Lumbar Adjacent Segment Degeneration and Disease After Arthrodesis and Total Disc Arthroplasty.
The authors reviewed available literature involving adjacent segment degeneration, ASDeg, and symptomatic adjacent segment disease, ASDis, following fusion or total disc replacement in the spine. Adjacent segment degeneration can be seen on radiographs. It does not necessarily cause symptoms. When the adjacent segment degeneration is identified on radiographs, and causes symptoms, it is considered adjacent segment disease.

Fusion of the segment is also called arthrodesis. Total disc replacement is also referred to as arthroplasty. The authors found 27 articles, none with class I or II evidence however, that fit the inclusion criteria. Twenty of the articles involved arthrodesis, and seven involved arthroplasty. A total of 1732 patients with arthrodesis was compared to 758 patients with arthroplasty.

The authors found that the odds of developing ASDeg remained larger when fusion was performed, with odds higher when the mean age was greater, or as the follow up period grew longer. Thirty four percent of arthrodesis patients were found to have ASDeg. This compared to an average of nine percent in arthroplasty patients. However, in one study, 53 patients who had a CHARITE disc replacement were found to have a 17 percent incidence of ASDeg after seventeen years. The authors concluded that there seems to be a correlation between fusion and the development of ASDeg compared to arthroplasty.

Fourteen percent of arthrodesis patients developed ASDis, whereas one to three percent of arthroplasty patients developed ASDis. The authors found that the length of follow up had a significant effect on the incidence of ASDis. The longer the follow up period, the greater the chance for developing ASDis. There is a stronger correlation between fusion and the development of ASDis compared to arthroplasty. This suggests that arthroplasy may have a protective effect against accelerating junctional degenerative changes and disease following surgery.

The authors noted that disc degeneration also correlated with a decreased lumbar range of motion. Those with five degrees or greater motion had zero percent prevalence of ASDdeg. Patients with less than five percent motion had a 34 percent prevalence of ASDeg. Those arthroplasty patients that maintained their motion did not develop any evidence of ASDeg.

Because the literature reviewed was not the most ideal in terms of reliability, the authors of the review could only give a class C, or lowest tier of recommendation, for the use of arthroplasty versus arthrodesis to reduce the development of adjacent segment degeneration and adjacent segment disease.
J. Harrop et al. Lumbar adjacent segment degeneration and disease after arthrodesis and total disc arthroplasty. SPINE. July 2008. volume 33, Number 15. Pp. 1701-1707.