Thoracolumbar Deformity Surgery Research Articles

The implementation of enhanced recovery after surgery pathway in patients undergoing posterior thoracolumbar fusion for degenerative spinal deformity

PurposeThe prevalence of degenerative spinal deformity (DSD) and the increased cost of correction surgery impose substantial burdens on the health care and insurance system. The aim of our study was to investigate the effects of the implementation of Enhanced Recovery After Surgery (ERAS) protocol on postoperative outcomes after complex spinal surgery.MethodsA retrospective analysis of prospectively established database of DSD was performed. The consecutive patients who underwent open correction surgery for degenerative spinal deformity between August 2016 and February 2022 were reviewed. We extracted demographic data, preoperative radiographic parameters, and surgery-related variables. The ERAS patients were 1:1 propensity-score matched to a historical cohort by the same surgical team based on age, gender, BMI, and number of levels fused. We then compared the length of hospital stay (LOS), physiological functional recovery, and the rates of complications and readmissions within 90 days after surgery between the groups.ResultsThere were 108 patients included, 54 patients in the ERAS cohort, and 54 patients matched control patients in the historical cohort. The historical and ERAS cohorts were not significantly different regarding demographic characteristics, comorbidities, preoperative parameters, operative time, and reoperation rate (P > 0.05). Patients in the ERAS group had significantly shorter postoperative LOS (12.0 days vs. 15.1 days, P = 0.001), average days of drain and urinary catheters placement (3.5 days vs. 4.4 days and 1.9 days vs 4.8 days, respectively), and lower 90-day readmission rate (1.8% vs. 12.9%, P = 0.027). The first day of assisted-walking and bowel movement occurred on average 1.9 days (2.5 days vs. 4.4 days, P = 0.001) and 1.7 days (1.9 days vs. 3.6 days, P = 0.001) earlier respectively in the ERAS group. Moreover, the rate of postoperative urinary retention (3.7% vs. 16.7%, P = 0.026) and surgical site infection (0% vs. 7.4%, P = 0.046) were significantly lower with ERAS protocol applied.ConclusionsOur study confirmed that the ERAS protocol was safe and essential for patients undergoing thoracolumbar deformity surgery for DSD. The ERAS protocol was associated with a shorter postoperative LOS, a lower rate of 90-day readmission, less rehabilitation discharge, and less postoperative complications.

O-Arm Accuracy and Radiation Exposure in Adult Deformity Surgery

In long thoracolumbar deformity surgery, accurate screw positioning is critical for spinal stability. We assessed pedicle and pelvic screw accuracy and radiation exposure in patients undergoing long thoracolumbar deformity fusion surgery (≥4 levels) involving 3-dimensional fluoroscopy (O-Arm/Stealth) navigation. In this retrospective single-center cohort study, all patients aged >18years who underwent fusion in 2016-2018 were reviewed. O-Arm images were assessed for screw accuracy. Effective radiation doses were calculated. The primary outcome was pedicle screw accuracy (Heary grade). Secondary outcomes were pelvic fixation screw accuracy, radiation exposure, and screw-related perioperative and postoperative complications or revision surgery within 3years. Of 1477 pedicle screws placed in 91 patients (mean 16.41±5.6 screws/patient), 1208 pedicle screws (81.8%) could be evaluated by 3-dimensional imaging after placement. Heary Grade I placement was achieved in 1150 screws (95.2%), Grade II in 47 (3.9%), Grade III in 10 (0.82%), Grade IV in 1 (0.08%), and Grade V in 0; Grade III-V were replaced intraoperatively. One of 60 (1.6%) sacroiliac screws placed showed medial cortical breach and was replaced. The average O-Arm-related effective dose was 29.54±14.29mSv and effective dose/spin was 8.25±2.65mSv. No postoperative neurological worsening, vascular injuries, or revision surgeries for screw misplacement were recorded. With effective radiation doses similar to those in interventional neuroendovascular procedures, the use of O-Arm in multilevel complex deformity surgery resulted in high screw accuracy, no need for surgical revision because of screw malposition, less additional imaging, and no radiation exposure for the surgical team.

178. All-cause mortality following cervical and thoracolumbar adult deformity surgery: incidence and causes

<h3>BACKGROUND CONTEXT</h3> Both cervical and thoracolumbar deformity surgeries are often complex and invasive, with a fairly comorbid patient population. However, few studies have assessed the mortality rates, frailty, and invasiveness between the two populations. <h3>PURPOSE</h3> The aim of this study was to determine the incidence density of all-cause mortality as well as the 30-day and 90-day mortality rates. Secondary objectives were to ascertain causes of death, frailty of patients, and invasiveness of surgeries. We hypothesize that the mortality rates and causes of death associated with cervical deformity surgery will be higher than those for thoracolumbar deformity surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective review. <h3>PATIENT SAMPLE</h3> A total of 146 cervical deformity and 1,380 thoracolumbar patients were included. <h3>OUTCOME MEASURES</h3> Outcomes included: mortality incidence density, 30- and 90-day mortality rates. <h3>METHODS</h3> Using two prospective, multicenter databases, we identified cervical and thoracolumbar deformity patients. Clinical parameters, surgical parameters and all-cause mortality were analyzed. Incidence density was calculated based on the equation: 100 × (number of deaths)/(sum of total years of follow-up for all patients). <h3>RESULTS</h3> DB1-CD: Death was reported for 23 patients (15.7%). Mean age 61.43 ± 10.45, 34% of individuals frail (CD-FI) and mean invasiveness (CD-SR) was 79 ± 96. The mean time to death 25.46 ± 18.86 months. The mortality incidence density 8.75 deaths/year/1,000 patients. The 30-day mortality rate was 0.68% (1/146), 90-day mortality rate 1.3% (2/146). The three most common causes of death: pneumonia (9.68%), congestive heart failure (6.45%) and myocardial infarction (6.45%). DB2-TL: death was reported for 38 patients (2.75%). Mean age 60.5 ± 14.24, 58% of individuals frail (ASD-FI), and mean invasiveness (ASD-SR) 92.7±34.7. Mean time to death 29.68 ± 20.26 months. Average follow-up 1.82 ± 1.5 years. The mortality incidence density was 1.5 deaths/year/1,000 patients. The 30-day mortality ratewas 072% (1/1,380) and 90-day mortality rate 0.22% (3/1,380). The three most common causes of death: pneumonia (13.16%), myocardial infarction (10.53%) and malignancy (7.89%). There were no intraoperative deaths. <h3>CONCLUSIONS</h3> Cervical deformity patients had significantly more deaths per year (8.75 cervical vs 1.5 thoracolumbar) per 1,000 patients than thoracolumbar deformity surgeries. Pneumonia and myocardial infarction were common causes of death in both cervical and thoracolumbar deformity surgery patients. No deaths occurred during surgery. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Outcome Measures of Medicare Patients With Diabetes Mellitus Undergoing Thoracolumbar Deformity Surgery.

This was a retrospective study. The objective of this study was to identify the impact of diabetes on postoperative outcomes in Medicare patients undergoing adult spinal deformity (ASD) surgery. We queried the MarketScan Medicare database to identify patients who underwent ASD surgery from 2007 to 2016. Patients were then stratified based on diabetes status at the time of the index operation. Patients not enrolled in the Medicare dataset and those with any prior history of trauma or tumor were excluded from this study. A total of 2564 patients met the inclusion criteria of this study, of which n=746 (29.1.%) were diabetic. Patients with diabetes had a higher rate of postoperative infection than nondiabetic patients (3.1% vs. 1.7%, P<0.05) within 90 days. Renal complications were also more elevated in the diabetic cohort (3.2% vs. 1.3%, P<0.05). Readmission rates were significantly higher in the diabetes cohort through of 60 days (15.2% vs. 11.8%, P<0.05) and 90 days (17.0% vs. 13.4%, P<0.05). When looking specifically at the outpatient payments, patients with diabetes did have a higher financial burden at 60 days ($8147 vs. $6956, P<0.05) and 90 days ($10,126 vs. $8376, P<0.05). In this study, diabetic patients who underwent ASD surgery had elevated rates of postoperative infection, outpatient costs, and rates of readmissions within 90 days. Further research should investigate the role of poor glycemic control on spine surgery outcomes.

The role of the fractional lumbosacral curve in persistent coronal malalignment following adult thoracolumbar deformity surgery: a radiographic analysis

Retrospective cohort. Assess radiographically the effect of an all-posterior approach on correction of coronal balance in primary adult thoracolumbar spinal deformities based on Bao's classification of coronal imbalance with a focus on lumbosacral curve correction. Achieving appropriate coronal alignment is difficult in adults with coronal malalignment due to trunk shift ipsilateral to degenerated thoracolumbar scoliosis' apex. Review of adults who underwent posterior spinal fusions to pelvis (≥ 5 levels) for thoracolumbar scoliosis. Exclusion: revisions, no coronal deformity, thoracic Cobb > 30°, and anterior operations. Patients were divided into three groups, as proposed by Bao et al.: type A: CSVL < 3cm; type B: CSVL > 3cm and C7 plumb shifted to scoliosis' concavity; type C: CSVL > 3cm and C7 plumb shifted to scoliosis' convexity. Radiographic parameters and surgical techniques were compared. 124 patients (male-6; female-118; avg. age 58 ± 10years; type A-87; type B-19; type C-18). Type C had significantly greater lumbosacral fractional curves. 28% of type C were treated with fractional curve TLIFs, while all, but one, type B had TLIFs of the fractional curve. Deformity parameters after surgery were similar, except type C had persistently greater fractional curves/coronal malalignment. All preop type B were appropriately corrected postop. For preop type C, 67% remained type C and 33% became type A postop. Compared to those who became type A, persistently undercorrected and malaligned (type C) patients had significantly greater preop lumbosacral fractional curves, greater preop coronal Cobb angles, and more commonly involved TLIFs of lumbosacral fractional curves. Compared to no interbody support, use of TLIFs provided better correction of the lumbosacral curve. In adults with primary, posterior-only operations for thoracolumbar spinal deformity, 67% of type C coronal deformities and 20% of type A deformities remained or had worse coronal malalignment postop. While the use of TLIFs improved correction of the lumbosacral curve compared to no interbody support, alternative surgical strategies should be considered to more adequately correct lumbosacral fractional curves and balance correction of lumbosacral and major thoracolumbar curves so as to maintain and/or restore coronal balance. III.

Enhanced recovery pathway in adult patients undergoing thoracolumbar deformity surgery

BACKGROUND CONTEXTEnhanced recovery (ERAS) pathways can help hospitals maximize the incentives of bundled payment models while maintaining high-quality patient care. A key component of an enhanced recovery pathway is the ability to predictably reduce inpatient length of stay, as this is a critical component of the cost equation. PURPOSETo determine the efficacy of an enhanced recovery pathway on reducing length of stay after thoracolumbar adult deformity surgery. STUDY DESIGNSingle surgeon retrospective review of prospectively-collected data. PATIENT SAMPLEForty adult deformity patients who underwent ≥5 levels of fusion to the pelvis (two to L5) with a single surgeon before and after implementation of an ERAS pathway. METHODSThe pathway involved participation by anesthesiology, hospital medicine, and physical therapy, and was designed to achieve goals previously associated with decreased LOS (eg, EBL<1200 mL, procedure time <4.5 hours, avoidance of ICU postoperatively, and mobilization POD0-1). Patients were propensity-score matched 1:1 to a historical cohort (enhanced recovery [ER] and historical [H] cohorts), based on demographics, medical comorbidities, radiographic alignment parameters, and surgical factors. Outcomes were compared to determine the effect of the enhanced recovery pathway. Primary outcomes included LOS and 90-day complications and readmissions. RESULTSAfter matching, gender, BMI, ASA class, preoperative opioid dependence, day of surgery, sagittal alignment parameters, rate of revision surgery, three-column osteotomies, and interbody fusions were comparable between the cohorts (p>.05). In the ER cohort, there was reduced EBL (920±640 vs. 1437±555, p=.004) and no ER patient went to the ICU immediately following surgery, compared with 30% of H patients (p=.022). The ER cohort also had a greater number of patients ambulating by POD1 compared to the H cohort (100% vs. 55%, p=.010). ER patients had a shorter LOS (4.5±1.3 vs. 7.3±4.4 days, p=.010). A 90-day readmission and complications were comparable between the cohorts (p>.05). CONCLUSIONSThe creation of an ERAS pathway for patients undergoing thoracolumbar adult deformity surgery reduced length of stay without negatively affecting short-term morbidity and complications. Given the specificity of this pathway to a single surgeon and hospital, the resources and staffing changes that were instrumental in creating the pathway may not be generalizable to other centers.

Risk Factors for Revision Surgery After Primary Adult Thoracolumbar Deformity Surgery.

This is a retrospective cohort study. The aim was to identify the risk factors for revision surgery within 2 years of patients undergoing primary adult spinal deformity (ASD) surgery. Previous literature reports estimate 20% of patients undergoing thoracolumbar ASD correction undergo reoperation within 2 years. There is limited published data regarding specific risk factors for reoperation in ASD surgery in the short term and long term. The authors queried the MarketScan database in order to identify patients who were diagnosed with a spinal deformity and underwent ASD surgery from 2007 to 2015. Patient-level factors and revision risk were investigated during 2 years after primary ASD surgery. Patients under the age of 18 years and those with any prior history of trauma or tumor were excluded from this study. A total 7422 patients underwent ASD surgery during 2007-2015 in the data set. Revision rates were 13.1% at 90 days, 14.5% at 6 months, 16.7% at 1 year, and 19.3% at 2 years. In multivariate multiple logistic regression analysis, obesity [adjusted odds ratio (OR): 1.58, P<0.001] and tobacco use (adjusted OR: 1.38, P=0.0011) were associated with increased odds of reoperation within 2 years. Patients with a combined anterior-posterior approach had lower odds of reoperation compared with those with posterior only approach (adjusted OR: 0.66, P=0.0117). Obesity and tobacco are associated with increased odds of revision surgery within 2 years of index ASD surgery. Male sex and combined surgical approach are associated with decreased odds of revision surgery.

Predictors of 2-year reoperation in Medicare patients undergoing primary thoracolumbar deformity surgery.

This was a retrospective cohort study in which the authors used a nationally representative administrative database. Their goal was to identify the risk factors for reoperation in Medicare patients undergoing primary thoracolumbar adult spinal deformity (ASD) surgery. Previous literature reports estimate that 20% of patients undergoing thoracolumbar ASD correction undergo revision surgery within 2 years. Most published data discuss risk factors for revision surgery in the general population, but these have not been explored specifically in the Medicare population. Using the MarketScan Medicare Supplemental database, the authors identified patients who were diagnosed with a spinal deformity and underwent ASD surgery between 2007 and 2015. The interactions of patient demographics, surgical factors, and medical factors with revision surgery were investigated during the 2 years following primary ASD surgery. The authors excluded patients without Medicare insurance and those with any prior history of trauma or tumor. Included in the data set were 2564 patients enrolled in Medicare who underwent ASD surgery between 2007 and 2015. The mean age at diagnosis with spinal deformity was 71.5 years. A majority of patients (68.5%) were female. Within 2 years of follow-up, 661 (25.8%) patients underwent reoperation. Preoperative osteoporosis (OR 1.58, p < 0.0001), congestive heart failure (OR 1.35, p = 0.0161), and paraplegia (OR 2.41, p < 0.0001) independently increased odds of revision surgery. The use of intraoperative bone morphogenetic protein was protective against reoperation (OR 0.71, p = 0.0371). Among 90-day postoperative complications, a wound complication was the strongest predictor of undergoing repeat surgery (OR 2.85, p = 0.0061). The development of a pulmonary embolism also increased the odds of repeat surgery (OR 1.84, p = 0.0435). Approximately one-quarter of Medicare patients with ASD who underwent surgery required an additional spinal surgery within 2 years. Baseline comorbidities such as osteoporosis, congestive heart failure, and paraplegia, as well as short-term complications such as pulmonary embolism and wound complications significantly increased the odds of repeat surgery.

Postoperative Complication Burden, Revision Risk, and Health Care Use in Obese Patients Undergoing Primary Adult Thoracolumbar Deformity Surgery.

Study Design:This is a retrospective cohort study using a nationally representative administrative database.Objective:To identify the impact of obesity on postoperative outcomes in patients undergoing thoracolumbar adult spinal deformity (ASD) surgery.Background:The obesity rate in the United States remains staggering, with approximately one-third of all Americans being overweight or obese. However, the impact of elevated body mass index on spine surgery outcomes remains unclear.Methods:We queried the MarketScan database to identify patients who were diagnosed with a spinal deformity and underwent ASD surgery from 2007 to 2016. Patients were then stratified by whether or not they were diagnosed as obese at index surgical admission. Propensity score matching (PSM) was then utilized to mitigate intergroup differences between obese and nonobese patients. Patients <18 years and those with any prior history of trauma or tumor were excluded from this study. Baseline demographics and comorbidities, postoperative complication rates, and short- and long-term reoperation rates were determined.Results:A total of 7423 patients met the inclusion criteria of this study, of whom 597 (8.0%) were obese. Initially, patients with obesity had a higher 90-day postoperative complication rate than nonobese patients (46.1% vs 40.8%, P < .05); however, this difference did not remain after PSM. Revision surgery rates after 2 years were similar across the 2 groups following primary surgery (obese, 21.4%, vs nonobese, 22.0%; P = .7588). Health care use occurred at a higher rate among obese patients through 2 years of long-term follow-up (obese, $152 930, vs nonobese, $140 550; P < .05).Conclusion:Patients diagnosed with obesity who underwent ASD surgery did not demonstrate increased rates of complications, reoperations, or readmissions. However, overall health care use through 2 years of follow-up after index surgery was higher in the obesity cohort.

Optimal Trajectory and Length of S2 Alar Iliac Screws: A 3-Dimensional Computed-aided Design Study.

A radiographic study of computed tomography scans of the pelvis converted to 3-dimensional imaging. The objective of this study was to determine the optimal length and trajectory of S2 alar iliac (S2AI) screws. Solid pelvic fixation is a necessary component in thoracolumbar deformity surgery to protect sacral fixation and promote arthrodesis. The S2AI technique has been promoted as a way to reduce hardware prominence and instrumentation issues associated with traditional iliac fixation. In total, 64 of 100 patients randomly selected from our institution's spine registry were able to be converted to 3-dimensional imaging. Virtual screws were then placed in the optimal position for an S2AI screw on each side of the pelvis. The lateral and inferior angles were measured off-axial and sagittal planes, respectively. The distances from the notch and the remaining available screw length were also recorded. The average patient age was 38±16 years. The average lateral angle was 42.5±2.0 degrees and the inferior angle was 18.2±1.8 degrees. The screws fit bilaterally in all 64 patients without cortical breach. The remaining available screw distance was measured in all patients and found to be 40.5±8.7 mm. The average distance from the sciatic notch was 13.8±4.1 mm. Men had significantly more potential screw length when compared with women. We found an average inferior angle of 18.2 degrees, which is less than the previously described angle range of 20-40 degrees. These findings suggest that an ideal trajectory may be significantly different than the previously described trajectory. We found that with the optimal trajectory, a 100 mm screw can fit in all patients without concern for cortical breach of the pelvis or violation of the hip joint.

The value of sitting radiographs: analysis of spine flexibility and its utility in preoperative planning for adult spinal deformity surgery.

Sitting radiographs are a valuable tool to consider the thoracic compensatory mechanism in patients who are candidates for thoracolumbar correction surgery.

The technique of S2-alar-iliac screw fixation: a literature review

The distal fixation in thoracolumbar deformity surgery can be challenging for spine surgeons. When isolated S1-pedicle screws are utilized as the sole distal fixation in long thoracolumbar posterior constructs, there is a high rate of failure, due to loosening, breakage, and pseudarthrosis. Unfortunately, with iliac screw fixation the entry point at the posterior superior iliac spine requires considerable soft tissue dissection and may potentially increase the likelihood of wound complications. S2-alar-iliac (S2AI) screw fixation technique was developed recently to provide increased fixation with a lower profile screw and rod construct. These screws can be inserted with percutaneous or free hand techniques. This fixation also has comparable biomechanical properties to the S1 iliac screw. This technique may provide advantages such as decreased rates of reoperation, surgical site infection, wound dehiscence and symptomatic screw prominence as compared to traditional iliac screw fixation. The purpose of this manuscript is to review the S2AI screw fixation literature including anatomy, technique, biomechanics, and clinical outcomes.

Utility of intraoperative rotational thromboelastometry in thoracolumbar deformity surgery.

OBJECTIVE Blood loss during surgery for thoracolumbar scoliosis often requires blood product transfusion. Rotational thromboelastometry (ROTEM) has enabled the more targeted treatment of coagulopathy, but its use in deformity surgery has received limited study. The authors investigated whether the use of ROTEM reduces transfusion requirements in this case-control study of thoracolumbar deformity surgery. METHODS Data were prospectively collected on all patients who received ROTEM-guided blood product management during long-segment (≥ 7 levels) posterior thoracolumbar fusion procedures at a single institution from April 2015 to February 2016. Patients were matched with a group of historical controls who did not receive ROTEM-guided therapy according to age, fusion segments, number of osteotomies, and number of interbody fusion levels. Demographic, intraoperative, and postoperative transfusion requirements were collected on all patients. Univariate analysis of ROTEM status and multiple linear regression analysis of the factors associated with total in-hospital transfusion volume were performed, with p < 0.05 considered to indicate statistical significance. RESULTS Fifteen patients who received ROTEM-guided therapy were identified and matched with 15 non-ROTEM controls. The mean number of fusion levels was 11 among all patients, with no significant differences between groups in terms of fusion levels, osteotomy levels, interbody fusion levels, or other demographic factors. Patients in the non-ROTEM group required significantly more total blood products during their hospitalization than patients in the ROTEM group (8.5 ± 4.2 units vs 3.71 ± 2.8 units; p = 0.001). Multiple linear regression analysis showed that the use of ROTEM (p = 0.016) and a lower number of fused levels (p = 0.022) were associated with lower in-hospital transfusion volumes. CONCLUSIONS ROTEM use during thoracolumbar deformity correction is associated with lower transfusion requirements. Further investigation will better define the role of ROTEM in transfusion during deformity surgery.

Reciprocal changes in cervical spine alignment after corrective thoracolumbar deformity surgery.

To identify changes in cervical alignment parameters following surgical correction of thoracolumbar deformity and then assess the preoperative parameters which induce changes in cervical alignment following corrective thoracolumbar deformity surgery. A retrospective study of 49 patients treated for thoracolumbar deformity with preoperative planning of an acceptably aligned coronal and sagittal plane in each case. We compared cervical spine parameters in two distinct low [preoperative C7 sagittal vertical axis (SVA) ≤ 6 cm] and high (preoperative C7 SVA ≥ 9 cm) C7 SVA groups. Multilinear regression analysis was performed and revealed the relationship between postoperative cervical lordosis and preoperative spinopelvic parameters and surgical plans. In the lower C7 SVA group, cervical lordosis was significantly increased after thoracic/lumbar deformity correction (p < 0.01). In contrast, the high C7 SVA group showed decreased cervical lordosis postoperatively (p < 0.01). Multilinear regression analysis demonstrated the preoperative parameters (preoperative C2-7 angle, T1 slope, surgical plan for PT and C7 SVA), which determine the postoperative cervical lordosis. In spinal deformity procedures, preoperative spinal alignment parameters, and surgical plans could affect postoperative cervical spine alignment.

Cervical stenosis in adults undergoing thoracolumbar deformity surgery: incidence, treatment, and complications

The goals of this study were to determine the incidence of occult cervical stenosis in patients over 50 years old with thoracolumbar deformity and to assess the risk of progressive cervical myelopathy after complex thoracolumbar reconstruction in asymptomatic or mildly symptomatic patients with cervical stenosis. Charts and cervical imaging for patients who were over 50 years old when they had undergone thoracolumbar deformity surgery between 2005 and 2008 were reviewed. Patients with primary neurological disorders were excluded from the study. Seventy-three patients (56 women and 17 men) met the study inclusion criteria. The minimum follow-up time was 2 years. Fifty-eight percent of patients (42 of 73) had cervical stenosis on advanced imaging. Thirty-three patients had mild or moderate stenosis; only 3 of these patients had clinical myelopathy. Nine patients (12%) had critical cervical stenosis, as determined from imaging; among these patients, 3 had moderate or severe myelopathy. Patients with noncritical stenosis and no or mild myelopathy underwent thoracolumbar reconstruction without any postoperative progression of myelopathy. Patients with critical stenosis and/or moderate or severe myelopathy were offered cervical decompression prior to thoracolumbar reconstruction; those who accepted this offer did not have progression of myelopathy. One patient underwent thoracolumbar reconstruction first despite critical cervical stenosis. At 20 months, her cervical myelopathy had progressed, and she ultimately required cervical decompression. Cervical stenosis, even critical stenosis in some cases, was seen in more than one-half of the patients. Most presented without obvious cervical complaints. In those with mild to moderate stenosis and no or mild myelopathy, lengthy thoracolumbar reconstruction procedures were not associated with progression of the myelopathy. The authors recommend that all adults with thoracolumbar deformity undergo a detailed upper- and lower-extremity neurological examination prior to major thoracolumbar reconstruction.

Implications of the center of rotation concept for the reconstruction of anterior column lordosis and axial preloads in spinal deformity surgery

In thoracolumbar deformity surgery, anterior-only approaches are used for reconstruction of anterior column failures. It is generally advised that vertebral body replacements (VBRs) should be preloaded by compression. However, little is known regarding the impact of different techniques for generation of preloads and which surgical principle is best for restoration of lordosis. Therefore, the authors analyzed the effect of different surgical techniques to restore spinal alignment and lordosis as well as the ability to generate axial preloads on VBRs in anterior column reconstructions. The authors performed a laboratory study using 7 fresh-frozen specimens (from T-3 to S-1) to assess the ability for lordosis reconstruction of 5 techniques and their potential for increasing preloads on a modified distractable VBR in a 1-level thoracolumbar corpectomy. The testing protocol was as follows: 1) Radiographs of specimens were obtained. 2) A 1-level corpectomy was performed. 3) In alternating order, lordosis was applied using 1 of the 5 techniques. Then, preloads during insertion and after relaxation using the modified distractable VBR were assessed using a miniature load-cell incorporated in the modified distractable VBR. The modified distractable VBR was inserted into the corpectomy defect after lordosis was applied using 1) a lamina spreader; 2) the modified distractable VBR only; 3) the ArcoFix System (an angular stable plate system enabling in situ reduction); 4) a lordosizer (a customized instrument enabling reduction while replicating the intervertebral center of rotation [COR] according to the COR method); and 5) a lordosizer and top-loading screws ([LZ+TLS], distraction with the lordosizer applied on a 5.5-mm rod linked to 2 top-loading pedicle screws inserted laterally into the vertebra). Changes in the regional kyphosis angle were assessed radiographically using the Cobb method. The bone mineral density of specimens was 0.72 ± 22.6 g/cm(2). The maximum regional kyphosis angle reconstructed among the 5 techniques averaged 9.7°-16.1°, and maximum axial preloads averaged 123.7-179.7 N. Concerning correction, in decreasing order the LZ+TLS, lordosizer, and ArcoFix System outperformed the lamina spreader and modified distractable VBR. The order of median values for insertion peak load, from highest to lowest, were lordosizer, LZ+TLS, and ArcoFix, which outperformed the lamina spreader and modified distractable VBR. In decreasing order, the axial preload was highest with the lordosizer and LZ+TLS, which both outperformed the lamina spreader and the modified distractable VBR. The technique enabling the greatest lordosis achieved the highest preloads. With the ArcoFix System and LZ+TLS, compression loads could be applied and were 247.8 and 190.6 N, respectively, which is significantly higher than the insertion peak load and axial preload (p < 0.05). Including the ability for replication of the COR in instruments designed for anterior column reconstructions, the ability for lordosis restoration of the anterior column and axial preloads can increase, which in turn might foster fusion.

Minimally invasive surgery for thoracolumbar spinal deformity: initial clinical experience with clinical and radiographic outcomes

Adult degenerative scoliosis can be a cause of intractable pain, decreased mobility, and reduced quality of life. Surgical correction of this problem frequently leads to substantial clinical improvement, but advanced age, medical comorbidities, osteoporosis, and the rigidity of the spine result in high surgical complication rates. Minimally invasive surgery is being applied to this patient population in an effort to reduce the high complication rates associated with adult deformity surgery. A retrospective study of 23 patients was undertaken to assess the clinical and radiographic results with minimally invasive surgery for adult thoracolumbar deformity surgery. All patients underwent a lateral interbody fusion followed by posterior percutaneous screw fixation and possible minimally invasive surgical transforaminal lumbar interbody fusion if fusion near the lumbosacral junction was necessary. A mean of 3.7 intersegmental levels were treated (range 2-7 levels). The mean follow-up was 13.4 months. The mean preoperative Cobb angle was 31.4 degrees , and it was corrected to 11.5 degrees at follow-up. The mean blood loss was 477 ml, and the operative time was 401 minutes. The mean visual analog scale score improvement for axial pain was 3.96. Clear evidence of fusion was seen on radiographs at 84 of 86 treated levels, with no interbody pseudarthroses. Complications included 2 returns to the operating room, one for CSF leakage and the other for hardware pullout. There were no wound infections, pneumonia, deep venous thrombosis, or new neurological deficits. However, of all patients, 30.4% experienced new thigh numbness, dysesthesias, pain, or weakness, and in one patient these new symptoms were persistent. The minimally invasive surgical treatment of adult deformities is a promising method for reducing surgical morbidity. Numerous challenges exist, as the surgical technique does not yet allow for all correction maneuvers used in open surgery. However, as the techniques are advanced, the applicability of minimally invasive surgery for this population will likely be expanded and will afford the opportunity for reduced complications.

Feasibility of Minimally Invasive Sacropelvic Fixation

A cadaveric study with postoperative computed tomography scan to evaluate instrumentation placement. To successfully place percutaneous sacropelvic instrumentation. S2 iliac fixation has been in use clinically at some centers. Recently, anatomic data have been presented on the technique. The purpose of this study is to determine the feasibility of percutaneous placement of S2 iliac sacropelvic fixation (1) without damage to vital structures and (2) with in-line placement with S1 pedicle screws. Eight cadaveric spines were used in this study. Percutaneous pedicle screws were placed from L3-S1 in 4 and from L2-S1 in the remainder. Percutaneous S2 iliac screws were placed using a modification of the open technique. Rods were placed using minimally invasive techniques. All specimens were CT scanned. Trajectory of the screws was measured from CT scans. Maximal length was judged by a k-wire left in the S2 iliac screw. CT scans were critically evaluated for risks to visceral and neurovascular structures as well as cortical breaches. Average length of the screws was 92.5 mm (range, 69-120 mm). No screw was intrapelvic or risked any visceral or neurovascular structure. No screws violated the cortex of the ilium. All S2 iliac screws were in-line with the S1 pedicle screws. The average cephalocaudad trajectory was 29 degrees caudal from direct lateral. The average anterior-posterior angulation was 42 degrees from a horizontal line connecting the PSIS. Use of the S2 iliac technique may be a viable option in minimally invasive thoracolumbar deformity surgery. The screws were all in-line and connected easily to the cephalad instrumentation. On average, a length of approximately 90 mm was attained. No visceral or neurovascular structure was injured. Visualization of the first dorsal foramen and a standard anteroposterior and inlet radiograph were used for placement.

FOREWORD

FigureThe treatment of thoracolumbar spinal deformity has traditionally been the purview of the orthopedic surgeon. Early specialization in deformity management arose primarily out of the need to treat postinfectious sequelae and idiopathic scoliosis in adolescents, who were managed primarily in infection wards and childrens' hospitals. Thus, a body of experience was amassed and refined in these environments, with the emphasis on biomechanics, spinal fixation, and arthrodesis. Traditionally, these areas had received less emphasis in neurosurgical education. The modern era has witnessed an increasing population of patients harboring degenerative, post-traumatic, and iatrogenic spinal deformities. Spinal deformity is also frequently associated with conditions such as syringomyelia, diastomyelia, myelomeningocele, and spinal cord tumors, patients who often come under the care of a neurosurgeon. Improvements in anesthetic and intensive care, along with advances in spinal instrumentation and imaging, have made the treatment of these complex pathologies more accessible to neurosurgeons. An assortment of other forms of deformity, including adolescent idiopathic scoliosis, have been increasingly treated by neurosurgeons with subspecialty interests in complex spinal surgery. In addition, neurosurgeons have begun to develop the necessary skills to perform complex spinal reconstructions which maintain or re-establish proper sagittal and coronal alignment. In this supplement to NEUROSURGERY, we have addressed some of the critical topics in thoracolumbar deformity surgery. While not intended to be comprehensive, this supplement should serve as an introduction to the evaluation and management of these complex patients. The first section begins with an overview of the history of spinal deformity and concludes with a new and practical methodology for classifying these pathologies. This is followed by a section addressing issues related to patient selection and decision making, which are critical in the preoperative stage. The third section reflects the myriad etiologies of deformity, with chapters on special pathologies and patient populations, followed by a section on specific techniques for spinal fixation and deformity reduction available to the contemporary neurosurgeon. The supplement concludes with an assessment of some of the emerging technologies in genetic testing, minimally invasive approaches, and growth modulation surgery. Included with this issue is a DVD with videos on specific deformity correction methods to introduce the reader to some of the techniques currently employed. Whether for the prevention of iatrogenic deformity, the management of challenging curvatures, or as an introduction to emerging technologies, we hope this supplement will be engaging for neurosurgeons treating spinal disorders. Robert F. Heary Newark, NJ Christopher I. Shaffrey Charlottesville, VA Michael Y. Wang Miami, FL