Adult spinal deformity surgery is reserved for a small subset of patients who have failed all reasonable conservative (non-operative) measures. They generally have disabling back and/or leg pain and spinal imbalance. Their functional activities are severely restricted and their overall quality of life has reduced substantially.
The goals of surgery are to restore spinal balance and reduce pain and discomfort by relieving pressure off the nerves (decompression) and maintaining corrected alignment by fusing and stabilizing the spinal segments. Surgical stabilization involves anchoring hooks, wires or screws to the spinal segments and using metal rods to link the anchors together. They act as a tether and allow the spine to fuse in the corrected position. Fusion is performed by using the patient’s own bone or using cadaver or synthetic bone substitutes. In more severe cases, spinal segments have to be cut and realigned (osteotomy) or entire segments may have to be removed prior to realigning the spine (vertebral column resection). There are many different types of surgical procedures designed to treat adult spinal deformities. A detailed description of each is beyond the scope of this discussion.
It is important to note that surgery in the adult deformity population is riskier than in the adolescent teenager. The complication rate is significantly higher and the recovery, a lot slower. Therefore, surgery should only be undertaken as a last resort and only after the patient has a clear understanding of the risks and benefits. All reasonable non-surgical measures should be attempted first. At the same time, when patients are carefully chosen and are mentally well-prepared for the surgery, excellent functional outcomes can be obtained which at times can be a positive life changing experience for a given individual patient.
Recent advances in surgical techniques include less invasive approaches by making smaller incisions as well as using biologic substances to accelerate the fusion process. Use of computer-assisted navigation systems and various forms of spinal cord and nerve monitoring may help in improving surgical precision and accuracy. Although promising, longer follow-ups are needed before one can conclude that they are superior to existing time-honored methods.
Minimally invasive surgery (MIS) techniques are increasingly used to treat adult spinal deformity. However, standard minimally invasive spinal deformity techniques have a more limited ability to restore sagittal balance and match the pelvic incidence-lumbar lordosis (PI-LL) than traditional open surgery.
A retrospective review of minimally invasive spinal deformity surgery cases was performed to identify parameters in the 20% of patients who had the greatest improvement in Oswestry Disability Index (ODI) scores versus those in the 20% of patients who had the least improvement in ODI scores at 2 years' follow-up.
One hundred four patients met the inclusion criteria, and the top 20% of patients in terms of ODI improvement at 2 years (best group, 22 patients) were compared with the bottom 20% (worst group, 21 patients). There were no statistically significant differences in age, body mass index, pre- and postoperative Cobb angles, pelvic tilt, pelvic incidence, levels fused, operating room time, and blood loss between the best and worst groups. However, the mean preoperative ODI score was significantly higher (worse disability) at baseline in the group that had the greatest improvement in ODI score (58.2 vs 39.7, p < 0.001). There was no difference in preoperative PI-LL mismatch (12.8° best vs 19.5° worst, p = 0.298). The best group had significantly less postoperative sagittal vertical axis (SVA; 3.4 vs 6.9 cm, p = 0.043) and postoperative PI-LL mismatch (10.4° vs 19.4°, p = 0.027) than the worst group. The best group also had better postoperative visual analog scale back and leg pain scores (p = 0.001 and p = 0.046, respectively).
The authors recommend that spinal deformity surgeons using MIS techniques focus on correcting a patient's PI-LL mismatch to within 10° and restoring SVA to < 5 cm. Restoration of these parameters seems to impact which patients will attain the greatest degree of improvement in ODI outcomes, while the spines of patients who do the worst are not appropriately corrected and may be fused into a fixed sagittal plane deformity 1).
Both hybrid (HYB) surgical approach and circumferential MIS (cMIS) approach approaches resulted in clinical improvement, as evidenced by decreased Oswestry Disability Index ODI and VAS pain scores. While there was no significant difference in degree of radiographic correction between groups, the HYB group had greater absolute improvement in degree of lumbar coronal Cobb angle correction, increased lumbar lordosis LL, decreased sagittal vertical axis SVA, and decreased LL-Pelvic incidence PI. The complication rate, however, was higher with the HYB approach than with the cMIS approach 2).
For successful multilevel correction and stabilization of degenerative spinal deformities, a rigid basal construct to the sacrum is indispensable.
The surgical treatment of multilevel degenerative spine disease carries a significant risk for pseudarthrosis and screw loosening, mandating a rigid sacropelvic fixation. The use of an iliosacral plate resulted in an inferior surgical and clinical outcome when compared to iliac screws 3).
Korean orthopedic surgeons (OS) and neurosurgeons (NS) received a questionnaire containing 16 cases and response forms via email. After reviewing the cases, physicians were asked to indicate whether they would treat each case with decompression or fusion. If fusion was chosen, physicians were also asked to indicate whether they would perform 3-column osteotomy. Retrospective chi-square analyses were performed to investigate whether the answers to each question differed according to training specialty or amount of surgical experience. Results:
Twenty-nine physicians responded to our survey, of whom 12 were OS and 17 were NS. In addition, 18 (62.1%) had more than 10 years of experience in ASD correction and were assigned to the M10 group, while 11 (37.9%) had less than 10 years of experience and were assigned to the L10 group. We found that for all cases, the surgical strategies favored did not significantly differ between OS and NS or between the M10 and L10 groups. However, for both fusion surgery and 3-column osteotomy, opinions were divided regarding the necessity of the procedures in 4 of the 16 cases. Conclusion:
The surgical strategies favored by physicians were similar for most cases regardless of their training specialty or experience. This suggests that these factors do not affect the surgical strategies selected for ASD treatment, with patient clinical and radiological characteristics having greater importance 4).