What Are the Risks of Surgery?
With any surgical procedure, the risks and benefits of the procedure must be carefully assessed for each individual patient. The risk to the patient of not having surgery must also be addressed.
In the case of progressive scoliosis, the risks of not having surgery if brace treatment has failed or is not indicated involve progressive deformity of the trunk with potential imbalance and offset between the trunk and pelvis when in an upright position. In addition, with thoracic curves, risk to the heart and lung function develops when curves reach 80-90°. This results from compression of the lung within the deformed chest cavity, which makes it difficult for the heart to pump blood through the compressed lung. Most cases of scoliosis are treated prior to curves reaching such a magnitude.
The specific surgical risks are dependent on multiple factors, including the general health of the patient, any underlying medical disorders, as well as the type of surgery that is required. In general, with all operations around the spine there are potential complications relating to the anesthesia, as well as risks of bleeding and wound infection. With anticipation preoperatively, blood loss can be managed by one of several means, depending on the anticipated magnitude of the blood loss. These include pre-donation of the patient’s blood (autologous) or of blood from family members or friends (donor specific). An additional option involves the use of banked blood components. Intraoperative blood conservation techniques can be utilized with either use of hemodilution or blood salvage with recirculation methods to minimize need for other forms of blood replacement.
Additional potential intraoperative complications relate to neurologic injury. Surgery involving the spine places the neural elements of the spinal cord and nerve roots at some risk for injury. Injury to these structures may result in a spectrum of disability that spans from mild numbness to loss of bowel or bladder function to complete paralysis below the area of injury. The risk of spinal cord injury can be minimized, although not completely eliminated, by use of sophisticated spinal cord monitoring systems. This spinal cord monitoring is performed during the exposure and correction of the spinal deformity and monitors electrical function of the spinal cord throughout the surgical procedure. When indicated a “wake-up” test may be utilized to ensure normal neurologic function. This involves decreasing the level of anesthesia, after completion of the deformity correction, to the point that the patient is able to hear and follow commands. The patient is instructed to move the lower extremities to confirm that voluntary motor function remains present. If normal function is observed, the procedure is completed with wound closure. If spinal cord functional problems are noted with spinal cord monitoring and confirmed by abnormality appreciated on a wake-up test, removal or adjustment of the instrumentation may be required. This decreases the stress applied to the spinal cord by the instrumentation system, improving the likelihood of neurological recovery.
Postoperatively, complications may also arise. These include development of a wound infection, pulmonary difficulties, as well as problems associated with the hardware system and fusion. Postoperative wound infections occur in roughly 1 percent of patients. Measures taken to minimize this risk include the use of antibiotics before, during, and after the operation. There are risk factors that increase the likelihood of wound infection, which include poor nutritional status, history of urinary tract infections and revision surgery. In most cases wound infection can be managed by a return to the operating room with cleaning of the wound and closure of the wound over drains, along with prolonged antibiotic use. In rare cases there is a delayed presentation of infection, which may come as late as 1–2 years postoperatively. In these cases, generally the treatment is cleaning of the wound and removal of the hardware. These delayed infections can be successfully managed with hardware removal and antibiotics.
Complications related to the instrumentation system and fusion are possible. In occasional instances, there is loss of fixation of the rod system to the spine, resulting in some loss of correction. This may require revision of the instrumentation system with replacement of hardware and reattachment to the spine. Additionally, there may be difficulties in obtaining fusion at each of the involved levels of the spine. If an area of nonunion (lack of fusion) or pseudarthrosis develops, there may eventually be breakage of the rod system. In many circumstances this does not cause further problems. However, in some cases it may require revision of the instrumentation system if there is pain or evidence of curve progression.