Bone marrow aspiration needle

An aspiration assembly including an outer cannulated needle having a tip, a threaded collar, and an inner aspiration needle. The threaded collar is mounted to an end of the outer cannulated needle opposite to the tip. The inner aspiration needle has a tip at a first end and a threaded portion proximate to a second end. The inner aspiration needle is inserted within the outer cannulated needle such that the tip of the inner aspiration needle extends beyond the tip of the outer cannulated needle and the threaded portion of the inner aspiration needle threadably engages the threaded collar. The distance that the tip of the inner aspiration needle extends from the tip of the outer cannulated needle increases when the inner aspiration needle is rotated in a first direction relative to the outer cannulated needle.