A posterior spinal fusion is indicated for patients diagnosed with a spinal deformity such as Scoliosis, Kyphosis, or Spondylolisthesis, where correction of the spine is necessary. The goal of surgery is to create spinal balance in both the sagittal (side) and coronal planes (front). In simple terms, the patient’s head should be balanced over their hips when viewed from the front, and when viewed from the side. See Spinal Balance.
After the patient is prepped and positioned for surgery, an incision is carefully made over the affected vertebra. The back muscle is neither cut nor pierced but is gently separated off the bone at its attachment, which exposes the spine. The ability to put the muscle off to the side exposes the spine, allows the following things to happen:
- All compression of nerves are adequately addressed
- The facet joints are made accessible
- The mobilization and removal of these facet joints induces the flexibility of the spine, which creates the exceptional correction that is achieved during the standard open procedure.
Using O-arm neurologic navigation, a CT scan is done intraoperatively. The O-arm uses a special computer software produces a 3D image of the spine. This allows the surgeon to place the pedicle screws with uncompromised accuracy.
During the posterior spinal fusion, the spine and its various components are manipulated into balance. The structural and compensatory components are equaled and balanced, and the spine is affixed. When the surgery is completed the patient’s spine is in perfect sagittal and frontal plane balance.
Once the spine is balanced, bone graft is gently laid down on the spine so that a confluent fusion mass can occur. The graft material is generally a combination combination of the patient’s own bone, donor bone, and a synthetic substance called rhBMP.
Once the surgery is finished the muscles are anatomically reaffixed to the bone and reattached. It should be noted that muscles across fusion masses are not a movable segment, therefore they do not contribute to range of motion.