Neurosurgery Coding Alert

Question: What's the difference between an autograft and an allograft? For example, how should I know whether to choose 20930 or 20937 for spinal bone grafts?

Missouri Subscriber Answer: An autograft describes a portion of bone taken from a patient for transplantation elsewhere on the same patient's body (for example, bone is taken from a rib to complete a spinal fusion). Autograft codes 20936 (Autograft for spine surgery only [includes harvesting the graft]; local [e.g., ribs, spinous process, or laminar fragments] obtained from same incision), 20937 (... morselized [through separate skin or fascial incision]) and 20938 (... structural, bicortical or tricortical [through separate skin or fascial incision]) describe both the harvesting and the placement of such grafts.

Allografts (20930, Allograft for spine surgery only; morselized; and 20931, ... structural) describe grafts harvested from a cadaver or living donor, frozen or freeze-dried, and kept in a surgical or regional bone bank until needed. The operating surgeon does not harvest the allograft but obtains it from the bone bank prior to surgery.

CPT also differentiates bone grafts as structural (20938, 20931) or morselized (20937, 20930). A structural bone graft consists of a single piece of bone that provides direct support for skeletal structures, while a morselized (or small-segment) graft consists of small pieces of bone joined together to fill bony cavities, primarily to promote new bone growth.