Paradigm Shift in Adult Spinal Deformity
Lead Author Christopher P. Ames, MD Comments
The evaluation and management of adult spinal deformity (ASD) is changing with the recognition that the severity of sagittal plane deformity drives pain, disability, and surgical outcomes. This is according to a new paper from the Scoliosis Research Society recently published in Spine Deformity.
“Sagittal deformity is the most significant driver of disability scores,” explained lead author Christopher P. Ames, MD. Dr. Ames is a Neurosurgeon at the University of California, San Francisco Medical Center. “If surgery is performed, restoration of the sagittal plane is most important in determining outcomes,” he continued.
However, many are still unaware of current research that deformity in the coronal plane (scoliosis) is not as impactful as a deformity in the sagittal plane. “Unfortunately, this is still a common misconception, especially in the general medical community and among patients. One of the main purposes of the article was to educate the medical community at large about the critical role of the sagittal plane in driving disability and determining the surgical outcome,” Dr. Ames said.
Health care reform is driving the need to improve patient outcomes and lower costs, which increases the importance of publishing an evidence-based approach to the evaluation and treatment of ASD.
“The number of hospital discharges with a diagnosis of abnormal spinal curvature in adults has increased by 157% in the past 10 years,” according to the authors. Additionally, there is an increase in the number of comorbidities with ASD as well as more complex surgical techniques, necessitating this evidence-based guide.
The sagittal vertical axis (SVA), measured as the distance between a plumb line dropped vertically from central C7 to a plumb line dropped vertically from the posterior superior corner of the sacrum is widely used in the assessment of ASD. This measurement along with pelvic tilt (PT) and the mismatch between pelvic incidence and lumbar lordosis (PI-LL) are three key radiographic measures for sagittal and spinopelvic alignment.
Impact of the Sagittal Plane in ASD
According to the authors, “When ASD patients are evaluated according to the type of spinal deformities that they manifest, patients with abnormalities in spinopelvic sagittal alignment report the worst HRQOL (health-related quality of life) scores.” More specifically, “patients who are pitched forward in the sagittal plane demonstrate the most pain and disability.”
The authors discussed a 2013 prospective study by Schwab et al. and commented, “The three parameters that most correlated with disability included SVA, PT, and PI-LL,” all important measurements in sagittal alignment.
Commenting on a 2016 study by Bess et al on the impact of ASD on general health the authors said, “patients with primarily sagittal deformities (scoliosis <20 degrees, SVA >5 cm) reported similar PCS (physcial HRQOL summary score) scores as patients with osteoarthritis and rheumatoid arthritis functioning below the 25th percentile.” Furthermore, “patients with severe sagittal deformity (SVA >10 cm) had similar PCS scores as patients with chronic lung disease that function below the 25th percentile.”
The authors summarize the treatment of ASD with nonsurgical approaches such as physical therapy by stating, “Medical/interventional treatment of ASD has few reports in the literature, with generally low levels of evidence. Furthermore, medical/interventional management is costly and does not appear to significantly improve the mean health statuses of patients over a short-term follow-up.”
Regarding bracing, there is limited data and although some may find relief, the authors stated, “braces have not been shown to reduce curve progression in ASD,” and “many patients stop wearing the brace because of discomfort.” Despite these limitations, there is a consensus that patients should be “generally encouraged” to try nonsurgical options if recommended.
If nonoperative treatment options fail, surgery may offer hope. The authors cite numerous examples of studies comparing surgical and conservative outcomes. The surgical groups are consistently superior to the conservative groups in improved pain and disability.
Indications for surgery include, “progression of deformity, neural compromise, pain and functional limitations that are generally severe enough to be unresponsive to the medical/interventional care options.” When asked what the most important determinants of a good surgical outcome were, Dr. Ames replied, “preoperative disability.”
Sagittal alignment correction is important for successful surgical outcomes. Commenting on a study by Blondel et al, “The authors determined that the patients that had the most improvement in HRQOL and were more likely to reach MCID (minimum clinically important difference) had greater SVA correction.” Furthermore, “this study complements other studies reporting worse baseline HRQOL for patients with sagittal malalignment, and that surgical correction of the sagittal deformities results in large improvements in function and health status,” they concluded.