B Stephens Richards, chief medical officer, Texas Scottish Rite Hospital for Children, Dallas, USA, and president of the Scoliosis Research Society, is moderating a session at the 19th International Meeting on Advanced Spine Techniques (IMAST; 18−21 July, Istanbul, Turkey) on preventing complications in adolescent idiopathic scoliosis (AIS) surgery. He talked to Spinal News International about the most common complications in AIS, their prevention and management
What are the most common complications after spinal surgery for AIS and what steps should you take prior to surgery to try to prevent them?
Fortunately, complications following surgery for AIS are uncommon. In the immediate postoperative period (within 48 hours after surgery), patients may have respiratory difficulties that require aggressive pulmonary treatment by the respiratory therapist as well as monitoring of their haemoglobin/haematocrit. The pulmonary issues usually resolve quickly, and occasionally postoperative transfusions are required.
In the patient with typical AIS deformity, the primary postoperative complication that we are most concerned about is acute operative site infection. This risk is low (less than 1%) but if it occurs, a return to the operating room for irrigation, debridement, and delayed primary closure is required. Over the longer term course of follow-up (one to six years), delayed infections can occur and actually are more common in their occurrence than acute infections. These will require removal of the implants to eradicate the infection. Fortunately, by this time, the fusion site is well healed and the removal of implants does not compromise the patient’s outcome.
Also, in the patient with typical AIS deformity, the implants may loosen, or disengage, leading to a loss of curve correction within several weeks of the initial operation. Although rare, in this instance, a return to surgery is needed to reconnect the implants and restore the correction.
The most concerning postoperative complication is a neurological deficit. Fortunately, this is rare—in part due to the availability of sophisticated present day intraoperative neuromonitoring. This is extremely important today, as the surgical complexity is increasing for some of the very severe AIS spinal deformities, many of which require aggressive operations such as vertebral column resections. Precautionary steps are actually started preoperatively for AIS patients needing surgery. Those whose nutritional status may be suboptimal are thoroughly evaluated and then treated by their primary care physician if needed. Patients with curves that seem slightly atypical, such as those whose curves are accompanied by excessive kyphosis, should be evaluated by MRI to rule out spinal canal abnormalities. In an effort to minimise surgical infections, patients shower the night before surgery using Hibiclens soap (Mölnlycke Healthcare) to minimise skin bacteria.
What steps should you take during surgery to prevent complications?
To minimise the potential of postoperative infections, intraoperative parenteral antibiotics are administered and, following the prep and drape, adherent skin barriers are used to prevent potential skin bacterial contamination. Regular use of irrigation during the procedure is encouraged, and a thorough irrigation at the conclusion of the procedure is mandatory. Some surgeons use antibiotics in the final irrigation, while others use Betadine (Purdue Products).
Intraoperative neuromonitoring is essential today. If a change occurs in the wave signals with monitoring, the patient’s blood pressure is increased by the anaesthesiologists to increase spinal cord perfusion, and the surgeon carefully evaluates implant placement and the amount of correction achieved. Many subtle changes made by the surgeon or anaesthesiologist as a response to wave signal changes in intraoperative neuromonitoring undoubtedly make a difference and will allow for normal neurological status at the completion of surgery.
During surgery, what are the early signs that a complication has occurred and what steps should you take to ensure that you identify them as soon as possible?
As mentioned before, the earliest signs of potential intraoperative neurological problems are seen by changes in wave signals that occur in the neuromonitoring.This requires expertise on the part of the individual actually performing the neuromonitoring in the operating room with regard to evaluating these changes. The surgeon and anaesthesiologist are notified, and they respond to the early warnings provided by the technician. Doing so probably prevents many neurological complications.
An increase in active bleeding in the surgical field may be the presenting signal of a coagulopathy. The anaesthesiologist, upon notification of this, will respond with the appropriate blood product adjustment to address this. Infection issues will not be identified at the time of surgery but, rather, represent a finding in the postoperative period.
If a complication has been identified, what remedial action should be taken?
If a neurological deficit has occurred, and does not respond to intraoperative measures described before, the curve correction should be released and the surgical implants should be removed. Some surgeons will initiate parenteral steroids, although this treatment remains controversial in its effectiveness. An MRI should be obtained to determine if there is a vascular change to the spinal cord, or if there is pressure on the spinal cord from haematoma or, if implants have been retained, from direct pressure from an implant. Plans should be organised for a future return to the operating room for re-instrumentation, though this timeline may vary considerably.