An age and sex matched study on the effect of obesity on the functional outcomes and complication rates in patients with adult spinal deformity undergoing primary multi-level thoracolumbar spinal fusion

Background

The objective of this study was to determine the effect of obesity on the functional outcomes and complication rates of patients with adult spinal deformity (ASD) undergoing multi-level thoracolumbar fusion.

Methods

An age and sex matched comparison of functional outcomes [Numeric Rating Scale (NRS) back and leg scores, Core Outcome Measurement Index (COMI) back scores, Scoliosis Research Society 22 (SRS22) satisfaction and total scores, Short Form 36 (SF36) general health scores, Physical Component Score (PCS), Mental Component Score (MCS), Oswestry Disability Index (ODI) (including all domains)] at 6 months, 1, 2, 3 and 4 years and the complication rates at final follow-up between obese [body mass index (BMI) >30] and normal BMI (18.5-24.9) patients undergoing more than 3 levels of thoracolumbar fusion with a minimum 2-year follow-up. Patients who had undergone any previous spinal surgery were excluded.

Results

Thirty patients were included in each arm of the study. Baseline demographics, including the number of levels fused, were similar between the groups. Estimated blood loss (EBL) was higher in obese patients (1,916 vs. 1,099 mL, P=0.001), but operative time was similar (282 vs. 320 min, P=0.351). The functional outcomes and satisfaction scores were consistently poorer in the obese group at all time-points, but their satisfaction scores were similar. Obese patients had a higher complication rate (OR 3.05, P=0.038) predominantly due to dural tears and nerve root injuries, but a similar reoperation rate.

Conclusions

In patients with ASD undergoing multi-level thoracolumbar fusion, obesity results in a higher blood loss, poorer sagittal correction, poorer post-operative functional scores and higher complication rates than patients with a normal BMI. However, obesity does not affect operative times, length of hospital stay or reoperation rates. Furthermore, patients with obesity have similar post-operative satisfaction scores to patients with normal BMIs.

Obeid-Coronal Malalignment Classification Is Age Related and Independently Associated to Personal Reported Outcome Measurement Scores in the Nonfused Spine

Objective

To evaluate Obeid-coronal malalignment (O-CM) modifiers according to age, sagittal alignment, and patient-reported outcome measures (PROMs), in the mobile spine.

Methods

Retrospective review of a prospective multicenter adult spinal deformity (ASD) database with 1,243 (402 nonoperative, 841 operative) patients with no prior fusion surgery. Patients were included if they were aged over 18 years and were affected by spinal deformity defined by one of: Cobb angle ≥ 20°, pelvic tilt ≥ 25°, sagittal vertical axis ≥ 5 cm, thoracic kyphosis ≥ 60°. Patients were classified according to the O-CM classification and compared to coronally aligned patients. Multivariate analysis was performed on the relationship between PROMs and age, global tilt (GT) and coronal malalignment (CM).

Results

Four hundred forty-three patients had CM of more than 2 cm compared to 800 who did not. The distribution of these modifiers was correlated to age. After multivariate analysis, using age and GT as confounding factors, we found that before the age of 50 years, 2A1 patients had worse sex life and greater satisfaction than patients without CM. After 50 years of age, patients with CM (1A1, 1A2) had worse self-image and those with 2A2, 2B had worse self-image, satisfaction, and 36-item Short Form Health Survey physical function. Self-image was the consistent determinant of patients opting for surgery for all ages.

Conclusion

CM distribution according to O-CM modifiers is age dependent. A clear correlation between the coronal malalignment and PROMs exists when using the O-CM classification and in the mobile spine, this typically affects self-image and satisfaction. Thus, CM classified according to O-CM modifiers is correlated to PROMs and should be considered in ASD.

Improvement of Life After PVCR in Complete Paraplegic Patients with Posttraumatic Severe Kyphosis

AIM

To determine the effect of posterior vertebral column resection (PVCR) in patients with paraplegia by using the American Spinal Injury Association (ASIA) score and Scoliosis Research Society (SRS)-22 questionnaire.

MATERIAL AND METHODS

Twelve patients with posttraumatic paraplegia and severe angular kyphosis ( > 60?) had undergone PVCR between 6-24 months after the trauma for severe pain, persistent vertebral instability and difficulty in adherence to rehabilitation. ASIA scores and SRS-22 questionnaire results obtained in the preoperative and postoperative periods, and the last control were statistically compared to assess the presence of any change.

RESULTS

The average age of twelve patients included in this study was 35.6 ± 10.2 (21-51) years. Female/male ratio was 2/10 (20.0%). The mean follow-up duration was 50.3 ± 17.6 (24-86) months. None of the patients had additional changes in neuromonitoring records during surgery. The mean preoperative kyphotic angle of the patients was 66.58° ± 7.1? (60?-82?) which decreased to 7.0? ± 5.4? in the postoperative period (p < 0.05). The mean ASIA score, which was 43.3 ± 5.1 preoperatively, increased to 44.4 ± 4.4 in the postoperative period. The SRS-22 score, which was 2.4 ± 0.3 in the preoperative period, increased to 4.2 ± 0.4 in the early postoperative period. This increase was found to be statistically significant (p < 0.05). The SRS-22 score was 4.1 ± 0.4 at last follow-up and was not statistically different from the early postoperative value (p > 0.05).

CONCLUSION

In the light of these data, it can be stated that PVCR is a safe and reliable procedure in paraplegic patients with rigid posttraumatic kyphosis and increases patient satisfaction.

The Effect of Discharging Patients with Low Hemoglobin Levels on Hospital Readmission and Quality of Life after Adult Spinal Deformity Surgery

Study Design

Retrospective cohort.

Purpose

This study aims to evaluate the impact of anemia on functional outcomes, health-related quality of life (HRQoL), and early hospital readmission (EHR) rates after adult spinal deformity (ASD) surgery at the time of discharge from the hospital.

Overview of Literature

Concerns with risks of transfusion, insufficient evidence for its benefits, and the possibility of associated adverse outcomes have led to restrictive transfusion practices. Therefore, patients are discharged according to patient blood management programs that are implemented in hospitals nationwide to reduce unnecessary blood transfusions. However, not many comprehensive kinds of studies exist on the effect of postoperative anemia on functional life and complications.

Methods

Anemia severity was defined following the 2011 World Health Organization guidelines. All patients had HRQoL tests as well as complete blood counts pre- and postoperatively. EHR is the admission within 30 days of discharge and was used as the dependent parameter.

Results

This study comprised 225 surgically treated ASD patients with a median age of 62.0 years, predominantly women (80%). Of the 225 patients, 82, 137, and six had mild, moderate, and severe anemia at the time of discharge, respectively. Seventeen of the patients (mild [11, 64.7%]; moderate [5, 29.4%]; severe [1, 5.9%]) were readmitted within 30 days. The mean hemoglobin values were higher in readmitted patients (p=0.071). Infection was the leading cause of readmission (n=12), but a low hemoglobin level was not observed in any of these patients at the time of discharge. Except for Scoliosis Research Society-22 questionnaire, HRQoL improvements did not reach statistical significance in early readmitted patients in the first year after surgery.

Conclusions

The results of this study demonstrated that the occurrence and the severity of postoperative anemia are not associated with EHR in surgically treated patients with ASD. The findings of the current research suggested that clinical awareness of the parameters other than postoperative anemia may be crucial. Thus, improvements in HRQoL scores were poor in early readmitted patients 1 year after surgery.

Blended Learning Is a Feasible and Effective Tool for Basic Pediatric Spinal Deformity Training

STUDY DESIGN

Descriptive study.

OBJECTIVE

Assessing the applicability of blended learning to specific domains of spine surgery.

METHODS

After the needs assessment, a blended pediatric spine deformity course program was designed. A total of 33 participants, including orthopedic and neurosurgeons, registered for the course and all of them completed an online entrance quiz. Thus, they were eligible to have online part of course, which included the theoretical part of the course and also a discussion forum where the discussions about the topics facilitated by faculty. Thirteen of 33 subjects participated second part of the blended pediatric spine deformity course. This face-to-face (F2F) part consisted of case discussions for each topic and discussions facilitated by faculty members. The same quiz was also taken before and after the F2F part. All quiz results were compared statistically.

RESULTS

There were 11 lectures within the online part and 6 case discussions in the F2F part. The quiz scores were improved significantly by having a complete blended pediatric deformity course (P < .05).

CONCLUSIONS

The current study has demonstrated that blended learning format, including online and F2F, is feasible and effective in training for a domain of spine surgery, pediatric deformity in this specific context.

Variation of Minimum Clinically Important Difference by Age, Gender, Baseline Disability, and Change of Direction in Adult Spinal Deformity Population: Is It a Constant Value?

BACKGROUND

The minimum clinically important difference (MCID), an important concept to evaluate the effectiveness of treatments, might not be a single "magical" constant for any given health-related quality of life (HRQoL) scale. Thus, we analyzed the effects of various factors on MCIDs for several HRQoL measures in an adult spinal deformity population.

METHODS

Surgical and nonsurgical patients from a multicenter adult spinal deformity database who had completed pretreatment and 1-year follow-up questionnaires (Core Outcome Measures Index [COMI], Oswestry Disability Index [ODI], Medical Outcomes Study 36-item short-form questionnaire, 22-item Scoliosis Research Society Outcomes questionnaire, and an anchor question of "back health"-related change during the previous year) were evaluated. The MCIDs for each HRQoL measure were calculated using an anchor-based method and latent class analysis for the overall population and subpopulations stratified by age, gender, and baseline scores (ODI and COMI) separately for patients with positive versus negative perceptions of change.

RESULTS

Patients with a baseline ODI score of <20, 20-40, and >40 had an MCID of 2.24, 11.35, and 26.57, respectively. Similarly, patients with a baseline COMI score of <2.75, 2.8-5.4, and >5.4 had an MCID of 0.59, 1.38, and 3.67 respectively. The overall MCID thresholds for deterioration and improvement were 0.27 and 2.62 for COMI, 2.23 and 14.31 for ODI, and 0.01 and 0.71 for 22-item Scoliosis Research Society Outcomes questionnaire, respectively.

CONCLUSIONS

The results from the present study have demonstrated that MCIDs change in accordance with the baseline scores and direction of change but not by age or gender. The MCID, in its current state, should be considered a concept rather than a constant.

Diverse approaches to scoliosis in young children

Management of scoliosis in young children needs a comprehensive approach because of its complexity. There are many debatable points; however, only serial casting, growing rods (including traditional and magnetically controlled) and anterior vertebral body tethering will be discussed in this article.Serial casting is a time-gaining method for postponing surgical interventions in early onset scoliosis, despite the fact that it has some adverse effects which should be considered and discussed with the family beforehand.Use of growing rods is a growth-friendly surgical technique for the treatment of early onset spine deformity which allows chest growth and lung development. Magnetically controlled growing rods are effective in selected cases although they sometimes have a high number of unplanned revisions.Anterior vertebral body tethering seems to be a promising novel technique for the treatment of idiopathic scoliosis in immature cases. It provides substantial correction and continuous curve control while maintaining mobility between spinal segments. However, long-term results, adverse effects and their prevention should be clarified by future studies. Cite this article: EFORT Open Rev 2020;5:753-762. DOI: 10.1302/2058-5241.5.190087.

Decision Analysis in Quest of the Ideal Treatment in Adult Spinal Deformity Adjusted for Minimum Clinically Important Difference

BACKGROUND

Surgery appears to yield better results in adult spinal deformity treatment when fixed minimum clinically important difference values are used to define success. Our objective was to analyze utilities and improvement provided by surgical versus nonsurgical treatment at 2 years using Oswestry Disability Index with treatment-specific minimum clinically important difference values.

METHODS

From a multicenter database including 1452 patients, 698 with 2 years of follow-up were analyzed. Mean age of patients was 50.95 ± 19.44 years; 580 patients were women, and 118 were men. The surgical group comprised 369 patients, and the nonsurgical group comprised 329 patients. The surgical group was subcategorized into no complications (192 patients), minor complications (97 patients) and major complications (80 patients) groups to analyze the effect of complications on results. Minimum clinically important differences using Oswestry Disability Index were 14.31, 14.96, and 2.48 for overall, surgical, and nonsurgical groups. Utilities were calculated by visual analog scale mapping.

RESULTS

Surgical treatment provided higher utility (0.583) than nonsurgical treatment (0.549) that was sensitive to complications, being 0.634, 0.564, and 0.497 in no, minor, and major complications. Probabilities of improvement, unchanged, and deterioration were 38.3%, 39.2%, and 22.5% for surgical treatment and 39.4%, 10.5%, and 50.1% for nonsurgical treatment. Improvement in the surgical group was also sensitive to complications with rates of 40.1%, 39.3%, and 33.3%.

CONCLUSIONS

Our results suggest that surgical treatment has less disease burden and less chance of deterioration, but equal chances for improvement at 2 years of follow-up. As it appears to be a better modality in the absence of complications, future efforts need be directed to decreasing the complication rates.

Anterior Spinal Artery Syndrome: Rare Precedented Reason of Postoperative Plegia After Spinal Deformity Surgery: Report of 2 Cases

BACKGROUND

Complications in spinal deformity surgery vary from insignificant to severe. Apart from direct mechanical insult, ischemia can also cause spinal cord injury. Ischemic injury may be detected during surgery or may manifest itself postoperatively. We present 2 cases of anterior spinal artery syndrome.

CASE DESCRIPTION

In the first case, a 12-year-old girl developed anterior spinal artery syndrome resulting in total quadriplegia 8 hours after spinal deformity surgery. She was treated with a steroid, immunoglobulin, and low-molecular-weight heparin. She showed complete recovery at 1 year postoperatively both clinically and radiographically. In the second case, a 62-year-old woman experienced sudden loss of motor evoked potentials intraoperatively during dural tear repair after sagittal and coronal alignment was established. The paraplegic patient was diagnosed with anterior spinal artery syndrome at the thoracic level postoperatively. She was treated with a steroid and heparin. At 1 year postoperatively, she has gained much of her strength and has myelomalacia in her spinal cord.

CONCLUSIONS

Anterior spinal artery syndrome is a serious condition with a generally poor prognosis. Though treatment should be directed at the underlying cause, the best strategy is to prevent it from occurring. Peroperative blood pressure control, intraoperative neuromonitoring, avoidance from mechanical stress during surgery, and close neurologic and hemodynamic monitorization postoperatively should be performed.

The effect of increasing body mass index on the pain and function of patients with adult spinal deformity

Background

Both adult spinal deformity (ASD) and obesity are growing concerns internationally. This study therefore aims to determine the effect of increasing body mass index (BMI) on the pain and function of patients with ASD.

Methods

A retrospective review of prospectively collected data from a multicentre European database was undertaken. Initially a univariate analysis was performed on the effect of BMI on the initial presentation of functional scores in patients with ASD. The functional scores included the Numerical Rating Scale (NRS) back and leg score, Core Outcome Measures Index (COMI) back score, SRS22 total score, Short Form 36 (SF-36) [general health, physical component score (PCS) and mental component score (MCS)] and Oswestry Disability Index (ODI) score (including all domains). Subsequently a multivariate analysis controlling for age, sex, comorbidities, employment status, smoking status and radiological parameters [coronal cobb, coronal balance, sagittal balance, global tilt, and pelvic incidence minus lumbar lordosis (PI - LL) mismatch] was performed.

Results

A total of 1,004 patients were included in this study (166 male, 838 female). On univariate analysis a statistically significant (P<0.05) moderate correlation between NRS leg pain, ODI (walking, standing, sex life, social life and total score), SF-36 (physical component), sagittal balance, global tilt and age were recognised (P<0.05). A statistically significant low correlation was identified for all other outcomes, except coronal balance (P=0.640). On multivariate analysis BMI remained significantly related to all functional outcomes except ODI-pain and ODI-travelling (P>0.05).

Conclusions

Increasing BMI has a significant adverse effect on the pain and functioning of patients with ASD. Clinicians should recognise this association and treat patients accordingly.

Does the Application of Topical Intrawound Vancomycin Powder Affect Deep Surgical Site Infection and the Responsible Organisms after Spinal Surgery?: A Retrospective Case Series with a Historical Control Group

STUDY DESIGN

Retrospective case series with a historical control group.

PURPOSE

To compare the deep wound infection rates in patients undergoing spinal surgery with the application of topical intrawound vancomycin powder (TIVP) in the surgical site in addition to standard systemic prophylaxis with those in a matched historical cohort of patients for whom TIVP was not used.

OVERVIEW OF LITERATURE

Surgical site infection (SSI) after spine surgery is debilitating and is responsible for a significant increase in the health care costs, hospital stay, and morbidities. Although the application of TIVP before surgical closure is a promising method for reducing the SSI rate after spine surgery, its use is controversial, and currently, research trials are focusing on identifying its safety, efficacy, and the potential patient population.

METHODS

A group of 88 patients who underwent posterior spinal surgery with TIVP administration (treatment group) was compared to a historical control group of 70 patients who had received only standard systemic intravenous prophylaxis (control group) for the analysis of deep SSI rate and the involved organisms.

RESULTS

The overall rate of deep SSIs was 2.5% (4/158). All the SSIs were observed in patients who had posterior instrumentation and fusion for ≥3 levels. In the treatment group, the SSI rate was 3.4% (3/88), and the bacteria isolated were Escherichia coli (n=2) and Pseudomonas aeruginosa (n=1). In the control group, the infection rate was 1.4% (1/70), and the isolated bacteria were Morganella morganii and Staphylococcus epidermidis. No statistically significant association was found between the SSI rates of the treatment and control groups.

CONCLUSIONS

Although the difference in the SSI rates was not statistically significant, the present results suggest that TIVP administration could not reduce the risk of deep SSIs after spinal surgery. Moreover, TIVP administration might also affect the underlying pathogens by increasing the propensity for gram-negative species.

Adult Spinal Deformity Over 70 Years of Age: A 2-Year Follow-Up Study

Background

Treatment of adult spinal deformity (ASD) in elderly patients remains controversial. The aim of this study was to identify the factors leading to the surgical treatment by comparing the baseline characteristics of operative versus nonoperative patients, to evaluate the safety and efficacy of surgery, and to compare operative and nonoperative management of elderly ASD patients at the end of the 2-year follow-up period.

Methods

Retrospective review of a multicenter, prospective ASD database was performed. Patients over 70 years of age with ASD who were scheduled to undergo surgical treatment and who were treated and/or followed without surgical intervention participated in the study. Demographic, clinical, surgical, and radiological characteristics and health-related quality-of-life (HRQOL) (Core Outcome Measures Index [COMI], Oswestry Disability Index [ODI], Short-Form-36 Mental Component Summary [SF-36 MCS], Short-Form-36 Physical Component Summary [SF36-PCS], and Scoliosis Research Society-22 [SRS-22]) parameters of such group of patients were evaluated pre- and posttreatment.

Results

A total 90 patients (females: 71, males: 29; operative: 61, nonoperative: 29) made up the study group. The comparison between the operative and the nonoperative groups at baseline showed statistical significance for all the HRQOL parameters and the major coronal Cobb angle (P < .05). The calculated optimal cutoff values to diverge operative and nonoperative groups for COMI, ODI, SF-36 PCS, and SRS-22 were 5.7, 37.0, 37.5, and 3.2, respectively (P < .05). All operative patients were treated with posterior surgery. Overall, 135 complications (71 major, 64 minor) and 1 death were observed. Surgically treated patients were found to be improved both clinically and in HRQOL parameters 2 years after surgery for all HRQOL parameters except SF-36 MCS, even in the presence of complications (P < .05), while nonoperative patients have not changed or deteriorated at the end of 2 years.

Conclusions

Despite a relatively high incidence of complications, the likelihood of achieving a clinically significant and relevant HRQOL improvement was superior for patients who were treated surgically in the present population.

Adult spinal deformity surgical decision-making score. Part 2: development and validation of a scoring system to guide the selection of treatment modalities for patients above 40 years with adult spinal deformity

PURPOSE

We aimed to develop and internally validate a scoring system, the adult spinal deformity surgical decision-making (ASD-SDM) score, to guide the decision-making process for ASD patients aged above 40 years.

METHODS

A multicentre prospective ASD database was retrospectively reviewed. The scoring system was developed using data from a derivation set and was internally validated in a validation set. The performance of the ASD-SDM score for predicting surgical management was assessed using the area under the receiver operating characteristic curve (AUC).

RESULTS

A total of 702 patients were included for analysis in the present study. The scoring system developed based on 562 patients, ranging from 0 to 12 points, included five parameters: leg pain scored by the numerical rating scale; pain and self-image domains in the Scoliosis Research Society-22 score; coronal Cobb angle; and relative spinopelvic alignment. Surgical indication was graded as low (score 0 to 4), moderate (score 5 to 7), and high (score 8 to 12) groups. In the validation set of 140 patients, the AUC for predicting surgical management according to the ASD-SDM score was 0.797 (standard error = 0.037, P < 0.001, 95% confidence interval = 0.714 to 0.861), and in the low, moderate, and high surgical indication groups, 23.7%, 43.5%, and 80.4% of the patients, respectively, were treated surgically.

CONCLUSIONS

The ASD-SDM score demonstrated reliability, with higher scores indicating a higher probability of surgery. This index could aid in the selection of surgery for ASD patients in clinical settings. These slides can be retrieved under Electronic Supplementary Material.

Validation of a Simplified SRS-Schwab Classification Using a Sagittal Modifier

STUDY DESIGN

Multicenter, prospective study of consecutive adult spinal deformity (ASD) patients.

OBJECTIVE

To Validate Schwab's classification accuracy for surgical indication, and to evaluate a simplified sagittal modifier.

SUMMARY OF BACKGROUND DATA

The SRS-Schwab Radiologic Classification based on clinical impact parameters, offers 27 different sagittal classification possibilities regarding sagittal vertical alignment (SVA), pelvic tilt (PT), and pelvic incidence-lumbar lordosis (PI-LL). The high number of classification possibilities makes it complex to use.

METHODS

Inclusion criteria were ASD patients, presenting at least 1 criteria: Cobb ≥ 20°, SVA ≥ 5 cm, thoracic kyphosis ≥ 60°, or PT ≥ 25°. A total of 1,004 patients (410 nonoperative and 594 operative) were classified regarding SVA, PT, and PI-LL (0, +, ++), and 27 possibilities were identified. Categories were formed by adding the number of + signs, considering PT, SVA, and PI-LL. Three specific categories were identified: Aligned: 0 +; Moderate deformity: 1 to 3+; and Severe deformity: 4 to 6+. A χ-square test was performed for surgical indication (operated or not) and an analysis of variance was performed to evaluate the relationship between categories and Oswestry Disability Index (ODI). Probability <.05 was considered significant.

RESULTS

Significant differences for HRQoL scores and surgical indication were found in the 27 sagittal parameter possibilities. For nonoperative patients, 230 (56.1%) were classified as aligned, 145 (35.4%) as moderate, and 35 (8.5%) as severe. For operative patients, there were 200 (33.7%), 215 (36.2%), and 179 (30.1%) in each respective subgroup. For HRQoL scores and surgical indication, no significant differences were found within each category, but significant differences were found when comparing the subgroups.

CONCLUSIONS

Despite the correlation between SRS-Schwab classification and surgical indication, it is complex to use, with a total of 27 possibilities regarding sagittal modifiers. This simplification into three categories offers more readability, without losing any significant information, and could replace Schwab sagittal modifiers. In association with other parameters, they could be used for decision-making.

LEVEL OF EVIDENCE

Level II.

Adult spinal deformity surgical decision-making score : Part 1: development and validation of a scoring system to guide the selection of treatment modalities for patients below 40 years with adult spinal deformity

PURPOSE

We aimed to develop and internally validate a simple scoring system: the adult spinal deformity (ASD) surgical decision-making (ASD-SDM) score, which is specific to the decision-making process for ASD patients aged below 40 years.

METHODS

A multicentre prospective ASD database was retrospectively reviewed. The scoring system was developed using data from a derivation cohort and was internally validated in a validation cohort. The accuracy of the ASD-SDM score was assessed using the area under the receiver operating characteristic curve (AUC).

RESULTS

A total of 316 patients were randomly divided into derivation (253 patients, 80%) and validation (63 patients, 20%) cohorts. A 10-point scoring system was created from four variables: self-image score in the Scoliosis Research Society-22 score, coronal Cobb angle, pelvic incidence minus lumbar lordosis mismatch, and relative spinopelvic alignment, and the surgical indication was graded into low (score 0-4), moderate (score 5-7), and high (score 8-10) surgical indication groups. In the validation cohort, the AUC for selecting surgical management according to the ASD-SDM score was 0.789 (SE 0.057, P < 0.001, 95% CI 0.655-0.880). The percentage of patients treated surgically were 21.1%, 55.0%, and 80.0% in the low, moderate, and high surgical indication groups, respectively.

CONCLUSIONS

The ASD-SDM score, to the best of our knowledge, is the first algorithm to guide the decision-making process for the ASD population and could be one of the indices for aiding the selection of treatment for ASD. These slides can be retrieved under Electronic Supplementary Material.

Radiographic Axial Malalignment is Associated With Pretreatment Patient-Reported Health-Related Quality of Life Measures in Adult Degenerative Scoliosis: Implementation of a Novel Radiographic Software Tool

STUDY DESIGN

Retrospective study of prospectively collected data.

OBJECTIVES

The purpose of this study was to evaluate the relationship between apical vertebral axial rotation and pretreatment patient-reported health-related quality of life (HRQOL), disability, and pain in patients with adult degenerative scoliosis (ADS) using a novel radiographic software tool.

SUMMARY OF BACKGROUND DATA

Recent studies have demonstrated that in ADS, sagittal and coronal plane deformity are weakly to moderately associated with HRQOL, disability, and pain. However, as ADS is a three-dimensional spinal deformity, the impact of axial malalignment on HRQOL is yet to be determined.

METHODS

A total of 74 ADS patients were enrolled. HRQOL measures included the Short Form-36v2 (SF-36v2) and Scoliosis Research Society questionnaire (SRS-22r). Disability and pain measures included the Oswestry Disability Index (ODI) and numeric rating scale back and leg pain. Radiographic measures included Cobb angle (CA), sagittal spinopelvic parameters, lateral and anteroposterior (AP) translation of the apical vertebra. The amount of apical vertebral axial rotation was measured on digital AP radiograph images using a novel software technology. Subjects were stratified into four clinical groups based on the degree of apical vertebral axial rotation.

RESULTS

Apical vertebral axial rotation showed no association with lateral (r = 0.21; p = .15) and AP (r = 0.08, p = .80) translation of the apical vertebra. A significant moderate association was found between apical vertebral axial rotation and Cobb angle (r = 0.57; p < .05). Patients in the group with the highest degree of apical vertebral axial rotation reported significantly worse ODI and SRS-22r Subtotal and Pain scores (p < .05), irrespective of sagittal spinopelvic parameters.

CONCLUSIONS

This is the first study that reports on the association between apical vertebral axial rotation and pretreatment HRQOL, disability, and pain in ADS. This study suggests that increased apical vertebral axial rotation is associated with suboptimal pretreatment health status scores.

LEVEL OF EVIDENCE

Level III.

Minimum clinically important difference of the health-related quality of life scales in adult spinal deformity calculated by latent class analysis: is it appropriate to use the same values for surgical and nonsurgical patients?

BACKGROUND CONTEXT

Health-related quality of life (HRQOL) parameters have been shown to be reliable and valid in patients with adult spinal deformity (ASD). Minimum clinically important difference (MCID) has become increasingly important to clinicians in evaluating patients with a threshold of improvement that is clinically relevant.

PURPOSE

To calculate MCID and minimum detectable change (MDC) values of total scores of the Core Outcome Measures Index (COMI), Oswestry Disability Index (ODI), Physical Component Summary (PCS), Mental Component Summary (MCS) of the Short Form 36 (SF-36), and Scoliosis Research Society 22R (SRS-22R) in surgically and nonsurgically treated ASD patients who have completed an anchor question at pretreatment and 1-year follow-up.

STUDY DESIGN/SETTING

Prospective cohort.

PATIENT SAMPLE

Surgical and nonsurgical patients from a multicenter ASD database.

OUTCOME MEASURES

Self-reported HRQOL measures (COMI, ODI, SF-36, SRS-22R, and anchor question).

METHODS

A total of 185 surgical and 86 nonsurgical patients from a multicenter ASD database who completed pretreatment and 1-year follow-up HRQOL scales and the anchor question at the first year follow-up were included. The anchor question was used to determine MCID for each HRQOL measure. MCIDs were calculated by an anchor-based method using latent class analysis (LCA) and MDCs by a distribution-based method.

RESULTS

All differences between means of baseline and first year postoperative total score measures for all scales demonstrated statistically significant improvements in the overall population as well as the surgically treated patients but not in the nonsurgical group. The calculated MDC and MCID values of HRQOL parameters in the entire study population were 1.34 and 2.62 for COMI, 10.65 and 14.31 for ODI, 6.09 and 7.33 for SF-36 PCS, 6.14 and 4.37 for SF-36 MCS, and 0.42 and 0.71 for SRS-22R. The calculated MCID values for surgical and non-surgical treatment groups were 2.76 versus 1.20 for COMI, 14.96 versus 2.45 for ODI, 7.83 versus 2.15 for SF-36 PCS, 5.14 versus 2.03 for SF-36 MCS, and 0.94 versus 0.11 for SRS-22R; the MDC values for surgical and nonsurgical treatment groups were 1.22 versus 1.51 for COMI, 10.27 versus 9.45 for ODI, 5.16 versus 6.77 for SF-36 PCS, 6.05 versus 5.67 for SF-36 MCS, and 0.38 versus 0.43 for SRS-22R.

CONCLUSIONS

This study has demonstrated that MCID calculations for the HRQOL scales in ASD using LCA yield values comparable to other studies that had used different methodologies. The most important finding was the significantly different MCIDs for COMI, ODI, SF-36 PCS and SRS-22 in the surgically and nonsurgically treated cohorts. This finding suggests that a universal MCID value, inherent to a specific HRQOL for an entire cohort of ASD may not exist. Use of different MCIDs for surgical and nonsurgical patients may be warranted.

The Influence of Diagnosis, Age, and Gender on Surgical Outcomes in Patients With Adult Spinal Deformity

STUDY DESIGN

Retrospective review of prospectively collected data from a multicentric database.

OBJECTIVES

To determine the clinical impact of diagnosis, age, and gender on treatment outcomes in surgically treated adult spinal deformity (ASD) patients.

METHODS

A total of 199 surgical patients with a minimum follow-up of 1 year were included and analyzed for baseline characteristics. Patients were separated into 2 groups based on improvement in health-related quality of life (HRQOL) parameters by minimum clinically important difference. Statistics were used to analyze the effect of diagnosis, age, and gender on outcome measurements followed by a multivariate binary logistic regression model for these results with statistical significance.

RESULTS

Age was found to affect SF-36 PCS (Short From-36 Physical Component Summary) score significantly, with an odds ratio of 1.017 (unit by unit) of improving SF-36 PCS score on multivariate analysis (P < .05). The breaking point in age for this effect was 37.5 years (AUC = 58.0, P = .05). A diagnosis of idiopathic deformity would increase the probability of improvement in Oswestry Disability Index (ODI) by a factor of 0.219 and in SF-36 PCS by 0.581 times (P < .05). Gender was found not to have a significant effect on any of the HRQOL scores.

CONCLUSIONS

Age, along with a diagnosis of degenerative deformity, may have positive effects on the likelihood of improvement in SF-36 PCS (for age) and ODI (for diagnosis) in surgically treated patients with ASD and the breaking point of this effect may be earlier than generally anticipated. Gender does not seem to affect results. These may be important in patient counseling for the anticipated outcomes of surgery.

Relative pelvic version: an individualized pelvic incidence-based proportional parameter that quantifies pelvic version more precisely than pelvic tilt

BACKGROUND CONTEXT

Pelvic tilt (PT) is used as an indicator of pelvic version with increased values indicating retroversion and disability. The concept of using PT solely as an absolute numerical value can be misleading, especially for the patients with pelvic incidence (PI) values near the upper and lower normal limits. Relative pelvic version (RPV) is a PI-based individualized measure of the pelvic version. Relative pelvic version indicates the individualized spatial orientation of the pelvis relative to the ideal sacral slope as defined by the magnitude of PI.

PURPOSE

The aim of this study was to compare RPV and PT for their ability to predict mechanical complications and their correlations with health-related quality of Life (HRQoL) scores.

STUDY DESIGN

A retrospective analysis of a prospectively collected data of adult spinal deformity patients was carried out. Mechanical complications (proximal junctional kyphosis or proximal junctional failure, distal junctional kyphosis or distal junctional failure, rod breakage, and implant-related complications) and HRQoL scores (Oswestry Disability Index [ODI], Core Outcome Measures Index [COMI], Short Form-36 Physical Component Summary [SF-36 PCS], and Scoliosis Research Society 22 Spinal Deformity Questionnaire [SRS-22]) were used as outcome measures.

METHODS

Inclusion criteria were ≥4 levels fusion, and ≥2-year follow-up. Correlations between PT, RPV, PI, and HRQoL were analyzed using Pearson correlation coefficient. Pelvic incidence values and mechanical complication rates in RPV subgroups for each PT category were compared using one-way analysis of variance, Student t test, and chi-squared tests. Predictive models for mechanical complications with RPV and PT were analyzed using binomial logistic regressions.

RESULTS

A total of 222 patients (168 women, 54 men) met the inclusion criteria. Mean age was 52.2±19.3 (18-84) years. Mean follow-up was 28.8±8.2 (24-62) months. There was a significant correlation between PT and PI (r=0.613, p<.001), threatening the use of PT to quantify pelvic version for different PI values. Relative pelvic version was not correlated with PI (r=-0.108, p>.05), being able to quantify pelvic version for all PI values. Compared with PT, RPV had stronger partial correlations with ODI, COMI, SF-36 PCS, and SRS-22 scores (p<.05). Discrimination performance assessed by area under the curve, percentage accuracy in classification, true positive rate, true negative rate, and positive and negative predictive values was better for the model with RPV than for PT. For average PI sizes, the agreement between RPV and PT were moderate (0.609, p<.001), whereas the agreement in small and large PI sizes were poor (0.189, p>.05; -0.098, p>.496, respectively). When analyzed by RPV, each PT "0," "+," and "++" category was further divided into two or three distinct subgroups of patients having different PI values (p=.000, p=.000, and p=.029, respectively). Relative pelvic version subgroups within the same PT category displayed different mechanical complication rates (p=.000, p=.020, and p=.019, respectively).

CONCLUSIONS

Pelvic tilt may be insufficient or misleading in quantifying normoversion for the whole spectrum of PI values when used as an absolute numeric value in conjunction with previously reported population-based average thresholds of 20 and 30 degrees. Relative pelvic version offers an individualized quantification of ante-, normo-, and retroversion for all PI sizes. Schwab PT groups were found to constitute inhomogeneous subgroup of patients with different mean PI values and mechanical complication rates. Compared with PT, RPV showed a greater association with both mechanical complications and HRQoL.

Factors associated with having an indication for surgery in adult spinal deformity: an international european multicentre study

PURPOSE

The aim of this study was to evaluate factors that distinguish between patients with adult spinal deformity (ASD) with and without an indication for surgery, irrespective of their final treatment.

METHODS

Baseline variables (demographics, medical history, outcome measures, coronal, sagittal and neurologic parameters) were evaluated in a multicentre, prospective cohort of patients with ASD. Multivariable analyses were carried out for idiopathic and degenerative patients separately with the dependent variable being "indication for surgery" and baseline parameters as independent variables.

RESULTS

In total, 342 patients with degenerative ASD and 624 patients with idiopathic ASD were included in the multivariable models. In patients with degenerative ASD, the parameters associated with having an indication for surgery were greater self-rated disability on the Oswestry Disability Index [odds ratio (OR) 1.04, 95% confidence interval (CI) 1.02-1.07] and a lower thoracic kyphosis (OR 0.97 95% CI 0.95-0.99), whereas in patients with idiopathic ASD, it was lower (worse) SRS self-image scores (OR 0.45 95% CI 0.32-0.64), a higher value for the major Cobb angle (OR 1.03 95% CI 1.01-1.05), lower age (OR 0.96 95% CI 0.95-0.98), prior decompression (OR 3.76 95% CI 1.00-14.08), prior infiltration (OR 2.23 95% CI 1.12-4.43), and the presence of rotatory subluxation (OR 1.98 95% CI 1.11-3.54) and sagittal subluxation (OR 4.38 95% CI 1.61-11.95).

CONCLUSION

Specific sets of variables were found to be associated with an indication for surgery in patients with ASD. These should be investigated in relation to patient outcomes for their potential to guide the future development of decision aids in the treatment of ASD. These slides can be retrieved under Electronic Supplementary Material.

Analysis of factors affecting baseline SF-36 Mental Component Summary in Adult Spinal Deformity and its impact on surgical outcomes

OBJECTIVES

To identify the factors that affect SF-36 mental component summary (MCS) in patients with adult spinal deformity (ASD) at the time of presentation, and to analyse the effect of SF-36 MCS on clinical outcomes in surgically treated patients.

METHODS

Prospectively collected data from a multicentric ASD database was analysed for baseline parameters. Then, the same database for surgically treated patients with a minimum of 1-year follow-up was analysed to see the effect of baseline SF-36 MCS on treatment results. A clinically useful SF-36 MCS was determined by ROC Curve analysis.

RESULTS

A total of 229 patients with the baseline parameters were analysed. A strong correlation between SF-36 MCS and SRS-22, ODI, gender, and diagnosis were found (p < 0.05). For the second part of the study, a total of 186 surgically treated patients were analysed. Only for SF-36 PCS, the un-improved cohort based on minimum clinically important differences had significantly lower mean baseline SF-36 MCS (p < 0.001). SF-36 MCS was found to have an odds ratio of 0.914 in improving SF-36 PCS score (unit by unit) (p < 0.001). A cut-off point of 43.97 for SF-36 MCS was found to be predictive of SF-36 PCS (AUC = 0.631; p < 0.001).

CONCLUSIONS

The factors effective on the baseline SF-36 MCS in an ASD population are other HRQOL parameters such as SRS-22 and ODI as well as the baseline thoracic kyphosis and gender. This study has also demonstrated that baseline SF-36 MCS does not necessarily have any effect on the treatment results by surgery as assessed by SRS-22 or ODI.

LEVEL OF EVIDENCE

Level III, prognostic study.

Decision-making factors in the treatment of adult spinal deformity

PURPOSE

We aimed to elucidate the factors for the decision-making process in the treatment of adult spinal deformity (ASD), including sagittal parameters, that impact health-related quality of life (HRQOL).

METHODS

A multicenter prospective ASD database was retrospectively reviewed. The demographic data, HRQOL, and radiographic measures were analyzed using multivariate analyses in younger (≤ 50 years) and older (> 50 years) age groups.

RESULTS

This study included 414 patients (134 surgical and 280 nonsurgical; mean age 30.7 years) in the younger age group and 575 patients (323 surgical and 252 nonsurgical; mean age 65.8 years) in the older age group. Worse HRQOL measures drove surgical treatment, both in younger and older patients. The SRS-22 self-image score was the most differentiating domain, both in the younger and older age groups, and an additional significant factor in the older age group was pain and disability. Coronal deformity drove surgical treatment for the younger age group; however, older surgical patients were less likely to have coronal malalignment. Sagittal parameters were associated with the decision-making process. Greater pelvic incidence minus lumbar lordosis mismatch in the younger age group and smaller lumbar lordosis index in the older age group were most correlated with the decision to undergo surgery.

CONCLUSIONS

Aside from the HRQOL measures and coronal deformity, sagittal parameters were identified as significant factors for the decision-making process in the ASD population, and the lack of lumbar lordosis in relation to pelvic incidence was a strong driver to pursue surgical treatment. These slides can be retrieved under Electronic Supplementary Material.

The Adult Deformity Surgery Complexity Index (ADSCI): a valid tool to quantify the complexity of posterior adult spinal deformity surgery and predict postoperative complications

BACKGROUND CONTEXT

In 2008, Mirza et al. designed and validated the first and only index capable of quantifying the complexity of spine surgery. However, this index is not fully applicable to adult spinal deformity (ASD) surgery as it does not include the surgical techniques most commonly used and most strongly associated with perioperative complications in patients with ASD.

PURPOSE

The objective of this study is to develop an "Adult Deformity Surgery Complexity Index" (ADSCI) to quantify objectively the complexity of the ASD posterior surgery.

STUDY DESIGN/SETTING

This is an expert consensus (Delphi process) and retrospective analysis of prospectively collected data using multiple regression models.

PATIENT SAMPLE

Patients were prospectively enrolled in two comparable multicenter ASD databases sharing the same inclusion criteria.

OUTCOME MEASURES

The ADSCI was internally and externally validated using R² for intraoperative bleeding and length of surgery. Receiver operating characteristics (ROC) and area under the curve (AUC) analysis was used to assess the sensitivity and specificity of ADSCI.

METHODS

The development and validation of ADSCI was based on the construction and comparison of three different tools: ADSCI score was constructed by three rounds of expert consensus (ADSCI-Delphi) and two multiple regression models (ADSCI-RM-Simple and ADSCI-RM-Mixed). Their predictive capability was compared by means of R² values in the same subrogated of surgical complexity as in the Mirza index validation: intraoperative bleeding and duration of surgery. Sensitivity and specificity were evaluated using ROC curves and AUC analysis. The external validity was also examined by evaluating its predictive capability in another multicenter ASD database of comparable patients in the United States.

RESULTS

At the time of the study, the database included 1,325 patients. Four hundred seventy-five patients were eligible for the study, having been treated surgically using a posterior approach only (52.2 years standard deviation 20; 77.7% women; 85.4% American Society of Anesthesiologists I/II). Fifty-one international experts participated in the Delphi consensus process. The surgical variables selected by consensus and included in the equation were divided into actions and factors. Actions selected were number of fused segments, decompressions, interbody fusions, and cemented levels; number and type of posterior osteotomies; and use of pelvic fixation. The factors included were implant density, revision surgery, and team experience. ADSCI-RM-Mixed (regression model with Delphi formula interactions) provided the best estimates and predictive value, well above Mirza's invasiveness index. The ADSCI-RM-Mixed, with greater AUCs (>0.70), was also the most sensitive and specific for both of the dependent variables studied and for complication prediction. ADSCI-RM-Mixed obtained also the highest R² value in the validation cohort in predicting blood loss (R²=0.34) and surgical time (R²=0.26) with effect sizes similar to those for the derivation cohort.

CONCLUSIONS

The ADSCI is the first tool to be specifically developed for the preoperative assessment of the complexity of ASD surgery. This study confirms its validity, specificity, and sensitivity, and shows that it has greater predictive capability than the more generic Mirza invasiveness index. The ADSCI should be useful for quantitatively estimating the increased risk associated with more invasive surgery and adjusting for surgical case-mix when making safety comparisons in ASDS.

Global Alignment and Proportion (GAP) Score: Development and Validation of a New Method of Analyzing Spinopelvic Alignment to Predict Mechanical Complications After Adult Spinal Deformity Surgery

BACKGROUND

The restoration of normal sagittal alignment is a critical goal in adult spinal deformity surgery to achieve favorable outcomes and prevent mechanical complications. Schwab sagittal modifiers have been accepted as targets for appropriate alignment, but addressing these targets does not always prevent high mechanical complication or revision rates. This may be because the linear absolute numerical parameters do not cover the whole pelvic incidence spectrum and the distribution of lordosis, pelvic anteversion, and negative malalignment are not considered as potential causes of failure. The aim of the present study was to develop and validate a score based on pelvic-incidence-based proportional parameters to better predict mechanical complications.

METHODS

Two hundred and twenty-two patients (168 women and 54 men) followed for ≥2 years after posterior fusion at ≥4 levels were included in the study. The mean age (and standard deviation) was 52.2 ± 19.3 years (range, 18 to 84 years), and the mean duration of follow-up was 28.8 ± 8.2 months (range, 24 to 62 months). The global alignment and proportion (GAP) score was developed and validated in groups of patients randomly assigned to derivation (n = 148, 66.7%) and validation (n = 74, 33.3%) cohorts. GAP score parameters were relative pelvic version (the measured minus the ideal sacral slope), relative lumbar lordosis (the measured minus the ideal lumbar lordosis), lordosis distribution index (the L4-S1 lordosis divided by the L1-S1 lordosis multiplied by 100), relative spinopelvic alignment (the measured minus the ideal global tilt), and an age factor. Proximal and distal junctional kyphosis and/or failure, rod breakage, and other implant-related complications were considered mechanical complications. The predictive accuracy of the GAP score was analyzed using receiver operating characteristic (ROC) analyses. Associations between GAP categories and mechanical complications and revisions were analyzed using Cochran-Armitage tests.

RESULTS

In the validation cohort, 32 patients (43%) experienced mechanical complications and 17 (23%) underwent mechanical revision. The area under curve for the GAP score predicting mechanical complications was 0.92 (standard error [SE] = 0.034, p < 0.001, 95% [confidence interval [CI] = 0.85 to 0.98). Postoperatively, patients with a proportioned spinopelvic state according to the GAP score had a mechanical complication rate of 6% while those with a moderately or severely disproportioned spinopelvic state had rates of 47% and 95%, respectively.

CONCLUSIONS

The GAP score is a new pelvic-incidence-based proportional method of analyzing the sagittal plane that predicts mechanical complications in patients undergoing surgery for adult spinal deformity. Setting surgical goals according to the GAP score may decrease the prevalence of mechanical complications.

Factor analysis of the SRS-22 outcome assessment instrument in patients with adult spinal deformity

PURPOSE

Designed for patients with adolescent idiopathic scoliosis, the SRS-22 is now widely used as an outcome instrument in patients with adult spinal deformity (ASD). No studies have confirmed the four-factor structure (pain, function, self-image, mental health) of the SRS-22 in ASD and under different contexts. Factorial invariance of an instrument over time and in different languages is essential to allow for precise interpretations of treatment success and comparisons across studies. This study sought to evaluate the invariance of the SRS-22 structure across different languages and sub-groups of ASD patients.

METHODS

Confirmatory factor analysis was performed on the 20 non-management items of the SRS-22 with data from 245 American English-, 428 Spanish-, 229 Turkish-, 95 French-, and 195 German-speaking patients. Item loading invariance was compared across languages, age groups, etiologies, treatment groups, and assessment times. A separate sample of SRS-22 data from 772 American surgical patients with ASD was used for cross-validation.

RESULTS

The factor structure fitted significantly better to the proposed four-factor solution than to a unifactorial solution. However, items 14 (personal relationships), 15 (financial difficulties), and 17 (days off work) consistently showed weak item loading within their factors across all language versions and in both baseline and follow-up datasets. A trimmed SRS (16 non-management items) that used the four least problematic items in each of the four domains yielded better-fitting models across all languages, but equivalence was still not reached. With this shorter version there was equivalence of item loading with respect to treatment (surgery vs conservative), time of assessment (baseline vs 12 months follow-up), and etiology (degenerative vs idiopathic), but not age (< vs ≥50 years). All findings were confirmed in the cross-validation sample.

CONCLUSION

We recommend removal of the worst-fitting items from each of the four domains of the SRS-instrument (items 3, 14, 15, 17), together with adaptation and standardization of other items across language versions, to provide an improved version of the instrument with just 16 non-management items.

Decision analysis to identify the ideal treatment for adult spinal deformity: What is the impact of complications on treatment outcomes?

Objective

The aim of this study was to analyze the impact of treatment complications on outcomes in adult spinal deformity (ASD) using a decision analysis (DA) model.

Methods

The study included 535 ASD patients (371 with non-surgical (NS) and 164 with surgical (S) treatment) from an international multicentre database of ASD patients. DA was structured in two main steps; 1) Baseline analysis (Assessing the probabilities of outcomes, Assessing the values of preference -utilities-, Combining information on probability and utility and assigning the quality adjusted life expectancy (QALE) for each treatment) and 2) Sensitivity analysis. Complications were analyzed as life threatening (LT) and nonlife threatening (NLT) and their probabilities were calculated from the database as well as a thorough literature review. Outcomes were analyzed as improvement, no change and deterioration. Death/complete paralysis was considered as a separate category.

Results

All 535 patients were analyzed in regard to complications. Overall, there were 78 NLT and 12 LT complications and 3 death/paralysis. Surgical treatment offered significantly higher chances of clinical improvement but also was significantly more prone to complications (31.7% vs. 11.1%, p < 0.001).

Conclusion

Surgical treatment of ASD is more likely to cause complications compared to NS treatment. On the other hand, surgery has been shown to provide a higher likelihood of improvement in HRQoL scores. So, the decision on the type of treatment in ASD needs to take both chances of improvement and burden associated with S or NS treatments and better be arrived by the active participation of patients and physicians equipped with the present information.

Level of evidence

Level II, Decision analysis.

Global tilt and lumbar lordosis index: two parameters correlating with health-related quality of life scores-but how do they truly impact disability?

BACKGROUND CONTEXT

Many radiological parameters have been reported to correlate with patient's disability including sagittal vertical axis (SVA), pelvic tilt (PT), and pelvic incidence minus lumbar lordosis (PI-LL). European literature reports other parameters such as lumbar lordosis index (LLI) and the global tilt (GT). If most parameters correlate with health-related quality of life scores (HRQLs), their impact on disability remains unclear.

PURPOSE

This study aimed to validate these parameters by investigating their correlation with HRQLs. It also aimed to evaluate the relationship between each of these sagittal parameters and HRQLs to fully understand the impact in adult spinal deformity management.

STUDY DESIGN

A retrospective review of a multicenter, prospective database was carried out.

PATIENT SAMPLE

The database inclusion criteria were adults (>18 years old) presenting any of the following radiographic parameters: scoliosis (Cobb ≥20°), SVA ≥5 cm, thoracic kyphosis ≥60° or PT ≥25°. All patients with complete data at baseline were included.

OUTCOME MEASURES

Health-related quality of life scores, demographic variables (DVs), and radiographic parameters were collected at baseline.

METHODS

Differences in HRQLs among groups of each DV were assessed with analyses of variance. Correlations between radiographic variables and HRQLs were assessed using the Spearman rank correlation. Multivariate linear regression models were fitted for each of the HRQLs (Oswestry Disability Index [ODI], Scoliosis Research Society-22 subtotal score, or physical component summaries) with sagittal parameters and covariants as independent variables. A p<.05 value was considered statistically significant.

RESULTS

Among a total of 755 included patients (mean age, 52.1 years), 431 were non-surgical candidates and 324 were surgical candidates. Global tilt and LLI significantly correlated with HRQLs (r=0.4 and -0.3, respectively) for univariate analysis. Demographic variables such as age, gender, body mass index, past surgery, and surgical or non-surgical candidate were significant predictors of ODI score. The likelihood ratio tests for the addition of the sagittal parameters showed that SVA, GT, T1 sagittal tilt, PI-LL, and LLI were statistically significant predictors for ODI score even adjusted for covariates. The differences of R² values from Model 1 were 1.5% at maximum, indicating that the addition of sagittal parameters to the reference model increased only 1.5% of the variance of ODI explained by the models.

CONCLUSION

GT and LLI appear to be independent radiographic parameters impacting ODI variance. If most of the parameters described in the literature are correlated with ODI, the impact of these radiographic parameters is less than 2% of ODI variance, whereas 40% are explained by DVs. The importance of radiographic parameters lies more on their purpose to describe and understand the malalignment mechanisms than their univariate correlation with HRQLs.

Lack of improvement in health-related quality of life (HRQOL) scores 6 months after surgery for adult spinal deformity (ASD) predicts high revision rate in the second postoperative year

PURPOSE

ASD is assessed radiologically with the spinopelvic parameters and clinically with HRQOL scores. The revision rate after ASD surgery is high and usually occurs during the first or second postoperative year. The aim of this study is to find clinical or radiological factors that could predict revision surgery in the second postoperative year.

MATERIALS AND METHODS

Inclusion criterion: ASD patients operated on by instrumented posterior fusion with more than 2 years follow-up were enrolled prospectively. Additional criterion was no revision surgery during the first postoperative year. From a multicenter database of 560 operated ASD patients, 164 patients met these criteria. The patients were divided into two groups depending on the need of revision surgery during the second postoperative year. Preoperative, 6-month, 1-year and 2-year data were collected and compared for both groups.

RESULTS

A total of 22 patients needed revision surgery and 142 did not. All revisions were for mechanical complications (non-fusion and implant related). Preoperatively, there was a significant difference between the groups (no revision vs. revision) for age (48 vs. 60 years), ODI (37 vs. 53), and SVA (29 vs. 76 mm), respectively. At 6 months, a significant difference in sagittal alignment was found, though HRQOL scores were similar. At 1 year, the no revision group scores improved, whereas the revision group scores remained stable or worsened. At 2 years, the no revision group scores remained stable. Comparing 6- and 12-month data, patients with improved, stable and worsened HRQOL scores had 8, 15 and 28% revision rates, respectively.

CONCLUSION

The revision rate at the second-year post-surgery (13.4%) remains high and demonstrated that a 2-year follow-up is mandatory. In addition to usual risk factors for mechanical complications in ASD surgery, stabilization or worsening of the HRQOL scores between the 6th and 12th month postop was highly predictive of revision rate. This observation is beneficial for ASD patient follow-up as clinical symptoms clearly precede mechanical failure.

Does Surgery for Adult Spinal Deformity Affect the Cognitive Abilities in Patients over 50 Years of Age?

AIM

To analyze the cognitive abilities of older patients undergoing spinal deformity surgery so as to understand whether adult spinal deformity (ASD) surgery is associated with postoperative cognitive malfunction.

MATERIAL AND METHODS

A prospective longitudinal study was performed on surgical patients older than 50 years, enrolled in a prospective multicenter database. Mini-mental state examination (MMSE) was performed to assess cognitive function in addition to the health-related quality of life (HRQOL) tests; (SF-36, ODI and SRS-22) at the pre-operative, post-operative 6 weeks and 6 months points. Demographics, preoperative health status, co-morbidities and surgical characteristics were also analyzed. Descriptive statistics and repeated measures of variance analysis were performed.

RESULTS

A total of 90 patients with a mean age of 67.4±8.2 years were enrolled in the study; all had MMSE evaluations at 6 weeks follow-up and 58 patients had both 6 weeks and 6 months follow-up. Average (SD) surgical time, estimated blood loss, number of levels fused and hospital stay were 240.1 (111.9) minutes, 1621.2 (1058.7) ml, 11.2 (4.4) levels and 14.2 (11.45) days, respectively. On analysis, a slight increase in mean MMSE score (p > 0.05) between time points was found despite decreases of > 2 points (3 or 4) in 6 patients (6.7%) at both time points.

CONCLUSION

Although ASD surgery in older patients is recognized as challenging, this study suggests that it is not necessarily associated with a significant deterioration in the cognitive abilities of patients undergoing surgery. This may be due to the relatively minor influence of ASD itself on the cognitive abilities of the patients involved as well as to the relatively stable hemodynamic conditions obtainable during modern ASD surgery.

Global tilt: a single parameter incorporating spinal and pelvic sagittal parameters and least affected by patient positioning

PURPOSE

Regarding the close interaction between the spinal alignment and the pelvis orientation, no parameter is routinely used to describe and to evaluate the global spinopelvic balance, taking into account simultaneously the spinal part and the pelvic part of the global alignment. We described the global tilt (GT) that could analyze malalignment considering the spine and the pelvis simultaneously. From a geometrical point of view, the global tilt is the sum of the pelvic tilt (PT) and the C7 vertical tilt (angular value of sagittal vertical axis). The aim of this study is to evaluate the global tilt with comparison to PT and sagittal vertical axis (SVA), with the hypothesis that GT would be the least sensitive to positional changes.

METHODS

A cohort of 22 patients with sagittal malalignment was identified from a multicentric database of adult spinal deformities (ASD). Inclusion criteria were age >30 years, SVA > 40 mm and/or PT > 20°. All patients had full spine EOS radiographs in positions 1 and 2 (P1 and P2), in which the patient was asked to stand and put his hands on his shoulders without any effort (P1), or to make an effort to be as straight as possible (P2). PT, SVA and GT were measured in both positions and changes between P1 and P2 were calculated and compared using Student's t test with significance level at p < 0.05.

RESULTS

No significant changes were observed for GT; SVA and PT were significantly influenced by patient positioning. SVA decreased and PT increased for all cases in P2 whereas the changes in GT were in either direction. The average increase in PT was 7.1° (±5.4) or 30.8 % (±24.9); decrease in SVA was 45.1 mm (±25.6) or 60.0 % (±44.2) while the change in GT was 4.4° (±3.3) or 12.6 % (±9.3).

DISCUSSION

GT appears to be less affected by the patient's position compared to SVA and PT. This seems logical because GT contains both spinal alignment and pelvic compensation; it is not affected by their changes in opposing directions.

CONCLUSION

GT appears to be the most reliable single sagittal plane parameter in ASD. It is the least affected by patient position and incorporates both the pelvic and the spinal alignment within one measure.

Decision-making in the treatment of adult spinal deformity

Adult spinal deformity (ASD) is a very diverse condition that affects the quality of life of the involved individuals deeply. There is an ongoing discussion as to whether treatment should be surgical (which is potentially dangerous) or non-surgical.In addition to a systematic review of literature on the surgical treatment of ASD with special emphasis on complications, a decision-analysis was performed using the patient information within a European multi-centric database of ASD.The probabilities of improvement and complications as well as associated disease burden (utility) were calculated at the baseline and at first-year follow-up.Decision-analysis suggests that the chances of clinical improvement are significantly higher with surgical treatment. Though surgical treatment is significantly more prone to complications, the likelihood of improvement remains higher than that offered by non-surgical treatment.Surgical treatment of ASD appears to be associated with a higher likelihood of clinical improvement. Future work needs to focus on refining the criteria for appropriate patient selection and decreasing the incidence of complications. Cite this article: Acaroglu E, European Spine Study Group. Decision-making in the treatment of adult spinal deformity. EFORT Open Rev 2016;1:167-176. DOI: 10.1302/2058-5241.1.000013.

A decision analysis to identify the ideal treatment for adult spinal deformity: is surgery better than non-surgical treatment in improving health-related quality of life and decreasing the disease burden?

BACKGROUND

Adult spinal deformity (ASD) is a major public health problem. There are pros and cons of the available treatment alternatives (surgical or non-surgical) and it had been difficult to identify the best treatment modality.

AIM

To construct a statistical DA model to identify the optimum overall treatment in ASD.

METHODS

From an international multicentre database of ASD patients (968 pts), 535 who had completed 1 year follow-up (371 non-surgical-NS, 164 surgical-S), constitute the population of this study. DA was structured in two main steps of: (1) baseline analysis (assessing the probabilities of outcomes, assessing the values of preference-utilities-, combining information on probability and utility and assigning the quality adjusted life expectancy (QALE) for each treatment) and (2) sensitivity analysis.

RESULTS

Four hundred and thirty-two patients (309 NS, 123 S) had baseline and 1 year follow-up ODI measurements. Overall, 104 (24.1 %) were found to be improved (a decrease in ODI > 8 points), 225 (52.1 %) unchanged (-8 > ODI > 8) and 65 deteriorated. Surgery presented with a higher chance of improvement (54.2 %) versus NS (9.7 %). The overall QALE ranged from 56 to 69 (of 100 years) and demonstrated better final QALE in the NS group (60 vs. 65, P = 0.0038), this group having started with higher QALE as well (56 vs. 65 years, P < 0.0001). There were improvements in overall QALE in both groups but this was significant only in the surgical group (S from 56 to 60 years, P < 0.0001; NS from 65 to 65 years, P = 0.27). In addition, in the subgroup of patients with significant baseline disability (ODI > 25) surgery appeared to yield marginally better final QALE (58 vs. 56 years, P = 0.1) despite very a similar baseline (54 vs. 54 years, P = 0.93).

DISCUSSION AND CONCLUSIONS

This study demonstrated that a single best treatment modality for ASD may not exist. Conservative treatment appears to yield higher (up to 6 %) QALE compared to surgery, most probably secondary to a higher baseline QALE. On the other hand, surgery provides a significantly higher increase in QALE. Especially in patients with significant disability at baseline, the final QALE tended higher in the S group (although not significant). Finally, chances of a relevant improvement at first year turned out to be significantly lower with NS treatment.

Analysis of the reliability of surgeons' ability to differentiate between idiopathic and degenerative spinal deformity in adults radiologically. What descriptive parameters help them decide?

PURPOSE

Adult spinal deformity (ASD) may be classified as idiopathic (ID) or degenerative (DD) (or other) based on classifier's perception, the reliability of and factors inherent to which remain unknown. The aim of this study is to evaluate the inter- and intra-observer reliability of surgeons' perception in differentiating ID from DD and to identify the determinants of this differentiation.

METHODS

From a multicentric prospective database of ASD, 179 patients were identified with the diagnosis of ID (n = 103) or DD (n = 76); without previous surgery; and a lumbar coronal curve larger than 20°. Standing antero-posterior and lateral X-rays of these patients were sent to five experienced spine surgeons to be identified as DD or ID (or other); followed by a second round after reshuffling. Weighted kappa statistics were used, the strength of agreement for the kappa coefficient was considered as; 0.81-1 = almost perfect, 0.61-0.8 = substantial, 0.41-0.60 = moderate, 0.21-0.40 = fair, 0.01-0.20 = slight, and ≤0 = poor. Patients were then stratified based on the number of agreements on a total of 10 rounds as excellent (10 out of 10), good (more than 7 out of 10) and fair/poor (7 and less). These excellent and good agreements were further compared for additional radiological parameters.

RESULTS

Agreement levels were moderate to substantial for intra but mostly fair for inter-observer comparisons. For ID patients, there were 42 cases with excellent and 38 with very good agreement whereas for DD, there were no excellent and only 17 cases with very good agreement. Upon comparison of these (ID vs DD for at least very good cases), it was seen that they were different for some coronal parameters such as lumbar Cobb angle (larger in ID, p < 0.001), central sacral vertical line (CSVL) modifier (C more common in ID, p = 0.007) and presence of rotatory subluxation (less common in DD, p = 0.017), but very different for sagittal parameters (lumbar lordosis, sagittal vertical axis, T2 sagittal tilt, pelvic tilt, sacral slope, and global tilt; increased sagittal imbalance in DD, all p ≤ 0.001).

CONCLUSION

Surgeons in this study demonstrated reasonable (moderate to substantial) intra-observer agreement, but only fair agreement amongst them. Alarming as it may appear, we should be cautious in interpreting these results based on only radiology and no clinical information. In patients with good agreement, the most consistent radiologic determinant of degenerative ASD appeared to be the presence of sagittal imbalance.

The Core Outcome Measures Index (COMI) is a responsive instrument for assessing the outcome of treatment for adult spinal deformity

INTRODUCTION

The Core Outcome Measures Index for the back (COMI-back) is a very brief instrument for assessing the main outcomes of importance to patients with back problems (pain, function, symptom-specific well-being, quality of life, disability). However, it might be expected to be less responsive than a disease-specific instrument when evaluating specific pathologies. In patients with adult spinal deformity, we compared the performance of COMI-back with the widely accepted SRS-22 questionnaire.

METHODS

At baseline and 12 months after non-operative (N = 121) and surgical (N = 83) treatment, patients (175 F, 29 M) completed the following: COMI-back, SRS-22, Oswestry Disability Index (ODI) and SF-36 PCS. At 12 months' follow-up, patients also indicated on a 15-point Global Rating of Change Scale (GRCS) how their back problem had changed relative to 1 year ago. Construct validity for the COMI-back was assessed by the correlation between its scores and those of the comparator instruments; responsiveness was assessed with receiver operating characteristics (ROC) analysis of COMI-back change scores versus the criterion 'treatment success' (dichotomized GRCS).

RESULTS

Baseline values for the COMI-back showed significant (p < 0.0001) correlations with SRS-22 (r = -0.85), ODI (r = 0.83), and SF-36 PCS (r = -0.82) scores; significantly worse scores for all measures were recorded in the surgical group. The correlation between the change scores (baseline to 12 months) for COMI and SRS-22 was 0.74, and between each of these change scores and the external criterion of treatment success were: COMI-back, r = 0.58; SRS-22, r = -0.58 (each p < 0.0001). The ROC areas under the curve for the COMI-back and SRS-22 change scores were 0.79 and 0.82, respectively.

CONCLUSION

Both baseline and change scores for the COMI-back correlated strongly with those of the SRS-22, and differed significantly in surgical and non-operative patients, suggesting good construct validity. With the "change in the back problem" serving as external criterion, COMI-back showed similar external responsiveness to SRS-22. The COMI-back was well able to detect important change. Coupled with its brevity, which minimizes patient burden, these favourable psychometric properties suggest the COMI-back is a suitable instrument for use in registries and can serve as a valid instrument in clinical studies emerging from such data pools.

Multiple Regression Analysis of Factors Affecting Health-Related Quality of Life in Adult Spinal Deformity

BACKGROUND

Previous studies demonstrated the adult spinal deformity (ASD) population is heterogeneous. Multiple parameters may affect health-related quality of life (HRQL).

AIM

To understand the ranking of parameters affecting HRQL in ASD using multiple regression analysis.

PATIENTS AND METHODS

A total of 483 patients enrolled in a prospective multicenter ASD database from the population. Multiple regression analysis was performed for Scoliosis Research Society-22 (SRS-22) and Oswestry Disability Index (ODI) separately. Initially proposed primary variables of diagnosis (highest correlation), age, lordosis gap (L gap), and coronal curve location were regressed for each response variable (SRS-22 and ODI) univariately. Age and L gap could not be used together because of high colinearity. Coronal curve location was removed owing to an insignificant correlation. Two initial models were considered per response, consisting of diagnosis and age in one and diagnosis and L gap in the other. The rest of the potentially predictive variables were introduced in these models one at a time. Final models were evaluated using stepwise automatic model selection.

RESULTS

For ODI, body mass index (BMI), gender, and sagittal and spinopelvic parameters were in the basic model but only BMI and gender in the model with L gap and only gender in the model with age were highly predictive. For SRS-22, a large number of parameters were in the basic model but BMI, gender, coronal balance, lordosis curve, and sagittal vertical axis in the model with L gap and only gender in the model with age were highly predictive. Coronal curve location was not significantly predictive in any model.

CONCLUSIONS

These findings reiterate the importance of patient diagnosis, age, and/or the amount of lordosis as the most important factors affecting HRQL in ASD. Gender, BMI, and sagittal vertical axis appear to be consistently important co-variables whereas coronal balance and magnitude of L curves may also be important in SRS-22. These may aid in better understanding the problem in ASD and may be useful in future classifications.

Long-term results of reconstruction with pelvic allografts after wide resection of pelvic sarcomas

Reconstruction after the resection of a pelvic tumor is a challenging procedure in orthopedic oncology. The main advantage of allograft reconstruction is restoration of the bony architecture of the complex pelvic region. However, high complication rates such as infection and allograft resorption had been reported in the literature. In this study, we aimed to retrospectively review nine patients treated with pelvic resection and structural pelvic allograft reconstruction. Functional results, complications, and survival of the patients and the allografts were evaluated. At a mean follow-up of 79 months, three patients were dead. Major complications were detected in eight of the nine patients. Infection (four of the nine patients) and allograft resorption (three of the nine patients) were the most common causes of failure. The cumulative survival of the patients was 66.7 percent at 70 months. However, allograft survival was only 26.7 percent at 60 months. Mean MSTS score was 69. In conclusion, we suggest that other reconstruction options should be preferred after pelvic resections because of the high complication rates associated with massive allograft reconstruction.

The metabolic basis of adolescent idiopathic scoliosis: 2011 report of the "metabolic" workgroup of the Fondation Yves Cotrel

OBJECTIVE

The purpose of this review is to elucidate the metabolic processes involved in the pathogenesis of adolescent idiopathic scoliosis (AIS) in light of research by the present authors as well as current literature.

METHODS

Pathogenetic mechanisms involved in AIS were modeled as (a) a form of neuromuscular scoliosis (in conjunction with an adverse mechanical environment such as bipedality), in which hormonal and other chemical factors act as regulators of skeletal muscle tone and function; (b) as a consequence of an abnormality in growth of the spinal column (in conjunction with an adverse mechanical environment such as bipedality), in which hormones and other chemical factors act as regulators of growth; and (c) as a mechanical failure of one side of the vertebral column due to a defect in trabecular formation or mineralization (in conjunction with an adverse mechanical environment such as bipedality); in which hormonal and other chemical factors act as regulators of bone formation, mineralization and/or resorption.

RESULTS AND CONCLUSION

Current evidence supporting these models individually or in combination is discussed.

Is decreased bone mineral density associated with development of scoliosis? A bipedal osteopenic rat model

BACKGROUND

An association between adolescent idiopathic scoliosis and osteopenia has been proposed to exist. It is still not clear whether there is such an association and if so, whether osteopenia is a causative factor or a consequence. Our previous pilot studies have suggested the presence of osteopenia in scoliotic animals. The aim of this study was to investigate the development of scoliosis in an unpinealectomized bipedal osteopenic rat model, implementing osteoporosis as a causative factor.

METHODS

Fifty Sprague-Dawley rats were rendered bipedal at the 3rd postnatal week and separated into control (25 rats) and heparin (25 rats receiving 1 IU/gr body weight/day) groups. DEXA scans after 4 weeks of heparin administration showed low bone mass in the heparin group. Anteroposterior and lateral x-rays of the surviving 42 animals (19 in heparin and 23 in control groups) were taken under anesthesia at the 40th week to evaluate for spinal deformity. Additional histomorphometric analysis was done on spine specimens to confirm the low bone mass in heparin receiving animals. Results of the DEXA scans, histomorphometric analysis and radiological data were compared between the groups.

RESULTS

Bone mineral densities of rats in the heparin group were significantly lower than the control group as evidenced by both the DEXA scans and histomorphometric analyses. However, the incidence of scoliosis (82% in heparin and 65% in control; p > 0.05) as well as the curve magnitudes (12.1 ± 3.8 in heparin versus 10.1 ± 4.3 degrees in control; p > 0.05) were not significantly different. Osteopenic rats were significantly less kyphotic compared to control specimens (p = 0.001).

CONCLUSIONS

This study has revealed two important findings. One is that bipedality (in the absence of pinealectomy) by itself may be a cause of scoliosis in this animal model. Further studies on animal models need to consider bipedality as an independent factor. Secondly, relative hypokyphosis in osteopenic animals may have important implications. The absence of sagittal plane analyses in previous studies makes comparison impossible, but nonetheless these findings suggest that osteopenia may be important in the development of 3D deformity in adolescent idiopathic scoliosis.

The effect of posterior distraction on vertebral growth in immature pigs: an experimental simulation of growing rod technique

STUDY DESIGN

Experimental study.

OBJECTIVE

The aim of this study is to evaluate the vertebral body growth under distraction forces in immature pigs treated with growing rod (GR) technique.

SUMMARY OF BACKGROUND DATA

Distraction forces applied on growth plate of appendicular skeleton stimulate longitudinal growth. However, the effect of distraction forces on axial skeletal growth has not been fully investigated yet.

METHODS

Twelve 10-week-old domestic pigs were used in this experimental model to simulate GR technique. Four of them were lost during postoperative period because of deep wound infection. Cranially T12-L1 and caudally L4-L5 vertebrae were instrumented by pedicle screws bilaterally, while L2 and L3 were skipped. Distraction between pedicle screws was applied at index surgery. The rods were then lengthened twice in a month interval. All subjects were evaluated with anteroposterior and lateral spinal radiograph before surgery, after surgery, and at the final follow-up. The vertebral body heights of distracted segments (HD = L2 and L3) and control segments (HC = T9, T10 and T11) were measured. Average vertebral body heights and the increase percentage in the vertebral body heights were compared among control segments and distracted segments.

RESULTS

The preoperative vertebral body height was similar in 2 groups (preHC: 10.81 mm, n = 19, preHD: 11.27 mm, n = 16, P > 0.05). At the final follow-up, the average vertebral body height in distraction group was significantly higher than the control group (postHC: 17.03 mm, postHD: 18.58 mm, P < 0.05). The increase percentage in vertebral body height was higher in distracted segments, but there was no statistically significant difference between the 2 groups.

CONCLUSION

The vertebral growth continues during GR instrumentation. Distraction forces might stimulate also apophyseal growth of axial skeleton.

The effect of calmodulin antagonists on scoliosis: bipedal C57BL/6 mice model

C57BL6 mice are melatonin deficient from birth and have been shown to develop scoliosis when rendered bipedal. Our previous work suggested that tamoxifen and trifluoperozine may change the natural course of scoliosis in a chicken model. The objective of this study was to analyze whether the incidence of scoliosis or the magnitude of curves may be decreased by the administration of pharmacological agents tamoxifen or trifluoperozine in a mice scoliosis model. Sixty female 3-week-old C57BL6 mice underwent amputations of forelimbs and tails. Available 57 mice were divided into three groups, Group-I received no medications whereas Groups II and III received 10 mg TMX and 10 mg TMX + 10 mg TFP per liter of daily water supply, respectively. PA scoliosis X-rays were obtained at 20th and 40th weeks. Deformities were compared for incidence and the severity of the curves as well as disease progression or regression. At 20th week, overall, upper thoracic (UT), lower thoracic (T), and lumbar (L) scoliosis rates were similar (P = 0.531; P = 0.209; P = 0.926; P = 0.215, respectively) but thoraco-lumbar (TL) scoliosis rate was higher inTMX group (P = 0.036). However, at 40th week, although TL and L rates were similar (P = 0.628, P = 0.080), overall rate as well as the rates of UT and T scoliosis of TMX group were significantly lower (P = 0.001, P = 0.011, P = 0.001, respectively). As for curve magnitudes, T mean Cobb angle at 20th week was significantly higher in the C group (14 +/- 2.55) compared to TMX + TFP group (9 +/- 2.708; P = 0.033); at 40th week, TL mean Cobb angle was lower in the TMX + TFP group (17.50 +/- 3.45) compared to C (29.40 +/- 5.98; P = 0.031); and TMX group had lower TL Cobb angles compared to C (8.67 +/- 11.72) although not significant (P = 0.109). Double curve incidence at 40th week was significantly lower in TMX group compared to other groups (P = 0.001), triple curve incidence was lower in TMX + TFP and TMX groups, albeit not significant (P = 0.167). Between the 20th and 40th weeks, overall, double curve, and UT scoliosis rates showed an increase in C and TMX + TFP groups whereas TMX group showed a decline (P = 0.01, P = 0.002, P = 0.007, respectively). When specific regions were compared a similar significant difference was observed (P = 0.012 for upper thoracic; P = 0.018 for thoracic; P = 0.047 for thoraco-lumbar). This study has demonstrated that TMX is effective in changing the natural history of scoliotic deformities in C57BL6 mice model favorably.

Radiographic measurement of the sagittal plane deformity in patients with osteoporotic spinal fractures evaluation of intrinsic error

Cobb method has been shown to be the most reliable technique with a reasonable measurement error to determine the kyphosis in fresh fractures of young patients. However, measurement errors may be higher for elderly patients as it may be difficult to determine the landmarks due to osteopenia and the degenerative changes. The aim of this study is to investigate the intrinsic error for different techniques used in evaluation of local sagittal plane deformity caused by OVCF. Lateral X-rays of OVCF patients were randomly selected. Patient group was composed of 28 females and 7 males and the mean age was 62.7 (55-75) years. The kyphosis angle and the vertebral body height were analyzed to reveal the severity of sagittal plane deformity. Kyphotic deformity was measured by using four different techniques; and the vertebral body heights (VBH) were measured at three different points. The mean intra-observer agreement interval for kyphosis angle measurement techniques ranged from +/-7.1 to +/-9.3 degrees while it ranged from +/-4.5 to +/-6.5 mm for VBH measurement techniques. The mean interobserver agreement interval for kyphosis angle ranged from +/-8.2 to +/-11.1 degrees , while it was between +/-4.5 to +/-6.5 mm for vertebral body height measurement techniques. This study revealed that although the intra and interobserver agreement were similar for all techniques, they are still higher than expected. These high intervals for measurement errors should be taken into account when interpreting the results of correction in local sagittal plane deformities of OVCF patients after surgical procedures such as vertebral augmentation techniques.

Safety and efficacy of posterior instrumentation for patients with congenital scoliosis and spinal dysraphism

OBJECTIVE

Instrumentation and correction of severe congenital scoliosis, particularly in patients with spinal dysraphism, has been reported to cause a high potential rate of neurological compromise after instrumentation. The aim of this study was to evaluate the safety and efficacy of posterior instrumentation and correction of congenital scoliosis with accompanying spinal dysraphism.

LEVEL OF EVIDENCE

Level IV therapeutic studies.

METHODS

Retrospective x-ray measurements to analyze the efficacy and the evaluation of hospital charts to document the intraoperative and postoperative complications were performed for a consecutive patient series. Scoliosis Research Society-22 questionnaire was used to analyze the health-related quality of life.

RESULTS

Twenty-two patients (18 girls and 4 boys) formed the basis of the study. The average age was 12 years (range, 7-18 years) and the average follow-up period was 3.2 years (range, 2-10 years). The types of spinal dysraphism were diastematomyelia in 20 patients and syringomyelia with tethered cord in 2 patients. Twelve patients had previous surgery and 3 patients had simultaneous surgeries for spinal dysraphism. Posterior instrumentation with/without anterior release and fusion was performed in all patients. Major curve was corrected from an average of 71 degrees to 40 degrees (correction rate, 43.6%). The compensatory curve was corrected from an average of 47 degrees to 25 degrees (correction rate, 46.8%). The average loss of correction at final follow-up was 2.2 degrees for major curve and 3.5 degrees for the compensatory curve. The average scores for the 5 domains of Scoliosis Research Society-22 questionnaire were 3.5 for function, 3.9 for pain, 3.5 for self-image, 3.6 for mental health, 3.9 for satisfaction, and 3.6 for total. Neurological monitoring was conducted by using the wake-up test in all patients. The overall complication rate was 31%, including neurological compromise in 2 patients (9%).

CONCLUSIONS

Spinal instrumentation was effective for the control of deformity with a relatively higher rate of complications. However, with respect to high complication rate, the ideal solution for managing the congenital cases is still to prevent the progression of the curve with early intervention by using the optimal surgical approach for that particular patient.

A biomechanical assessment of thoracic spine stapling

STUDY DESIGN

An in vitro immature bovine study of thoracic spine fixation using shape memory alloy for minimally invasive adolescent scoliosis treatment.

OBJECTIVE

The purpose of this study was to detect differences in thoracic spine range of motion due to the placement of spinal staples manufactured from a common shape memory alloy.

SUMMARY OF BACKGROUND DATA

Scoliosis surgery attempts to both correct the existing deformity and prevent further curve progression. The gold standard in surgical treatment of scoliosis is posterior instrumentation and fusion using pedicle screws or hooks. Fusionless techniques generally use less invasive procedures than fusion methods. One such technique, anterior stapling of the vertebrae, theoretically enables preservation of growth, motion, and spinal function. However, the degree of stability afforded by this method has not been reported.

METHODS

Eight immature bovine specimens (T4-T9) were used in this study. Nitinol staples were cooled to below the transition temperature and placed on the spine such that they spanned the disc space. The specimen was then heated above the critical temperature and the staple tines engaged the vertebral endplates. A common flexibility protocol was used to determine the ranges of motion (ROM) in flexion-extension, lateral bending, and axial rotation. The intact spine and 4 construct variants (combinations of staple type and placement) were evaluated using this testing protocol. ANOVA statistics with post hoc testing was used to discern statistical differences.

RESULTS

Not all staple variants were able to achieve significant reductions with respect to the intact condition. ROM was significantly restricted in axial rotation and lateral bending with the introduction of staple instrumentation. Further, there seemed to be a mechanical equivalence between a single double-prong staple and 2 single-prong staples. Our data indicate that staple fixation does not result in consistently elevated adjacent segment motion.

CONCLUSIONS

Our results imply that staples are able to significantly restrict motion while not achieving motion reductions that one would achieve with fusion-promoting instrumentation. The choice between double- and single-prong staples remains a matter of preference. Neither staple variant provided a mechanical advantage. The single-prong staple did allow more control in the placement of the staple over the disc space. The addition of an anterior staple significantly reduced the overall flexion-extension ROM.

The effect of pedicle expansion on pedicle morphology and biomechanical stability in the immature porcine spine

STUDY DESIGN

Biomechanical study in an animal model.

OBJECTIVE

To evaluate the feasibility of sequential dilation of the immature pedicles by dilators and to determine the biomechanical stability of screws placed in these expanded pedicles.

SUMMARY OF BACKGROUND DATA

Pedicle screws have become the implant of choice in spinal fixation. Secondary to the small vertebra sizes of pediatric patients and difficulty in finding appropriate screw sizes, they have found limited use in pediatric spine. Dilation of the pediatric pedicles may overcome the limitation secondary to discrepancy between screw sizes. However, there are no data in the literature regarding dilation capacity of pediatric pedicles to enable larger pedicle screw fixation.

METHODS

Two-month-old domestic pig vertebrae were used. The right pedicles were dilated with stainless steel dilators just before there is visual evidence of pedicle failure. The left pedicles served as a control group. The inner and outer diameters of the pedicles were measured on the CT scans before and after dilation. The pedicles were instrumented with 3.5-mm pedicle screws at the thoracic level and 4.0-mm pedicle screws at the lumbar level. The pullout strength of each pedicle was measured.

RESULTS

The dilation procedure resulted in an increase in both inner (2.59 +/- 0.75 to 3.32 +/- 0.58 mm) and outer diameters (5.43 +/- 0.95 to 6.21 +/- 0.96 mm) (P < 0.05). The inner diameters dilated more than the outer diameters (34.3% vs. 15.0%). The pullout strength of the expanded pedicles (320.1 +/- 83.9 N) was significantly lower than the nonexpanded ones (408.1 +/- 102.0 N) (P < 0.01).

CONCLUSIONS

This study demonstrated that immature pedicles can be expanded by application of serial dilators. However, dilation significantly decreases the pullout strength of the pedicle.