In some patients who have developed a painful lower back condition, disc replacement surgery may be a successful surgical strategy, as long as the disc itself is the pain generator and they have healthy, stable facet joints. It is also important that they do not have vertebral osteoporosis, excision of the disc or replacement with an artificial disc.
Disc replacement may also be considered in patients who have unusually large disc protrusions with a large proportion of the disc nucleus having herniated into the spinal canal, or in whom a structurally deteriorated disc is associated with multiple symptomatic disc protrusions.
The advantage of disc replacement over the alternative strategy of fusion is the preservation of movement at the treated level and the avoidance of altered stresses on the adjacent segments.
Disc replacement is not suitable when there is instability of the treated segment; when the facet joints are significantly degenerate or symptomatic; when there is vertebral osteoporosis; or in the presence of infection.
In certain anatomical situations, fusion may be a better option than disc arthroplasty.
It may also be contraindicated by certain vascular anomalies or conditions that would make the necessary surgical approach unsafe.
Currently Medicare funding is only available for single level lumbar disc arthroplasty. Two level disease is sometimes dealt with by utilising a hybrid procedure, in which one level is fused and the adjacent level disc is replaced.
Lumbar disc replacement devices are now in their fourth generation. These devices frequently replicate closely the function of a healthy disc. Based on “in vitro” laboratory testing, the expected lifespan of these discs exceeds thirty years. However, it is important to note that no current device has been implanted for a period of time that approaches that, meaning long term clinical results are not available – beyond 10 years for most devices.