There was a time about 30 years ago called the “rod long fuse short” days. These patients had a one or two level fusion with a three or four level instrumentation. At about one year, the rods were removed, expecting the unfused levels to return to normal. This did not happen. The unfused but immobilized levels became stiff and painful. It turns out that motion is needed to keep facets or other joints healthy.
A mild example of this effect is seen with simple immobilization of the elbow for six weeks. A forearm fracture sometimes needs a cast that includes the elbow. When the cast comes off, the elbow is very stiff due to the immobilization even though this joint was uninjured.
Barriers can often prevent fusion (or bone formation). In fact, I see patients that have had prior unsuccessful surgery resulting in a pseudoarthrosis (non-union). Many of the times, the reason this occurs is due to poor preparation of the two bony surfaces. Without meticulous preparation (careful removal of all soft tissues to uncover raw bone surfaces), the two bones won’t heal together.
Bone wax is a substance that will prevent fusion. Remember that when a surgeon attempts to fuse a facet joint, he or she will remove all the cartilage off the bone joint surfaces. This cannot be replaced (at least at this times but I have ideas about this that I am developing). The disc in front will also become stiff while held still due to the instrumentation that typically is included to immobilize the fused segment.
Dr. Corenman
Donald Corenman, MD, DC is a highly-regarded spine surgeon, considered an expert in the area of neck and back pain. Trained as both a Medical Doctor and Doctor of Chiropractic, Dr. Corenman earned academic appointments as Clinical Assistant Professor and Assistant Professor of Orthopaedic Surgery at the University of Colorado Health Sciences Center, and his research on spine surgery and rehabilitation has resulted in the publication of multiple peer-reviewed articles and two books.