Frank J. Schwab

The Impact of Positive Sagittal Balance in Adult Spinal Deformity

Study Design. This study is a retrospective review of 752 patients with adult spinal deformity enrolled in a multicenter prospective database in 2002 and 2003. Patients with positive sagittal balance (N = 352) were further evaluated regarding radiographic parameters and health status measures, including the Scoliosis Research Society patient questionnaire, MOS short form-12, and Oswestry Disability Index. Objectives. To examine patients with adult deformity with positive sagittal balance to define parameters within that group that might differentially predict clinical impact. Summary of Background Data. In a multicenter study of 298 adults with spinal deformity, positive sagittal balance was identified as the radiographic parameter most highly correlated with adverse health status outcomes. Methods. Radiographic evaluation was performed according to a standarized protocol for 36-inch standing radiographs. Magnitude of positive sagittal balance and regional sagittal Cobb angle measures were recorded. Statistical correlation between radiographic parameters and health status measures were performed. Potentially confounding variables were assessed. Results. Positive sagittal balance was identified in 352 patients. The C7 plumb line deviation ranged from 1 to 271 mm. All measures of health status showed significantly poorer scores as C7 plumb line deviation increased. Patients with relative kyphosis in the lumbar region had significantly more disability than patients with normal or lordotic lumbar sagittal Cobb measures. Conclusions. This study shows that although even mildly positive sagittal balance is somewhat detrimental, severity of symptoms increases in a linear fashion with progressive sagittal imbalance. The results also show that kyphosis is more favorable in the upper thoracic region but very poorly tolerated in the lumbar spine.

Pelvic tilt and truncal inclination: two key radiographic parameters in the setting of adults with spinal deformity.

Study Design. Prospective radiographic and clinical analysis. Objective. Investigate the relationship between spino-pelvic parameters and patient self reported outcomes on adult subjects with spinal deformities. Summary of Background Data. It is becoming increasingly recognized that the study of spinal alignment should include pelvic position. While pelvic incidence determines lumbar lordosis, pelvic tilt (PT) is a positional parameter reflecting compensation to spinal deformity. Correlation between plumbline offset (sagittal vertical axis [SVA]) and Health Related Quality of Life (HRQOL) measures has been demonstrated, but such a study is lacking for PT. Methods. This prospective study was carried out on 125 adult patients suffering from spinal deformity (mean age: 57 years). Full-length free-standing radiographs including the spine and pelvis were available for all patients. HRQOL instruments included: Oswestry Disability Index, Short Form-12, Scoliosis Research Society. Correlation analysis between radiographic spinopelvic parameters and HRQOL measures was pursued. Results. Correlation analysis revealed no significance pertaining to coronal plane parameters. Significant sagittal plane correlations were identified. SVA and truncal inclination measured by T1 spinopelvic inclination (T1–SPI) (angle between T1–hip axis and vertical) correlated with: Scoliosis Research Society (appearance, activity, total score), Oswestry Disability Index, and Short Form-12 (physical component score). Correlation coefficients ranged from 0.42 < r < 0.55 (P < 0.0001). T1–SPI revealed greater correlation with HRQOL compared to SVA. PT showed correlation with HRQOL (0.28 < r < 0.42) and with SVA (r = 0.64, P < 0.0001). Conclusion. This study confirms that pelvic position measured via PT correlates with HRQOL in the setting of adult deformity. High values of PT express compensatory pelvic retroversion for sagittal spinal malalignment. This study also demonstrates significant T1–SPI correlation with HRQOL measures and outperforms SVA. This parameter carries the advantage of being an angular measurement which avoids the error inherent in measuring offsets in noncalibrated radiographs.

Adult Spinal Deformity-Postoperative Standing Imbalance : How Much Can You Tolerate? An Overview of Key Parameters in Assessing Alignment and Planning Corrective Surgery

Study Design. Current concepts review. Objective. Outline the basic principles in the evaluation and treatment of adult spinal deformity patients with a focus on goals to achieve during surgical realignment surgery. Summary of Background Data. Proper global alignment of the spine is critical in maintaining standing posture and balance in an efficient and pain-free manner. Outcomes data demonstrate the clinical effect of spinopelvic malalignment and form a basis for realignment strategies. Methods. Correlation between certain radiographic parameters and patient self-reported pain and disability has been established. Using normative values for several important spinopelvic parameters (including sagittal vertical axis, pelvic tilt, and lumbar lordosis), spinopelvic radiographic realignment objectives were identified as a tool for clinical application. Because of the complex relationship between the spine and the pelvis in maintaining posture and the wide range of “normal” values for the associated parameters, a focus on global alignment, with proportionality of individual parameters to each other, was pursued to provide clinical relevance to planning realignment for deformity across a range of clinical cases. Conclusion. Good clinical outcome requires achieving proper spinopelvic alignment in the treatment of adult spinal deformity. Although variations in pelvic morphology exist, a framework has been established to determine ideal values for regional and global parameter in an individualized patient approach. When planning realignment surgery for adult spinal deformity, restoring low sagittal vertical axis and pelvic tilt values are critical goals, and should be combined with proportional lumbar lordosis to pelvic incidence.

Sagittal Plane Considerations and the Pelvis in the Adult Patient

Study Design. Research update, focused review. Objective. Identify the role of the pelvis in the setting of adults with spinal deformity. Summary of Background Data. Sagittal plane alignment is increasingly recognized as a critical parameter in the setting of adult spinal deformity. Additionally, pelvic parameters reveal to be a key component in the regulation of sagittal alignment. Methods. Analysis of the pelvis in the sagittal plane is commonly assessed by 3 angular measurements: the pelvic incidence (morphologic parameter directly linked to sagittal morphotypes), the pelvic tilt (or pelvis retroversion used to maintain an upright posture in the setting of spinal deformity), and the sacral slope. Recent work using force plate technology has revealed that in the setting of anterior trunk inclination (“spinal imbalance”), the pelvis shifted posteriorly (toward the heels) in order to maintain a balanced mass distribution. The complex relationship between pelvic and spinal parameter were investigated in order to construct predictive formulas of postoperative spinopelvic alignment. It has emerged that pelvic tilt is highly correlated with patient self reported function (ODI, SF-12, and SRS). Conclusion. It has become evident that good clinical outcome in the treatment of spinal deformity requires proper alignment. Pelvis parameters play an essential role not only in terms of spine morphotypes but also in regulating standing balance and postoperative alignment. Thus, optimal treatment of a patient with spinal deformity requires integration of the pelvis in the preoperative evaluation and treatment plan.

Adult scoliosis : Prevalence, SF-36, and nutritional parameters in an elderly volunteer population

Study Design. A prospective self-assessment analysis and evaluation of nutritional and radiographic parameters in a consecutive series of healthy adult volunteers older than 60 years. Objectives. To ascertain the prevalence of adult scoliosis, assess radiographic parameters, and determine if there is a correlation with functional self-assessment in an aged volunteer population. Summary of Background Data. There exists little data studying the prevalence of scoliosis in a volunteer aged population, and correlation between deformity and self-assessment parameters. Methods. There were 75 subjects in the study. Inclusion criteria were: age ≥60 years, no known history of scoliosis, and no prior spine surgery. Each subject answered a RAND 36-Item Health Survey questionnaire, a full-length anteroposterior standing radiographic assessment of the spine was obtained, and nutritional parameters were analyzed from blood samples. For each subject, radiographic, laboratory, and clinical data were evaluated. The study population was divided into 3 groups based on frontal plane Cobb angulation of the spine. Comparison of the RAND 36-Item Health Surveys data among groups of the volunteer population and with United States population benchmark data (age 65−74 years) was undertaken using an unpaired t test. Any correlation between radiographic, laboratory, and self-assessment data were also investigated. Results. The mean age of the patients in this study was 70.5 years (range 60−90). Mean Cobb angle was17° in the frontal plane. In the study group, 68% of subjects met the definition of scoliosis (Cobb angle >10°). No significant correlation was noted among radiographic parameters and visual analog scale scores, albumin, lymphocytes, or transferrin levels in the study group as a whole. Prevalence of scoliosis was not significantly different between males and females (P > 0.03). The scoliosis prevalence rate of 68% found in this study reveals a rate significantly higher than reported in other studies. These findings most likely reflect the targeted selection of an elderly group. Although many patients with adult scoliosis have pain and dysfunction, there appears to be a large group (such as the volunteers in this study) that has no marked physical or social impairment. Conclusions. Previous reports note a prevalence of adult scoliosis up to 32%. In this study, results indicate a scoliosis rate of 68% in a healthy adult population, with an average age of 70.5 years. This study found no significant correlations between adult scoliosis and visual analog scale scores or nutritional status in healthy, elderly volunteers.

Adult scoliosis: a quantitative radiographic and clinical analysis.

Study Design. Prospective analysis of a consecutive series of adult patients with adolescent idiopathic scoliosis of the adult and de novo degenerative scoliosis. Objectives. To clinically and radiographically study two populations of adult patients with either adolescent idiopathic scoliosis of the adult or de novo degenerative scoliosis in a quantitative manner to identify reliable radiographic parameters that correlate with clinical symptoms. Summary and Background. Although there are many causes of spinal deformity in the adult, there are two main categories of adult scoliosis: adolescent idiopathic scoliosis of the adult and de novo degenerative scoliosis. Unlike pediatric scoliosis, in adults there are no established radiographic parameters or classification systems that reliably provide a clinical correlation or offer a useful language for communication among specialists. This study gathered complete clinical and radiographic information on 95 patients with adult scoliosis and established several radiographic parameters that correlated with clinical symptoms. Methods. Each of the 95 patients completed a clinical questionnaire that included a self-reported visual analog scale and underwent full-length standing anteroposterior and lateral radiography. Radiographic analysis was performed by use of digital analysis and included measurement of the Cobb angle, the number of vertebrae in each curve, plumbline offset from T1 to the midsacral line, the upper endplate obliquities of L3 and L4, and maximal lateral olisthy between two adjacent lumbar vertebrae. Sagittal plane measurements included lumbar lordosis, thoracolumbar kyphosis, and the Sagittal Pelvic Tilt Index. Statistical analysis of both radiographic and clinical parameters of pain was performed to determine any significant correlations between the two. Results. This study showed that lateral vertebral olisthy, L3 and L4 endplate obliquity angles, lumbar lordosis, and thoracolumbar kyphosis were significantly correlated with pain. Conclusion. This quantitative analysis identified several clinically relevant radiographic parameters in adult scoliosis patients. Additionally, excellent predictive for-mulas for self-reported pain levels were obtained.

Radiographical spinopelvic parameters and disability in the setting of adult spinal deformity: a prospective multicenter analysis.

Study Design. Prospective multicenter study evaluating operative (OP) versus nonoperative (NONOP) treatment for adult spinal deformity (ASD). Objective. Evaluate correlations between spinopelvic parameters and health-related quality of life (HRQOL) scores in patients with ASD. Summary of Background Data. Sagittal spinal deformity is commonly defined by an increased sagittal vertical axis (SVA); however, SVA alone may underestimate the severity of the deformity. Spinopelvic parameters provide a more complete assessment of the sagittal plane but only limited data are available that correlate spinopelvic parameters with disability. Methods. Baseline demographic, radiographical, and HRQOL data were obtained for all patients enrolled in a multicenter consecutive database. Inclusion criteria were: age more than 18 years and radiographical diagnosis of ASD. Radiographical evaluation was conducted on the frontal and lateral planes and HRQOL questionnaires (Oswestry Disability Index [ODI], Scoliosis Research Society-22r and Short Form [SF]-12) were completed. Radiographical parameters demonstrating highest correlation with HRQOL values were evaluated to determine thresholds predictive of ODI more than 40. Results. Four hundred ninety-two consecutive patients with ASD (mean age, 51.9 yr) were enrolled. Patients from the OP group (n = 178) were older (55 vs. 50.1 yr, P < 0.05), had greater SVA (5.5 vs. 1.7 cm, P < 0.05), greater pelvic tilt (PT; 22° vs. 11°, P < 0.05), and greater pelvic incidence/lumbar lordosis PI/LL mismatch (PI-LL; 12.2 vs. 4.3; P < 0.05) than NONOP group (n = 314). OP group demonstrated greater disability on all HRQOL measures compared with NONOP group (ODI = 41.4 vs. 23.9, P < 0.05; Scoliosis Research Society score total = 2.9 vs. 3.5, P < 0.05). Pearson analysis demonstrated that among all parameters, PT, SVA, and PI-LL correlated most strongly with disability for both OP and NONOP groups (P < 0.001). Linear regression models demonstrated threshold radiographical spinopelvic parameters for ODI more than 40 to be: PT 22° or more (r = 0.38), SVA 47 mm or more (r = 0.47), PI − LL 11° or more (r = 0.45). Conclusion. ASD is a disabling condition. Prospective analysis of consecutively enrolled patients with ASD demonstrated that PT and PI-LL combined with SVA can predict patient disability and provide a guide for patient assessment for appropriate therapeutic decision making. Threshold values for severe disability (ODI > 40) included: PT 22° or more, SVA 47 mm or more, and PI − LL 11° or more.

Gravity line analysis in adult volunteers: age-related correlation with spinal parameters, pelvic parameters, and foot position.

Study Design. Prospective radiographic and forceplate analysis in adult volunteers. Objective. Assess gravity line (GL) location and foot position regarding anatomic spinal structures to evaluate key correlations and age-related changes in balance. Summary of Background Data. Global spinal balance is commonly assessed by the C7 plumbline. This radiographic parameter does not offer information on foot position or forces transmitted, and poor correlation with the true GL has been demonstrated. Methods. A total of 75 asymptomatic adult volunteers were equally distributed into three age groups. Full length, free-standing spine radiographs were obtained with simultaneous acquisition of GL and feet location (forceplate). GL and heels were projected on each radiograph to compute their distance from anatomic entities and to investigate correlations with radiologic parameters and age-related changes. Results. In this study group, advancing age led to a significant increase in thoracic kyphosis. The plumbline from C7 shifted anteriorly with age. In the sagittal plane, the GL was anterior to the vertebral column for all groups. With age, the GL location regarding the heels remained constant, while the pelvis moved posteriorly toward the heels and underwent a small retroversion (increasing pelvic tilt). The acetabulum was the most reliable radiographic marker of the GL location. Conclusions. This quantitative study in volunteers reveals clear age-related changes in the spino-pelvic association and offers quantitative support to the “cone of economy” concept proposed by Dubousset. The pelvis can be seen as a regulator to help maintain a rather fixed GL-heel association with age-related changes in the spinal column. Further study in patients suffering from deformity can confirm the importance of radiographic-gravity line correlations and enhance our understanding of optimal balance.

The impact of perioperative complications on clinical outcome in adult deformity surgery.

Study Design. Retrospective case-control series. Objective. The purpose of this study is to determine whether perioperative complications alter subsequent clinical outcome measures in adult spinal deformity surgery. Summary of Background Data. Increasingly, the benefit of surgical intervention is being evaluated based on patient reported outcomes and standardized health related quality of life (HRQOL) measures. As improvement or deterioration in HRQOL scores becomes a standard for clinical evaluation in adult spinal deformity, the correlation between HRQOL outcome scores and historic benchmarks, such as curve correction, sagittal balance, fusion healing, or the occurrence of a complication, must be clarified. Methods. This study analyzes a prospective multicenter data base for adult spinal deformity. Patients with major, minor, and no complications were matched using a logistic regression technique producing 46 patients in each group. Standardized outcome measures at baseline and at 1 year postop were compared. Results. Forty-seven major complications were reported in 46 patients. Sixty-two minor complications were noted in 46 patients. Comparison between the 3 complication groups revealed that 1-year postoperative outcome measures were not statistically different for the Scoliosis Research Society Outcomes Instrument, Medical Outcomes Short Form-36 (SF-12), Oswestry Disability Index, or Numerical Pain Scales. The only significant interaction was in the rate of change from preop to 1-year postop for the SF-12 general health subscale. For the group with major complications, SF-12 general health deteriorated by 2.1 points from preop to 1-year postop. During the same period, the group with minor complications experienced an improvement of 4.2 points and the group with no complications experienced an improvement of 1.5 points. Conclusion. This study suggests that risk for minor complications may be a less substantial obstacle than previously assumed for surgical treatment in adult spinal deformity. In contrast, major complications were reported in approximately 10% of cases and adversely affected outcome as evidenced by the deterioration in SF-12 general health scores at 1 year after surgery.

Standing Balance and Sagittal Plane Spinal Deformity: Analysis of Spinopelvic and Gravity Line Parameters

Study Design. Prospective study of 131 patients and volunteers recruited for an analysis of spinal alignment and gravity line (GL) assessment by force plate analysis. Objective. To determine relationships between GL, foot position, and spinopelvic landmarks in subjects with varying sagittal alignment. Additionally, the study sought to analyze the role of the pelvis in the maintenance of GL position. Summary of Background Data. Force plate technology permits analysis of foot position and GL in relation to radiographically obtained landmarks. Previous investigation noted fixed GL-heel relationship across a wide age range despite changes in thoracic kyphosis. The pelvis as balance regulator has not been studied in the setting of sagittal spinal deformity. Methods. The 131 subjects were grouped by sagittal vertical axis (SVA) offset from the sacrum: sagittal forward (>2.5 cm), neutral (−2.5 cm ≤ SVA ≤ 2.5 cm), and sagittal backward (SVA <−2.5 cm). Simultaneous spinopelvic radiographs and GL measure were obtained. Offsets between spinopelvic landmarks, heel position, and GL were calculated. Group comparisons were made for all offsets to determine significance. Results. Aside from the offset T9-GL and GL-heels, all other offsets between spinopelvic landmarks and GL revealed significant differences (P < 0.001) across the 3 subject groups. However, with increasing SVA, the GL kept a rather fixed location relative to the feet. A correlation between posterior pelvic shift in relation to the heels with increasing SVA in this study population was confirmed (r = 0.6, P < 0.001). Conclusion. Increasing SVA in standing subjects leads to a posterior pelvic shift in relation to the feet. However, no significant difference in GL-heel offset is noted with increasing SVA. It thus appears that pelvic shift (in relation to the feet) is an important component in maintaining a rather fixed GL-Heels offset even in the setting of variable SVA and trunk inclination.