An implant for installation into a portion of an articular surface includes a protrusion configured to cover an un-excised portion of articular surface proximate to the implant. Another implant may form a cavity to allow the un-excised portion of articular surface to remodel over a perimeter edge of the implant. The implant may also include indentations such as grooves to promote articular cartilage remodeling over a portion of the load bearing surface of the implant. An elongated or non-round implant is also provided having two opposing concentric arcuate shaped sides, as well as a method to seat such an implant in an articular surface. A method for seating an implant without cutting articular cartilage is also provided.