the mating surface is in mating contact with the patient tissue; a cutting plane indicator providing a physical indication of a desired cutting plane for the resection, the cutting plane indicator being positioned on the locating block to guide a cutting implement in performing the resection of the patient tissue along the desired cutting plane when the mating surface is in mating contact with the patient tissue; a placement indicator, spaced apart from the locating block and including a component-contacting feature; and an elongate spacing arm operative to space the placement indicator apart from the locating block, the spacing arm having oppositely disposed first and second spacing arm ends, the first spacing arm end. being attached to the locating block and the second spacing arm being attached to the placement indicator, the spacing arm being configured to place the component-contacting feature of the placement indicator at a predetermined placement position in three-dimensional space relative to the patient tissue; characterized in that the locating block further comprises a mating surface contoured for mating contact with the patient tissue, the mating surface being custom-configured for the patient tissue responsive to pre-operative imaging of the patient tissue; and in that when the prosthetic implant component is being placed with respect to the resected patient tissue, a preselected surface of the prosthetic implant component is brought into contact with the component-contacting feature to indicate that the prosthetic implant component has achieved the desired implant position.