Does vertebral level of pedicle subtraction osteotomy correlate with degree of spinopelvic parameter correction?

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Pedicle subtraction osteotomy (PSO) is a spinal realignment technique that may be used to correct sagittal spinal imbalance. Theoretically, the level and degree of resection via a PSO should impact the degree of sagittal plane correction in the setting of deformity. However, the quantitative effect of PSO level and focal angular change on postoperative spinopelvic parameters has not been well described. The purpose of this study is to analyze the relationship between the level/degree of PSO and changes in global sagittal balance and spinopelvic parameters.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>In this multicenter retrospective study, 70 patients (54 women and 16 men) underwent lumbar PSO surgery for spinal imbalance. Preoperative and postoperative free-standing sagittal radiographs were obtained and analyzed by regional curves (lumbar, thoracic, and thoracolumbar), pelvic parameters (pelvic incidence and pelvic tilt [PT]) and global balance (sagittal vertical axis [SVA] and T-1 spinopelvic inclination). Correlations between PSO parameters (level and degree of change in angle between the 2 adjacent vertebrae) and spinopelvic measurements were analyzed.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Pedicle subtraction osteotomy distribution by level and degree of correction was as follows: L-1 (6 patients, 24°), L-2 (15 patients, 24°), L-3 (29 patients, 25°), and L-4 (20 patients, 22°). There was no significant difference in the focal correction achieved by PSO by level. All patients demonstrated changes in preoperative to postoperative parameters including increased lumbar lordosis (from 20° to 49°, p &lt; 0.001), increased thoracic kyphosis (from 30° to 38°, p &lt; 0.001), decreased SVA and T-1 spinopelvic inclination (from 122 to 34 mm, p &lt; 0.001 and from +3° to −4°, p &lt; 0.001, respectively), and decreased PT (from 31° to 23°, p &lt; 0.001). More caudal PSO was correlated with greater PT reduction (r = −0.410, p &lt; 0.05). No correlation was found between SVA correction and PSO location. The PSO degree was correlated with change in thoracic kyphosis (r = −0.474, p &lt; 0.001), lumbar lordosis (r = 0.667, p &lt; 0.001), sacral slope (r = 0.426, p &lt; 0.001), and PT (r = −0.358, p &lt; 0.005).</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>The degree of PSO resection correlates more with spinopelvic parameters (lumbar lordosis, thoracic kyphosis, PT, and sacral slope) than PSO level. More importantly, PSO level impacts postoperative PT correction but not SVA.</jats:p></jats:sec>

Pedicle subtraction osteotomies (PSO) in the lumbar spine for sagittal deformities

“…2). An • Morbidity status (pulmonary, cardiac, renal thromboembolic disorder, allergies, overweight, previous spine and other surgery • Expectations of the patient additional reason to perform the osteotomy at L4 (unless the most relevant deformity is in the upper lumbar spine) is that a PSO at a more caudal level provides better correction of the PT while maintaining good potential of correction of the SVA [20]. In the authors' experience, PSOs at L3 or higher frequently result in good correction of SVA with persisting increased PT, suggesting that the need for active compensation (which leads to persistence of symptoms) has not been completely been solved.…”

Repeated adjacent-segment degeneration after posterior lumbar interbody fusion

“…A decrease in sacral slope implies loss of lumbar lordosis. 2,9,10 Although each PLIF achieved local lordosis at the fused segment, lumbar lordosis decreased gradually due to kyphosis of the cranial adjacent segment. A decrease in sacral slope might cause kyphotic mechanical force adjacent to the fused segment.…”

“…At that time, she was postmenopausal but did not demonstrate generalized osteoarthritis and secondary osteoporosis (rheumatoid arthritis-or steroid-induced). The bone mineral density of the femoral neck and young adult mean were 0.847 g/ cm 2 and 98%, respectively. No osteoporosis was detected.…”

Mechanical Complications and Loss of Correction in Osteotomies of the Three Columns

“…Using the same line of reasoning, a correction was considered to be successful only in cases that satisfied 3 postoperative criteria: SVA ≤ 5cm, -10˚ ≤ PI-LL ≤ 10˚, and PT ≤ 24˚. [8][9][10][11]18 Thus, the effect of the surgery was evaluated not only on overall sagittal balance, but also on the use of compensatory spinopelvic mechanisms. Using these criteria to analyze a multicenter database with 99 cases of pedicle subtraction, 8 corrections were achieved in 55% of cases, while by considering only the normalization of the SVA, success would be 65%, similar to the 62% observed by Schwab.…”