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The mainstay of scoliosis surgery is from the posterior or from the back approach. The original Harrington rod instrumentation and fusion have evolved into many more generations of instrumentation which allow better capture and movement of the spine into a more anatomic position. Many of the problems of Harrington instrumentation have been eliminated in the hands of skilled spine surgeons. Metallic constructs used include stainless steel, alloys and titanium. There is no right or wrong choice for metal as each surgeon uses the particular metal that he is most comfortable with. Each has its advantages and drawbacks but all are capable of allowing correction, and maintaining it while the spine heals.
In the posterior approach, an incision is made down the midline of the back and the subcutaneous tissues and muscle layers are peeled back from the spine. The spine is further cleaned and prepared for the fusion. Next a variety of screws and hooks are placed in the spine to gain control of as many vertebrae as possible. These are attached to two rods which allow the surgeon to then bend the rods and mobilize each fixation point on the spine. Through careful manipulation, the spine is moved slowly to a straighter more anatomic position. Throughout this entire procedure the spinal cord function is carefully monitored with somatosensory evoked potential, SSEPs, and motor evoked potentials, MEPs, which allow the surgeon and his team to carefully monitor any changes in spinal cord function to help prevent neurologic injury.
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Intraoperative view of posterior instrumentation | After the surgeon is satisfied with the amount of correction, a bone graft is usually harvested from the iliac crest, often from the same incision. A small window is made in the pelvis and the cancellous or spongy bone is removed. After this the outer cortical bone is removed from the spine by curettes, osteotomes and high speed burrs. This effectively prepares the spine for fusion and the cancellous bone is then placed over the prepared spine segments and the spine is fused, although this complete fusion take place over the next 6-9 months or longer. Sometimes additional bone bank graft or bone growth factors are added to accelerate healing and add a volume matrix for fusion. The soft tissues are placed back over the spine and the incision closed and the procedure completed.
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