William C. Horton

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.

Correlation of radiographic parameters and clinical symptoms in adult scoliosis.

Study Design. This study is a retrospective review of the initial enrollment data from a prospective multicentered study of adult spinal deformity. Objectives. The purpose of this study is to correlate radiographic measures of deformity with patient-based outcome measures in adult scoliosis. Summary of Background Data. Prior studies of adult scoliosis have attempted to correlate radiographic appearance and clinical symptoms, but it has proven difficult to predict health status based on radiographic measures of deformity alone. The ability to correlate radiographic measures of deformity with symptoms would be useful for decision-making and surgical planning. Methods. The study correlates radiographic measures of deformity with scores on the Short Form-12, Scoliosis Research Society-29, and Oswestry profiles. Radiographic evaluation was performed according to an established positioning protocol for anteroposterior and lateral 36-inch standing radiographs. Radiographic parameters studied were curve type, curve location, curve magnitude, coronal balance, sagittal balance, apical rotation, and rotatory subluxation. Results. The 298 patients studied include 172 with no prior surgery and 126 who had undergone prior spine fusion. Positive sagittal balance was the most reliable predictor of clinical symptoms in both patient groups. Thoracolumbar and lumbar curves generated less favorable scores than thoracic curves in both patient groups. Significant coronal imbalance of greater than 4 cm was associated with deterioration in pain and function scores for unoperated patients but not in patients with previous surgery. Conclusions. This study suggests that restoration of a more normal sagittal balance is the critical goal for any reconstructive spine surgery. The study suggests that magnitude of coronal deformity and extent of coronal correction are less critical parameters.

Risk-benefit assessment of surgery for adult scoliosis: an analysis based on patient age.

Study Design. Retrospective review of a prospective, multicenter database. Objective. The purpose of this study was to assess whether elderly patients undergoing scoliosis surgery had an incidence of complications and improvement in outcome measures comparable with younger patients. Summary of Background Data. Complications increase with age for adults undergoing scoliosis surgery, but whether this impacts the outcomes of older patients is largely unknown. Methods. This is a retrospective review of a prospective, multicenter spinal deformity database. Patients complete the Oswestry Disability Index (ODI), SF-12, Scoliosis Research Society-22 (SRS-22), and numerical rating scale (NRS; 0–10) for back and leg pain. Inclusion criteria included age 25 to 85 years, scoliosis (Cobb ≥ 30°), plan for scoliosis surgery, and 2-year follow-up. Results. Two hundred six of 453 patients (45%) completed 2-year follow-up, which is distributed among age groups as follows: 25 to 44 (n = 47), 45 to 64 (n = 121), and 65 to 85 (n = 38) years. The percentages of patients with 2-year follow-up by age group were as follows: 25 to 44 (45%), 45 to 64 (48%), and 65 to 85 (40%) years. These groups had perioperative complication rates of 17%, 42%, and 71%, respectively (P < 0.001). At baseline, elderly patients (65–85 years) had greater disability (ODI, P = 0.001), worse health status (SF-12 physical component score (PCS), P < 0.001), and more severe back and leg pain (NRS, P = 0.04 and P = 0.01, respectively) than younger patients. Mean SRS-22 did not differ significantly at baseline. Within each age group, at 2-year follow-up there were significant improvements in ODI (P ⩽ 0.004), SRS-22 (P ⩽ 0.001), back pain (P < 0.001), and leg pain (P ⩽ 0.04). SF-12 PCS did not improve significantly for patients aged 25 to 44 years but did among those aged 45 to 64 (P < 0.001) and 65 to 85 years (P = 0.001). Improvement in ODI and leg pain NRS were significantly greater among elderly patients (P = 0.003, P = 0.02, respectively), and there were trends for greater improvements in SF-12 PCS (P = 0.07), SRS-22 (P = 0.048), and back pain NRS (P = 0.06) among elderly patients, when compared with younger patients. Conclusion. Collectively, these data demonstrate the potential benefits of surgical treatment for adult scoliosis and suggest that the elderly, despite facing the greatest risk of complications, may stand to gain a disproportionately greater improvement in disability and pain with surgery.

Does Treatment (Nonoperative and Operative) Improve the Two-Year Quality of Life in Patients With Adult Symptomatic Lumbar Scoliosis: A Prospective Multicenter Evidence-Based Medicine Study

Study Design. Prospective observational cohort study with matched and unmatched comparisons. Level II evidence. Objective. The purpose of this study is to compare results of adult symptomatic lumbar scoliosis (ASLS) patients treated nonoperatively and operatively. This is an evidence-based prospective multicenter study to answer the question of whether nonoperative and operative treatment improves the quality of life (QOL) in these patients at 2-year follow-up. Summary of Background Data. Only 1 paper in the peer-reviewed published data directly addresses this question. That paper suggested that operative treatment was more beneficial than nonoperative care, but the limitations relate to historical context (all patients treated with Harrington implants) and the absence of validated patient-reported QOL (QOL) data. Methods. This study assesses 160 consecutively enrolled patients (ages 40–80 years) with baseline and 2-year follow-up data from 5 centers. Lumbar scoliosis without prior surgical treatment was defined as a minimum Cobb angle of 30° (mean: 54° for patients in this study). All patients had either an Oswestry Disability Index (ODI) score of 20 or more (mean: 33) or Scoliosis Research Society (SRS) domain scores of 4 or less in pain, function, and self-image (mean: 3.2) at baseline. Pretreatment and 2-year follow-up data collected prospectively included basic radiographic parameters, complications and SRS QOL, ODI, and Numerical Rating Scale back and leg pain scores. Results. At 2 years, follow-up on the operative patients was 95% and for the nonoperative patients it was 45%.The demographics for the nonoperative patients who were followed up for 2 years versus those who were lost to follow-up were identical. The operative cohort significantly improved in all QOL measures. The nonoperativecohort did not improve and nonsignificant decline in QOL scores was common. At minimum 2-year follow-up, operative patients outperformed nonoperative patients by all measures. Conclusion. It would appear from this study that common nonoperative treatments do not change the QOL in patients with ASLS at 2-year follow-up. However, operative treatment does significantly improve the QOL for this group of patients. Our conclusions are limited by the fact that we were only able to follow-up 45% of the nonoperative group to 2-year follow-up, in spite of extensive efforts on our part to accomplish such.

A clinical impact classification of scoliosis in the adult.

Study Design. Multicenter, prospective, consecutive clinical series. Objectives. To establish and validate classification of scoliosis in the adult. Summary of Background Data. Studies of adult scoliosis reveal the impact of radiographic parameters on self-assessed function: lumbar lordosis and frontal plane obliquity of lumbar vertebrae, not Cobb angle, correlate with pain scores. Deformity apex and intervertebral subluxations correlate with disability. Methods. A total of 947 adults with spinal deformity had radiographic analysis: frontal Cobb angle, deformity apex, lumbar lordosis, and intervertebral subluxation. Health assessment included Oswestry Disability Index and Scoliosis Research Society instrument. Deformity apex, lordosis (T12–S1), and intervertebral subluxation were used to classify patients. Outcomes measures and surgical rates were evaluated. Results. Mean maximal coronal Cobb was 46° and lumbar lordosis 46°. Mean maximal intervertebral subluxation (frontal plane) was 4.2 mm (sagittal plane, 1.2 mm). In thoracolumbar/lumbar deformities, the loss of lordosis/higher subluxation was associated with lower Scoliosis Research Society pain/function and higher Oswestry Disability Index scores. Across the study group, lower apex combined with lower lordosis led to higher disability. Higher surgical rates with decreasing lumbar lordosis and higher intervertebral subluxation were detected. Conclusions. A clinical impact classification has been established based on radiographic markers of disability. The classification has shown correlation with self-reported disability as well as rates of operative treatment.

Is there an optimal patient stance for obtaining a lateral 36" radiograph? A critical comparison of three techniques.

Study Design. Scoliosis patients were prospectively x-rayed in three positions with independent analysis. Objectives. To determine if one positioning technique provides superior visualization of critical landmarks (C7, T2, T12, L5–S1) and to determine any position dependent variations in regional measures or sagittal balance. Summary of Background Data. Different techniques for positioning patient’s arms are used for 36” lateral radiograph with no data on relative effects. Methods. A total of 25 scoliosis patients were prospectively studied with 36” lateral radiographs in three positions varying arm location (straight out, partially flexed, and the ”clavicle“ position). Films were analyzed independently by three surgeons. Vertebral landmarks were scored for clarity; and lordosis, kyphosis, and global balance were analyzed. Statistical analysis was done with a General Estimating Equations model. Results. The overall visualization score for the clavicle position was superior to either the 60° or 90° positions (clavicle vs. 60°, P < 0.0001; clavicle vs. 90°, P < 0.0003). Analysis of vertebral landmarks showed significantly better visualization of T2 with clavicle versus 90° (P < 0.047), better visualization of T12 with clavicle versus either 60° (P < 0.006) or 90° (P < 0.049), and better visualization of L5-S1 with clavicle versus 90° (P < 0.02). Regional measures showed no differences, but sagittal balance was significantly more positive in the 60° position than either clavicle (P < 0.04) or 90° (P < 0.015). Conclusions. The clavicle position for obtaining lateral 36” radiographs produces significantly better overall visualization of critical vertebral landmarks. Regional measures do not differ between the three positions, but global balance is more positive with the 60° position. Clinically, the clavicle position may result in more accurate radiographic measures and may minimize repeated radiograph exposures.

Correlations between screw hole preparation, torque of insertion, and pullout strength for spinal screws.

The bone-screw interface is critical in the use of spinal instrumentation. The purpose of these experiments described here was twofold. First, to determine whether a correlation existed between torque generated during screw insertion and the pullout strength. Second, to determine how differing surgical methods of screw hole preparation influenced torque of insertion and screw pullout strength. A series of experiments were carried out in which screws were inserted into synthetic bone (experiment 1) and into calf vertebrae (experiment 2). The method of screw hole preparation (i.e., diameter of entrance hole and pilot hole) was varied while the resulting torque of insertion and the pullout strength of the screw was measured in each case. A torque screwdriver was used to measure the torque of insertion of the screws. Screw pullout strength was measured using a materials testing machine. Two important results emerged from these experiments. First, a higher torque of insertion correlated with a higher screw pullout force. This correlation may be useful intraoperatively in evaluating fixation. Second, torque of insertion and pullout force were more influenced by cortex over-drill diameter than pilot hole diameter. These experiments show the importance of the dorsal cortex in pedicle screw fixation.

Improvement of back pain with operative and nonoperative treatment in adults with scoliosis.

OBJECTIVEThe purpose of this study was to assess whether back pain is improved with surgical treatment compared with nonoperative management in adults with scoliosis. METHODSThis is a retrospective review of a prospective, multicentered database of adults with spinal deformity. At the time of enrollment and follow-up, patients completed standardized questionnaires, including the Oswestry Disability Index (ODI) and Scoliosis Research Society 22 questionnaire (SRS-22), and assessment of back pain using a numeric rating scale (NRS) score, with 0 and 10 corresponding to no and maximal pain, respectively. The initial plan for surgical or nonoperative treatment was made at the time of enrollment. RESULTSOf 317 patients with back pain, 147 (46%) were managed surgically. Compared with patients managed nonoperatively, operative patients had higher baseline mean NRS scores for back pain (6.3 versus 4.8; P < 0.001), higher mean ODI scores (35 versus 26; P < 0.001), and lower mean SRS-22 scores (3.1 versus 3.4; P < 0.001). At the time of the 2-year follow-up evaluation, nonoperatively managed patients did not have significant change in the NRS score for back pain (P = 0.9), ODI (P = 0.7), or SRS-22 (P = 0.9). In contrast, at the 2-year follow-up evaluation, surgically treated patients had significant improvement in the mean NRS score for back pain (6.3 to 2.6; P < 0.001), ODI score (35 to 20; P < 0.001), and SRS-22 score (3.1 to 3.8; P < 0.001). Compared with nonoperatively treated patients, at the time of the 2-year follow-up evaluation, operatively treated patients had a lower NRS score for back pain (P < 0.001) and ODI (P = 0.001), and higher SRS-22 (P < 0.001). CONCLUSIONSDespite having started with significantly greater back pain and disability and worse health status, surgically treated patients had significantly less back pain and disability and improved health status compared with nonoperatively treated patients at the time of the 2-year follow-up evaluation. Compared with nonoperative treatment, surgery can offer significant improvement of back pain for adults with scoliosis.

Operative versus nonoperative treatment of leg pain in adults with scoliosis: a retrospective review of a prospective multicenter database with two-year follow-up.

Study Design. Retrospective review of a prospective, multicenter study. Objective. The purpose of this study was to assess the prevalence and severity of leg pain in adults with scoliosis and to assess whether surgery significantly improved leg pain compared with nonoperative management. Summary of Background Data. Patients with adult scoliosis characteristically present with pain. The presence of leg pain is an independent predictor of a patients choice for operative over nonoperative care. Methods. Data were extracted from a prospective, multicenter database for adult spinal deformity. At enrollment and follow-up, patients complete the Oswestry Disability Index (ODI) and assessment of leg pain using the numerical rating scale (NRS) score, with 0 and 10 representing no pain and unbearable pain, respectively. Plan for operative or nonoperative treatment was made at enrollment. The vast majority of adult scoliosis patients seen in our surgical clinics have received nonoperative therapies and are being seen for a surgical evaluation. Patients are counseled regarding operative and nonoperative management options and are in general encouraged to maximize nonoperative treatments. Results. Two hundred eight (64%) of 326 adults with scoliosis had leg pain at presentation (mean NRS score = 4.7). Ninety-six patients with leg pain (46%) were managed operatively and 112 were treated nonoperatively. The operative group had higher baseline mean NRS score for leg pain (5.4 vs. 4.1, P < 0.001) and higher mean ODI (41 vs. 30, P < 0.001). At 2-year follow-up, nonoperative patients had no significant change in ODI or NRS score for leg pain (P = 0.2). In contrast, at 2-year follow-up surgically treated patients had significant improvement in mean NRS score for leg pain (5.4 vs. 2.2, P < 0.001) and ODI (41 vs. 24, P < 0.001). Compared with nonsurgically treated patients, at 2-year follow-up operative patients had lower mean NRS score for leg pain (2.2 vs. 3.8, P < 0.001) and mean ODI (24 vs. 31, P = 0.005). Conclusion. Despite having started with significantly greater leg pain and disability, surgically treated patients at 2-year follow-up had significantly less leg pain and disability than nonoperatively treated patients. Surgical treatment has the potential to provide significant improvement of leg pain in adults with scoliosis.

The validity of the SRS-22 instrument in an adult spinal deformity population compared with the Oswestry and SF-12: a study of response distribution, concurrent validity, internal consistency, and reliability.

Study Design. Prospective analysis of a consecutive cohort of adult spinal deformity patients queried over a 12-month period. Objectives. To assess the SRS-22 instrument compared with the SF-12 and Oswestry. Summary of Background Data. Very few reports in the literature have applied the SRS-22 to adult spinal deformity patients. Methods. Consecutive adult spinal deformity patients were applied the SRS-22, SF-12, and Oswestry. Four analyses were done: 1) floor/ceiling effect; 2) Pearson’s correlation coefficients between the SRS-22, SF-12, and Oswestry; 3) Cronbach’s alpha analysis for internal consistency within the SRS-22; and 4) test/retest. Results. Floor/ceiling range for the SRS-22 compared favorably with the SF-12 and Oswestry. The Pearson’s coefficients correlating the two questionnaires relative to the SRS-22 were > 0.7. The Cronbach’s alpha within each domain for the SRS-22 were > 0.7, except for pain (0.67). Test/retest correlation coefficients ranged from 0.84 to 0.95 for the subscales. Conclusions. The SRS-22 is a disease-specific instrument with the capacity to demonstrate change in health status more effectively than the SF-12 and in more domains than the Oswestry. The SRS-22 showed high criterion validity with the SF-12 and Oswestry based on Pearson’s coefficients. High Cronbach’s alpha scores suggested a high internal consistency within each domain of the SRS-22, except for pain (0.67). Test/retest reliability was excellent.