Adjacent segment disease refers to patients who develop new symptoms from the spine in the area adjacent to where they have had surgery previously. This is a real concern for both patients and spine surgeons and in many cases it is not clear whether the changes represent the normal progression of a general degenerate process or if they are due to the consequences of the spine surgery.
The spine is made up of multiple moving segments. If one or more segments are stiffened by fusion surgery then there will be consequences for the rest of the spinal motion segments in terms of the stress and strain that go through those segments. This can lead to accelerated wear and degeneration and for some patients the segment may become symptomatic. This is one reason why spine surgery “fails”.
Motion preservation surgery refers to procedures that aim to avoid fusion with the aim of restoring more normal spinal motion and thus minimise the risk of adjacent segment disease. So far there is little in the way of clinical evidence that proves that motion preservation prevents adjacent segment disease. However it may take some time from the introduction of these technologies before the evidence is available. In the meantime, there is good biomechanical data that suggests that motion preservation is a worthy goal of treatment.
Treatment of adjacent segment disease can be a challenge and sometimes involves more surgery. There are now many options in terms of surgical approaches and implants that help the spine surgeon to solve these problems and minimise risk. Sometimes, the revision surgery may need to be extensive and involve a combination of decompression of neural structures, removal of implants, correction of deformity, reconstruction with implants and bone grafting. Naturally, this type of surgery has many technical difficulties and comes with more risk than primary spine surgery and so needs to be carefully planned and customised to the specific condition and patient being treated.