Comparison of Staged vs Same-Day Circumferential Spinal Fusions for Adult Spinal Deformity.

BACKGROUND: Patients often undergo circumferential (anterior and posterior) spinal fusions to maximize adult spinal deformity (ASD) correction and achieve adequate fusion. Currently, such procedures are performed in staged (ST) or same-day (SD) procedures with limited evidence to support either strategy. This study aims to compare perioperative outcomes and costs of ST vs SD circumferential ASD corrective surgeries. METHODS: This is a retrospective review of patients undergoing circumferential ASD surgeries between 2013 and 2018 in a single institution. Patient characteristics, preoperative comorbidities, surgical details, perioperative complications, readmissions, total hospital admission costs, and 90-day postoperative care costs were identified. All variables were tested for differences between ST and SD groups unadjusted and after applying inverse probability weighting (IPW), and the results before and after IPW were compared. RESULTS: The entire cohort included a total of 211 (ST = 50, SD = 161) patients, 100 of whom (ST = 44, SD = 56) underwent more than 4 levels fused posteriorly and anterior lumbar interbody fusion (ALIF). Although patient characteristics and comorbidities were not dissimilar between the ST and SD groups, both the number of levels fused in ALIF and posterior spinal fusion (PSF) were significantly different. Thus, using IPW, we were able to minimize the cohort incongruities in the number of levels fused in ALIF and PSF while maintaining comparable patient characteristics. In both the whole cohort and the long segment fusions, postoperative pulmonary embolism was more common in ST procedures. After adjustment utilizing IPW, both groups were not significantly different in disposition, 30-day readmissions, and reoperations. However, within the whole cohort and the long segment fusion cohort, the ST group continued to show significantly increased rates of pulmonary embolism, longer length of stay, and higher hospital admission costs compared with the SD group. CONCLUSIONS: Adjusted comparisons between ST and SD groups showed staging associated with significantly increased length of stay, risk of pulmonary embolism, and admission costs.

Pelvic Fixation With a Quad-Rod Technique Using S2 Alar Iliac and Medialized Entry Iliac Screws for Long Fusion Constructs.

PURPOSE: Patients with adult spinal deformity (ASD) may have risk factors for nonunion and subsequent instrumentation failure. This study reviews a novel surgical technique for a quad-rod construct to the pelvis using both S2 alar iliac (S2AI) screw fixation and medialized entry iliac screw fixation as described through three separate cases and a review of the literature. METHODS: This technique facilitates alignment of the construct and rod insertion into the tulip heads. The medialized iliac screw technique also avoids the potential soft-tissue complications of the conventional iliac screw bolt given that it is deeper and has more soft-tissue coverage. RESULTS: Three cases performed by the most senior author (V.A.) in which this novel technique was used are presented in this report along with clinical and radiographic images to educate the reader on appropriate execution of this technique. A review of the existing literature regarding pelvic fixation techniques for ASD was also done. CONCLUSION: Quad-rod augmentation of long thoracolumbar spinal constructs with two independent SI anchoring points is potentially an effective technique to increase lumbar sacral construct rigidity, thereby promoting fusion rates and decreasing revision rates. The described technique provides spine surgeons with an additional tool in their armamentarium to treat patients with complex ASD.

Do Prophylactic Inferior Vena Cava Filters Affect the Rates of Venous Thromboembolism and Pulmonary Embolism in Patients Undergoing Major Spine Surgery?

STUDY DESIGN: Retrospective Analysis. BACKGROUND: Venous thromboembolism (VTE) represents a significant cause of morbidity and mortality in major spine surgery. Placement of prophylactic inferior vena cava filters (IVCF) in patients undergoing major spine surgery was previously adopted at our institution. This study reports our experience and compares VTE rates between patients with and without preoperative IVCF placement. METHODS: A Retrospective comparative study was conducted on adult patients who underwent IVCF placement and those who did not prior to their spinal fusion procedure, between 2013 and 2016. Thoracolumbar fusions (anterior and/or posterior) of 7 or more levels, spinal osteotomies, and a minimum of a 3-month follow-up were included. Traumatic, oncologic, and cervical pathology were excluded. Primary outcomes measured included the incidence of overall VTE (DVT/PE), death, IVCF related complications, and IVCF retrieval. RESULTS: 386 patients who underwent major spine surgery, 258 met the eligibility criteria. Of those patients, 105 patients (40.7%) had prophylactic IVCF placement. All patients had postoperative SCDs and chemoprophylaxis. The presence of an IVCF was associated with an increased rate of overall VTE (14.3% vs 6.5%, P ≤ .05) and DVT episodes (8.6% vs 2.6%, P = .04). The rate of PE for the IVCF group and non-IVCF group was 8.6% and 4.6%, respectively, which was not statistically significant (P = .32). The all-cause mortality rate overall of 2.3% was statistically similar between both groups (P = 1.0). The IVCF group had higher rates of hematoma/seroma vs the non-IVCF group (12.4% vs 3.9%, P ≤ .05). 99 IVCFs were retrievable designs, and 85% were successfully retrieved. Overall IVCF-related complication rate was 11%. CONCLUSIONS: No statistical difference in PE or mortality rates existed between the IVCF and the control group. Patients with IVCF placement experienced approximately twice the rate of VTE and three times the rate of DVT compared to those without IVCF. The IVCF-related complication rate was 11%. Based on the results of this study, the authors recommend against the routine use of prophylactic IVCFs in adults undergoing major spine surgery. LEVEL OF EVIDENCE: III.

The Rise and Fall of Bone Morphogenetic Protein 2 Throughout the United States.

STUDY DESIGN: Retrospective Database Study. OBJECTIVE: Investigate utilization of bone morphogenetic protein (BMP-2) between 2004 and 2014. SUMMARY OF BACKGROUND DATA: The utilization, particularly off-label utilization, of BMP-2 has been controversial and debated in the literature. Given the concerns regarding cancer and potential complications, the risk benefit profile of BMP must be weighed with each surgical case. The debate regarding the costs and potential side effects of BMP-2 compared with autologous iliac crest bone harvest has continued. METHODS: The National Inpatient Sample (NIS) database was queried for the use of BMP-2 (ICD-9-CM 84.52) between 2004 and 2014 across 44 states. The NIS database represents a 20% sample of discharges, weighted to provide national estimates. BMP-2 utilization rates in spine surgery fusion procedures were calculated as a fraction of the total number of thoracic, lumbar, and sacral spinal fusion surgeries performed each year. RESULTS: Between 2004 and 2014, BMP-2 was utilized in 927,275 spinal fusion surgeries. In 2004, BMP-2 was utilized in 28.3% of all cases (N=48,613). The relative use of BMP-2 in spine fusion surgeries peaked in 2008 at 47.0% (N=112,180). Since then, it has continued to steadily decline with an endpoint of 23.6% of cases in 2014 (N=60,863). CONCLUSIONS: Throughout the United States, the utilization of BMP-2 in thoracolumbar fusion surgeries increased from 28.3% to 47.0% between 2004 and 2008. However, from 2008 to 2014, the utilization of BMP-2 in thoracolumbar spine fusion surgeries decreased significantly from 47.0% to 23.4%. While this study provides information on the utilization of BMP-2 for the entire United States over an 11-year period, further research is needed to the determine the factors affecting these trends.

The Expanding Frontier of Outpatient Spine Surgery.

BACKGROUND: In 2014, inpatient spinal fusion surgery had the highest aggregate cost of any inpatient surgery performed in the United States, costing 12 billion dollars. As the national health care system seeks to improve value-based care, there is increased motivation to perform surgery on an outpatient basis. To ensure improved patient outcomes with this transition, patient selection has become increasingly important to identify who would most benefit from outpatient spine fusion, for example. This demands an improved understanding of the demographics of patients who have been receiving outpatient spine fusion on which the spine surgery community can build to improve cost-effective care delivered. METHODS: The Healthcare Cost and Utilization Project, State Ambulatory Surgery Databases, and Agency for Healthcare Research and Quality databases were queried for demographic data regarding all-cause outpatient spine surgery between 2012 and 2014. Outpatient surgery volume was compared with inpatient surgery volume-which was provided by the State Inpatient Databases. RESULTS: A total of 1,164,040 spine fusion procedures were identified between 2012 and 2014, of which 132,900 procedures were performed as outpatient surgery (11.4%). Of all fusion procedures amongst 18- to 44-year-old patients, 18.4% were outpatient. A larger proportion of white patients, rather than black or Hispanic patients, underwent ambulatory procedures (12.14% vs 9.53% vs 7.46%, respectively); 16.54% of spinal fusion procedures for patients with private insurance was performed on an outpatient basis. Based on patient income, 76% of all outpatient fusions were performed on patients who live in "not low" income ZIP codes. CONCLUSIONS: There has been a gradual trend toward performing more outpatient spinal fusion procedures over the studied period. This study has also revealed unique trends in the demographics of patients who have received outpatient spine fusion during this time. LEVEL OF EVIDENCE: 3.

Soft Landing technique as a possible prevention strategy for proximal junctional failure following adult spinal deformity surgery.

BACKGROUND: This cross sectional study describes a "Soft Landing" strategy utilizing hooks for minimizing proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). The technique creates a gradual transition from a rigid segmental construct to unilateral hooks at the upper instrumented level and preservation of the soft tissue attachments on the contralateral side of the hooks. Authors devise a novel classification system for better grading of PJK severity. METHODS: Thirty-nine consecutive adult spinal deformity (ASD) patients at a single institution received the "Soft Landing" technique. The proximal junctional angle was measured preoperatively and at last follow-up using standing 36-inch spinal radiographs. Changes in proximal junctional angle and rates of PJK and PJF were measured and used to create a novel classification system for evaluating and categorizing ASD patients postoperatively. RESULTS: The mean age of the cohort was 61.4 years, and 90% of patients were women. Average follow up was 2.2 years. The mean change in proximal junctional angle was 8° (SD 7.4°) with the majority of patients (53%) experiencing less than 10° and only 1 patients with proximal junctional angle over 20°. Four patients (10%) needed additional surgery for proximal extension of the uppermost instrumented vertebra (UIV) secondary to PJF. CONCLUSIONS: Soft Landing technique is a possibly effective treatment strategy to prevent PJK and PJF following ASD that requires further evaluation. The described classification system provides management framework for better grading of PJK. The "Soft Landing" technique warrants further comparison to other techniques currently used to prevent both PJK and failure.

Postoperative Sagittal Spinal Alignment Changes Following Corrective Surgery in Adult Spinal Deformity.

BACKGROUND: There is a paucity of literature covering the spinal alignment changes following adult spinal deformities (ASD) corrective surgeries. In theory, patients' posture and overall alignment may vary with postoperative pain, bracing, and other external variables requiring further radiographic follow-up. The purpose of the study is to investigate changes in sagittal alignment in the first 3 months postoperatively. METHODS: This is a retrospective case series of ASD patients who underwent deformity surgeries from October 2015 to June 2018. Patients < 40 years old, had < 6 levels fused, had acute proximal junctional kyphosis (PJK) or failure, or lacked imaging were excluded. Physiologic measures, spine alignment changes measured in whole-spine radiographs. Lumbar lordosis (LL), thoracic kyphosis (TK), and sagittal vertical axis (SVA) at immediate and 3-month postoperative time points were measured, then compared via 2-sample Student t tests. Furthermore, TK after upper thoracic to pelvis (UT-P) fusions was compared with lower thoracic to pelvis (LT-P) fusions via paired t test. RESULTS: Thirty-six patients (24 females, 67%) with a mean age of 61.5 years (range, 40-75 years) were included. Spinal alignment comparisons showed a significant increase in TK at the 3-month time point (P = 0.006). Additionally, wide variations in SVA (range, 47-144 mm) were noted, yet not statistically significant, likely due to the changes being in both positive and negative directions (P = 0.18). No significant difference was found when TK was compared in the UT-P vs LT-P groups. CONCLUSIONS: Our results suggest that as postoperative pain subsides and the body settles into its new alignment, significant changes occur in spine sagittal parameters in the subacute period following surgery. LEVEL OF EVIDENCE: 4.

Restoration of sagittal alignment in high-grade isthmic spondylolisthesis using the reverse Bohlman technique with anterior lumbar interbody fusion using a hyperlordotic cage at L4-5: illustrative case.

BACKGROUND: Circumferential fusion with or without reduction is the preferred treatment for high-grade isthmic spondylolisthesis. Reduction presents significant risk of neurological injury. The authors present one case in which the "reverse Bohlman" technique was used with the addition of a hyperlordotic interbody cage at L4-5 as a means to correct sagittal malalignment while avoiding the reduction of L5 on S1. OBSERVATIONS: The patient was a 22-year-old woman with a long-term history of lower back pain and bilateral L5 radiculopathy secondary to high-grade isthmic lumbar spondylolisthesis. She underwent anterior lumbar interbody fusion using the reverse Bohlman technique plus a hyperlordotic interbody cage at L4-5, followed by decompression and posterior spinal instrumentation and fusion from L4 to the pelvis. At 2-year follow-up, she was found to have complete resolution of symptoms with clinical and radiographic evidence of fusion. Her spinopelvic parameters had significantly improved. LESSONS: The reverse Bohlman technique with the addition of a hyperlordotic interbody cage at L4-5 is a potential alternative treatment method to correct sagittal malalignment while avoiding possible injury to the L5 nerve roots that can be seen in the reduction of high-grade isthmic spondylolisthesis.

Proximal junctional kyphosis following T10-pelvis fusion presenting with neurologic compromise: case presentations and review of the literature.

Purpose: Proximal Junctional Kyphosis (PJK) is a well-documented phenomenon following spinal instrumented fusion. Myelopathy associated with proximal junctional failure (PJF) is poorly described in the literature. Adjacent segment disease, fracture above the upper instrumented vertebrae and subluxation may all cause cord compression, ambulatory dysfunction, and/or lower extremity weakness in the postoperative period.Materials and methods: We review the literature on PJK and PJF, and discusses the postoperative management of three patients who experienced myelopathy associated with PJF following T9/10 to pelvis fusion at a single institution.Results and conclusions: PJF with myelopathy must be diagnosed and surgically corrected early on so as to minimize permanent neurologic injury. Patients requiring significant sagittal deformity correction are at greater risk for PJF, and may benefit from constructs terminating in the upper thoracic spine.

Revision surgery for non-union in adult spinal deformity.

As adult spinal deformity surgery is performed more and more, the spine surgeon is faced with the challenge to treat pseudoarthrosis. The presentation may vary, from asymptomatic patients, who should be observed in most of the cases, to patients with acute episode of broken rods, and or chronic pain with often trunk imbalance. In some instances, patients will present with neurologic symptoms. The evaluation of such patients must start with a good understanding of why the surgery failed first place. Poor host, smoking, lack of anterior column support, poor sagittal balance, lack of fusion, poor construct. Often a combination of all of the above is encountered. The workup for such cases consists of imaging studies (with often a CT myelogram as the excessive metal artifact will render the MRI imaging useless), nutrition labs, DEXA scan, EOS films and internal medicine or cardiology consult for risk stratification as this may represent major surgery. Indication of surgery is mostly based on pain and imbalance and/or poor function. The surgeon planning a revision adult deformity surgery has many tasks to perform: Identify and avoid the reasons that lead to failure of the previous surgeries. Plan the anterior column reconstruction either through posterior or anterior interbody fusion. Restore the global alignment through anterior or posterior osteotomies to achieve sagittal and coronal balance. Obtain a solid fixation with sufficient levels above and below the osteotomies sites with in some cases the use of pelvic screws and four rods (Quad-Rod) techniques. The use of bone graft (either autologous, allograft, bone graft enhancers and inducer) agents. The requirement of decompression either through a virgin spine or a previous laminectomy bed. Despite the extent of these surgeries and the potential for immediate postoperative complications, the outcome is in most cases satisfactory if these goals are achieved. In this review, the authors explore different scenarios for pseudoarthrosis in the adult spine deformity patient and the preferred treatment method to obtain the best outcome for every individual patient. These slides can be retrieved under Electronic Supplementary Material.

Occipital neuralgia: A neurosurgical perspective.

Occipital neuralgia typically arises in the setting of nerve compression by fibrosis, surrounding anatomic structures, or osseous pathology, such as bone spurs or hypertrophic atlanto-epistropic ligament. It generally presents as paroxysmal bouts of sharp pain in the sensory distribution of the first three occipital nerves. Due to the long course of the greater occipital nerve (GON), and its peculiar anatomy, and location in a mobile region of the neck, it is unsurprising that the GON is at high risk for compression. Little is known how to diagnose or treat this neuropathic pain syndrome. The objective of this paper is to isolate the etiology involved, and treat this condition promptly. After all nonoperative efforts are exhausted, surgical transection of the nerve is the treatment of choice in these cases. An isolated C2 neurectomy or ganglionectomy is performed for an optimal pain relief. C1-2 instrumented fusion can be considered if, extensive facet arthropathy with instability is identified. Authors review the spectrum of treatment options for this debilitating condition, and discuss the case example of a patient who required conversion to a C1-C2 instrumented fusion following C2 ganglionectomy due to an underlying extensive degenerative disease and intraoperative findings suggestive of atlantoaxial instability.

Surgical Treatment of Flat Back Syndrome With Anterior Hyperlordotic Cages.

BACKGROUND: Traditional correction for flat back syndrome is performed with a posterior-based surgery or combined approaches in revision cases. OBJECTIVE: To evaluate outcome from anterior surgery with the use of hyperlordotic cages (HLCs) in patients with flat back syndrome. METHODS: All patients operated with or without prior posterior lumbar surgery were studied. Pre- to postoperative sagittal alignment was analyzed. Radiographic parameters were analyzed including T1 pelvic angle (T1PA), sagittal vertical axis (SVA), pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL), sacral slope (SS), pelvic incidence and lumbar lordosis (PI-LL), and T4-12TK. RESULTS: All 50 patients (mean age of 58 yr, 72% female with mean body mass index of 28) demonstrated significant radiographic alignment difference in their spinopelvic and global parameters from pre- to postoperative standing: LL (-37.04° vs -59.55°, P < .001), SS (35.12 vs 41.13, P < .001), PI-LL (23.55 vs 6.46), T4-12 TK (30.59 vs 41.67), PT (28.22 vs 22.13), SVA in mm (80.94 vs 37.39), and T1PA (28.70° vs 18.43°, P < .001). Using linear regression analysis, predicted pre- to postoperative change in standing LL corresponded to a pre- to postoperative changes in standing PI-LL mismatch, T1PA, TK, SS, PT, and SVA (R2 = 0.59, 0.38, 0.25, 0.16, 0.12, and 0.17, respectively). Five degrees of pre- to postoperative change in T1PA translates to -4.15° change in LL. CONCLUSION: Anterior surgery with HLCs followed by posterior instrumentation is an effective technique to treat flat back syndrome. HLCs are effective to maximize LL up to 30°, which is equivalent in magnitude to a pedicle subtraction osteotomy, but associated with less blood loss, quicker recovery, lower complications, and good surgical outcome.

Technical Consideration for TLIF Cage Retrieval and Deformity Correction With Anterior Interbody Fusion in Lumbar Revision Surgeries.

INTRODUCTION: Symptomatic pseudoarthrosis after transforaminal lumbar interbody fusion (TLIF) could result in sagittal malalignment. Revision posterior surgery with TLIF cage removal poses a challenge intraoperatively. The authors have proposed salvage anterior approach for cage removal and have discussed unique experience with the correction in their deformity patients. METHODS: All patients with symptoms of clinical deformity or symptomatic pseudoarthrosis operated from January of 2012 to February of 2018 were included in the study. TLIF cage removal followed by anterior lumbar interbody fusion (ALIF) surgery was performed in all patients. Radiographic sagittal parameters including thoracic kyphosis (TK; T4-T12), sagittal vertical axis (SVA), T1 pelvic angle (TPA), lumbar lordosis (LL), the mismatch between pelvic incidence (PI) and LL (PI-LL), sacral slope (SS), pelvic tilt (PT), and PI were analyzed. RESULTS: 6 patients (mean age of 57 years, 83% female) underwent TLIF retrieval through anterior approach and ALIF with hyperlordotic cages (HLCs), followed by posterior spinal fusion surgery. Described technique entails use of tailored instruments with sequential gentle distraction of end plates with TLIF spreader could facilitate in the cage removal. Mean number of interbody levels fused pre as well as post were 1.5. The radiographic sagittal parameters from preoperative versus postoperative standing were as follows: T4-T12 TK, 16° vs. 37.6°; LL, -25° vs. -47.6°; PT, 36° vs. 26°; PI-LL, 35° vs. 12.4°; SVA, 12° vs. 5.6°; and TPA, 44° vs. 25°, with p<.001. Mean number of instrumented level fused were 8.1. Using linear regression analysis, change from pre-to postoperative standing in LL predicted pre-to postoperative change in SVA and TPA for global correction (R= -0.30 and -0.80, respectively). CONCLUSIONS: Anterior approach is a suitable technique for TLIF cage removal while preserving the end plates for subsequent optimal interbody fusion at the index level in symptomatic pseudoarthrosis patients or those with clinical deformity. ALIF with HLCs with or without Ponte osteotomy can restore segmental and overall sagittal alignment.

Utilization and Economic Impact of Posterolateral Fusion and Posterior/Transforaminal Lumbar Interbody Fusion Surgeries in the United States.

STUDY DESIGN: Retrospective database study. OBJECTIVE: To analyze the economic and age data concerning primary and revision posterolateral fusion (PLF) and posterior/transforaminal lumbar interbody fusion (PLIF/TLIF) throughout the United States to improve value-based care and health care utilization. METHODS: The National Inpatient Sample (NIS) database was queried by the International Classification of Diseases, Ninth Revision, Clinical Modification codes for patients who underwent primary or revision PLF and PLIF/TLIF between 2011 and 2014. Age and economic data included number of procedures, costs, and revision burden. The National Inpatient Sample database represents a 20% sample of discharges from US hospitals weighted to provide national estimates. RESULTS: From 2011 to 2014, the annual number of PLF and PLIF/TLIF procedures decreased 18% and increased 23%, respectively, in the Unites States. During the same period, the number of revision PLF decreased 19%, while revision PLIF/TLIF remained relatively unchanged. The average cost of PLF was lower than the average cost of PLIF/TLIF. The aggregate national cost for PLF was more than $3 billion, while PLIF/TLIF totaled less than $2 billion. Revision burden (ratio of revision surgeries to the sum of both revision and primary surgeries) remained constant at 8.0% for PLF while it declined from 3.2% to 2.9% for PLIF/TLIF. CONCLUSION: This study demonstrated a steady increase in PLIF/TLIF, while PLF alone decreased. The increasing number of PLIF/TLIF procedures may account for the apparent decline of PLF procedures. There was a higher average cost for PLIF/TLIF as compared with PLF. Revision burden remained unchanged for PLF but declined for PLIF/TLIF, implying a decreased need for revision procedures following the initial PLIF/TLIF surgery.

Technical nuances of percutaneous sacroiliac joint fixation: A cadaveric study.

Sacroiliac (SI) joint can produce debilitating lower back pain with radiation to groin, buttocks, and lower extremities. SI joint dysfunction poses a clinical challenge to the spine surgeons. Studies entailing surgical arthrodesis utilizing Titanium implants have been reported with reputedly high level of patient satisfaction. Authors have described technical aspects of surgical technique with use of titanium screw implants. The transarticular technique is used to places SI joint screw implants across the articular portion of SI joint. Cadaveric SI joint instrumentation is performed under fluoroscopic guidance. Moreover, Medline literature search is conducted to study surgical outcome, and patient satisfaction. 4 cadavers are prepped prone for the percutaneous approach. Bilaterally 6 screws are placed using transarticular placement technique under fluoroscopic guidance. The posterior technique utilizes alignment guide to place the screws inline on the inlet view, parallel in the outlet view, and parallel to the dorsal aspect of the sacral body in the lateral view. One C-arm is used in the entire technique. The technical aspects of surgical technique have been described in a stepwise fashion for easy reproducibility in the operating room. Each screw track is checked with tactile feel of a blunt K-wire before final deployment. All bilateral screws were checked on a set of fluoroscopic views. A detail clinical examination, diagnostic joint injection, with the radiological imaging must be considered before surgical consideration. SI Joint fusion utilizing 3 transarticular sacral screws is equally effective and safe procedure to treat chronic lower back pain ensuing from SI joint dysfunction.

Overpowering the Previously Posterior Instrumented Cervical Spine With Cage-Assisted Anterior Cervical Discectomy and Fusion: A Cadaveric Study.

PURPOSE: Cervical spines previously posteriorly instrumented and fused with a kyphotic deformity represent a surgical challenge. Current treatment strategies include C7 pedicle subtraction osteotomy or a posterior-anterior-posterior approach, which carry the risk of significant complications. The objective of this study was to attempt to achieve lordosis with multiple anterior cervical discectomy and fusion (ACDF) cages to overpower the posterior instrumentation. METHODS: Four adult cadaveric specimens were selected and underwent C3-C7 posterior laminectomy with posterior instrumentation in a kyphotic alignment using a 3.5-mm titanium screw-rod system. Next, ACDF from C3 to C7 was performed with 15° lordotic cages to restore cervical lordosis. Posterior instrumentation was then inspected for failure. Fluoroscopic images were obtained to calculate total construct lordosis and change in segmental lordosis. CT scans were obtained after ACDF to assess for loosening, instrumentation failure, endplate damage, or impaction. Bone mineral density was calculated on CT scans. RESULTS: Age ranged from 59 to 82, and all specimens were male. No gross instrumentation failure was observed. Mean pre-ACDF lordosis between C3 and C7 was 0° (-5° to 5°). Post-ACDF lordosis increased to 37° (35°-38°). Mean segmental lordosis achieved with no endplate destruction was 13.1° (8°-17°). T scores for the cadavers were -0.5, -0.5, -3.2, and -5.1. Two levels of impaction were observed (12.5%). Failure of bone screw interface occurred in the cadaver, with a T score of -5.1 in the middle of the construct. CONCLUSION: Our study demonstrates the validity of overpowering posterior instrumentation through multiple level ACDF with lordotic cages. This may obviate the need to perform posterior-anterior-posterior procedures. LEVEL OF EVIDENCE: Level III.

The etiology of congenital scoliosis: genetic vs. environmental-a report of three monozygotic twin cases.

PURPOSE: To describe the presence of congenital scoliosis in a genetically identical population as it relates to the possible genetic vs. environmental etiologic factors. METHODS: The authors describe three cases of congenital scoliosis in monozygotic twins. The first pair includes two 4-year-old girls presenting with mirror curves, one of whom had an associated stage I Chiari malformation. The second pair is a 4-year-old girl who presented with thoracic scoliosis, a T10-11 hemivertebra, and multilevel failure of segmentation in the lumbar spine whose identical sibling is unaffected. The third pair includes a 4-month-old boy with T9 and L4 hemivertebra whose brother is also unaffected. RESULTS: All three cases were managed conservatively with observation and remained asymptomatic throughout the duration of follow-up. There were no associations with extraspinal deformities, although one patient presented with concomitant type I Chiari malformation. CONCLUSION: The variable presentation of congenital scoliosis in a genetically unique population serves as testament to the complexity associated with its development, likely involving both environmental factors and a genetic predisposition.

Sacral pedicle subtraction osteotomy for an extreme case of positive sagittal balance: case report.

The importance of sagittal spinal balance and lumbopelvic parameters is now well understood. The popularization of various osteotomies, including Smith-Peterson, Ponte, and pedicle subtraction osteotomies (PSOs), as well as vertebral column resections, have greatly enhanced the spine surgeon's ability to recognize and effectively treat sagittal imbalance. Yet rare circumstances remain, most notably in distal kyphotic deformities and patients with extremely elevated pelvic incidences, where these techniques remain inadequate. In this article, the authors describe a patient with severe sagittal imbalance despite multiple prior anterior and posterior reconstructive surgeries in which a sacral PSO was performed with good results. A description of this technique as well as a brief review of the literature is provided.

Can Posterior Lumbar Instrumentation and Fusion Be Overpowered by Anterior Lumbar Fusion With Hyperlordotic Cages? A Cadaveric Study.

STUDY DESIGN: Technical report on cadavers. OBJECTIVE: To evaluate preliminary feasibility and safety of lumbar sagittal alignment correction with anterior hyperlordotic cages used to overpower previous posterior spinal instrumentation. METHODS: Hyperlordotic 30° anterior lumbar interbody fusion (ALIF) cages were inserted in collapsed L5-S1 disc space of 2 cadavers to overpower prior posterior L5-S1 pedicle screws and rod constructs. A distinct technique of opening up the disc space and creation of intersegmental lordosis was employed using a large endplate distractor and transforaminal lumbar interbody fusion (TLIF) paddle distractor. Assessment of increase in the intersegmental lordosis (ISL) was made using lateral fluoroscopic imaging. Postprocedural computed tomography (CT) scans were obtained to evaluate any failure of posterior instrumentation and to serve as a surrogate marker for bone quality. RESULTS: The 2 cadavers selected (from an available number of 10) were males: 82 and 84 years of age, respectively. Both had marked L5-S1 disc space collapse. The ISL achieved with hyperlordotic cages was 27.6° for the first cadaver (up from 4.9°) and 23.1° for the second one (up from 4.6°). No obvious screw-rod failure or cutout of instrumentation occurred. Postprocedure CT scans did not reveal any loosening of screws or cutout through endplates. Hounsfield unit values calculated on axial CT cuts were 73.50 (osteoporosis) and 80.70 (osteopenia) respectively for the 2 cadavers. CONCLUSION: Based on the results of the cadaveric experiment, overpowering of posterior instrumentation can be effectively achieved. Biomechanical and clinical studies are indicated to further evaluate the suitability and safety of this technique.