A patella drill guide includes a base portion rotatably mounted on a bone-gripping component. A trial portion with a contoured articulation surface is above the base portion. The base portion and trial portion have aligned drill guide bores. The base portion and trial portion can be rotated together on the bone-gripping component to optimize the positions of the drill guide bores with respect to the patella surface, thereby optimizing the locations of the mounting pegs of the patella implant component on the patella to optimize the orientation of the patella implant component. The base and the bone-gripping component may be unitary so that the entire assembly rotates on the patella about the central longitudinal axis of the bone-gripping component.