Stepwise, Standardized Staged Protocol for Surgical Correction of Adult Spinal Deformity Improves Functional Outcomes

First longitudinal study of CMIS for adult spinal deformity with comments by Neel Anand, MD, and Jeffrey Goldstein, MD.

Peer Reviewed

A new stepwise, standardized approach to circumferential minimally invasive surgery (CMIS) for the correction of adult spinal deformity showed improved radiographic scores and functional outcomes as well as markedly lower complication rates compared with previous methodology in a single-center prospective study conducted at the Cedars-Sinai Spine Center in Los Angeles. The findings were published in the May issue of Spine Deformity.

The study is the first longitudinal study of CMIS for adult spinal deformity and “shows the evolution and 10-year learning curve in developing a CMIS protocol,” lead author Neel Anand, MD, told SpineUniverse.

stepwise arrows point in different directionsThe study is the first longitudinal study of CMIS for adult spinal deformity and “shows the evolution and 10-year learning curve in developing a CMIS protocol”. Photo“The current protocol is an improvement with regard to sagittal alignment and deformity correction, and also is muscle sparing,” commented Jeffrey Goldstein, MD, Orthopaedic Spine Surgeon, Director of Spine Service for Education, and Director of Spine Fellowship at NYU Langone Medical Center Hospital for Joint Diseases. “This new CMIS approach improved the rate of both minor and major complications, and decreased the rate of pseudarthrosis seen with the original protocol to zero.”

“This is another study that emphasizes the clinical significance of understanding the benefits of improving sagittal alignment and provides multiple strategies towards that end,” said Dr. Goldstein, who also is Clinical Professor of Orthopaedic Surgery at NYU School of Medicine.

Prospective Study Design

Dr. Anand and colleagues prospectively examined data from all patients who underwent CMIS correction of adult spinal deformity at 3 or more levels using an old protocol (n=76) and compared them to the new protocol (n=53). All patients had at least 2 years of followup.

The old protocol was in use from 2006-2011 and consisted of two stages: 1) transpsoas lateral interbody fusion above L5-S1 followed by radicular symptomatology assessment; and 2) presacral approach to fusion of L5-S1 (axialLIF) followed by multilevel percutaneous posterior instrumentation.

The new protocol (Figure) was instituted in 2011 and uses an antepsoas or prepsoas approach, achieves lordosis using multilevel 12-degree cages placed as anteriorly as possible, uses a mini-anterior lumbar interbody fusion (mini-ALIF) approach to L5-S1, and uses hypercontoured rods with aggressive reduction techniques.
Figure.New Protocol for CMIS Correction of Adult Spinal DeformityFigure. New Protocol for CMIS Correction of Adult Spinal Deformity. Adapted from Anand et al. ALIF, anterior lumbar interbody fusion; MIS, minimally invasive surgery; PCO, posterior column osteotomy; PI-LL, pelvic incidence–lumbar lordosis; SVA, sagittal vertical axis; TFO, transforaminal osteotomy; TLIF, transforaminal lumbar interbody fusion. Figure © Used With Permission.

Improved Outcomes, Fewer Complications Found With New Protocol

While both protocols were linked to significant improvement in visual analog scale, Oswestry disability index, and the Short Form-36 physical component scores, the new protocol showed significantly greater improvements in delta-Cobb angle, latest SVA, and latest PI-LL mismatch compared with the old protocol (Table).
Table. Comparison of Radiographic OutcomesThe rate of surgical complications were significantly lower using the new protocol than with the original protocol, with rates of minor complications decreasing from 56.6% to 24.5% (P=0.002), and major complications decreasing from 30.3% to 9.4% (P=0.007).

Dr. Anand said the change from a transpsoas lateral approach to an antepsoas lateral approach may have had the greatest impact on outcomes. In particular, this approach led to a significant reduction in quadriceps palsy compared with use of the original transpsoas approach (0% vs 5.3%; P=0.045).

In addition, use of ALIF led to zero cases of pseudarthrosis compared with 9 cases with use of axialLIF under the original protocol. In addition, the new protocol used greater reduction, better translation, and improved contouring of the rod than what was previously done under the older protocol, which is reflected in the better post-operative SVA and PI-LL mismatch outcomes, Dr. Anand said.

Clinical Implications of the Findings

“The antepsoas approach decreased post-operative quadriceps palsy, and the improved instrumentation with larger reduction window used in the revised protocol allows for more aggressive deformity reduction,” Dr. Goldstein said. “ALIF at L5-S1 and the antepsoas approach with hyperlordotic anterior cage provide improvements over presacral in situ fusion,” Dr. Goldstein added.

“Because multiple variables were changed and the surgeon’s learning curve, it is difficult to point to a single variable that led to the improvements seen in the current protocol,” Dr. Goldstein said. “The improvements may be due to one or all the following: surgeon experience, lordotic anterior cage and techniques to improve lordosis from an anterior approach, antepsoas approach, and improved posterior instrumentation.”

Minimally Invasive Approach Versus Open Surgery

Dr. Anand added that the radiological results and clinical outcomes were “as good or better than historical data with open surgery, with a significant reduction in complications. The complication rate with open surgery for this same patient population is in the range of 40% to 60%,” Dr. Anand said.

“Using a staged approach to surgery, which consists of two short surgeries of approximately 3 hours each completed on different days, rather than one long 8- to 10-hour surgery, is beneficial, particularly for elderly patients who do not tolerate long surgeries well,” Dr. Anand said.

“The 3-day staging offers the ability to assess the adequacy of indirect compression,” Dr. Goldstein noted.

Updated on: 05/11/19
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Neel Anand, MD
Clinical Professor of Surgery
Cedars-Sinai Spine Center
Los Angeles, CA

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