A drill guide system provides a means of improved tunnel placement accuracy by allowing the drill guide to articulate to seat against the bone being drilled. The drill guide includes an articulating drill guide adapter constructed in four parts: a top cap, a thumbscrew, a lock tab, and a spring mechanism. The drill guide adapter is part of an aimer arm which mates with a handle on the proximal end and an aimer guide on the distal end. The drill guide adaptor allows the aimer guide to articulate relative to an irregular mating surface, allowing for increased area contact between the aimer guide template and bone. Examples of the drill guide adaptor also include a means for locking the aimer guide into place relative to the aimer arm.