The main reason for lumbar disc replacement (LDR) instead of a fusion is to keep the motion in the spine. But does the long-term result depend on motion? If it doesn’t, what’s the point of using LDRs? That’s the focus of this study from France.
More than 5000 LDRs have been done around the world now. Enough time has passed to gather some long-term data. In this study patients with single or two-level LDRs were followed for up to 8.6 years. X-rays of spine motion were taken, and motion was compared with pain and function.
The authors report a weak to moderate link between range of motion and results. Patients with low motion (less than five degrees) had poor results compared to patients with more than five degrees of motion after surgery. This makes sense since fusion with no motion often leads to disc degeneration at the next level.
The authors think that since none of the patients with more than five degrees of motion had degeneration at the next level, this amount of motion may protect the spine. Longer-term follow-up is needed to see if increased motion may cause problems later. The 8.6 years of this study is about the halfway mark for the life of the LDRs.