Revision surgery of spinal dynamic implants: a literature review and algorithm proposal

INTRODUCTION

Dynamic stabilization of the spine has been performed since the 1990s with the double purpose of restoring spinal segmental stability and allowing residual movement at the operated level. When we take into account the different motion-preserving devices and the spinal areas where they are applied, we can identify three categories of spinal implants: anterior cervical, anterior lumbar, and posterior lumbar. However, as in all prosthetic procedures performed in orthopedic surgery, the life span of a joint replacement device is a central topic of discussion, and this is true also for spinal dynamic devices, being revision surgery a complex procedure in specific cases.

MATERIALS AND METHODS

We performed a literature review on the different dynamic spinal implants and the most common causes of failure, providing clinical cases as illustrative options for revision surgery.

RESULTS

The review of the literature showed a 11.3% to 22.6% revision rate in posterior lumbar dynamic systems, with a peak of 40.6% in case of adjacent segment disease. In lumbar TDRs, infection and severe dislocations are the most frequent causes of anterior revisions, while posterior pedicle screw fixation could be a suitable option in minimal subsidence or TDR displacement. An algorithm for the planning of revision surgery is proposed.

CONCLUSIONS

Surgical revision of spinal dynamic implants could be a demanding surgery especially in anterior approaches. Anterior cervical revision remains globally safe, but careful preoperative evaluation of vessels and ureter are suggested to avoid intraoperative complications in the lumbar spine. In posterior revision, a proper sagittal alignment of the spine should be restored. These slides can be retrieved under Electronic Supplementary Material.

Thoracic Kyphotic Deformity Secondary to Old Pseudomonas aeruginosa Spondylodiscitis in an Immunocompromised Patient With Persistent Infection Foci-A Case Report

Background

Kyphosis secondary to pyogenic spondylodiscitis is rare and its management can be very challenging.

Methods

In this report, we present the case of a 28-year-old woman, with past history of type 1 diabetes and kidney failure on hemodialysis. Her current complaint is chronic middle and low back pain with kyphotic attitude. She had undergone posterior fixation for T12 fracture 3 years earlier, which was complicated by surgical site infection to Pseudomonas aeruginosa, with secondary kyphosis proximally. X-ray showed a 64° kyphosis with complete fusion between T8 and T10, and MRI showed persistent infection foci.

Results

The patient underwent a pedicle subtraction osteotomy at the level of T9 with instrumentation from T5 to L1. Thoracic kyphosis was corrected to 39°. Samples taken from the remaining collections returned positive for multidrug-resistant Pseudomonas aeruginosa, and the patient was kept on intravenous antibiotic (Colistine) for 2 months. She could walk on day 1, with a satisfactory clinical and radiological result at 3 years.

Conclusions

Literature is sparse on the management of post-pyogenic infection kyphosis in immunocompromised patients. The current case shows that aggressive correction techniques such as pedicle subtraction osteotomy can be performed in such cases but within a multidisciplinary team to deal simultaneously with the different issues of the fragile patient.

Single Level Proximal Thoracic Pedicle Subtraction Osteotomy for Fixed Hyperkyphotic Deformity: Surgical Technique and Patient Series

BACKGROUND

Thoracic hyperkyphosis can display pathological deterioration, resulting in either hyperlordotic cervical compensation or sagittal malalignment. Various techniques have been described to treat fixed malalignment. Pedicle subtraction osteotomy (PSO) is commonly used in the lumbar spine and frequently limited to the distal thoracic spine. This series focuses on the surgical specificities of proximal thoracic PSO, with clinical and radiological outcomes.

OBJECTIVE

To report the surgical specificities and assess the clinical and radiological outcomes of proximal thoracic osteotomies for correction of rigid kyphotic deformities.

METHODS

This is a retrospective review of 10 consecutive patients who underwent single level proximal thoracic PSO (T2-T5). Preoperative and postoperative full-body EOSTM radiographs, perioperative data, and complications were recorded. The surgical technique and its nuances were described in detail.

RESULTS

Patients had mean age of 41.8 yr and 50% were female. The technique provided correction of segmental and global kyphosis, 26.6° and 29.5°, respectively. Patients reported reciprocal reduction in C2-C7 cervical lordosis (37.6°-18.6°, P < .001), significantly correlating with the reduction of thoracic hyperkyphosis (R = 0.840, P = .002). Mean operative time was 291 min, blood loss 1650 mL, and mean hospital stay was 13.8 d. Three patients reported complications that were resolved, including 1 patient who was revised because of a painful cross link. There were no neurological complications, pseudarthroses, instrumentation breakage, or wound infections at a minimum of 2-yr follow-up.

CONCLUSION

Proximal thoracic PSO can be a safe and effective technique to treat fixed proximal thoracic hyperkyphosis leading to kyphosis reduction and craniocervical relaxation.

Spinal Aneurysmal Bone Cysts (ABCs): Optimal Management

Aim

To review the published literature on the treatment of aneurysmal bone cysts (ABCs).

Method

A systematic review of the English literature to April 2019 for all articles, with a minimum of three patients and 2-year follow-up, reporting on the treatment of spinal ABCs. The various treatment options were compared for the rates of recurrence, complications and mortality.

Results

Twenty-one articles and 272 patients (mean age 16.9 years, range 3–67) were included in this review. The overall recurrence rate for ABCs following all treatments is 12.8%. This is highest in those lesions described as being treated with isolated surgiflo injection into the lesion (100%), decompression/laminectomy (42.3%), partial excision/resection (35.7%) and curettage alone (25.0%). Radiotherapy alone or in conjunction with operative intervention offers excellent cure rates. Adjuncts to operative intervention, including cryotherapy or phenol reduce the recurrence rates, whereas embolization does not. The most common complications are persistent neurological deficits, spinal deformity, and continued pain. The overall mortality rates are low (1.5%). The reoperation rates are higher in surgical than non-surgical treatments and most are performed for progressive deformity.

Discussion

ABCs are highly radiosensitive. However, with the unknown longer-term risk of radiotherapy, surgical treatments, ideally with complete resection, and the use of adjunctive therapies such as cryotherapy or phenol, offer the best chance of cure. SAE is a useful adjunct to reduce intraoperative bleeding, but this study suggests that it only modestly improves recurrence rates. Newer techniques including bisphosphonate and doxycycline administration offer potential benefits, but their efficacy requires further investigation.

Restoring the ideal Roussouly sagittal profile in adult scoliosis surgery decreases the risk of mechanical complications

PURPOSE

There are still no data proving whether restoring the ideal sagittal profile (according to Roussouly classification) in adult scoliosis (AS) patients leads to any additional benefit, especially regarding mechanical complications.

METHODS

Retrospective analysis of operated AS patients recorded in a prospective multicenter database. Demographic and radiographic (preoperative and 6-week postoperative) data were analyzed. Patients with and without mechanical complications were compared looking especially at the surgical restoration of the ideal (based on Pelvic Incidence) sagittal profile. Univariate and multivariate analysis was performed to identify causes of mechanical complications at 2-year minimum follow-up.

RESULTS

Ninty-six AS patients were analyzed. Thirty-nine patients suffered a mechanical complication (18 PJK, 11 pseudoarthrosis, 10 screw pull-out), and 57 patients had no mechanical complications. Postoperatively, 72% of patients not matching the ideal Roussouly-type suffered mechanical complications compared to 15% of matched patients (P < 0.001). Univariate analysis showed that older patients 64.9 ± 13 versus 40.7 ± 15.6 years (P < 0.001), higher postoperative Global Tilt (27° vs. 14.7°) and Pelvic Tilt (25° vs. 16°) (P < 0.001), upper instrumented vertebra at the thoracolumbar junction (62% vs. 21%) (P < 0.001), fixation to the Iliac (76% vs. 6%) (P < 0.001), and postoperative Roussouly-type mismatch (72% vs. 15%) (P < 0.001) significantly increased the rate of mechanical complications. Multivariate logistic regression analysis selected: postoperative Roussouly-type mismatch (OR = 41.9; 95%CI = 5.5-315.7; P < 0.001), iliac instrumentation (OR = 19.4; 95%CI = 2.6-142.5; P = 0.004), and age (OR = 1.1; 95%CI = 1.02-1.16; P = 0.004), as the most important variables.

CONCLUSIONS

Adult scoliosis surgery should restore the ideal Roussouly sagittal profile to decrease the rate of mechanical complications, especially in patients older than 65, instrumented to the pelvis. These slides can be retrieved under Electronic Supplementary Material.

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.

Carbon-fibre cage reconstruction in anterior cervical corpectomy for multilevel cervical spondylosis: mid-term outcomes

Background

Mid-term clinical and radiological evaluation of a carbon-fiber cage in multilevel cervical spondylosis (MCS). Anterior cervical corpectomy and fusion (ACCF) using titanium mesh cages (TMC) has shown satisfactory outcomes, but with subsidence of up to 20%. Conventional long-fiber carbon fiber cages have shown a safe profile in discectomy/fusion (ACDF) but with minimal data in the setting of corpectomy.

Methods

Retrospective review of a single centre multi-surgeon cohort of MCS patients from 2007-2012. Follow-up period was a minimum of 3.5 years, mean 6 years. Outcomes included peri-operative, clinical [Nurick, European Myelopathy, Visual Analogue Scores (VAS), modified Japanese Orthopaedic Association (mJOA) scores and radiographic (C2C7, Cobb & ROM angles)].

Results

A total of 102 consecutive patients were included. Mean length of stay was 5.5 (SD 3.5) days, blood loss 322 (SD 358) mL and operative time 98 (SD 31) min. Corpectomy levels included 72 single-level ACCF and 30 multiple ACCF. Fourteen had peri-operative complications. Three patients required early cage revisions. Mean pain scores improved from VAS neck 4.6 to 2.6 (P<0.01) and VAS arm 5.1 to 2.0 (P<0.01). Mean Nurick score improved from 1.2 to 0.4/4 (P<0.01). Mean follow-up EMS was 15.9/18 and mJOA was 14.0/17. Seventy follow-up radiographs were obtained. Flexion-extension angulation differences of >3 mm across the instrumented level were present in 5 patients, all of which displayed fusion of either grade 1 or 2. 7 had C2C7 kyphosis. Severe subsidence (>3 mm) was seen in 9 cases (13%).

Conclusions

Mid-term outcomes of this carbon-fiber cage indicate that it is safe and durable for the treatment of MCS with a similar radiological profile to that of TMC.

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.

Dual iliac screws in spinopelvic fixation: a systematic review

PURPOSE

The classical spinopelvic fixation includes 1 iliac screw on each side. The purpose of this study is to specify the indications of the "dual iliac screw" (DIS) construct, i.e., when to put 2 iliac screws on each side, to describe its biomechanical advantages, and to define its related technical aspects.

METHODS

A primary search on Medline through PubMed distribution was performed, with the use of the terms "pelvic fixation" or "spinopelvic" or "lumbo-iliac" and the terms "dual iliac screw" or "double iliac screw." English papers corresponding to the inclusion criteria were analyzed regarding the specific indications of the DIS construct and its surgical technique and advantages.

RESULTS

Eleven papers were identified according to the research criteria and included in this review. Three main indications were identified for the DIS technique according to three types of pathologies: in adult deformities when a long construct is needed in an osteoporotic patient or when correction requires three-column osteotomy of the sacrum; in trauma when a U-shaped fracture-dislocation of the sacrum is involved; in sacral tumors when a sacrectomy is performed or when destructive metastatic lesions of the sacrum require palliative surgical treatment. Biomechanically, the DIS technique proved to have higher construct stiffness in terms of compression and torsion.

CONCLUSION

In specific cases, affecting different areas of spinal diseases, the DIS technique is more advantageous, when compared to the "single iliac screw" version, as it would provide a stronger and safer fixation at the base of the spinopelvic construct. These slides can be retrieved under Electronic Supplementary Material.

Development and validation of risk stratification models for adult spinal deformity surgery

OBJECTIVE

Adult spinal deformity (ASD) surgery has a high rate of major complications (MCs). Public information about adverse outcomes is currently limited to registry average estimates. The object of this study was to assess the incidence of adverse events after ASD surgery, and to develop and validate a prognostic tool for the time-to-event risk of MC, hospital readmission (RA), and unplanned reoperation (RO).

METHODS

Two models per outcome, created with a random survival forest algorithm, were trained in an 80% random split and tested in the remaining 20%. Two independent prospective multicenter ASD databases, originating from the European continent and the United States, were queried, merged, and analyzed. ASD patients surgically treated by 57 surgeons at 23 sites in 5 countries in the period from 2008 to 2016 were included in the analysis.

RESULTS

The final sample consisted of 1612 ASD patients: mean (standard deviation) age 56.7 (17.4) years, 76.6% women, 10.4 (4.3) fused vertebral levels, 55.1% of patients with pelvic fixation, 2047.9 observation-years. Kaplan-Meier estimates showed that 12.1% of patients had at least one MC at 10 days after surgery; 21.5%, at 90 days; and 36%, at 2 years. Discrimination, measured as the concordance statistic, was up to 71.7% (95% CI 68%-75%) in the development sample for the postoperative complications model. Surgical invasiveness, age, magnitude of deformity, and frailty were the strongest predictors of MCs. Individual cumulative risk estimates at 2 years ranged from 3.9% to 74.1% for MCs, from 3.17% to 44.2% for RAs, and from 2.67% to 51.9% for ROs.

CONCLUSIONS

The creation of accurate prognostic models for the occurrence and timing of MCs, RAs, and ROs following ASD surgery is possible. The presented variability in patient risk profiles alongside the discrimination and calibration of the models highlights the potential benefits of obtaining time-to-event risk estimates for patients and clinicians.

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.

Anterior cervical spine blood supply: a cadaveric study

PURPOSE

To describe the origin of the vessels supplying the anterior sub-axial cervical vertebrae (C3-C7) to further understand their potential influence on anterior bone loss after anterior cervical spinal surgery.

METHOD

Cadaveric dissection was performed on ten adult human necks after latex perfusion of their subclavian, common carotid and vertebral arteries. The nutrient vessels of the sub-axial cervical spine were identified and traced to their origin. The course and distribution of these vessels and their nutrient foraminae are described.

RESULTS

In all cases the anterior nutrient vessels were derived from the thyro-cervical trunk with branches that passed over the longus coli muscles forming a leash of vessels in the pre-vertebral fascia which subsequently extended in a frond-like pattern to pass onto the anterior aspect of vertebrae. The more cranial the cervical level the fewer the number of nutrient vessels and foraminae. The distribution of the foraminae on the anterior vertebral body followed the oblique supero-medial course of the nutrient vessels.

CONCLUSION

Nutrient vessels perforate the cervical vertebrae on their anterior surface. These are derived from a leash of vessels that lie within the pre-vertebral fascia overlying the longus coli muscles. The origin of these vessels is the ascending cervical artery with a variable contribution from the transverse cervical artery.

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.

Global Sagittal Alignment and Proximal Junctional Kyphosis in Adolescent Idiopathic Scoliosis

STUDY DESIGN

Case-control study.

OBJECTIVES

To analyse global sagittal alignment including the cranial center of mass (CCOM) and proximal junctional kyphosis (PJK) in adolescent idiopathic scoliosis (AIS) patients treated with posterior instrumentation.

SUMMARY OF BACKGROUND DATA

PJK plays an important role in the global sagittal alignment in AIS patients. Maintaining the head above the pelvis allows for a minimization of energy expense in ambulation and upright posture. Numerous studies have been performed to understand the PJK phenomena in AIS patients. However, to our knowledge, no study performed on AIS patients included the head in the analysis of global sagittal alignment and PJK.

METHODS

This study included 85 AIS patients and 51 asymptomatic adolescents. Low-dose bi-planar radiographs were acquired for each subject preoperatively and at the two-year follow-up. Two global sagittal alignment parameters were calculated, that is, the angle between the vertical and the line joining the center of the bi-coxofemoral axis (HA) and either the most superior point of the dentiform apophysis of C2 (OD) or the cranial center of mass (CCOM).

RESULTS

Among normal adolescents, the average OD-HA and CCOM-HA angles were -2.3° ± 2° and -1.5° ± 1.8°, respectively. Among AIS patients, the average OD-HA and CCOM-HA angles were, respectively, -2.3° ± 1.9° and -1.3° ± 1.8° preoperatively and -2.8° ± 1.7° and -1.9° ± 1.7° at the last follow-up. Overall, 13% of the patients developed PJK postoperatively. Case-by-case analysis showed that adjusting the thoracic kyphosis and the compensations required to maintain this constant could provide explanatory elements.

CONCLUSIONS

OD-HA and CCOM-HA angles remain almost constant among the normal group and patients, pre- and postoperatively, whether PJK or non-PJK. Five patients without PJK and only one patient with PJK produced abnormal values relative to the asymptomatic subjects. Therefore, it could be concluded that PJK is a compensation mechanism, which allows for CCOM-HA and, to a lesser extent, OD-HA to remain invariant.

LEVEL OF EVIDENCE

Level III.

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.

Radiographic Classification for Degenerative Spondylolisthesis of the Lumbar Spine Based on Sagittal Balance: A Reliability Study

STUDY DESIGN

Inter- and intraobserver reliability study.

OBJECT

To assess the reliability of a new radiographic classification of degenerative spondylolisthesis of the lumbar spine (DSLS).

SUMMARY OF BACKGROUND DATA

DSLS is a common cause of chronic low back and leg pain in adults. To this date, there is no consensus for a comprehensive analysis of DSLS. The reliability of a new DSLS classification system based on sagittal alignment was assessed.

METHODS

Ninety-nine patients admitted to our spinal surgery department for surgical treatment of DSLS between January 2012 and December 2015 were included. Three observers measured sagittal alignment parameters with validated software: segmental lordosis (SL), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and sagittal vertical axis (SVA). Full body low-dose lateral view radiographs were analyzed and classified according to three main types: Type 1A: preserved LL and SL; Type 1B: preserved LL and reduced SL (≤5°); Type 2A: PI-LL ≥10° without pelvic compensation (PT <25°); Type 2B: PI-LL ≥10° with pelvic compensation (PT ≥25°); Type 3: global sagittal malalignment (SVA ≥40 mm). The three observers classified radiographs twice with a 3-week interval for intraobserver reproducibility. Interobserver reproducibility was calculated using Fleiss κ and intra-class coefficient. Intraobserver reproducibility was calculated using Cohen κ.

RESULTS

Mean age was 68.8 ± 9.8 years. Mean sagittal alignment parameters values were the following: PI: 60.1° ± 12.7°; PI-LL was 12.2° ± 13.9°, PT: 24.7° ± 8.5°; SVA: 44.9 mm ± 44.6 mm; SL: 16.6° ± 8.4°. Intraobserver repeatability showed an almost perfect agreement (ICC > 0.92 and Cohen κ > 0.89 for each observer). Fleiss κ value for interobserver reproducibility was 0.82, with percentage agreement among observers between 88% and 89%.

CONCLUSION

This new classification showed an excellent inter- and intraobserver reliability. This simple method could be an additional sagittal balance tool helping surgeons improve their preoperative DSLS analysis.

Location of correction within the lumbar spine impacts acute adjacent-segment kyphosis

OBJECTIVE

The surgical correction of adult spinal deformity (ASD) often involves modifying lumbar lordosis (LL) to restore ideal sagittal alignment. However, corrections that include large changes in LL increase the risk for development of proximal junctional kyphosis (PJK). Little is known about the impact of cranial versus caudal correction in the lumbar spine on the occurrence of PJK. The goal of this study was to investigate the impact of the location of the correction on acute PJK development.

METHODS

This study was a retrospective review of a prospective multicenter database. Surgically treated ASD patients with early follow-up evaluations (6 weeks) and fusions of the full lumbosacral spine were included. Radiographic parameters analyzed included the classic spinopelvic parameters (pelvic incidence [PI], pelvic tilt [PT], PI−LL, and sagittal vertical axis [SVA]) and segmental correction. Using Glattes’ criteria, patients were stratified into PJK and noPJK groups and propensity matched by age and regional lumbar correction (ΔPI−LL). Radiographic parameters and segmental correction were compared between PJK and noPJK patients using independent t-tests.

RESULTS

After propensity matching, 312 of 483 patients were included in the analysis (mean age 64 years, 76% women, 40% with PJK). There were no significant differences between PJK and noPJK patients at baseline or postoperatively, or between changes in alignment, with the exception of thoracic kyphosis (TK) and ΔTK. PJK patients had a decrease in segmental lordosis at L4-L5-S1 (−0.6° vs 1.6°, p = 0.025), and larger increases in segmental correction at cranial levels L1-L2-L3 (9.9° vs 7.1°), T12-L1-L2 (7.3° vs 5.4°), and T11-T12-L1 (2.9° vs 0.7°) (all p < 0.05).

CONCLUSIONS

Although achievement of an optimal sagittal alignment is the goal of realignment surgery, dramatic lumbar corrections appear to increase the risk of PJK. This study was the first to demonstrate that patients who developed PJK underwent kyphotic changes in the L4–S1 segments while restoring LL at more cranial levels (T12–L3). These findings suggest that restoring lordosis at lower lumbar levels may result in a decreased risk of developing PJK.

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.

Classification of coronal imbalance in adult scoliosis and spine deformity: a treatment-oriented guideline

INTRODUCTION

In adult spinal deformity (ASD), sagittal imbalance and sagittal malalignment have been extensively described in the literature during the past decade, whereas coronal imbalance and coronal malalignment (CM) have been given little attention. CM can cause severe impairment in adult scoliosis and ASD patients, as compensatory mechanisms are limited. The aim of this paper is to develop a comprehensive classification of coronal spinopelvic malalignment and to suggest a treatment algorithm for this condition.

METHODS

This is an expert's opinion consensus based on a retrospective review of CM cases where different patterns of CM were identified, in addition to treatment modifiers. After the identification of the subgroups for each category, surgical planning for each subgroup could be specified.

RESULTS

Two main CM patterns were defined: concave CM (type 1) and convex CM (type 2), and the following modifiers were identified as potentially influencing the choice of surgical strategy: stiffness of the main coronal curve, coronal mobility of the lumbosacral junction and degeneration of the lumbosacral junction. A surgical algorithm was proposed to deal with each situation combining the different patterns and their modifiers.

CONCLUSION

Coronal malalignment is a frequent condition, usually associated to sagittal malalignment, but it is often misunderstood. Its classification should help the spine surgeon to better understand the full spinal alignment of ASD patients. In concave CM, the correction should be obtained at the apex of the main curve. In convex CM, the correction should be obtained at the lumbosacral junction. These slides can be retrieved under Electronic Supplementary Material.

Anterior Bone Loss in Cervical Disc Arthroplasty

Study Design

Retrospective, longitudinal observational study.

Purpose

To describe the natural history of anterior bone loss (ABL) in cervical disc arthroplasty (CDA) and introduce a classification system for its assessment.

Overview of Literature

ABL has recently been recognized as a complication of CDA, but its cause and clinical effects remain unknown.

Methods

Patients with non-keeled CDA (146) were retrospectively reviewed. X-rays were examined at 6 weeks, 3, 6, 9, 12, 18, and 24 months, and annually thereafter for a minimum of 5 years. These were compared with the initial postoperative X-rays to determine the ABL. Visual Analog Scale pain scores were recorded at 3 months and 5 years. Neck Disability Index was recorded at postoperative 5 years. The natural history was determined and a classification system was introduced.

Results

Complete radiological assessment was available for 114 patients with 156 cervical disc replacements (CDRs) and 309 endplates (average age, 45.3 years; minimum, 28 years; maximum, 65 years; 57% females). ABL occurred in 57.1% of CDRs (45.5% mild, 8.3% moderate, and 3.2% severe) and commenced within 3 months of the operation and followed a benign course, with improvement in the bone stock after initial bone resorption. There was no relationship between ABL degree and pain or functional outcome, and no implants were revised.

Conclusions

ABL is common (57.1%). It occurs at an early stage (within 3 months) and typically follows a non-progressive natural history with stable radiographic features after the first year. Most ABL cases are mild, but severe ABL occurs in approximately 3% of CDAs. ABL does not affect the patients’ clinical outcome or the requirement for revision surgery. Surgeons should thus treat patients undergoing CDA considering ABL.

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.

Sagittal radiographic parameters demonstrate weak correlations with pretreatment patient-reported health-related quality of life measures in symptomatic de novo degenerative lumbar scoliosis: a European multicenter analysis

OBJECTIVE

Previous studies have demonstrated that among patients with adult spinal deformity (ASD), sagittal plane malalignment is poorly tolerated and correlates with suboptimal patient-reported health-related quality of life (HRQOL). These studies included a broad range of radiographic abnormalities and various types of ASD. However, the clinical and radiographic characteristics of de novo degenerative lumbar scoliosis (DNDLS), a subtype of ASD, may influence previously reported correlation strengths. The aim of this study was to correlate sagittal radiographic parameters with pretreatment HRQOL in patients with symptomatic DNDLS.

METHODS

In this multicenter retrospective study of prospectively collected data, 74 patients with symptomatic DNDLS were enrolled based on anteroposterior and lateral 36-inch standing radiographs. Measurements included Cobb angle, coronal imbalance, pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), sagittal vertical axis (SVA), thoracic kyphosis, pelvic incidence minus lumbar lordosis (PI−LL), T1-pelvic angle, and global tilt. HRQOL questionnaires included the Oswestry Disability Index (ODI), Scoliosis Research Society (SRS-22r), 36-item Short-Form Health Survey, and numeric rating scale (NRS) for back and leg pain. Correlations between radiographic parameters and HRQOL were assessed. Finally, HRQOL and increasing severity of sagittal modifiers (SVA, PI−LL, and PT) were evaluated.

RESULTS

Weak correlations were found between SVA and ODI (r = 0.296, p < 0.05) and PT with NRS back pain and the SRS pain domain (r = −0.260, p < 0.05, and r = 0.282, p < 0.05, respectively). Other sagittal radiographic parameters did not show any significant correlation with HRQOL. No significant differences in HRQOL were found concerning the increasing severity of PT, PI−LL, and SVA.

CONCLUSIONS

While DNDLS is a severe disabling condition, no noteworthy association between clinical and sagittal radiographic parameters was found through this study, demonstrating that sagittal radiographic parameters should not be considered the unique predictor of pretreatment suboptimal health status in this specific group of patients. Future studies addressing classification and treatment algorithms will have to take into account the existing subgroups of ASD.