Minimally Invasive Spinal Deformity Surgery

摘要

First of all, we would like to address our appreciation to the Congress of Neurological Surgeons for allowing us to speak about an issue that we have great passion for, which is the development of minimally invasive spinal deformity surgery. The most important thing when we are treating a patient with deformity, no matter what kind of approach we choose to use, is that the goals and principles of open vs minimally invasive surgery (MIS) are very similar. The following discussion covers 3 topics: scope and context, current practice and outcomes, and the future directions of MIS. SCOPE AND CONTEXT When we look at an age histogram (Figure 1) depicting the change in population distribution in 1950 and 2007 and the projection in 2050, we can appreciate the reversal from a predominantly young population to a predominantly older population. The US Census predicts that by 2050 there will be >1 million centenarians. So what does this have to do with spinal deformities? In the National Health and Nutrition Examination Survey (NHANES) data,1 it was estimated that 8.3% of the general adult population was affected by scoliosis, which was defined by a Cobb angle ≥10°. Even though not everyone in that group should be surgically corrected, that is a sizeable and growing population. The data also showed that women, who have a longer life expectancy, were affected twice as often as men. Furthermore, as deformities worsen with advancing age, they became more difficult and complicated to correct.FIGURE 1: Age histogram showing the trend of changes in the population in the first world.These data provide supportive evidence that we should expect a growth in the prevalence of complex spinal surgery. The growth of deformity surgery was shown well in a Journal of the American Medical Association article by Deyo et al2 illustrating that there was a recent and significant increase in complex fusion surgery, while the total number of decompression for lumbar stenosis surgeries remains relatively stable and constant. This is not altogether surprising, considering that modern principles of spinal surgery have involved the ideas that correction of deformity and maintenance of sagittal balance are important for improving the clinical outcomes of the patients. However, we are challenged with the conundrum that the intrinsically complex nature of these surgeries is associated with potentially more complications. Data from the Scoliosis Research Society show that 29% of the patients with a deformity surgery have complications.3 Another study conducted by Charosky et al4 in 2012 found that about 39% of patients experienced complications from the surgery. Some groups reported even higher complication rates, as demonstrated by a Weistroffer et al5 study that 42% of the patients undergoing long fusion surgeries to treat scoliosis experienced some form of complication. The reality is that about half of the patients undergoing these complex spinal surgeries may have complications. So the question really is whether the minimally invasive approach allows us to operate on older, sicker, or less healthy patients with a lower rate of complications. Another problem exists when we derive much of our education from the medical society with which we are interacting. Societies specializing in traditional adult deformity surgeries, for example, the Scoliosis Research Society, have been the pioneers of many of the modern principles we apply, although other new societies such as the Society for Minimally Invasive Spine Surgery are focused on less invasive surgery. However, these societies are not communicating on a regular basis. Many of the deformity principles that are promulgated actually work very well, but can they be applied in the MIS realm and in what the MIS surgeon brings to the table? CURRENT PRACTICE AND OUTCOMES It is always good to review the current state of affairs. If we look at the less invasive surgical approaches for deformity, plenty of credit would go to Dr