Spinal fusion coding has never been easy. But it can now be much more precise with the introduction of three new ICD-9-CM procedure codes on Oct. 1, 2002. After taking a quick look at spinal anatomy and fusion techniques, we'll review spinal fusion coding in ICD-9-CM and see where the new codes fit in.
The spine consists of 25 vertebrae grouped into three regions. The vertebrae within each region are identified in a standard order by number:
Lumbar and Sacral: L1, L2, L3, L4, L5, S1
Vertebrae are bone. In between them are the intervertebral discs, cartilage rings that act as shock absorbers. Discs have a hard outer band that can sometimes tear, allowing the squishy central nucleus pulposus to "herniate" or squeeze out.
When medical management is insufficient, the gold standard for surgically treating many spinal disorders is spinal fusion. In fusion, the disc between two bony vertebrae is removed and the vertebrae are essentially welded by the bones growing together. This prevents the vertebrae from moving. Although it sounds bad, it's actually desirable when the grinding motion is a source of pain. Fusing vertebrae can also stop progression of spinal deformities like scoliosis and stabilize a spine weakened by disease.
There are two surgical approaches for accessing the vertebrae to perform the fusion. In an anterior approach, the surgeon goes in through the patient's front, pushing the internal organs and structures to the side. In a conventional posterior approach, the surgeon goes in through the back and strips the muscles off the vertebrae.
Once the vertebrae are exposed, fusion requires the use of various devices. Most commonly, this means placing bone graft material between the vertebrae so they will grow together. The grafts can be autogenous, usually bone harvested from the patient's hip, or they can be allografts taken from cadavers. Interbody fusion devices (IFDs) can also be placed between the vertebrae after the disc is removed to promote fusion and help restore height. Finally, spinal instrumentation, such as Harrington rods or pedicle screws for some cases, can also be used. Although instrumentation is not fusion, it provides fixation to hold the vertebrae firmly in place. Many spinal fusion procedures use more than one kind of device.
General Coding for Spinal Fusion
ICD-9-CM uses procedure codes 81.00 to 81.08 for spinal fusion. To use these codes properly, the coder must know: 1) the region being fused–cervical, dorsal or lumbosacral, and 2) the approach–anterior or posterior. Note that spinal refusion is coded 81.30 to 81.39 and follows the same logic.
The spinal fusion codes include the use of bone grafts and spinal instrumentation so coders should not try to code these components separately. However, they don't include use of IFDs and use of a bone graft substitute called rhBMP. They also don't include a special type of approach. That's where the new codes come in.
New Code 84.51: Insertion of Interbody Spinal Fusion Device
IFDs are placed between the vertebrae after all or part of the disc is removed. There are several types of IFDs. The most common are metal "cages," though they look more like hollow threaded cylinders with holes in them. The cages are packed with bone graft material and then, usually, two are placed side by side into the intervertebral space. The bone inside grows through the holes in the cage and fuses the vertebrae. Some common models of IFD cages are the LT-CAGE™ device, the BAK® and the BP™ cage.
IFDs also include spacers. These are similar to cages though usually only one spacer is needed within each intervertebral space. Common models include the IBS™ and the AO TIS™. Bone dowels are another kind of IFD. Here, cadaver bone is lathed to the patient's specifications and then screwed into the space between the vertebrae. Bone dowels sometimes have slots drilled into them that can be packed with bone graft material.
To code a spinal fusion with interbody fusion device, use a code from 81.0X for region and approach and also add new code 84.51 for the use of an IFD.
New Code 84.52: Insertion of Recombinant Human Bone Morphogenetic Protein (rhBMP)
BMP is a revolutionary bone graft substitute, an engineered version of a naturally occurring bone growth protein. When used in spinal fusion, BMP's great advantage is that it spares patients the morbidity associated with a separate incision and harvesting bone from the hip. Typically, BMP is placed on a collagen sponge, then packed into the LT-CAGE™ device and placed together into the intervertebral space.
The only rhBMP approved for spinal fusion in the United States is called INFUSE™ Bone Graft.
To code a spinal fusion with rhBMP, use a code from 81.0X for the region and approach and also add new code 84.52 for use of a rhBMP. Note that when rhBMP is delivered via an IFD cage, it is also separately coded with 84.51.
New Code 81.61: 360
Degree Spinal Fusion, Single Incision Approach
Both the front and back of a vertebra can be fused during the same operative episode. This is called an anterior-posterior, circumferential, or a 360o fusion. Conventionally, the surgeon performs the anterior fusion through a front incision then flips the patient over and performs the posterior fusion through a second incision in the back. That requires two codes from 81.0X, one for the anterior incision and one for the posterior incision.
Recent advancements in surgical technique now make it possible to reach and fuse the front and back of a vertebra by making just one incision. Not having to reposition the patient and make a second incision reduces morbidity.
In this new technique, the single incision can be either posterior (from the back) or transforaminal (also from the back but more to the side). IFDs or other constructs are then placed between the vertebrae for the anterior fusion. For the posterior fusion, bone is laid along the transverse processes of the vertebrae; this is sometimes called laying bone "in the gutters." Alternately, some surgeons accomplish the posterior fusion by abrading the facets and then laying the resulting bone chips posteriorly. Also, almost always, spinal instrumentation is placed posteriorly to promote the fusion by fixing the vertebrae in place.
You may sometimes see this new technique abbreviated as PLIF (posterior interbody fusion) or TLIF (transforaminal interbody fusion). But be careful with this wording! It's important to understand that both the front and back of the vertebra must actually be fused to use code 81.61. Sometimes, anterior fusion is performed with an IFD but only instrumentation is used posteriorly. This does not qualify as a 360o fusion because instrumentation is technically used for fixation.
Regardless of the instrumentation, it's the use of bone grafts or chips, or a bone substitute that actually constitutes the fusion. For a 360o fusion, these devices must be used front and back.
To code a 360º fusion through a single incision, use one code from 81.0X to show how the incision was made and add new code 81.61 to show that both the front and back of the vertebra were fused. Note that when IFDs and rhBMP are used, that is coded separately with 84.51 and 84.52.
Linda Holtzman is the founder of Clarity Coding, a consulting group.