Using Machine Learning (ML) Models to Predict Risk of Venous Thromboembolism (VTE) Following Spine Surgery.

STUDY DESIGN: A retrospective cohort study. OBJECTIVES: Venous thromboembolism (VTE) is a potentially high-risk complication for patients undergoing spine surgery. Although guidelines for assessing VTE risk in this population have been established, development of new techniques that target different aspects of the medical history may prove to be of further utility. The goal of this study was to develop a predictive machine learning (ML) model to identify nontraditional risk factors for predicting VTE in spine surgery patients. SUMMARY OF BACKGROUND DATA: A cohort of 63 patients was identified who had undergone spine surgery at a single center from 2015 to 2021. Thirty-one patients had a confirmed VTE, while 32 had no VTE. A total of 113 attributes were defined and collected via chart review. Attribute categories included demographics, medications, labs, past medical history, operative history, and VTE diagnosis. METHODS: The Waikato Environment for Knowledge Analysis (WEKA) software was used in creating and evaluating the ML models. Six classifier models were tested with 10-fold cross-validation and statistically evaluated using t tests. RESULTS: Comparing the predictive ML models to the control model (ZeroR), all predictive models were significantly better than the control model at predicting VTE risk, based on the 113 attributes ( P <0.001). The Random Forest model had the highest accuracy of 88.89% with a positive predictive value of 93.75%. The Simple Logistic algorithm had an accuracy of 84.13% and defined risk attributes to include calcium and phosphate laboratory values, history of cardiac comorbidity, history of previous VTE, anesthesia time, selective serotonin reuptake inhibitor use, antibiotic use, and antihistamine use. The J48 model had an accuracy of 80.95% and it defined hemoglobin laboratory values, anesthesia time, beta-blocker use, dopamine agonist use, history of cancer, and Medicare use as potential VTE risk factors. CONCLUSION: Further development of these tools may provide high diagnostic value and may guide chemoprophylaxis treatment in this setting of high-risk patients.

Worse Preoperative Disability is Predictive of Improvement in Disability After Complex Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective Cohort Study. OBJECTIVES: Few previous studies have examined the relationship between preoperative disability and patient outcomes after complex adult spinal deformity surgery. In this study, we hypothesized that patients with worse preoperative disability would be more likely achieve a clinically significant improvement in their symptoms after surgery. METHODS: Demographics, comorbidities, surgical data, and health related survey results were analyzed from a consecutive series of adults (≥18 years old) who underwent spinal deformity correction, instrumentation, and fusion. Patients included had 6 or more levels fused and their surgery performed at single institution between 2015 and 2018 with minimum 2 year follow up. RESULTS: A total of 108 patients met inclusion criteria. Bivariate analysis demonstrated the following as having a greater probability of reaching minimum clinically important difference (MCID) at 2 years postoperatively: >50th percentile Oswestry Disability Index (ODI) score (ODI >36), cardiac comorbidities, and use of pelvic fixation, pedicle subtraction osteotomy, and transforaminal lumbar interbody fusion. Conversely, baseline Scoliosis research society score (SRS) >50th percentile (SRS ≥62) and use of vertebral column resection (VCR) were significant predictors of not reaching MCID at 2 years. On logistic regression analysis, >50th percentile ODI score (ODI >36) was identified as the only independent predictor of achieving MCID. CONCLUSIONS: Patients with greater disability, independent of other preoperative or surgical factors, are more likely to have clinically significant improvement in their daily functioning after complex deformity surgery. For patients who undergo surgical intervention for severe or progressive deformity, including VCR, MCID might be an ineffective outcome measure.

The Telehealth Spine Physical Examination: A Practical Approach Learned During the COVID-19 Pandemic.

BACKGROUND: The COVID-19 pandemic has led to a surge in the use of telehealth visits across the country to minimize in-person visits and to limit the spread of COVID-19. To date, no standards or outlines for telehealth spine examinations have been detailed and many surgeons simply defer the physical examination when performing telehealth visits. Nevertheless, just as physical examination of the spine is an integral part of live clinical encounters, appropriately modified physical examinations should also be part of virtual visits. METHODS: In this study we provide our methodology for guiding providers and patients in efficiently performing telehealth spine examinations. RESULTS: The study details steps for efficiently performing a physical examination in the telehealth setting. Our written suggestions are supplemented with photographs and video recordings to help streamline the virtual examination. CONCLUSIONS: An effective and efficient spine physical examination can be performed during telehealth visits. Future directions include verifying the findings from our virtual physical examination with in-person examinations.

Flexion-extension standing radiographs underestimate instability in patients with single-level lumbar spondylolisthesis: comparing flexion-supine imaging may be more appropriate.

BACKGROUND: Generally, most spine surgeons agree that increased segmental motion viewed on flexion-extension radiographs is a reliable predictor of instability; however, these views can be limited in several ways and may underestimate the instability at a given lumbar segment. METHODS: Consecutively collected adult (≥18 years old) patients with symptomatic single-level lumbar spondylolisthesis were reviewed from a two-surgeon database from 2015 to 2019. Routine standing lumbar X-rays (neutral, flexion, extension) and supine lumbar MRI (sagittal T2-weighted imaging sequence) were performed. Patients were excluded if they had prior lumbar surgery, missing radiographic data, or if the time between X-rays and MRI was >6 months. RESULTS: All 39 patients with symptomatic, single-level lumbar spondylolisthesis were identified. The mean age was 57.3±16.7 years and 66% were female. There was good intra- and inter-rater reliability agreement between measured values on the presence of instability. The slip percentage (SP) difference was significantly highest in the flexion-supine (FS) (5.7 mm, 12.3%) and neutral standing-supine (NS) (4.3 mm, 8.7%) groups, both of which were significantly higher compared with the flexion-extension (FE) group (1.8 mm, 4.5%, P<0.001). Ventral instability based on SP >8% was observed more frequently in FS (79.5%) and NS (52.6%) groups compared with FE group (16.7%, P<0.001). No statistically significant correlation was found between SP and disc angle for all radiographic views. CONCLUSIONS: Comparing standing lateral and flexion X-rays with supine MRIs provides higher sensitivity to assess instability than standard flexion-extension radiographs. The FS and NS comparisons also show greater slip percentage differences at higher slip grades, but not at different lumbar levels. These changes are not dependent on age or gender.

Surgeons' Learning Curve of Renaissance Robotic Surgical System.

INTRODUCTION: A few articles on robot-assisted pedicle screw placement described the learning curve but failed to report on the overall operative time, including cases in which the robotic system malfunctioned. The purpose of this study was to identify a single surgeon's learning curve including estimated blood loss, surgery time, anesthesia time, robot time, and complications. METHODS: A retrospective study was performed between January 2016 and August 2018 for patients who underwent posterior spinal fusion using the Mazor robot. Based on the charts, the robot time, time of anesthesia, and surgery time were recorded, as were the complications, misplacement of screws, and blood loss. RESULTS: Of 62 robot-assisted surgeries scheduled, only 46 were performed (74.2%) upon patients with a mean age of 63.3 ± 13.0 years. The mean follow-up time was 13.2 ± 8.0 months and most commonly a fusion from L4 to S1 was performed (20/46, 43.5%). A high improvement in estimated intraoperative blood loss was observed of 755.7 ± 344.7 mL (slope = -9.89). A decrease in time in anesthesia, surgery, and robotic usage was identified with a slope factor of -3.64 (R 2 = .22, SE = 85.4, P < .005), -3.97 (R 2 = 0.30, SE 75.8, P < .005), -0.69 (R 2 = .07, SE = 27.8, P < .09), respectively. Furthermore, a decrease in pedicle screw insertion time and operative time was found (slope = -0.05, R 2 = .02, SE = 3.4, P = .37). In total, 5 major complications (cases 8, 19, 21, 35, 43) and 6 minor complications (cases 4, 14, 15, 20, 29), were identified (21.7%) without any learning curve. CONCLUSIONS: Robot pedicle screw insertion shows no major learning curve; however, the blood loss and the installation process of the system improved with experience. LEVEL OF EVIDENCE: 3.

Tissue Engineered Bone Differentiated From Human Adipose Derived Stem Cells Inhibit Posterolateral Fusion in an Athymic Rat Model.

STUDY DESIGN: Biological augmentation spinal arthrodesis trial in athymic rats. OBJECTIVE: To assess the efficacy of tissue-engineered bone to promote L4-L5 intertransverse process fusion in an athymic rat model. SUMMARY OF BACKGROUND DATA: Each year in the United States, over 400,000 spinal fusion surgeries are performed requiring bone graft. The current gold standard for posterolateral lumbar fusion is autogenous iliac crest bone graft (ICBG), but the harvesting of ICBG is associated with increased operative time and significant complications. This being the case, an alternative cost-effective bone graft source is needed. METHODS: Bovine bone cores were sterilized and decellularized for scaffold production. Human adipose derived mesenchymal stem cells (ADSC) were obtained and verified by tridifferentiation testing and seeded onto dried scaffolds. The seeded cores were cultured for 5 weeks in culture medium designed to mimic endochondral ossification and produce hypertrophic chondrocytes. Single-level intertransverse process fusions were performed at the L4-L5 level of 31 athymic rats. Fifteen rats were implanted with the hypertrophic chondrocyte seeded scaffold and 16 had scaffold alone. Half of the study rats were sacrificed at 3 weeks and the other half at 6 weeks. Spinal fusion was assessed using 2D and 3D micro computed tomography (µCT) analysis and tissue histology. RESULTS: At 3 weeks, none of the tissue engineered rats had partial or complete fusion, whereas 62.5% of the decellularized rats fused and another 12.5% had partial fusions (P = 0.013). At 6 weeks, none of the tissue engineered rats fused and 50% had partial fusions, whereas 87.5% of the decellularized rats fused (P = 0.002). CONCLUSION: Tissue engineered bone composed of hypertrophic chondrocytes inhibits posterolateral fusion in an athymic rat model and therefore does not represent a promising cost-effective bone graft substitute. LEVEL OF EVIDENCE: N/A.

The medicolegal landscape of spine surgery: how do surgeons fare?

BACKGROUND CONTEXT: Because of the limited and confidential nature of most legal data, scarce literature is available to physicians about reasons for litigation in spine surgery. To optimally compensate patients while protecting physicians, further understanding of the medicolegal landscape is needed for high-risk procedures such as spine surgery. Based on these, surgeons can explore ways to better protect both their patients and themselves. PURPOSE: To characterize the current medicolegal environment of spine surgery by analyzing a recent dataset of malpractice litigation. STUDY DESIGN: A retrospective study. PATIENT SAMPLE: All malpractice cases involving spine surgery available to public query between the years of 2010 and 2014. OUTCOME MEASURES: Case outcome for spine surgery malpractice cases between the years of 2010 and 2014. METHODS: WestlawNext was used to analyze spine surgery malpractice cases at the state and federal level between the years 2010 and 2014. WestlawNext is a subscription-based, legal search engine that contains publicly available federal and state court records. All monetary values were inflation adjusted for 2016. One hundred three malpractice cases were categorized by case descriptors and outcome measures. Claims were categorized as either intraoperative complaints or preoperative complaints. RESULTS: Rulings in favor of the defendant (surgeon) were noted in 75% (77 of 103) of the cases. Lack of informed consent was cited in 34% of cases. For the 26 cases won by the plaintiff, the average amount in settlement was $2,384,775 versus $3,945,456 in cases brought before a jury. Cases involving consent averaged a compensation of $2,029,884, whereas cases involving only intraoperative complaints averaged a compensation of $3,667,530. A significant correlation was seen between increased compensation for plaintiffs and cases involving orthopedic surgeons (p=.020) or nerve injury (p=.005). Wrong-level surgery may be associated with lower plaintiff compensation (p=.055). The length of cases resulting in defense verdicts averaged 5.51 years, which was significantly longer than the 4.34 years average length of settlements or verdicts in favor of plaintiffs (p=.016). CONCLUSIONS: Spine surgeons successfully defended themselves in 75% of lawsuits, although the cases won by physicians lingered significantly longer than those settled. Better understanding of these cases may help surgeons to minimize litigation. More than one third of cases involved a claim of insufficient informed consent. Surgeons can protect themselves and optimize care of patients through clear and documented patient communication, education, and intraoperative vigilance to avoid preventable complications.

Hip and knee arthroplasty are common among patients with transthyretin cardiac amyloidosis, occurring years before cardiac amyloid diagnosis: can we identify affected patients earlier?

Transthyretin cardiac amyloidosis (ATTR-CA) causes a restrictive cardiomyopathy in older adults, often diagnosed at advanced stages when emerging therapies in late phase clinical trials may not have clinical benefit. This investigation aimed to detect clinical entities that may provide more advanced warning of ATTR-CA. Since ATTR preferentially deposits in ligaments, tendons, and articular cartilage, we hypothesized that ATTR-CA patients have a greater prevalence of total hip (THA) and knee (TKA) arthroplasties compared with the general population, and that arthroplasty occurs significantly before ATTR-CA diagnosis. Three-hundred and thirteen patients with cardiac amyloidosis (172 with ATTR-CA, 141 with light-chain) from our institutional database were analyzed and compared to published data in over 300 million patients. Overall, 23.3% of patients with ATTR-CA and 9.2% of patients with light-chain cardiac amyloidosis (AL-CA) underwent lower extremity arthroplasty. Compared to the general population, both THA and TKA were significantly more common among patients with ATTR-CA (THA: RR 5.61, 95% CI 2.25-4.64; TKA: RR 3.32, 95% CI 2.25-4.64) but not those with AL-CA (THA: RR 1.87, 95% CI 0.85-4.08; TKA: RR 1.42, 95% CI 0.73-2.84). On an average, arthroplasty occurred 7.2 years before ATTR-CA diagnosis.

Reliability of the Spinal Deformity Study Group classification of lumbosacral spondylolisthesis.

STUDY DESIGN: Reliability study of the computer-assisted SDSG (Spinal Deformity Study Group) classification of lumbosacral spondylolisthesis. OBJECTIVE: To assess the intra- and interobserver reliability of the computer-assisted SDSG classification of lumbosacral spondylolisthesis. SUMMARY OF BACKGROUND DATA: The SDSG has proposed a new classification of lumbosacral spondylolisthesis based on slip grade, pelvic incidence (PI), and sacro-pelvic and spinal balance. Three types of low-grade spondylolisthesis are described: low PI (type 1), normal PI (type 2), and high PI (type 3). High-grade spondylolisthesis are defined as type 4 (balanced sacro-pelvis), type 5 (retroverted sacro-pelvis with balanced spine), and type 6 (retroverted sacro-pelvis with unbalanced spine). METHODS: Full-length standing lateral radiographs of the spine of 40 subjects with lumbosacral spondylolisthesis were reviewed twice by 7 observers. Custom software was used by the observers to identify 7 anatomical landmarks on each radiograph to determine the SDSG type for all subjects. Percentage of agreement and κ coefficients were used to determine the intra- and interobserver reliability. RESULTS: All 6 types of spondylolisthesis described in the computer-assisted SDSG classification were identified. Overall intra- and interobserver agreements were 80% (κ: 0.74) and 71% (κ: 0.65), respectively. The intra- and interobserver agreements associated with computerized determination of slip grade were 92% (κ: 0.83) and 88% (κ: 0.78), respectively. As for computerized determination of sacro-pelvic and spinal balance, intra- and interobserver agreements were 86% (κ: 0.76) and 75% (κ: 0.63) for low-grade slips, whereas they were 88% (κ: 0.80) and 83% (κ: 0.75) for high-grade slips. CONCLUSION: Substantial intra- and interobserver reliability was found for the computer-assisted SDSG classification, and all 6 types of lumbosacral spondylolisthesis were identified. Refinement of the computer-assisted classification technique is, however, needed to further increase the reliability of the SDSG classification and facilitate its clinical use.

Recurrent lumbar disk herniation.

Recurrent lumbar disk herniation is the most common complication following primary open diskectomy. It is defined as recurrent back and/or leg pain after a definite pain-free period lasting at least 6 months from initial surgery. Careful neurologic examination is critical, and laboratory tests should be ordered to evaluate for infection. Imaging demonstrates disk herniation at the previously operated level. It is important to differentiate recurrent disk herniation from postoperative epidural scar because the latter may not benefit from reoperation. Treatment of recurrent lumbar disk herniation includes aggressive medical management and surgical intervention. Surgical techniques include conventional open diskectomy, minimally invasive open diskectomy, and open diskectomy with fusion. Fusion is necessary in the presence of concomitant segmental instability or significant foraminal stenosis resulting from disk space collapse.

An anatomical study of the mid-lateral pars relative to the pedicle footprint in the lower lumbar spine.

STUDY DESIGN: An anatomic study that describes the relationship of the pedicle center to the mid-lateral pars (MLP) in the lower lumbar spine as a guide to pedicle screw placement. OBJECTIVE: Describe morphometric data of the lower lumbar pedicles, the unique coronal pedicle footprints of L4 and L5, and their impact on the relationship of the pedicle center to the MLP. SUMMARY OF BACKGROUND DATA: Traditional medial-lateral starting points for lumbar pedicle screws use the facet as an anatomic reference for all lumbar levels. The facet is often a difficult landmark to use secondary to degenerative changes and the desire to minimize damage to the facet capsule in the most cephalad level. These techniques can also result in pedicle violation particularly in the lower lumbar spine. Use of the nonarthritic MLP is proposed in this study as an alternative anatomic reference point for the pedicle center. METHODS: Seventy-two pedicles (L3-S1) from embalmed cadaveric spines were used. Linear and angular dimensions of the pedicle were measured, including the degree of coronal pedicle tilt of L4 and L5. The center of the pedicle relative to the MLP and relative to the midline of the base of the transverse process was measured. The axial superior facet angle and angle of pedicle screw insertion were also measured. RESULTS: The minimum pedicle width was 10.9 and 12.4 mm and the coronal pedicle tilt was 36 degrees and 55 degrees for L4 and L5, respectively. A classification of 2 types of L5 pedicles relevant to pedicle center location was developed. In the medial-lateral direction, the pedicle center is 2.9 mm lateral to the MLP at L3 and L4. At L5, it is 1.5 and 4.5 mm lateral to the MLP for a type I and type II pedicle, respectively. In the superior-inferior direction, the pedicle center is 1 mm superior to the midline of the transverse process base for all lower lumbar levels. Significant differences between a type I and II L5 pedicle were a larger pedicle width and distance of the pedicle center to the MLP for a type II pedicle. The difference between the axial pedicle screw insertion angle and anatomic superior facet angles was 8 degrees from L4-S1. CONCLUSION: The MLP is a reliable anatomic reference point for the center of the pedicle in the lower lumbarspine. Consideration needs to be taken when inserting pedicle screws at L4 and L5 because of the degree of their coronal tilts and unique pedicle footprints. It is important to distinguish a type I from type II L5 pedicle as a type II pedicle is wider, has a more lateral pedicle center relative to the MLP, and has the potential for lateral screw placement while still remaining within the pedicle.

An anatomic and radiographic study of lumbar facets relevant to percutaneous transfacet fixation.

STUDY DESIGN: An anatomic study of lumbar facet anatomy for transfacet fixation. OBJECTIVE: Describe the ideal starting point and trajectory for percutaneous transfacet fixation. SUMMARY OF BACKGROUND DATA: Percutaneous transfacet fixation is gaining popularity for posterior stabilization after anterior lumbar interbody fusion. Despite biomechanical and clinical studies, there are no anatomic guidelines for safe placement of percuatenous transfacet screws. METHODS: Eighty L3-S1 facet joints from embalmed cadaveric spines were analyzed. Linear and angular measurements of the facets were recorded. Under direct visualization, the segments were pinned with an ipsilateral transfacet technique. The degrees of angulation in the sagittal and axial plane were recorded. The distances of the starting point relative to landmarks of the superior body were measured. Under fluoroscopy, radiographic parameters for ideal visualization of the pin and pin ending points were determined. RESULTS: Inferior and superior facet heights ranged from 15.7 to 17.5 mm at all levels. The percentage of inferior facet extending below the L3 and L4 end plates was 84% and 86% respectively and decreased at L5 to 72%. The percentage of superior facet extending above the end plate ranged from 36% to 44% at all levels. The transverse facet angle progressively increased from L3 to S1. The L2-L3 segments could not be instrumented from the ipsilateral side due to the vertical facet orientation. For L3-S1 segments, the starting point in the coronal plane is based on the superior body of the instrumented segment and should be in line with the medial border of the pedicle in the medial-lateral direction and in line with the inferior end plate in the cranial-caudal direction. The screw should be laterally angulated approximately 15 degrees in the axial plane approximately 30 degrees caudally in the sagittal plane. The screw should end in the inferolateral quadrant of the pedicle on the AP radiograph and at the pedicle-vertebral body junction on the lateral radiograph. 35 degrees of axial rotation is the optimal fluoroscopic view for confirming screw placement. CONCLUSION: Ipsilateral transfacet fixation can be successfully performed in the L3-S1 segments by using the inferior end plate and medial pedicle wall of the superiorly instrumented level as anatomic landmarks in conjunction with axial and sagittal angles of insertion.

Reliability and development of a new classification of lumbosacral spondylolisthesis.

BACKGROUND: A classification of lumbosacral spondylolisthesis has been proposed recently. This classification describes eight distinct types of spondylolisthesis based on the slip grade, the degree of dysplasia, and the sagittal sacro-pelvic balance. The objectives of this study are to assess the reliability of this classification and to propose a new and refined classification. METHODS: Standing posteroanterior and lateral radiographs of the spine and pelvis of 40 subjects (22 low-grade, 18 high-grade) with lumbosacral spondylolisthesis were reviewed twice by six spine surgeons. Each radiograph was classified based on the slip grade, the degree of dysplasia, and the sagittal sacro-pelvic balance. No measurements from the radiographs were allowed. Intra- and inter-observer reliability was assessed using kappa coefficients. A refined classification is proposed based on the reliability study. RESULTS: All eight types of spondylolisthesis described in the original classification were identified. Overall intra- and inter-observer agreement was respectively 76.7% (kappa: 0.72) and 57.0% (kappa: 0.49). The specific intra-observer agreement was 97.1% (kappa: 0.94), 85.0% (kappa: 0.69) and 88.8% (kappa: 0.85) with respect to the slip grade, the degree of dysplasia, and the sacro-pelvic balance, respectively. The specific inter-observer agreement was 95.2% (kappa: 0.90), 72.2% (kappa: 0.43) and 77.2% (kappa: 0.69) with respect to the slip grade, the degree of dysplasia, and the sacro-pelvic balance, respectively. CONCLUSION: This study confirmed that surgeons can classify radiographic findings into all eight types of spondylolisthesis. The intra-observer reliability was substantial, while the inter-observer reliability was moderate mainly due to the difficulty in distinguishing between low- and high-dysplasia. A refined classification excluding the assessment of dysplasia, while incorporating the assessment of the slip grade, sacro-pelvic balance and global spino-pelvic balance is proposed, and now includes five types of lumbosacral spondylolisthesis.

Intra- and inter-observer reliability of determining radiographic sagittal parameters of the spine and pelvis using a manual and a computer-assisted methods.

Sagittal imbalance is a significant factor in determining clinical treatment outcomes in patients with deformity. Measurement of sagittal alignment using the traditional Cobb technique is frequently hampered by difficulty in visualizing landmarks. This report compares traditional manual measurement techniques to a computer-assisted sagittal plane measurement program which uses a radius arc methodology. The intra and inter-observer reliability of the computer program has been shown to be 0.92-0.99. Twenty-nine lateral 90 cm radiographs were measured by a computer program for an array of sagittal plane measurements. Ten experienced orthopedic spine surgeons manually measured the same parameters twice, at least 48 h apart, using a digital caliper and a standardized radiographic manual. Intraclass correlations were used to determine intra- and interobserver reliability between different manual measures and between manual measures and computer assisted-measures. The inter-observer reliability between manual measures was poor, ranging from -0.02 to 0.64 for the different sagittal measures. The intra-observer reliability in manual measures was better ranging from 0.40 to 0.93. Comparing manual to computer-assisted measures, the ICC ranged from 0.07 to 0.75. Surgeons agreed more often with each other than with the machine when measuring the lumbar curve, the thoracic curve, and the spino-sacral angle. The reliability of the computer program is significantly higher for all measures except for lumbar lordosis. A computer-assisted program produces a reliable measurement of the sagittal profile of the spine by eliminating the need for distinctly visible endplates. The use of a radial arc methodology allows for infinite data points to be used along the spine to determine sagittal measurements. The integration of this technique with digital radiography's ability to adjust image contrast and brightness will enable the superior identification of key anatomical parameters normally not available for measurement on traditional radiographs, improving the consistency of sagittal measurement.

Coronal and sagittal plane correction in adolescent idiopathic scoliosis: a comparison between all pedicle screw versus hybrid thoracic hook lumbar screw constructs.

STUDY DESIGN: This was a retrospective cohort study using a previously matched convenience sample of 34 patients. OBJECTIVE: This study sought to determine the relative corrective benefits of these 2 types of constructs in the correction of coronal and sagittal curves in patients with adolescent idiopathic scoliosis (AIS). In addition, the 2 constructs were compared for coronal and sagittal balance. SUMMARY OF BACKGROUND INFORMATION: Recent clinical research suggests that thoracic pedicle screw constructs (all-screw constructs) are more effective than hybrid lumbar screw thoracic hook constructs (hybrid constructs) in correcting spine deformity. METHODS: The sample consisted of patients with AIS who underwent isolated posterior spinal fusion and instrumentation. Seventeen patients underwent fusion using all-screw constructs, and 17 underwent fusion with hybrid constructs; preoperative and postoperative radiographs and measurements were compared. RESULTS: There was no significant difference observed when comparing the 2 groups, although there was a trend toward better correction of the main thoracic curve in the all-screw construct group (P = 0.089). In the all-screw group, mean thoracic kyphosis decreased from 29.6 degrees to 19.4 degrees (P = 0.012). Sagittal balance changed in the hybrid group from -21.2 mm to 8.2 mm, and in the all-screw group changed from -28.8 mm to 1.5 mm. The major curve in the hybrid group improved from 54.06 degrees to 20.25 degrees and improved from 54.88 degrees to 15.06 degrees in the all-screw group. CONCLUSIONS: There was no statistically significant difference comparing the 2 groups, although a trend was observed toward better correction of the main thoracic curve in the all-screw construct group. The all-screw group demonstrated a significant decrease in kyphosis, which was not seen in the hybrid group. Hybrid constructs were comparable to all-screw constructs in the correction of coronal plane deformity and sagittal balance.

Sagittal alignment of the spine and pelvis in the presence of L5-s1 isthmic lysis and low-grade spondylolisthesis.

STUDY DESIGN: A radiographic study of 82 patients with L5-S1 spondylolysis or spondylolisthesis of less than 50% displacement of L5 on S1. OBJECTIVE: To measure and describe the sagittal alignment of the spine and pelvis in patients with spondylolysis before the development of a large secondary deformity associated with progression of the spondylolisthesis. SUMMARY OF BACKGROUND DATA: Several publications have addressed the alignment of the spine and pelvis as an important factor in the occurrence, symptomatology, progression, and treatment of spondylolysis and spondylolisthesis. To our knowledge, this is the first report to systematically document the native sagittal alignment of affected patients and compare them to a large control population. MATERIALS AND METHODS: The sagittal alignment in this cohort of 82 patients was compared with a control population of 160 patients without symptoms of back pain or radiographic abnormalities of the spine and pelvis that was the subject of a previous study. RESULTS: Patients with spondylolysis and low-grade spondylolisthesis demonstrate increased pelvic incidence, increased lumbar lordosis, but less segmental extension between L5 and S1 than in a normal population. CONCLUSIONS: These data suggest that differences in the sagittal alignment of the spine and pelvis may influence the biomechanical environment that results in the development of spondylolysis and progressive spondylolisthesis.

Considerations for focused surgical intervention in the presence of adult spinal deformity.

STUDY DESIGN: Case studies, literature review. OBJECTIVES: The goal of this review is to raise awareness and stimulate contributions on this topic. SUMMARY OF BACKGROUND DATA: Surgical management of adult patients presenting with intractable back and leg pain in conjunction with spinal deformity often raises the question of need for curve arthrodesis. Meticulous patient assessment is essential in determining if the deformity underlies patient symptoms. If so, then the deformity must be stabilized according to criteria established in the literature. However, when patient evaluation suggests that the deformity is not the source of symptoms, other surgical options may be considered. These include limited decompression without fusion or decompression with short fusion limited only to the site of pathology. MATERIALS AND METHODS: Three cases are presented illustrating situations where decompression alone or decompression with short fusion was indicated. RESULTS: When an adult spinal deformity is stable and is not the source of symptoms, symptomatic relief may be provided through limited decompression within the curve but without curve arthrodesis. Similarly, symptomatic pathology arising from levels adjacent to or remote from the deformity may be addressed with short-segment decompression and fusion. CONCLUSIONS: This brief and limited communication reviews some of the pertinent issues and provides several examples of selective surgical treatment options without curve arthrodesis in patients with deformity. These options are typically much smaller surgical undertakings, particularly in adult patients who generally have complicating comorbidities. Little has been published to guide surgical management for these conditions.