Complications and neurological deficits following minimally invasive anterior column release for adult spinal deformity: a retrospective study

Deformity angular distance ratio independently predicts intraoperative neuromonitoring alerts in spinal deformity correction

BACKGROUND

Intraoperative neuromonitoring (IONM) alerts are critical concerns for surgeons performing spinal deformity corrective surgeries, as they indicate a heighteded risk of postoperative neurological deficits. Previous studies have demonstrated that patients with large Cobb angle or elevated deformity angular ratio (DAR) are at an increased risk of IONM alerts. However, spinal curves with similar Cobb angles and DARs may exhibit significantly different risks of IONM alerts during surgery. Current methods for evaluating spinal deformity fail to comprehensively and accurately reflect its severity. The purpose of this study was to investigate whether the deformity angular distance ratio (DADR) serves as an independent predictor of IONM alerts during corrective surgery for spinal deformity.

METHODS

This study analyzed a consecutive series of 404 patients undergoing corrective surgery at a single academic center. Preoperative radiographs were used to calculate the DAR and DADR. Twelve clinically relevant candidate variables were selected for univariable analysis. Multivariable logistic regression analysis was then conducted to identify independent predictors of IONM alerts.

RESULTS

The incidence of IONM alerts in this cohort was 25.2%. Univariable analysis identified several factors potentially associated with IONM alerts, including older age, type-III spinal cord morphology, location of apex, etiological diagnosis, preoperative sagittal Cobb angle, sagittal DAR, sagittal DADR, coronal DADR, total DAR, total DADR, three-column osteotomy, and preoperative neurological deficits. Multivariable analysis revealed that an apex location at C7-T4, preoperative neurological deficits, sagittal DADR, and total DADR were independent predictors of IONM alerts.

CONCLUSIONS

Among patients undergoing corrective surgeries for spinal deformities, the DADR is a robust measure of spinal deformity severity and is strongly correlated with the risk of IONM alerts. Compared to other deformity parameters, DADR is an independent predictor of IONM alerts. Additional independent predictors include the location of the apex and the presence of preoperative neurological deficits.

Anterior Column Release: With Great Lordosis Comes Great Risk of Complications-A Case Series

STUDY DESIGN

Retrospective review.

OBJECTIVE

We sought to characterize complications associated with anterior column release (ACR).

SUMMARY OF BACKGROUND DATA

Correction of positive sagittal imbalance was traditionally completed with anterior column grafts or posterior osteotomies. ACR is a minimally invasive technique for addressing sagittal plane deformity by restoring lumbar lordosis.

METHODS

We conducted a retrospective review of consecutive patients who underwent ACR in a prospectively kept database at a tertiary care academic center from January 2012 to December 2018. The prespecified complications were hardware failure (rod fracture, hardware loosening, or screw fracture), proximal junctional kyphosis, ipsilateral thigh numbness, ipsilateral femoral nerve weakness, arterial injury requiring blood transfusion, bowel injury, and abdominal pseudohernia.

RESULTS

Thirty-eight patients were identified. Thirty-five patients had ACR at L3-4, 1 had ACR at L4-5, and 1 patient had ACR at L2-3 and L3-4. Eighteen patients (47.4%) had one of the prespecified complications (10 patients had multiple). Ten patients developed hardware failure (26.3%); 8 patients (21.1%) had rod fracture, 4 (10.5%) had screw fracture, and 1 (2.6%) had screw loosening. At discharge, rates of ipsilateral thigh numbness (37.8%) and hip flexor (37.8%)/quadriceps weakness (29.7%) were the highest. At follow-up, 6 patients (16.2%) had ipsilateral anterolateral thigh numbness, 5 (13.5%) suffered from ipsilateral hip flexion weakness, and 3 patients (5.4%) from ipsilateral quadriceps weakness. Arterial injury occurred in 1 patient (2.7%). Abdominal pseudohernia occurred in 1 patient (2.7%). There were no bowel injuries observed.

CONCLUSIONS

ACR is associated with a higher than initially anticipated risk of neurological complications, hardware failure, and proximal junctional kyphosis.

Proximal Lumbar Anterior Column Realignment for Iatrogenic Sagittal Plane Adult Spinal Deformity Correction: A Retrospective Case Series

BACKGROUND

Anterior column realignment (ACR) is a powerful minimally invasive surgery technique to restore sagittal alignment in adult spinal deformity (ASD). This can accomplish similar segmental lordosis restoration as 3-column osteotomy with less blood loss and comparable complication rates. ACR can be performed at adjacent disease segments in the proximal lumbar spine in revision cases. However, two thirds of physiologic lordosis occurs between L4-S1, and concerns remain about altered lumbar morphology. We evaluated patients who underwent proximal lumbar ACR for iatrogenic flatback deformity.

METHODS

A total of 19 consecutive patients who underwent L1-2 or L2-3 ACR were retrospectively analyzed. All patients were treated with lateral minimally invasive surgery interbody technique, followed by posterior reconstruction with Smith-Peterson osteotomy. Preoperative and postoperative radiographic and clinical outcomes were obtained.

RESULTS

Mean follow-up was 19 months. All but 1 patient had a history of prior lumbar or lumbo-sacral fusion. Sagittal vertical axis and pelvic incidence-lumbar lordosis decreased from 11.9 cm to 6.1 cm (P < 0.0001) and 34.2° to 12.8° (P < 0.0001). Segmental lordosis increased from -2.7° to 21.9° (P < 0.0001). Proximal lumbar lordosis increased from -0.4° to 22.6° (P < 0.0001), and lordosis distribution index decreased from 79.5% to 48.9% (P < 0.0001). Mean Oswestry Disability Index and numeric pain rating scale back pain scores decreased from 58.0 to 36.2 (P = 0.0041) and 7.9 to 3.4 (P < 0.0001), respectively. Patient-Reported Outcomes Measurement Information System Physical and Mental Health T-scores increased from 34.1 to 43.3 (P = 0.0049) and 40.4 to 45.0 (P = 0.0993), respectively. Major complication rate was 15.8%. One patient required revision for mechanical failure. There were no permanent neurological or vascular injuries.

CONCLUSIONS

Proximal lumbar ACR plus Smith-Peterson osteotomy can achieve sagittal correction with low major complication rates in patients with ASD and prior distal fusion. Differentially increasing proximal lumbar lordosis and lowering lumbar distribution index did not have deleterious effects on radiographic or clinical outcomes. Further work is needed to understand the effect of proximal ACR in the surgical management of ASD.

Indications, complications and outcomes of minimally-invasive lateral lumbar interbody fusion with anterior column realignment vs. standard LLIF using expandable interbody spacers

Background

Anterior column realignment (ACR), using a lateral lumbar or thoracic interbody fusion (LLIF) approach to release the anterior longitudinal ligament (ALL), is a powerful technique to increase segmental lordosis. We here report our experience with the use of expandible LLIF cages for ACR.

Methods

Retrospective, single-center observational cohort study including consecutive patients treated by LLIF using an expandible interbody implant. Patients with ACR were compared to patients without ACR. Our outcomes include adverse events (AEs), radiological (segmental sagittal cobb angle, spinopelvic parameters) and clinical outcomes until 12 months postoperative.

Results

We identified 503 patients, in which we performed LLIF at 732 levels. In 63 patients (12.5%) and 70 levels (9.6%) an expandable cage was used. Of those, in 30 patients (47.6%) and 30 levels, the ALL was released (42.8%). Age (mean 61.4 years), sex (57.1% female), comorbidities and further demographic features were similar, but patients in the ACR group had a higher anesthesiologic risk, were more frequently operated for degenerative deformity and had a more severely dysbalanced spine (all p < 0.05). ACR was most frequently done at L3/4 (36.7%) and L4/5 (23.3%), entailing multilevel fusions in 50% (3-7 levels) and long constructs in 26.7% (>7 levels). Intraoperative AEs occurred in 3.3% (ACR) and 3.0% (no ACR; p = 0.945). In ACR cases, mean segmental lordosis changed from -2.8° (preoperative) to 16.4° (discharge; p < 0.001), 15.0° (3 months; p < 0.001) and 16.9° (12 months; p < 0.001), whereas this change was less in non-ACR cases [4.3° vs. 10.5° (discharge; p < 0.05), 10.9 (3 months; p < 0.05) and 10.4 (12 months; p > 0.05)]. Total lumbar lordosis increased from 27.8° to 45.2° (discharge; p < 0.001), 45.8° (3 months; p < 0.001) and 41.9° (12 months; p < 0.001) in ACR cases and from 37.4° to 46.7° (discharge; p < 0.01), 44.6° (3 months; n.s.) and 44.9° (12 months; n.s.) in non-ACR cases. Rates of AEs and clinical outcomes at 3 and 12 months were similar (all p > 0.05) and no pseudarthrosis at the LLIF level was noted.

Conclusions

ACR using an expandible LLIF interbody implant was safe, promoted solid fusion and restored significantly more segmental lordosis compared to LLIF without ALL release, which was maintained during follow-up.

Lateral Anterior Column Release in Short Lumbar Fusion… Is It Worth It?

BACKGROUND

Radiographic adjacent segment disease (ASD) ranges from 10% to 84%, depending on technique. Occurrence of symptomatic ASD is lower, with a range of 1.9% to 13%. ASD can be very debilitating and necessitate further procedures, leading to high morbidity. Herein, we explore the occurrence of adjacent segment disease when performing anterior column release in lateral interbody fusion.

METHODS

After institutional review board approval, 120 total patients who underwent lateral lumbar interbody fusion (LLIF) at our facility from 2013 to 2020 were retrospectively reviewed, allowing for a minimum of 3 years for follow-up time. Surgical variables and spinopelvic parameters were measured and collected by our team. Statistical measures of significance were calculated using IBM SPSS Statistics Version 29.

RESULTS

One hundred twenty total patients were included. 73.3% of patients had percutaneous screws, and 11.7% had open. Thirteen patients underwent LLIF with anterior column release (ACR). The mean lumbar lordosis (LL) was 50.1 ± 12.9, pelvic incidence (PI) was 52.8 ± 11.2, sacral slope was 33.6 ± 9.2, pelvic tilt was 18.1 ± 6.8, and sagittal vertical axis was 6.8 mm ± 30.5.Twenty four total patients had ASD after LLIF. In univariable analysis, ACR (P < 0.001) and PI-LL Mismatch (P < 0.035) were risk factors for developing ASD. In multivariable analysis, greater PI-LL mismatch was predictive of ASD (P < 0.005, OR = 1.097, and 95% confidence interval = 1.029-1.171), as was ACR (P < 0.001, OR = 9.667, and 95% confidence interval = 2.669-35.09).

CONCLUSIONS

Higher PI-LL mismatch after lumbar interbody fusion, and performance of an ACR during LLIF increased the likelihood of developing symptomatic ASD in our patients. Considering ACR to achieve the goal of correcting spinopelvic parameters should be carefully evaluated when undertaking a lateral approach.

Clinical and radiographic outcomes following 120 consecutive patients undergoing prone transpsoas lateral lumbar interbody fusion

PURPOSE

The prone transpsoas approach is a single-position alternative to traditional lateral lumbar interbody fusion (LLIF). Earlier prone LLIF studies have focused on technique, feasibility, perioperative efficiencies, and immediate postoperative radiographic alignment. This study was undertaken to report longer-term clinical and radiographic outcomes, and to identify learnings from experiential evolution of the prone LLIF procedure.

METHODS

All consecutive patients undergoing prone LLIF for any indication at one institution were included (n = 120). Demographic, diagnostic, treatment, and outcomes data were captured via prospective institutional registry. Retrospective analysis identified 31 'pre-proceduralization' and 89 'post-proceduralization' prone LLIF approaches, enabling comparison across early and later cohorts.

RESULTS

187 instrumented LLIF levels were performed. Operative time, retraction time, LLIF blood loss, and hospital stay averaged 150 min, 17 min, 50 ml, and 2.2 days, respectively. 79% of cases were without complication. Postoperative hip flexion weakness was identified in 14%, transient lower extremity weakness in 12%, and sensory deficits in 10%. At last follow-up, back pain, worst-leg pain, Oswestry, and EQ-5D health state improved by 55%, 46%, 48%, and 51%, respectively. 99% improved or maintained sagittal alignment with an average 6.5° segmental lordosis gain at LLIF levels. Only intra-psoas retraction time differed between pre- and post-proceduralization; proceduralization saved an average 3.4 min/level (p = 0.0371).

CONCLUSIONS

The largest single-center prone LLIF experience with the longest follow-up to-date shows that it results in few complications, quick recovery, improvements in pain and function, high patient satisfaction, and improved sagittal alignment at an average one year and up to four years postoperatively.

Anterior Column Realignment: Adult Sagittal Deformity Treatment Through Minimally Invasive Surgery

This article focuses on the treatment of sagittal spinal deformity using a minimally invasive technique, anterior column realignment. Traditional methods to address sagittal spine deformity have been associated with high morbidity, long operative times, and excessive blood loss. This technique uses a minimally invasive lateral retroperitoneal approach to release the anterior longitudinal ligament and apply a hyperlordotic implant for interbody fusion to restore lumbar lordosis and sagittal alignment.

Clinical Results of Utilizing the Satellite Rod Technique in Treating Ankylosing Spondylitis Kyphosis

Objective

According to the literature, there are no clinical reports documenting the use of the satellite rod technique in the treatment of ankylosing spondylitis kyphosis. The purpose of this retrospective study was to compare the clinical outcome of patients with ankylosing spondylitis kyphosis who adopted satellite rods versus those who did not.

Methods

Patients with ankylosing spondylitis kyphosis who underwent one or two‐level pedicle subtraction osteotomy (PSO) were reviewed, and total of 119 patients (112 males and seven females, average age 39.89 ± 6.61 years) were eligible and included in this present study. Anterior–posterior and lateral full‐length spine X‐ray films were performed preoperatively and at the two‐year follow‐up visit. Global kyphosis (GK), lumbar lordosis (LL), thoracolumbar kyphosis (TLK), thoracic kyphosis (TK), and osteotomy angle (OA) were measured. The complications of every group of patients were collected. Pre‐ and postoperative health‐related quality of life instruments, including the Bath Ankylosing Spondylitis Functional Index (Basfi) and Scoliosis Research Society outcomes instrument‐22 (SRS‐22), were recorded. The patients were divided into three groups based on features of their osteotomy including PSO levels and whether the satellite rod technique was applied. Patients who underwent one‐level PSO without the satellite rod technique were categorized in the one‐level group. Patients who underwent one‐level PSO with the satellite rod technique were classified in the satellite rod group. Patients who underwent two‐level PSO without the satellite rod technique were included in the two‐level group. The paired sample t test was used to compare pre‐ and postoperative parameters. One‐way ANOVA was performed for multiple group comparisons.

Results

The average follow‐up time is 29.31 ± 3.66 months. The patients' GK were significantly improved from 46.84 ± 20.37 degree to 3.31 ± 15.09 degree. OS achieved through each osteotomy segment of one‐level group (39.78 ± 12.29 degree) and satellite rods group (42.23 ± 9.82 degree), was larger than that of two‐level group (34.73 ± 7.54 and 28.85 ± 7.26 degree). There was no significant difference between the one‐level group and the satellite rod group in achieving the OS. Thirteen patients experienced different complications (10.92%). Three patients experienced rod fracture in the one‐level group. There was no rod fracture or screw failure in the satellite rod group or the two‐level group.

Conclusion

The satellite rod technique is also recommended for patients who undergo PSO osteotomy to correct ankylosing spondylitis kyphosis deformities.

Combined anterior-posterior versus all-posterior approaches for adult spinal deformity correction: a matched control study

PURPOSE

Anterior approaches are gaining popularity for adult spinal deformity (ASD) surgeries especially with the introduction of hyperlordotic cages and improvement in MIS techniques. Combined Approaches provide powerful segmental sagittal correction potential and increase the surface area available for fusion in ASD surgery, both of which would improve overall. This is the first study directly comparing surgical outcomes between combined anterior-posterior approaches and all-posterior approach in a matched ASD population.

METHODS

This is a retrospective matched control cohort analysis with substitution using a multicenter prospectively collected ASD data of patients with > 2 year FU. Matching criteria include: age, American Society of Anesthesiologists Score, Lumbar Cobb angle, sagittal deformity (Global tilt) and ODI.

RESULTS

In total, 1024 ASD patients were available for analysis. 29 Combined Approaches patients met inclusion criteria, and only 22 could be matched (1:2 ratio). Preoperative non-matched demographical, clinical, surgical and radiological parameters were comparable between both groups. Combined approaches had longer surgeries (548 mns vs 283) with more blood loss (2850 ml vs 1471) and needed longer ICU stays (74 h vs 27). Despite added morbidity, they had comparable complication rates but with significantly less readmissions (9.1% vs 38.1%) and reoperations (18.2% vs 43.2%) at 2 years. Combined Approaches achieved more individualised and harmonious deformity correction initially. At the 2 years control, Combined Approaches patients reported better outcomes as measured by COMI and SRS scores. This trend was maintained at 3 years.

CONCLUSION

Despite an increased initial surgical invasiveness, combined approaches seem to achieve more harmonious correction with superior sagittal deformity control; they need fewer revisions and have improved long-term functional outcomes when compared to all-posterior approaches for ASD deformity correction.

Post-operative L5 radiculopathy after L5-S1 hyperlordotic anterior lumbar interbody fusion (HL-ALIF) is related to a greater increase of lordosis and smaller post-operative posterior disc height: results from a cohort study

STUDY DESIGN

A single-centre retrospective study.

BACKGROUND AND PURPOSE

This study aims to investigate the rate of L5 radiculopathy, to identify imaging features associated with the complication and to evaluate the clinical outcomes in adult spine deformity patients undergoing L5-S1 ALIF with hyperlordotic cages.

METHODS

Design: retrospective cohort study. A single-centre prospective database was queried to analyse patients undergoing hyperlordotic (HL) ALIF with posterior fusion to correct spinal deformity. Clinical status was evaluated by back and leg pain numeric rate scale and Oswestry Disability Index pre-operatively and at 3-, 6- and 12-month follow-up. Spinopelvic parameters, such as pelvic incidence, pelvic tilt, lumbar lordosis and L5-S1 lordosis, posterior disc height (PDH) and anterior disc height, were assessed pre-operatively and post-operatively on standardized full-spine standing EOS images. The sagittal foraminal area was measured pre- and post-operatively on a CT scan.

RESULTS

Thirty-nine patients with a mean age of 63.2 ± 8.6 years underwent HL-ALIF from January 2016 to December 2019. Seven of them developed post-operative root pain (5) or weakness (2) (Group A), while thirty-two did not (Group B). Root impairment was associated with greater segmental correction magnitude, 26° ± 11.1 in Group A versus 15.1° ± 9.9 in Group B (p < 0.05), and to smaller post-operative PDH, 5.9 mm ± 2.7 in Group A versus 8.3 mm ± 2.6 (p < 0.05).

CONCLUSIONS

Post-operative root problems were observed in 17.9% of patients undergoing HL-ALIF for adult spine deformity. L5 radiculopathy was associated with larger sagittal angular corrections and smaller post-operative posterior disc height. One patient (2.6%) needed L5 root decompression. At 12 months of follow-up, results were equivalent between groups.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Anterior longitudinal ligament release from a posterior approach: an alternative to three-column osteotomy

PURPOSE

Expansion of the anterior column and compression of the posterior column restores lordosis and sagittal imbalance. Anterior longitudinal ligament (ALL) release has been described from lateral and anterior approaches as a technique to improve lumbar lordosis; however, posterior approach to release the ALL has not been adequately assessed.

METHODS

We demonstrate a case series of ALL release using a posterior approach performed in conjunction with posterior column osteotomy (PCO), with or without transforaminal lumbar interbody fusion (TLIF) for spinal deformity. Eleven cases were identified from billing records between 2010 and 2019. Retrospective review was conducted for perioperative complications and revision surgery. Overall and segmental lumbar lordosis (LL) correction was measured from pre- and postoperative imaging.

RESULTS

Eleven patients underwent ALL release with a PCO. Kyphosis, scoliosis, and flat back syndrome were the most common spinal deformities. On average, patients had 9 ± 3 levels fused and a single level ALL release. ALL release was most commonly performed at L1-L2 and L2-L3 levels. An overall LL correction of 28.6° ± 19.8^o was achieved; ALL release introduced 16.7° ± 11.9° of lordotic correction and accounted for 49.2 ± 30.4% of the overall lordotic correction. Average blood loss was 1030 ± 573 mL.

CONCLUSIONS

ALL release as an adjunct to PCO and TLIF is a viable technique for providing increased deformity correction without subjecting the patient to a more invasive three-column osteotomy. While this approach may not be appropriate for all patients, it represents a useful option in spinal deformity correction while limiting blood loss and additional anterior surgery.

LEVEL OF EVIDENCE

IV.

Complications of adult spinal deformity surgery: A literature review

Purpose:

Adult spinal deformity incidence increases accordingly as the population ages. Even though surgery is the best option for the treatment, the complications due to surgery are pretty challenging. This study aims to review the complication rates of adult spinal deformity surgery.

Methods:

A literature review of the last decade was performed searching for the query “Adult spine deformity and complication.” This search yielded 2781 results, where 79 articles were chosen to investigate the complications of adult spinal deformity surgery. In addition, the demographic data, surgical interventions, and complications were extracted from the publications.

Results:

A total of 26,207 patients were analyzed, and 9138 complications were found (34.5%). Implant failure, including screw loosening, breakage, distal and proximal junctional kyphosis, were the most common complications. The neurologic complications were about 10.8%, and the infection rate was 3.6%. Cardiac and pulmonary complications were about 4.8%.

Discussion:

Age, body mass index, smoking, osteoporosis, and other comorbidities are the significant risk factors affecting adult spinal deformity surgery. Presurgical planning and preoperative risk factor assessment must be done to avoid complications. Furthermore, intra and postoperative complications affect the patients’ quality of life and length of stay, and hospital readmissions. Revision surgery also increases the risk of complications.

Conclusion:

Good patient evaluation before surgery and careful planning of the surgery are essential in avoiding complications of adult spinal deformity.

Lateral lumbar interbody fusion in adult spine deformity - A review of literature

INTRODUCTION

Surgery for adult spine deformity presents a challenging issue for spinal surgeons with high morbidity rates reported in the literature. The minimally invasive lateral approach aims at reducing these complications while maintaining similar outcomes as associated with open spinal surgeries. The aim of this paper is to review the literature on the use of lateral lumbar interbody fusion in the cases of adult spinal deformity.

METHODS

A literature review was done using the healthcare database Advanced Research on NICE and NHS website using Medline. Search terms were "XLIF" or "LLIF" or "DLIF" or "lateral lumbar interbody fusion" or "minimal invasive lateral fusion" and "adult spinal deformity" or "spinal deformity".

RESULTS

A total of 417 studies were considered for the review and 44 studies were shortlisted after going through the selection criteria. The data of 1722 patients and 4057 fusion levels were analysed for this review. The mean age of the patients was 65.18 years with L4/5 being the most common level fused in this review. We found significant improvement in the radiological parameters (lordosis, scoliosis, and disk height) in the pooled data. Transient neurological symptoms and cage subsidence were the two most common complications reported.

CONCLUSION

LLIF is a safe and effective approach in managing adult spinal deformity with low morbidity and acceptable complication rates. It can be used alone for lower grades of deformity and as an adjuvant procedure to decrease the magnitude of open surgeries in high-grade deformities.

Comparison of Clinical Outcomes and Complications of Primary and Revision Surgery Using a Combined Anterior and Posterior Approach in Patients with Adult Spinal Deformity and Sagittal Imbalance

Backgroud

The purpose of this study was to compare clinical outcomes and complications of primary and revision surgery in patients with adult spinal deformity (ASD) accompanied by sagittal imbalance. Revision surgery has been associated with poor clinical outcomes and increased risk of complications. Previous studies comparing primary versus revision surgery included data for a wide variety of diseases and ages, but few investigated patients with ASD with sagittal imbalance undergoing anterior and posterior combined surgery.

Methods

Retrospective cohort analysis of prospectively collected data. We identified 60 consecutive patients with ASD combined with sagittal imbalance who underwent primary or revision surgery; of these, 6 patients were excluded for lack of a minimal 2-year follow-up. Patients' surgical and radiological data, clinical outcomes, and complications were reviewed.

Results

There were 30 patients in the primary group and 24 patients in the revision group. Patient characteristics, including the prevalence of sarcopenia, were similar between the two groups. Pedicle subtraction osteotomy was performed more frequently in the revision group although there was no statistically significant difference between groups. The primary group had more proximal junctional problems, whereas the revision group had more rod breakage (p < 0.05). There were significant improvements in clinical outcomes in both groups when the preoperative and 2-year postoperative values were compared. The Oswestry disability index and visual analog scale score were similar in both groups 2 years postoperatively.

Conclusions

Considering the greater pain and disability at the time of the revision procedure, revision patients benefited more from surgery at the 2-year follow-up than the primary surgery patients. Complication rates were similar between the groups except for proximal junctional problems and rod breakage. Therefore, revision surgery should not be avoided in the treatment of ASD patients with sagittal imbalance.

Cadaveric Evidence of Complete Transection of the Lumbar Sympathetic Trunk After Extreme Lateral Transpsoas Approach to the Lumbar Spine: A Word of Caution

Lateral transpsoas approaches to the lumbar spine are believed to entail less risk of injury to the lumbar sympathetic trunk and plexus than anterior approaches. However, even the lateral approach can occasionally injure the sympathetic trunk. We report a literature review and cadaveric case of complete resection of the left sympathetic trunk at L3 following lateral transpsoas approach performed by a well-trained spine surgeon. A left lateral approach to the lumbar spine for a two-level total discectomy at L3-L4 and L4-L5 was undertaken on a fresh-frozen cadaver by an experienced spinal surgeon. The procedure followed standard spinal technique under fluoroscopy guidance. The cadaver was placed in a right lateral position and an operative corridor to the lateral aspect of the psoas major muscle was developed. Blunt dissection was carried through the muscle and standard total discectomy was completed at the target levels. Following the procedure, the lumbar spine and adjacent structures were anatomically dissected. It was found that the sympathetic trunk had been completely transected at the L3 level during the surgical procedure. Other major structures such as the femoral nerve, obturator nerve, and roots of the lumbar spinal nerves had not been injured. The above case highlights the proximity of the sympathetic trunk to lateral transpsoas approaches and the possibility of injury to it. We review the literature on postoperative cases of lumbar sympathetic dysfunction (SD) following such procedures and posit that some of these are due to direct iatrogenic injury.

The Safety and Efficacy of Stand-Alone Lateral Lumbar Interbody Fusion for Adjacent Segment Disease in a Cohort of 44 Patients

BACKGROUND

A mainstay of treatment for symptomatic adjacent segment disease (ASD) has consisted of revision with posterior decompression and fusion. This carries significant morbidity and can be technically difficult. An alternative is stand-alone lateral lumbar interbody fusion (LLIF), which may avoid complications associated with revision surgery. We describe the largest cohort of patients treated with LLIF for ASD to our knowledge.

METHODS

We conducted a retrospective cohort study on all patients who underwent transpsoas LLIF for ASD at a single academic center between 2012 and 2019. Postoperative improvement was measured using the Visual Analog Scale (VAS) and the Oswestry Disability Index (ODI).

RESULTS

Forty-four patients who underwent LLIF for ASD were identified. Median age was 65 years. Median time from index surgery to ASD development was 78 months. Median levels fused via LLIF was 1. Our median follow-up was 358 days. At follow-up, the median VAS back pain score was 0 (mean, 0.884), median VAS leg pain score was 1 (mean, 0.953), and median ODI was 8. The median improvement for VAS back pain was 8, for VAS leg pain was 6, and for ODI was 40. No patients suffered new neurologic symptoms postoperatively. Of the 17 patients who initially presented with non-pain neurologic symptoms, 8 (47.1%) experienced complete resolution of symptoms, and 5 (29.4%) experienced only some improvement.

CONCLUSIONS

To our knowledge, this is the largest cohort study of patients to date evaluating stand-alone LLIF for ASD. Our patient outcomes show it is safe and effective with low risk of morbidity.

Restoring spinopelvic harmony with lateral lumbar interbody fusion: is it a realistic goal?

Background

The importance of spinopelvic harmony [pelvic incidence (PI) = lumbar lordosis (LL) ±10 degrees] is well established in the literature. We aimed to determine whether lateral lumbar interbody fusion (LLIF) surgery in isolation is successful in restoring spinopelvic harmony, and whether the surgery maintained the relationship in those who present in a balanced state.

Methods

A retrospective radiographic analysis was performed on patients who underwent LLIF surgery, followed by posterior instrumented fusion, between January 2012 to August 2019 by a single surgeon (AD). Pre- and post-operative X-rays were reviewed by two authors using Surgimap spinal imaging 2.2.15.5. The LL, PI, and PI-LL mismatch, as well as a range of coronal and segmental sagittal radiographic parameters, were recorded.

Results

A total of 71 patients with 170 levels treated via LLIF were analysed. A mean pre-operative PI-LL of 14.3 degrees and post-operative value of 13.4 degrees was recorded (P=0.43). Of the 41 patients who were imbalanced pre-operatively, 13 (31.7%) were restored to a LL within 10 degrees of PI post-LLIF procedure. 30 patients presented in spinopelvic harmony, and 25 (83.3%) of those maintained that relationship following LLIF. Mean coronal global Cobb angles (13.7 degrees pre-operatively to 7.7 degrees post-operatively), segmental coronal Cobb angles (3.8 to 0.9 degrees), and anterior (5.2 to 9.8 mm) and posterior (3.2 to 6.7 mm) disc heights all improved significantly post-LLIF surgery (P<0.0001).

Conclusions

Although an effective treatment for coronal deformities and providing indirect decompression for degenerative lumbar disc disease, LLIF surgery alone is unlikely to result in correction of sagittal deformity and in particular spinopelvic harmony.

Anterior Column Realignment: Analysis of Neurological Risk and Radiographic Outcomes

BACKGROUND

Anterior column realignment (ACR) is a less invasive alternative to 3-column osteotomy for the correction of sagittal imbalance. We hypothesized that ACR would correct sagittal imbalance with an acceptable neurological risk.

OBJECTIVE

To assess long-term neurological and radiographic outcomes after ACR.

METHODS

Patients ≥18 yr who underwent ACR from 2005 to 2013 were eligible. Standing scoliosis radiographs were studied at preoperation, postoperation (≤6 wk), and at minimum 2 yr of follow-up. Clinical/radiographic data were collected through a retrospective chart review, with thoracic 1 spino-pelvic inclination (T1SPi) used as the angular surrogate for sagittal vertical axis.

RESULTS

A total of 26 patients had complete data, with a mean follow-up of 2.8 yr (1.8-7.4). Preoperative, sagittal parameters were lumbar lordosis (LL) of -16.1°, pelvic incidence (PI)-LL of 41.7°, T1SPi of 3.6°, and pelvis tilt (PT) of 32.4°. LL improved by 30.6° (P < .001) postoperation. Mean changes in PT (-8.3), sacral slope (8.9), T1SPi (-4.9), and PI-LL (-33.5) were all significant. The motion segment angle improved by 26.6°, from 5.2° to -21.4° (P < .001). Neurological complications occurred in 32% patients postoperation (n = 8; 1 patient with both sensory and motor). New thigh numbness/paresthesia developed in 3 (13%) patients postoperation; only 1 (4%) persisted at latest follow-up. A total of 6 (24%) patients developed a new lower extremity motor deficit postoperation, with 4 (8%) having persistent new weakness at last follow-up. Out of 8 patients with preoperative motor deficit, half saw improvement postoperation and 75% improved by last follow-up.

CONCLUSION

There was net motor improvement, with 24% of patients improving and 16% having persistent new weakness at latest follow-up; 60% were unchanged. Radiographic results demonstrate that ACR is a useful tool to treat severe sagittal plane deformity.

Minimally Invasive Anterior Longitudinal Ligament Release for Anterior Column Realignment

STUDY DESIGN

Review of the literature.

OBJECTIVES

Anterior column realignment (ACR) is a powerful but relatively new minimally invasive technique for deformity correction. The purpose of this study is to provide a literature review of the ACR surgical technique, reported outcomes, and future directions.

METHODS

A review of the literature was performed regarding the ACR technique. A review of patients at our single center who underwent ACR was performed, with illustrative cases selected to demonstrate basic and nuanced aspects of the technique.

RESULTS

Clinical and cadaveric studies report increases in segmental lordosis in the lumbar spine by 73%, approximately 10° to 33°, depending on the degree of posterior osteotomy and lordosis of the hyperlordosis interbody spacer. These corrections have been found to be associated with a similar risk profile compared with traditional surgical options, including a 30% to 43% risk of proximal junctional kyphosis in early studies.

CONCLUSIONS

ACR represents a powerful technique in the minimally invasive spinal surgeon's toolbox for treatment of complex adult spinal deformity. The technique is capable of significant sagittal plane correction; however, future research is necessary to ascertain the safety profile and long-term durability of ACR.

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.

Neurologic Injury in Complex Adult Spinal Deformity Surgery: Staged Multilevel Oblique Lumbar Interbody Fusion (MOLIF) Using Hyperlordotic Tantalum Cages and Posterior Fusion Versus Pedicle Subtraction Osteotomy (PSO)

STUDY DESIGN

A retrospective review of prospectively collected data.

OBJECTIVE

The aim of this study was to determine the safety of MOLIF versus PSO.

SUMMARY OF BACKGROUND DATA

Complex adult spinal deformity (CASD) represents a challenging cohort of patients. The Scoli-RISK-1 study has shown a 22.18% perioperative risk of neurological injury. Restoration of sagittal parameters is associated with good outcome in ASD. Pedicle subtraction osteotomies (PSO) is an important technique for sagittal balance in ASD but is associated with significant morbidity. The multilevel oblique lumbar interbody fusion (MOLIF) is an extensile approach from L1 to S1.

METHODS

Single surgeon series from 2007 to 2015. Prospectively collected data. Scoli-RISK-1 criteria were refined to only include stiff or fused spines otherwise requiring a PSO. Roentograms were examined preoperatively and 2 year postoperatively. Primary outcome measure was the motor decline in American Spinal Injury Association (ASIA) at hospital discharge, 6 weeks, 6 months, and 2 years. Demographics, blood loss, operative time, spinopelvic parameters, and spinal cord monitoring (SCM) events.

RESULTS

Sixty-eight consecutive patients were included in this study, with 34 patients in each Group. Group 1 (MOLIF) had a mean age 62.9 (45-81) and Group 2 (PSO) had a mean age of 66.76 years (47-79); 64.7% female versus PSO 76.5%; Body Mass Index (BMI) Group 1 (MOLIF) 28.05 and Group 2 (PSO) 27.17. Group 1 (MOLIF) perioperative neurological injury was 2.94% at discharge but resolved by 6 weeks. Group 2 (PSO) had five neurological deficits (14.7%) with no recovery by 2 years. There were four SCM events (SCM). In Group 1 (MOLIF), there was one event (2.94%) versus three events (8.88%) in Group 2 (PSO).

CONCLUSION

Staged MOLIF avoids passing neurological structures or retraction of psoas and lumbar plexus. It is safer than PSO in CASD with stiff or fused spines with a lower perioperative neurological injury profile. MOLIF have less SCM events, blood loss, and number of levels fused.

LEVEL OF EVIDENCE

3.

Treatment of Adult Spinal Deformity with Sagittal Imbalance Using Oblique Lumbar Interbody Fusion: Can We Predict How Much Lordosis Correction Is Possible?

Study Design

Prospective, single-center study.

Purpose

The current trend of operative treatment for adult spinal deformity (ASD) is combined anterior-posterior staged surgery. When anterior surgery was first performed, oblique lumbar interbody fusion (OLIF) was employed; this method became increasing popular. This study aimed to determine the lordosis correction that can be achieved using OLIF and assess whether we can preoperatively predict the lordosis correction angle achieved using OLIF.

Overview of Literature

Many previous studies on OLIF have shown improved clinical and radiologic outcomes. With the increase in the popularity of OLIF, several surgeons have started using larger cages to attain greater lordosis correction. Moreover, some studies have reported complications of OLIF because of immoderate cage insertion. To our knowledge, this is the first prospective study that attempted to determine whether it is possible to predict the lordosis correction angle achieved with OLIF preoperatively, using fullextension lateral view (FELV).

Methods

Forty-six patients with ASD were enrolled. All the operations were performed by a single surgeon in two stages (first, anterior and second, posterior) with a 1-week interval. Radiological evaluation was performed by comparing the Cobb’s angle of the segmental and regional lordosis obtained using preoperative and postoperative simple radiography (including the FELV) and magnetic resonance imaging (MRI).

Results

Regional lordosis (L1–S1) in the whole-spine standing lateral radiograph was −3.03°; however, in the supine lateral MRI, it was 20.92°. The regional lordosis of whole-spine standing lateral and supine lateral (MRI) was significantly different. In the FELV, regional lordosis was 25.72° and that in the postoperative supine lateral (MRI) was 25.02°; these values were not significantly different.

Conclusions

Although OLIF offers many advantages, it alone plays a limited role in ASD treatment. Lordosis correction using OLIF as well as lordosis determined in the FELV was possible. Hence, our results suggest that FELV can help predict the lordosis correction angle preoperatively and thus aid the selection of the appropriate technique in the second staged operation.

Technical Note: Pedicle Cement Augmentation with Proximal Screw Toggle and Loosening

Background

Cement augmentation is a technique used to increase the stability and purchase of pedicle screws in poor quality bone. Various methods can be applied for cement delivery, such as cement injection before screw placement and the use of fenestrated screws. However, potential problems can arise with the use of cement augmentation.

Case Presentation

A 66‐year‐old man with a lower trunk deformity, severe kyphosis, and sagittal imbalance following fusion (L_2‐5), with minimal comorbidities, was referred to our unit 9 months after surgery. Pain and progressive kyphosis were investigated clinically and radiographically with computed tomography (CT) scans to assess the status of the hardware and fusion. CT imaging revealed that cement was present only at the distal tip of the fenestrated screws at the L4 vertebral level. A non‐union was present along with loosening and a halo around the body of the pedicle screws, and there was evidence of pullout of inferior screws.

Conclusion

Single‐level cement augmentation of pedicle screw in a posterior construct and distal tip cement augmentation of the screw results in a fixed pivot point. Micromotion in cranio‐caudal loading during flexion and extension may result in screw toggling with the single‐level cement‐augmented tip as a fulcrum. This may cause screw loosening, which can lead to pullout and loss of construct stability. The halo around the screw suggests bone loss and/or a fibrous tissue interface, which further complicates revision surgery. Stress shielding and polymethylmethacrylate cement present additional difficulties.

The findings of this technical note question the risks and benefits of cement‐augmented fenestrated pedicle screw fixation for spinal fusion. Although incidences of such cases are uncommon, surgeons should perform this technique with caution. Accurate restoration of lumbar lordosis during index procedures is important to minimize the risk of construct failure.

Anterior Column Realignment (ACR) With and Without Pre-ACR Posterior Release for Fixed Sagittal Deformity

Background

Multiple studies have demonstrated a strong correlation between sagittal malalignment and health-related quality of life measures. Thus, correction of sagittal vertical axis (SVA), pelvic tilt (PT), lumbar lordosis-pelvic incidence (LL-PI), and T1 spinopelvic inclination (T1SPi) have become a primary objective of adult spinal deformity surgery. Anterior column realignment (ACR) has emerged as a less invasive technique and while the addition of posterior osteotomies has shown greater correction in ACR, it is unknown if a pre-ACR posterior release is necessary for optimal correction. The purpose of this study was to determine if pre-ACR posterior release allows for greater sagittal deformity correction.

Methods

Seventeen patients were identified that underwent minimum 1-level ACR. Ten patients underwent an anterior-posterior surgical sequence without a pre-ACR posterior release, and 7 underwent a posterior-anterior-posterior (PAP) sequence with a pre-ACR posterior release. Radiographic outcomes at final follow-up and complications were compared.

Results

Both groups saw significant improvements in LL, LL-PI, PT, SVA, and T1SPi but the correction was not significantly different between cohorts. With the exception of PT in the PAP group, the improvements in LL-PI, PT, and SVA correlated to improvement in Scoliosis Research Society-Schwab classification. The correction achieved at the ACR level, represented by motion segment angle, was greater in the PAP group by a degree that approached statistical significance. Five patients (29%) had 6 complications.

Conclusions

Both techniques achieved meaningful improvements in overall sagittal alignment. Our results suggest that a pre-ACR posterior release may allow for greater correction specifically at the ACR level but may not always be necessary to achieve clinically meaningful correction of sagittal plane deformity.

Level of Evidence

3.

Clinical Relevance

We present our experience with and without pre-ACR posterior release. To our knowledge, this is the first study to show that pre-ACR posterior release may achieve greater correction at the ACR level.

The comprehensive anatomical spinal osteotomy and anterior column realignment classification

OBJECTIVESpinal osteotomies and anterior column realignment (ACR) are procedures that allow preservation or restoration of spine lordosis. Variations of these techniques enable different degrees of segmental, regional, and global sagittal realignment. The authors propose a comprehensive anatomical classification system for ACR and its variants based on the level of technical complexity and invasiveness. This serves as a common language and platform to standardize clinical and radiographic outcomes for the utilization of ACR.METHODSThe proposed classification is based on 6 anatomical grades of ACR, including anterior longitudinal ligament (ALL) release, with varying degrees of posterior column release or osteotomies. Additionally, a surgical approach (anterior, lateral, or posterior) was added. Reliability of the classification was evaluated by an analysis of 16 clinical cases, rated twice by 14 different spine surgeons, and calculation of Fleiss kappa coefficients.RESULTSThe 6 grades of ACR are as follows: grade A, ALL release with hyperlordotic cage, intact posterior elements; grade 1 (ACR + Schwab grade 1), additional resection of the inferior facet and joint capsule; grade 2 (ACR + Schwab grade 2), additional resection of both superior and inferior facets, interspinous ligament, ligamentum flavum, lamina, and spinous process; grade 3 (ACR + Schwab grade 3), additional adjacent-level 3-column osteotomy including pedicle subtraction osteotomy; grade 4 (ACR + Schwab grade 4), 2-level distal 3-column osteotomy including pedicle subtraction osteotomy and disc space resection; and grade 5 (ACR + Schwab grade 5), complete or partial removal of a vertebral body and both adjacent discs with or without posterior element resection. Intraobserver and interobserver reliability were 97% and 98%, respectively, across the 14-reviewer cohort.CONCLUSIONSThe proposed anatomical realignment classification provides a consistent description of the various posterior and anterior column release/osteotomies. This reliability study confirmed that the classification is consistent and reproducible across a diverse group of spine surgeons.

Anterior Column Release/Realignment

Lateral anterior column release (ACR) is a powerful extension of the minimally invasive lateral lumbar interbody fusion procedure that incorporates division of the anterior longitudinal ligament to allow manipulation of the anterior and middle spinal columns. The resulting surgical control permits restoration of significant segmental lordosis that, when combined with varying posterior column releases, can achieve global sagittal realignment on par with traditional 3-column osteotomies. As a result, ACR is a factor in the growth of minimally invasive strategies for the correction of spinal deformities.

Patients with High Pelvic Tilt Achieve the Same Clinical Success as Those with Low Pelvic Tilt After Minimally Invasive Adult Deformity Surgery

BACKGROUND

Pelvic tilt (PT) is a compensatory mechanism for adult spinal deformity patients to mitigate sagittal imbalance. The association between preop PT and postop clinical and radiographic outcomes has not been well studied in patients undergoing minimally invasive adult deformity surgery.

OBJECTIVE

To evaluate clinical and radiographic outcomes in adult spinal deformity patients with high and low preoperative PT treated surgically using less invasive techniques.

METHODS

Retrospective case-control, institutional review board-approved study. A multicenter, minimally invasive surgery spinal deformity patient database was queried for 2-yr follow-up with complete radiographic and health-related quality of life (HRQOL) data. Hybrid surgery patients were excluded. Inclusion criteria were as follows: age > 18 and either coronal Cobb angle > 20, sagittal vertical axis > 5 cm, pelvic incidence-lumbar lordosis (PI-LL) > 10 or PT > 20. Patients were stratified by preop PT as per Schwab classification: low (PT< 20), mid (PT 20-30), or high (>30). Postoperative radiographic alignment parameters (PT, PI, LL, Cobb angle, sagittal vertical axis) and HRQOL data (Visual Analog Scale Back/Leg, Oswestry Disability Index) were evaluated and analyzed.

RESULTS

One hundred sixty-five patients had complete 2-yr outcomes data, and 64 patients met inclusion criteria (25 low, 21 mid, 18 high PT). High PT group had higher preop PI-LL mismatch (32.1 vs 4.7; P < .001). At last follow-up, 76.5% of patients in the high PT group had continued PI-LL mismatch compared to 34.8% in the low PT group (P < .006). There was a difference between groups in terms of postop changes of PT (-3.9 vs 1.9), LL (8.7 vs 0.5), and PI-LL (-9.5 vs 0.1). Postoperatively, HRQOL data (Oswestry Disability Index and Visual Analog Scale) were significantly improved in both groups (P < .001).

CONCLUSION

Adult deformity patients with high preoperative PT treated with minimally invasive surgical techniques had less radiographic success but equivalent clinical outcomes as patients with low PT.

Sexual activity after spine surgery: a systematic review

INTRODUCTION

Sexual function is an important determinant of quality of life, and factors such as surgical approach, performance of fusion, neurological function and residual pain can affect it after spine surgery. Our aim was to perform a systematic review to collate evidence regarding the impact of spine surgery on sexual function.

METHODS

A systematic review of studies reporting measures of sexual function, and incidence of adverse sexual outcomes (retrograde ejaculation) after major spine surgery was done, regardless of spinal location. Pubmed (MEDLINE) and Google Scholar databases were queried using the following search words "Sex", "Sex life", "Sexual function", "Sexual activity", "retrograde ejaculation", "Spine", "Spine surgery", "Lumbar surgery", "Lumbar fusion", "cervical spine", "cervical fusion", "Spinal deformity", "scoliosis" and "Decompression". All articles published between 1997 and 2017 were retrieved from the database. A total of 81 studies were included in the final review.

RESULTS

Majority of the studies were retrospective case series and were low quality (Level IV) in evidence. Anterior lumbar approaches were associated with a higher incidence of retrograde ejaculation, especially with the utilization of transperitoneal laparoscopic approach. There is inconclusive evidence on the preferred sexual position following fusion, and also on the impact of BMP-2 usage on retrograde ejaculation/sexual dysfunction.

CONCLUSION

Despite limited evidence from high-quality articles, there is a general trend towards improvement of sexual activity and function after spine surgery. Future studies incorporating specific assessments of sexual activity will be required to address this important determinant of quality of life so that appropriate pre-operative counselling can be done by providers. These slides can be retrieved under Electronic Supplementary Material.

Minimally Invasive Spinal Surgery for Adult Spinal Deformity

The purpose of this review is to present the current techniques and outcomes of adult spine deformity (ASD) surgery using the minimally invasive spine surgery (MISS) approach. We performed a systemic search of PubMed for literature published through January 2018 with the following terms: "minimally invasive spine surgery," "adult spinal deformity," and "degenerative scoliosis." Of the 138 items that were found through this search, 57 English-language articles were selected for full-text review. According to the severity of the deformity and the symptoms, various types of MISS have been utilized, such as MISS decompression, circumferential MISS, and hybrid surgery. With proper indications, the MISS approach achieved satisfactory clinical and radiological outcomes for ASD, with reduced complication rates. Future studies should aim to define clear indications for the application of various surgical options.

Understanding Retroperitoneal Anatomy for Lateral Approach Spine Surgery

Lateral approach spine surgery provides effective interbody stabilization, and correction and indirect neural decompression with minimal-incision and less invasive surgery compared with conventional open anterior lumbar fusion. It may also avoid the trauma to paraspinal muscles or facet joints found with transforaminal lumbar interbody fusion and posterior lumbar interbody fusion. However, because lateral approach surgery is fundamentally retroperitoneal approach surgery, it carries potential risk to intra- and retroperitoneal structures, as seen in a conventional open anterior approach. There is an innovative lateral approach technique that reveals different anatomical views; however, it requires reconsideration of the traditional surgical anatomy in more detail than a traditional open anterior approach. The retroperitoneum is the compartmentalized space bounded anteriorly by the posterior parietal peritoneum and posteriorly by the transversalis fascia. The retroperitoneum is divided into three compartments by fascial planes: anterior and posterior pararenal spaces and the perirenal space. Lateral approach surgery requires mobilization of the peritoneum and its content and accurate exposure to the posterior pararenal space. The posterior pararenal space is confined anteriorly by the posterior renal fascia, anteromedially by the lateroconal fascia, and posteriorly by the transversalis fascia. The posterior renal fascia, the lateroconal fascia or the peritoneum should be detached from the transversalis fascia and the psoas fascia to allow exposure to the posterior pararenal space. The posterior pararenal space, however, does not allow a clear view and identification of these fasciae as this relationship is variable and the medial extent of the posterior pararenal space varies among patients. Correct anatomical recognition of the retroperitoneum is essential to success in lateral approach surgery. Spine surgeons must be aware that the retroperitoneal membrane and fascia is multilayered and more complex than is commonly understood. Preoperative abdominal images would facilitate more efficient surgical considerations of retroperitoneal membrane and fascia in lateral approach surgery.

Preliminary results of anterior lumbar interbody fusion, anterior column realignment for the treatment of sagittal malalignment

OBJECTIVE

Sagittal malalignment decreases patients’ quality of life and may require surgical correction to achieve realignment goals. High-risk posterior-based osteotomy techniques are the current standard treatment for addressing sagittal malalignment. More recently, anterior lumbar interbody fusion, anterior column realignment (ALIF ACR) has been introduced as an alternative for correction of sagittal deformity. The objective of this paper was to report clinical and radiographic results for patients treated using the ALIF-ACR technique.

METHODS

A retrospective study of 39 patients treated with ALIF ACR was performed. Patient demographics, operative details, radiographic parameters, neurological assessments, outcome measures, and preoperative, postoperative, and mean 1-year follow-up complications were studied.

RESULTS

The patient population comprised 39 patients (27 females and 12 males) with a mean follow-up of 13.3 ± 4.7 months, mean age of 66.1 ± 11.6 years, and mean body mass index of 27.3 ± 6.2 kg/m2. The mean number of ALIF levels treated was 1.5 ± 0.5. Thirty-three (84.6%) of 39 patients underwent posterior spinal fixation and 33 (84.6%) of 39 underwent posterior column osteotomy, of which 20 (60.6%) of 33 procedures were performed at the level of the ALIF ACR. Pelvic tilt, sacral slope, and pelvic incidence were not statistically significantly different between the preoperative and postoperative periods and between the preoperative and 1-year follow-up periods (except for PT between the preoperative and 1-year follow-up, p = 0.018). Sagittal vertical axis, T-1 spinopelvic inclination, lumbar lordosis, pelvic incidence–lumbar lordosis mismatch, intradiscal angle, and motion segment angle all improved from the preoperative to postoperative period and the preoperative to 1-year follow-up (p < 0.05). The changes in motion segment angle and intradiscal angle achieved in the ALIF-ACR group without osteotomy compared with the ALIF-ACR group with osteotomy at the level of ACR were not statistically significant. Total visual analog score, Oswestry Disability Index, and Scoliosis Research Society–22 scores all improved from preoperative to postoperative and preoperative to 1-year follow-up. Fourteen patients (35.9%) experienced 26 complications (15 major and 11 minor). Eleven patients required reoperation. The most common complication was proximal junctional kyphosis (6/26 complications, 23%) followed by vertebral body/endplate fracture (3/26, 12%).

CONCLUSIONS

This study showed satisfactory radiographic and clinical outcomes at the 1-year follow-up. Proximal junctional kyphosis was the most common complication followed by fracture, complications that are commonly associated with sagittal realignment surgery and may not be mitigated by the anterior approach.

Overpowering posterior lumbar instrumentation and fusion with hyperlordotic anterior lumbar interbody cages followed by posterior revision: a preliminary feasibility study

OBJECTIVE The authors' aim in this study was to evaluate whether sagittal plane correction can be obtained from the front by overpowering previous posterior instrumentation and/or fusion with hyperlordotic anterior lumbar interbody fusion (ALIF) cages in patients undergoing revision surgery for degenerative spinal conditions and/or spinal deformities. METHODS The authors report their experience with the application of hyperlordotic cages at 36 lumbar levels for ALIFs in a series of 20 patients who underwent revision spinal surgery at a single institution. Included patients underwent staged front-back procedures: ALIFs with hyperlordotic cages (12°, 20°, and 30°) followed by removal of posterior instrumentation and reinstrumentation from the back. Patients were divided into the following 2 groups depending on the extent of posterior instrumentation and fusion during the second stage: long constructs (≥ 6 levels with extension into thoracic spine and/or pelvis) and short constructs (< 6 levels). Preoperative and postoperative standing radiographs were evaluated to measure segmental lordosis (SL) along with standard sagittal parameters. Radiographic signs of pseudarthrosis at previously fused levels were also sought in all patients. RESULTS The average patient age was 54 years (range 30-66 years). The mean follow-up was 11.5 months (range 5-26 months). The mean SL achieved with 12°, 20°, and 30° cages was 13.1°, 19°, and 22.4°, respectively. The increase in postoperative SL at the respective surgically treated levels for 12°, 20°, and 30° cages that were used to overpower posterior instrumentation/fusion averaged 6.1° (p < 0.05), 12.5° (p < 0.05), and 17.7° (p < 0.05), respectively. No statistically significant difference was found in SL correction at levels in patients who had pseudarthrosis (n = 18) versus those who did not (n = 18). The mean overall lumbar lordosis increased from 44.3° to 59.8° (p < 0.05). In the long-construct group, the mean improvement in sagittal vertical axis was 85.5 mm (range 19-249.3 mm, p < 0.05). Endplate impaction/collapse was noted in 3 of 36 levels (8.3%). The anterior complication rate was 13.3%. No neurological complications or vascular injuries were observed. CONCLUSIONS ALIF in which hyperlordotic cages are used to overpower posterior spinal instrumentation and fusion can be expected to produce an increase in SL of a magnitude that is roughly half of the in-built cage lordotic angle. This technique may be particularly suited for lordosis correction from the front at lumbar levels that have pseudarthrosis from the previous posterior spinal fusion. Meticulous selection of levels for ALIF is crucial for safely and effectively performing this technique.

Biomechanical study of rod stress after pedicle subtraction osteotomy versus anterior column reconstruction: A finite element study

BACKGROUND

In an effort to minimize rod fractures and nonunion in pedicle subtraction osteotomy (PSO) constructs, surgeons have adopted multirod constructs and interbody cages. Anterior column realignment (ACR) with posterior column osteotomies is a minimally invasive alternative to PSO in sagittal balance correction, however, there is a paucity of evidence with respect to rod survival.

METHODS

Three-dimensional (3D) finite-element-model of a T12-sacrum spine segment was used to compare a 25° PSO at L3 and an ACR with a posterior column osteotomy and 30° hyperlordotic interbody cage at L3-4. The amount of overall T12-S1 lordosis correction was the same for each condition. Each simulation included cobalt chromium alloy primary rods with: (1) PSO; (2) PSO with an interbody cage (IB) at L2-3 (PSO+IB); (3) PSO with accessory (A) rods and IB at L2-3 (PSO+IB+A); (4) PSO with satellite (S) rods and IB at L2-3 (PSO+IB+2S); (5) ACR; 6) ACR with satellite rods (ACR + 2S). A 400 N follower preload was simulated for each condition.

RESULTS

PSO condition had the largest rod stress of 286 MPa in flexion. Adding interbody support reduced the rod stress by 15%. The 4-rod constructs further reduced rod stress, with the satellite rod condition facilitating the largest reduction. The rod stress in the ACR+2S was equivalent to the PSO+2S, with 50% reduction in rod stress.

CONCLUSION

The rod stress with an ACR was comparable to a PSO coupled with interbody support. These results suggest an ACR is a viable MIS alternative to a PSO without the need for a large posterior osteotomy.

Management of Spinal Conditions in Patients With Parkinson Disease

Parkinson disease (PD) is increasingly prevalent in the aging population. Spine disorders in patients with PD may be degenerative in nature or may arise secondary to motor effects related to the parkinsonian disease process. Physicians providing care for patients with PD and spine pathologies must be aware of several factors that affect treatment, including the patterns of spinal deformity, complex drug interactions, and PD-associated osteoporosis. Following spine surgery, complication rates are higher in patients with PD than in those without the disease. Literature on spine surgery in this patient population is limited by small cohort size, the heterogeneous patient population, and variable treatment protocols. However, most studies emphasize the need for preoperative optimization of motor control with appropriate medications and deep brain stimulation, as well as consultation with a movement disorder specialist. Future studies must control for confounding variables, such as the type of surgery and PD severity, to improve understanding of spinal pathology and treatment options in this patient population.

Correction of severe spinopelvic mismatch: decreased blood loss with lateral hyperlordotic interbody grafts as compared with pedicle subtraction osteotomy

OBJECTIVE

Pedicle subtraction osteotomy (PSO) provides extensive correction in patients with fixed sagittal plane imbalance but is associated with high estimated blood loss (EBL). Anterior column realignment (ACR) with lateral graft placement and sectioning of the anterior longitudinal ligament allows restoration of lumbar lordosis (LL). The authors compare peri- and postoperative measures in 2 groups of patients undergoing correction of a sagittal plane imbalance, either through PSO or the use of lateral lumbar fusion and ACR with hyperlordotic (20°–30°) interbody cages, with stabilization through standard posterior instrumentation in all cases.

METHODS

The authors performed a retrospective chart review of cases involving a lumbar PSO or lateral lumbar interbody fusion and ACR (LLIF-ACR) between 2010 and 2015 at the authors’ institution. Patients who had a PSO in the setting of a preexisting fusion that spanned more than 4 levels were excluded. Demographic characteristics, spinopelvic parameters, EBL, operative time, and LOS were analyzed and compared between patients treated with PSO and those treated with LLIF-ACR.

RESULTS

The PSO group included 14 patients and the LLIF-ACR group included 13 patients. The mean follow-up was 13 months in the LLIF-ACR group and 26 months in the PSO group. The mean EBL was significantly lower in the LLIF-ACR group, measuring approximately 50% of the mean EBL in the PSO group (1466 vs 2910 ml, p < 0.01). Total LL correction was equivalent between the 2 groups (35° in the PSO group, 31° in the LLIF-ACR group, p > 0.05), as was the preoperative PI-LL mismatch (33° in each group, p > 0.05) and the postoperative PI-LL mismatch (< 1° in each group, p = 0.05). The fusion rate as assessed by the need for reoperation due to pseudarthrosis was lower in the LLIF-ACR group but not significantly so (3 revisions in the PSO group due to pseudarthrosis vs 0 in the LLIF-ACR group, p > 0.5). The total operative time and LOS were not significantly different in the 2 groups.

CONCLUSIONS

This is the first direct comparison of the LLIF-ACR technique with the PSO in adult spinal deformity correction. The study demonstrates that the LLIF-ACR provides equivalent deformity correction with significantly reduced blood loss in patients with a previously unfused spine compared with the PSO. This technique provides a powerful means to avoid PSO in selected patients who require spinal deformity correction.

The Top 50 Articles on Minimally Invasive Spine Surgery

STUDY DESIGN

Bibliometric study of current literature.

OBJECTIVE

To catalog the most important minimally invasive spine (MIS) surgery articles using the amount of citations as a marker of relevance.

SUMMARY OF BACKGROUND DATA

MIS surgery is a relatively new tool used by spinal surgeons. There is a dynamic and evolving field of research related to MIS techniques, clinical outcomes, and basic science research. To date, there is no comprehensive review of the most cited articles related to MIS surgery.

METHODS

A systematic search was performed over three widely used literature databases: Web of Science, Scopus, and Google Scholar. There were four searches performed using the terms "minimally invasive spine surgery," "endoscopic spine surgery," "percutaneous spinal surgery," and "lateral interbody surgery." The amount of citations included was averaged amongst the three databases to rank each article. The query of the three databases was performed in November 2015.

RESULTS

Fifty articles were selected based upon the amount of citations each averaged amongst the three databases. The most cited article was titled "Extreme Lateral Interbody Fusion (XLIF): a novel surgical technique for anterior lumbar interbody fusion" by Ozgur et al and was credited with 447, 239, and 279 citations in Google Scholar, Web of Science, and Scopus, respectively. Citations ranged from 27 to 239 for Web of Science, 60 to 279 for Scopus, and 104 to 462 for Google Scholar. There was a large variety of articles written spanning over 14 different topics with the majority dealing with clinical outcomes related to MIS surgery.

CONCLUSION

The majority of the most cited articles were level III and level IV studies. This is likely due to the relatively recent nature of technological advances in the field. Furthermore level I and level II studies are required in MIS surgery in the years ahead.

LEVEL OF EVIDENCE

5.

Lateral lumbar retroperitoneal transpsoas approach in the setting of spondylodiscitis: A technical note

Thoracolumbar spondylodiscitis is a morbid disease entity, impacting a sick patient population with multiple comorbidities. Wherever possible, surgical measures in this population should limit the extent of soft tissue disruption and overall morbidity that is often associated with anteroposterior thoracolumbar decompression and fusion. The authors describe the rationale, technique, and use of the lateral lumbar transpsoas retroperitoneal approach in tandem with posterior decompression and instrumented fusion in the treatment of circumferential thoracolumbar spondylodiscitis with or without epidural abscesses. The authors have routinely implemented the lateral lumbar transpsoas retroperitoneal approaches to address all pyogenic vertebral abscesses, spondylodiscitis, and ventral epidural abscesses with anterior column debridement and reconstruction with iliac crest autograft, posterior decompression, and pedicle screw instrumentation. In five consecutive patients, the mean blood loss and operative duration was 275mL and 259min, respectively. There were no instances of major vascular injury as this corridor obviates the need for retraction of inflamed retroperitoneal structures. The use of the lumbar lateral retroperitoneal transpsoas approach to the lumbar spine for the treatment of destructive and pyogenic spondylodiscitis is a potential alternative to the traditional anterior lumbar retroperitoneal approach in tandem with posterior spinal decompression and instrumented stabilization.

Long fusion correction of degenerative adult spinal deformity and the selection of the upper or lower thoracic region as the site of proximal instrumentation: a systematic review and meta-analysis

OBJECTIVE

The aim of this study was to compare outcomes when the upper and lower thoracic regions were used as the site of proximal instrumentation to treat adult spinal deformity.

METHODS

MEDLINE, Embase and Cochrane library searches were performed to identify studies that compared outcome measures when the upper and lower thoracic vertebrae (UTV and LTV, respectively) were used as the site of proximal instrumentation. The weighted mean difference (WMD) was calculated for continuous outcomes, and the relative risk (RR) was calculated for dichotomous outcomes.

RESULTS

Seven articles (n=554 patients) met the final inclusion criteria, and we compared the outcome measures of a long fusion extending to the upper and lower thoracic regions. The pooled analysis revealed that extending fixation into the upper thoracic region decreased the risk of proximal junctional kyphosis (PJK) revision surgery (RR: 0.36, 95% CI 0.14 to 0.90, p<0.05). The operation time (WMD: 0.93, 95% CI 0.48 to 1.39, p<0.05) and estimated blood loss (WMD: 0.59, 95% CI 0.33 to 0.85, p<0.05) were significantly greater in the UTV group than in the LTV group. No significant differences were found in the Scoliosis Research Society pain, self-image, function, mental health, subtotal, satisfaction or total scores; the total number of complications or the total number of revision surgeries.

CONCLUSIONS

Long posterior fixation extending into the upper thoracic region reduces the incidence of revision surgery related to PJK; however, it increased the operative level resulting in a longer operative time and greater estimated blood loss. This initial analysis indicates that extending fixation to the upper thoracic region is appropriate for patients who are likely to develop PJK following initial scoliosis correction.

The Oblique Anterolateral Approach to the Lumbar Spine Provides Access to the Lumbar Spine With Few Early Complications

BACKGROUND

During the last 20 years several less-invasive anterior approaches to the lumbar spine have become standard, including the extreme lateral transpsoas approach. Although it is associated with a lower risk of vascular injury compared with anterior midline approaches, neuromonitoring is considered mandatory to avoid neurologic complications. Interestingly, despite neuromonitoring, the reported risk of neurologic deficits with the extreme lateral transpsoas approach is greater than observed with other anterior approaches. An alternative lateral, oblique, psoas-sparing approach, recently named the oblique lumbar interbody fusion, uses the anatomic pathway between the abdominal vessels anteriorly and the lumbar plexus laterally to decrease the risk of neurologic and vascular injury; however, as yet, little on this new approach has been reported.

QUESTIONS/PURPOSES

We asked: what proportion of patients experienced (1) perioperative complications (overall complications), (2) vascular complications, and (3) neurologic complications after less-invasive anterior lumbar interbody fusion through the oblique lumbar interbody approach at one high-volume center?

METHODS

We performed a chart review of intra- and perioperative complications of all patients who had undergone minimally invasive anterior lumbar interbody fusion through a lateral psoas-sparing approach from L1 to L5 during a 12-year period (1998-2010). During the study period, the oblique, psoas-sparing approach was the preferred approach of the participating surgeons in this study, and it was performed in 812 patients, all of whom are studied here, and all of whom have complete data for assessment of the short-term (inpatient-only) complications that we studied. In general, we performed this approach whenever possible, although it generally was avoided when a patient previously had undergone an open retro- or transperitoneal abdominal procedure, or previous implantation of hernia mesh in the abdomen. During the study period, posterior fusion techniques were used in an additional 573 patients instead of the oblique lumbar interbody fusion when we needed to decompress the spinal canal beyond what is possible through the anterior approach. In case of spinal stenosis calling for fusion in combination with a high disc space, severe endplate irregularity, or severe biomechanical instability, we combined posterior decompression with oblique lumbar interbody fusion in 367 patients. Complications were evaluated by an independent observer who was not involved in the decision-making process, the operative procedure, nor the postoperative care by reviewing the inpatient records and operative notes.

RESULTS

A total of 3.7% (30/812) of patients who underwent the oblique lumbar interbody fusion experienced a complication intraoperatively or during the hospital stay. During the early postoperative period there were two superficial (0.24%) and three deep (0.37%) wound infections and five superficial (0.62%) and six deep (0.86%) hematomas. There were no abdominal injuries or urologic injuries. The percentage of vascular complications was 0.37% (n = 3). The percentage of neurologic complications was 0.37% (n = 3).

CONCLUSIONS

The risk of vascular complications after oblique lumbar interbody fusion seems to be lower compared with reported risk for anterior midline approaches, and the risk of neurologic complications after oblique lumbar interbody fusion seems to be lower than what has been reported with the extreme lateral transpsoas approach; however, we caution readers that head-to-head studies will need to be performed to confirm our very preliminary comparisons and results with the oblique psoas-sparing approach. Similarly, future studies will need to evaluate this approach in terms of later-presenting complications, such as infection and pseudarthrosis formation, which could not be assessed using this inpatient-only approach. Nevertheless, with the results of this study the oblique psoas-sparing approach can be described as a less-invasive alternative for anterior lumbar fusion surgery from L1 to L5 with a low risk of vascular and neurologic damage and without costly intraoperative neuromonitoring tools.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Appropriate Use of Limited Interventions vs Extensive Surgery in the Elderly Patient With Spinal Disorders

Surgical management of spinal deformity is elderly patients is characterized by significant variability. In a value-based health care economy, minimization of risks and maximization of benefit and durability of surgery are a priority. The choice of a surgical approach is a significant determinant of risk, cost, and outcome. Informed choice regarding a surgical approach requires participation of the patient and surgeon. Limited interventions may be appropriate for patients with radicular symptoms and focal pain. More extensive surgery may be required for patients with global imbalance of the spine. The role of minimally invasive approaches in limiting complications and improving outcome remains in evolution. An optimal choice of surgical approach requires consideration of patient preferences, values, comorbidities, and goals of care.