A patellar resection instrument has an integral depth adjustment assembly that is easily, intuitively, and intra-operatively adjustable between a plurality of discrete positions. Each position corresponds to a particular, known depth of resection, and this depth may optionally be inscribed on the depth adjustment knob for easy visual selection and/or confirmation of the resection depth. The depth adjustment assembly provides positive tactile feedback as the stylus is moved between positions. The unique configuration of the depth adjustment assembly maintains the resection depth stylus in a chosen position throughout the patellar resection procedure, even if the procedure causes vibration or other forces to be transmitted to the patellar resection instrument.