Update on use of instrumentation in lumbar spine disorders

The past 20 years have witnessed significant changes in the indications for and use of instrumentation in lumbar spine surgery. Absolute indications for surgical instrumentation include cases of clearly defined instability that commonly occur in the setting of trauma, tumour and infection. Relative indications for instrumentation must consider the clinical context and individual patient characteristics but may include cases of spondylolisthesis, junctional stenosis and pseudarthrosis. The use of instrumentation in the surgical treatment of degenerative disc disease is prevalent but remains highly controversial. Pedicle screws and interbody cages represent alternative forms of instrumentation with substantial clinical evidence supporting their safety and efficacy when applied in the correct clinical settings. Minimally invasive and computer-assisted surgical techniques have shown promising early results but must be subject to longer-term scrutiny. The development of prosthetic disc replacements is an exciting area of research, but clinical results have not approached the success currently enjoyed by hip and knee prostheses, and these devices should be considered experimental. One of the goals of instrumentation is to enhance the rate of spinal fusion. However, achievement of solid radiographic fusion does not guarantee a clinically successful outcome and, conversely, excellent results can be obtained in the setting of radiographic pseudarthrosis. The most important determinant of favourable surgical outcome is appropriate patient selection through a sound understanding of surgical indications.