Minimally invasive surgery for adult spinal deformity [Neurosurgery Wiki]

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====== Minimally invasive surgery for adult spinal deformity ======

MIS management recommendations based on severity of ASD with approximate SRS-Schwab Class equivalence

{{::minimally_invasive_surgery_for_adult_spinal_deformity.png?600|}}


[[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
((Than KD, Park P, Fu KM, Nguyen S, Wang MY, Chou D, Nunley PD, Anand N, Fessler
RG, Shaffrey CI, Bess S, Akbarnia BA, Deviren V, Uribe JS, La Marca F, Kanter AS,
Okonkwo DO, Mundis GM Jr, Mummaneni PV; International Spine Study Group. Clinical
and radiographic parameters associated with best versus worst clinical outcomes
in minimally invasive spinal deformity surgery. J Neurosurg Spine. 2016
Jul;25(1):21-5. doi: 10.3171/2015.12.SPINE15999. Epub 2016 Mar 4. PubMed PMID:
26943254.
)).

----


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
((Park P, Wang MY, Lafage V, Nguyen S, Ziewacz J, Okonkwo DO, Uribe JS, Eastlack
RK, Anand N, Haque R, Fessler RG, Kanter AS, Deviren V, La Marca F, Smith JS,
Shaffrey CI, Mundis GM Jr, Mummaneni PV; , on behalf of the International Spine
Study Group. Comparison of two minimally invasive surgery strategies to treat
adult spinal deformity. J Neurosurg Spine. 2015 Jan 30:1-7. [Epub ahead of print]
PubMed PMID: 25635632.
)).

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
((Finger T, Bayerl S, Onken J, Czabanka M, Woitzik J, Vajkoczy P. Sacropelvic
fixation versus fusion to the sacrum for spondylodesis in multilevel degenerative
spine disease. Eur Spine J. 2014 Jan 22. [Epub ahead of print] PubMed PMID:
24448893.)).
----
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
((Kang J, Hosogane N, Ames C, Schwab F, Hart R, Burton D, Shaffrey C, Smith JS, 
Bess S, Lafage V, Cho KJ, Ha Y; International Spine Study Group and Asian Pacific
Spine Study Group. Diversity in Surgical Decision Strategies for Adult Spine
Deformity Treatment: The Effects of Neurosurgery or Orthopedic Training
Background and Surgical Experience. Neurospine. 2018 Aug 29. doi:
10.14245/ns.1836086.043. [Epub ahead of print] PubMed PMID: 30157582.
)).