Management of sagittal balance in adult spinal deformity with minimally invasive anterolateral lumbar interbody fusion: a preliminary radiographic study

Effects of Minimally Invasive Lateral Lumbar Interbody Fusion with Accessory Rod Technique on Rod Fracture in Adult Spinal Deformity Surgery: Analysis of 239 Patients

STUDY DESIGN

A retrospective study.

OBJECTIVES

To analyze factors associated with rod fracture (RF) in adult spinal deformity (ASD), and to assess whether the accessory rod (AR) technique can reduce RF occurrence in deformity correction in the setting of minimally invasive lateral lumbar interbody fusion (LLIF).

SUMMARY OF BACKGROUND DATA

Instrumentation failure is the most common reason for revision surgery in ASD. Several RF reduction methods have been introduced. However, there are insufficient studies on postoperative RF after deformity correction using minimally invasive LLIF.

MATERIALS AND METHODS

This study included 239 patients (average age 71.4 y and a minimum 2-year follow-up) with ASD who underwent long-segment fusion from T10 to sacrum with sacropelvic fixation. Patients were classified into the non-RF group and the RF group. After logistic regression analysis of the risk factors for RF, subgroup analyses were performed: pedicle subtraction osteotomy (PSO) with two-rod (P2 group) versus PSO with two-rod and AR (P4 group), and LLIF with two-rod (L2 group) versus LLIF with two-rod and AR (L4 group).

RESULTS

RF occurred in 50 patients (21%) at an average of 25 months. RF occurred more frequently in patients who underwent PSO than in those who underwent LLIF ( P =0.002), and the use of the AR technique was significantly higher in the non-RF group ( P <0.05).Following logistic regression analysis, preoperative PI-LL mismatch, PSO, and the AR technique were associated with RF. In subgroup analyses, RF incidence was 65% (24/37 cases) of the P2 group, 8% (4/51 cases) of the P4 group, and 21% (22/105 cases) of the L2 group. In the L4 group, there was no RF.

CONCLUSION

Minimally invasive multilevel LLIF with the AR technique is capable of as much LL correction as conventional PSO and appears to be an effective method for reducing RF.

Lumbar pedicle subtraction osteotomy: techniques and outcomes

Pedicle subtraction osteotomy has been thoroughly described and studied over the past 2 decades, being applied mainly in the lumbar spine, followed by the thoracic spine. Our better understanding of alignment biomechanics, and the progressive refinements of the surgical technique over time made it a very efficient procedure for the management of fixed sagittal malalignment. However, a long learning curve is mandatory to mitigate the associated risks particularly neurological deficits and achieve satisfactory clinical and radiological outcomes with an acceptable rate of complications.

Assessing the Fractional Curve for Proper Management of Adult Degenerative Scoliosis

Adult degenerative scoliosis (ADS) is a coronal plane deformity often accompanied by sagittal plane malalignment. Surgical correction may involve the major and/or distally-located fractional curves (FCs). Correction of the FC has been increasingly recognized as key to ameliorating radicular pain localized to the FC levels. The present study aims to summarize the literature on the rationale for FC correction in ADS. Three databases were systematically reviewed to identify all primary studies reporting the rationale for correcting the FC in ADS. Articles were included if they were English full-text studies with primary data from ADS ( ≥ 18 years old) patients. Seventy-four articles were identified, of which 12 were included after full-text review. Findings suggest FC correction with long-segment fusion terminating at L5 increases the risk of distal junctional degeneration as compared to constructs instrumenting the sacrum. Additionally, circumferential fusion offers greater FC correction, lower reoperation risk, and shorter construct length. Minimally invasive surgery (MIS) techniques may offer effective radiographic correction and improve leg pain associated with foraminal stenosis on the FC concavity, though experiences are limited. Open surgery may be necessary to achieve adequate correction of severe, highly rigid deformities. Current data support major curve correction in ASD where the FC concavity and truncal shift are concordant, suggesting that the FC contributes to the patient's overall deformity. Circumferential fusion and the use of kickstand rods can improve correction and enhance the stability and durability of long constructs. Last, MIS techniques show promise for milder deformities but require further investigation.

Predicting adequate segmental lordosis correction in lumbar spinal stenosis patients undergoing oblique lumbar interbody fusion: a focus on the discontinuous segment

PURPOSE

To identify the factors associated with a correction of the segmental angle (SA) with a total change greater than 10° in each level following minimally invasive oblique lumbar interbody fusion (MIS-OLIF).

METHODS

Patients with lumbar spinal stenosis who underwent single- or two-level MIS-OLIF were reviewed. Segments with adequate correction of the SA >10° after MIS-OLIF in immediate postoperative radiograph were categorized as discontinuous segments (D segments), whereas those without such improvement were assigned as continuous segments (C segments). Clinical and radiological parameters were compared, and multivariate logistic regression analysis was performed to identify factors associated with SA correction >10° after MIS-OLIF.

RESULTS

Of 211 segments included, 38 segments (18.0%) were classified as D segments. Compared with C segments, D segments demonstrated a significantly smaller preoperative SA (mean ± standard deviation [SD], - 1.1° ± 6.7° vs. 6.6° ± 6.3°, p < 0.001), larger change of SA (mean ± SD, 13.5° ± 3.4° vs. 3.1° ± 3.9°, p < 0.001), and a higher rate of presence of facet effusion (76.3% vs. 48.6%, p = 0.002). Logistic regression revealed preoperative SA (odds ratio (OR) [95% confidence interval (CI)]:0.733 [0.639-0.840], p < 0.001) and facet effusion (OR [95% CI]:14.054 [1.758-112.377], p = 0.027) as significant predictors for >10° SA correction after MIS-OLIF.

CONCLUSION

Preoperative kyphotic SA and facet effusion can predict SA correction >10° following MIS-OLIF. For patients with lordotic SA and no preoperative facet effusion, supplemental procedures, such as anterior column release or posterior osteotomy, should be prepared for additional lumbar lordosis correction required for remnant global sagittal imbalance after MIS-OLIF.

Anterior lumbar interbody fusion versus transforaminal lumbar interbody fusion for correction of lumbosacral fractional curves in adult (thoraco)lumbar scoliosis: A systematic review

Background

Anterior lumbar interbody fusion (ALIF) or transforaminal lumbar interbody fusion (TLIF) may be used to correct the lumbosacral fractional curve (LsFC) in de novo adult (thoraco) lumbar scoliosis. Yet, the relative benefits of ALIF and TLIF for LsFC correction remain largely undetermined.

Purpose

To compare the currently available data comparing radiographic correction of the LsFC provided by ALIF and TLIF of LsFC in adult (thoraco)lumbar scoliosis.

Methods

A systematic review was performed on original articles discussing fractional curve correction of lumbosacral spinal deformity (using search criteria: "lumbar" and "fractional curve"). Articles which discussed TLIF or ALIF for LsFC correction were presented and radiographic results for TLIF and ALIF were compared.

Results

Thirty-one articles were returned in the original search criteria, with 7 articles included in the systematic review criteria. All 7 articles presented radiographic results using TLIF for LsFC correction. Three of these articles also discussed results for patients whose LsFC were treated with ALIFs; 2 articles directly compared TLIF and ALIF for LsFC correction. Level III and level IV evidence indicated ALIF as advantageous for reducing the coronal Cobb angle of the LsFC. There were mixed results on relative efficacy of ALIF and TLIF in the LsFC for restoration of adequate global coronal alignment.

Conclusions

Limited level III and IV evidence suggests ALIF as advantageous for reducing the coronal Cobb angle of the LsFC in de novo adult (thoraco) lumbar scoliosis. Relative efficacy of ALIF and TLIF in the LsFC for restoration of global coronal alignment may be dictated by several factors, including directionality and magnitude of preoperative coronal deformity. Given the limited and low-quality evidence, additional research is warranted to determine the ideal interbody support strategies to address the LsFC in adult (thoraco) lumbar scoliosis.

Anterior Column Realignment Through Open Pre-posterior Release-Anterior-Posterior Fusion Versus Hybrid Minimally Invasive-Anterior-Posterior Fusion for Dynamic Sagittal Imbalance of the Spine

STUDY DESIGN

Retrospective comparative study.

OBJECTIVES

To investigate the clinical and radiological outcomes after anterior column realignment (ACR) through pre-posterior release-anterior-posterior surgery (PAP) and minimally invasive surgery -lateral lumbar interbody fusion (MIS-LLIF) using hybrid anterior-posterior surgery (AP).

METHODS

A total of 91 patients who underwent ACR with long fusions from T10 vertebra to the sacropelvis with a follow-up period of at least 2 years after corrective surgery for adult spinal deformity were included and divided into two groups by surgical method: AP and PAP. AP was performed in 26 and PAP in 65 patients. Clinical outcomes and radiological parameters were investigated and compared. A further comparison was conducted after propensity score matching between the groups.

RESULTS

The more increase of LL and decrease of PI-LL mismatch were observed in the PAP group than in the AP group postoperatively. After propensity score matching, total operation time and intraoperative bleeding were greater, and intensive care unit care and rod fracture were more frequent in the PAP group than in the AP group with statistical significance. Reoperation rate was higher in PAP (29.2%) than in AP (16.7%) without statistical significance.

CONCLUSIONS

PAP provides a more powerful correction for severe sagittal malalignment than AP procedures. AP results in less intraoperative bleeding, operation time, and postoperative complications. Therefore, this study does not suggest that one treatment is superior to the other.

LEVEL OF EVIDENCE

III.

Does the Global Alignment and Proportion score predict mechanical complications in circumferential minimally invasive surgery for adult spinal deformity?

OBJECTIVE

The Global Alignment and Proportion (GAP) score was developed to serve as a tool to predict mechanical complication probability in patients undergoing surgery for adult spinal deformity (ASD), serving as an aid for setting surgical goals to decrease the prevalence of mechanical complications in ASD surgery. However, it was developed using ASD patients for whom open surgical techniques were used for correction. Therefore, the purpose of this study was to assess the applicability of the score for patients undergoing circumferential minimally invasive surgery (cMIS) for correction of ASD.

METHODS

Study participants were patients undergoing cMIS ASD surgery without the use of osteotomies with a minimum of four levels fused and 2 years of follow-up. Postoperative GAP scores were calculated for all patients, and the association with mechanical failure was analyzed.

RESULTS

The authors identified 182 patients who underwent cMIS correction of ASD. Mechanical complications were found in 11.1% of patients with proportioned spinopelvic states, 20.5% of patients with moderately disproportioned spinopelvic states, and 18.8% of patients with severely disproportioned spinopelvic states. Analysis with a chi-square test showed a significant difference between the cMIS and original GAP study cohorts in the moderately disproportioned and severely disproportioned spinopelvic states, but not in the proportioned spinopelvic states.

CONCLUSIONS

For patients stratified into proportioned, moderately disproportioned, and severely disproportioned spinopelvic states, the GAP score predicted 6%, 47%, and 95% mechanical complication rates, respectively. The mechanical complication rate in patients undergoing cMIS ASD correction did not correlate with the calculated GAP spinopelvic state.

A Modified Anterior Column Realignment With Partial Anterior Longitudinal Ligament Release in Oblique Lateral Interbody Fusion

STUDY DESIGN

Retrospective radiological analysis.

OBJECTIVE

To demonstrate the radiological outcome after a modified anterior column realignment (mACR) with partial anterior longitudinal ligament (ALL) release in oblique lateral interbody fusion (OLIF).

SUMMARY OF BACKGROUND DATA

Anterior column realignment (ACR) remains a powerful sagittal correction technique in minimally invasive adult spinal deformity surgery and is often combined with posterior column osteotomy (PCO) to achieve more lordosis. OLIF is ideal for ACR because the anterior-to-psoas corridor typically involves the anterolateral half of the disk.

METHODS

This study included 112 operated disk levels of 101 consecutive patients who underwent OLIF between L2-L3 and L4-L5 using a 12° lateral cage. The mACR was performed at 73 (65.2%) levels with 30% to 50% sectioning of the ALL. Each operated level was grouped according to the mACR and additional PCO as: (1) no mACR, OLIF only (n=39); (2) mACR with no PCO (n=18); (3) mACR with grade 1 PCO (n=27); (4) mACR with grade 2 PCO (n=22); or (5) mACR with grade 3 PCO (n=6).

RESULTS

At the last follow-up, the mean disk lordotic angles were 10.9±2.9°, 12.6±3.0°, 13.3±3.9°, 16.7±3.2°, and 16.8±2.4° in the no mACR, mACR with no PCO, mACR with grade 1 PCO, mACR with grade 2 PCO, and mACR with grade 3 PCO groups, respectively ( P <0.001). The mean increases in disk lordotic angle were 5.8±4.1°, 12.1±6.1°, 13.5±8.7°, 15.8±6.7°, and 17.9±6.2° in each group, respectively ( P <0.001).

CONCLUSIONS

ACR can be performed with partial ALL release under direct vision in OLIF without deep dissection into the ventral disk space. The mACR in OLIF is a simple, safe, and effective technique for anterior column lengthening.

LEVEL OF EVIDENCE

4.

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.

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 Prone Transpsoas and Standard Lateral Lumbar Interbody Fusion Surgery for Degenerative Lumbar Spine Disease: A Retrospective Radiographic Propensity Score-Matched Analysis

BACKGROUND

Prone transpsoas lateral lumbar interbody fusion (PTP-LLIF) is a recently introduced modification to standard LLIF. To date, no study has compared the radiographic outcomes of standard LLIF and PTP-LLIF. We performed a radiographic parameter-based propensity score-matched analysis to compare postoperative clinical and radiographic outcomes between PTP-LLIF and standard LLIF for degenerative lumbar spine disease.

METHODS

A total of 30 consecutive patients met the inclusion criteria. The preoperative standing scoliosis radiographs were retrospectively reviewed for global and segmental sagittal alignment. Propensity score matching was calculated using the baseline radiographic parameters. One-to-one matching of patients who had undergone PTP-LLIF with those who had a similar propensity score but had undergone standard LLIF was performed to compare the radiographic (primary) and clinical (secondary) outcomes.

RESULTS

Propensity score matching resulted in 10 pairs of PTP-LLIF and standard LLIF patients. The PTP-LLIF group had had significantly better improvement in lumbar lordosis (P = 0.047). The difference in the improvement in pelvic incidence minus lumbar lordosis mismatch approached statistical significance for the PTP-LLIF group (P = 0.05). This led to better improvement in the short-form 12-item physical score (P = 0.03) and Oswestry disability index (P = 0.1) in the PTP-LLIF group. No significant differences were found between the 2 groups in the other clinical and radiographic outcomes. The PTP-LLIF group had a shorter operative time (P = 0.4) and hospital stay (P = 0.1), without a statistically difference, and shorter radiation exposure time (P = 0.5). The standard LLIF group had experienced less intraoperative bleeding, without a statistically significant difference (P = 0.3). The mean follow-up time was 10.2 ± 5.2 months in the PTP-LLIF group and 30.9 ± 17.2 months in the standard LLIF group (P < 0.05).

CONCLUSIONS

The PTP-LLIF group showed significantly better improvement in lumbar lordosis and short-form 12-item physical score.

Predictors of indirect neural decompression in minimally invasive transpsoas lateral lumbar interbody fusion

OBJECTIVE

An advantage of lateral lumbar interbody fusion (LLIF) surgery is the indirect decompression of the neural elements that occurs because of the resulting disc height restoration, spinal realignment, and ligamentotaxis. The degree to which indirect decompression occurs varies; no method exists for effectively predicting which patients will respond. In this study, the authors identify preoperative predictive factors of indirect decompression of the central canal.

METHODS

The authors performed a retrospective evaluation of prospectively collected consecutive patients at a single institution who were treated with LLIF without direct decompression. Preoperative and postoperative MRI was used to grade central canal stenosis, and 3D volumetric reconstructions were used to measure changes in the central canal area (CCA). Multivariate regression was used to identify predictive variables correlated with radiographic increases in the CCA and clinically successful improvement in visual analog scale (VAS) leg pain scores.

RESULTS

One hundred seven levels were treated in 73 patients (mean age 68 years). The CCA increased 54% from a mean of 0.96 cm2 to a mean of 1.49 cm2 (p < 0.001). Increases in anterior disc height (74%), posterior disc height (81%), right (25%) and left (22%) foraminal heights, and right (12%) and left (15%) foraminal widths, and reduction of spondylolisthesis (67%) (all p < 0.001) were noted. Multivariate evaluation of predictive variables identified that preoperative spondylolisthesis (p < 0.001), reduced posterior disc height (p = 0.004), and lower body mass index (p = 0.042) were independently associated with radiographic increase in the CCA. Thirty-two patients were treated at a single level and had moderate or severe central stenosis preoperatively. Significant improvements in Oswestry Disability Index and VAS back and leg pain scores were seen in these patients (all p < 0.05). Twenty-five (78%) patients achieved the minimum clinically important difference in VAS leg pain scores, with only 2 (6%) patients requiring direct decompression postoperatively due to persistent symptoms and stenosis. Only increased anterior disc height was predictive of clinical failure to achieve the minimum clinically important difference.

CONCLUSIONS

LLIF successfully achieves indirect decompression of the CCA, even in patients with substantial central stenosis. Low body mass index, preoperative spondylolisthesis, and disc height collapse appear to be most predictive of successful indirect decompression. Patients with preserved disc height but severe preoperative stenosis are at higher risk of failure to improve clinically.

Optimized Surgical Strategy for Adult Spinal Deformity: Quantitative Lordosis Correction versus Lordosis Morphology

BACKGROUND

In surgical correction of adult spinal deformity (ASD), pelvic incidence (PI)-lumbar lordosis (LL) plays a key role to restore normal sagittal alignment. Recently, it has been found that postoperative lordosis morphology act as an important factor in preventing mechanical complications. However, there have been no studies on the effect of postoperative lordosis morphology on the restoration of sagittal alignment. The primary objective of this study was to evaluate the effect of postoperative lordosis morphology on achievement of optimal sagittal alignment. The secondary objective was to find out which radiographic or morphologic parameter affects sagittal alignment in surgical correction of ASD.

METHODS

228 consecutive patients with lumbar degenerative kyphosis who underwent deformity correction and long-segment fixation from T10 to S1 with sacropelvic fixation and follow-up over 2 years were enrolled. Patients were divided according to whether optimal alignment was achieved (balanced group) or not (non-balanced group) at last follow-up. We analyzed the differences of postoperative radiographic parameters and morphologic parameters between two groups. Correlation analysis and stepwise multiple linear regression analysis was performed to predict the effect of PI-LL and morphologic parameters on the sagittal vertical axis (SVA).

RESULTS

Of 228 patients, 195 (85.5%) achieved optimal alignment at last follow-up. Two groups significantly differed in postoperative and last follow-up LL (p < 0.001 and p = 0.028, respectively) and postoperative and last follow-up PI-LL (p < 0.001 and p = 0.001, respectively). Morphologic parameters did not significantly differ between the two groups except lower lordosis arc angle (=postoperative sacral slope). In correlation analysis and stepwise multiple linear regression analysis, postoperative PI-LL was the only parameter which had significant association with last follow-up SVA (R² = 0.134, p < 0.001). Morphologic parameters did not have any association with last follow-up SVA.

CONCLUSIONS

When planning spine reconstruction surgery, although considering postoperative lordosis morphology is necessary, it is still very important considering proportional lordosis correction based on individual spinopelvic alignment (PI-LL) to achieve optimal sagittal alignment.

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.

Spino-Pelvic Thresholds for Prevention of Proximal Junctional Kyphosis Following Combined Anterior Column Realignment and Short Posterior Spinal Fusion in Degenerative Lumbar Kyphosis

Objective

To analyze ideal indication for combined anterior column realignment (ACR) with short posterior spinal fusion (PSF) and posterior column osteotomy (PCO) for preventing proximal junctional kyphosis (PJK) in adult spinal deformity (ASD) patients with lower lumbar kyphosis and compensatory thoracolumbar lordosis.

Methods

A retrospective study was conducted. This study included 27 ASD patients (average age of 66.6 years; one male and 26 females) with lower lumbar kyphosis and compensated thoracolumbar lordosis who underwent short PSF with PCO following ACR from 2006 to 2010. The minimum follow‐up period was 5 years. The patients were divided into two groups based on the sagittal vertical axis (SVA) of the last follow‐up radiographs, and a comparative analysis was performed evaluating spino‐pelvic parameters and clinical outcomes including the Oswestry Disability Index (ODI), Visual Analog Scale (VAS), and complications.

Results

The mean follow‐up time of included patients was 109.7 months, and the mean number of fused segments was 3.7. The uppermost instrumented vertebra was L₂ in 18 patients or L₃ in nine patients, and lowermost instrumented vertebra was sacrum in all patients. The mean lumbar lordosis (LL) values in the optimal SVA and suboptimal SVA groups were 4.4° and 4.2° preoperatively (P = 0.639), −48.1° and −35° postoperatively (P = 0.007), and −45.2° and −20.7° at the last follow‐up (P < 0.05). Overcorrection was seen in seven patients in the optimal SVA group, whereas all of the patients of the suboptimal SVA group were in the category of undercorrection (P = 0.021). Pelvic incidence (PI) of optimal SVA group (<50 mm, n = 16) and suboptimal SVA group (≥50 mm, n = 11) was 44.1° and 53.8° (P = 0.009). The prevalence of PJK was significantly higher in the suboptimal SVA group (P = 0.008), and last follow‐up VAS for back pain (P < 0.05), and postoperative and last follow‐up ODI (P = 0.002 and P < 0.05) were statistically larger for the suboptimal group than the optimal group.

Conclusions

Combined ACR with short PSF and PCO could effectively prevent sagittal decompensation of PJK and help achieve sagittal balance in the treatment of ASD patients with lower lumbar kyphosis, compensatory thoracolumbar lordosis, and especially low PI (<50°).

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.

Individual Lordotic Cages Implantation and Radiographic Evaluation of Segmental and Lumbar Lordosis Correction for Patients with Adult Degenerative Scoliosis

Relevance. The development of minimally invasive surgery has led to the development of new methods for surgical treatment of the spine. Conventional surgical technique, such as vertebrotomy is accompanied by a several number of disadvantages (high blood loss, prolonged hospital stay, long intraoperative time, postoperative neurological deficit). An alternative to improve sagittal balance in the spine is to use custom-made hyperlordotic cages, which can also be used for indirect decompression of neural structures.

The objective is to compare the degree of segmental and total lumbar lordosis using hyperlordotic cages through ALIF and TLIF with posterior instrumentation.

Materials and Methods. A single-center retrospective cohort study using 96 patients treated from 2018 to 2019 about degenerative spinal deformities. Comparison of two groups: group 1 (A) consisted of 30 patients who were held anterior spinal fusion with individual lordotic cages from minimally invasive anterior approach (MISS ALIF) without posterior fixation. Group 2 (B) consisted of 33 patients whom were performed spinal fusion from the posterior approach (TLIF) with Smith-Peterson Osteotomy (SPO) and transpedicular fixation. Measuring segmental and lumbar lordosis, teleradiographs were used in a standing position. For an accurate assessment, the non-commercial available Surgimap software, © Nemaris, was used.

Results. Segmental lordosis were superior to preoperative ones. In the intergroup comparison, the ALIF group showed an excellent increase in the enlarged lordosis segment (L3-L4 in 8 degrees; p = 0.0005, L4-L5 in 7 degrees; p = 0.0002, L5-S1 in 7 degrees; p = 0.0001). When conducting an intergroup comparison of total lumbar lordosis in the preoperative period, there was a statistically significant difference between them (p = 0.0043). At the same time, a greater degree of correction of lordosis is shown in ALIF compared to TLIF group (29,1 in comparison with 22,5; p = 0.00005).

Conclusion. The results of this study confirm that the using of custom-made lordotic cages can significantly increase segmental and total lumbar lordosis for patients with degenerative scoliosis in adults.

Minimally invasive multilevel lateral lumbar interbody fusion with posterior column osteotomy compared with pedicle subtraction osteotomy for adult spinal deformity

BACKGROUND CONTEXT

Pedicle subtraction osteotomy (PSO) is highly effective as a sagittal correction approach in patients with adult spinal deformity, but relevant issues such as surgical complexity and long-term complications limit its applicability. Recently, minimally invasive techniques have been reported to be useful for surgical treatment of adult spinal deformity; however, few reports have directly compared these techniques with PSO.

PURPOSE

The purpose of this study was to evaluate the radiological and clinical efficacies of oblique lateral interbody fusion (OLIF) with posterior column osteotomy (PCO) using stiff rods (6.35-mm cobalt chrome [CoCr]).

STUDY DESIGN

Retrospective comparative study.

PATIENT SAMPLE

One-hundred six patients (average age 71.3 years) diagnosed with adult spinal deformity presenting with sagittal imbalance for whom follow-up of over 2 years after sagittal correction (between 2013 and 2017) was available.

OUTCOME MEASURES

Description and analysis of X-ray, computed tomography scans, operative time, estimated blood loss, and clinical outcomes (Oswestry Disability Index [ODI] and Visual Analog Scale [VAS]).

METHODS

A comparative analysis was performed evaluating spinopelvic parameters and clinical outcomes including the ODI, VAS, and complications in patients who underwent PSO (PSO group; n=65) or multilevel prepsoas OLIF combined with PCO and open posterior spinal fusion using 6.35-mm CoCr rods (OLIF group; n=41). The authors have no conflicts of interest to disclose.

RESULTS

There were no differences in preoperative spinopelvic parameters between the PSO and OLIF groups. Although no differences were observed between the two groups in terms of postoperative SVA (-12.66 mm vs. -16.44 mm), postoperative lumbar lordosis (-71.46° vs. -72.55°), lumbar lordosis correction (77.96° vs. 73.54°), or postoperative pelvic tilt (9.35° vs. 7.17°), the estimated blood loss was significantly lower in the OLIF group (2824 mL vs. 1736 mL, p<.05). No differences were observed in clinical outcomes (ODI, VAS, and clinical complications), proximal junctional kyphosis, and spinopelvic parameters between the two groups 2 years after surgery. However, pseudarthrosis during the follow-up period, including rod fracture, occurred less frequently in the OLIF group compared with that in the PSO group (p<.05). OLIF was performed from the T12-L1 to L5-S1 regions (124 segments), with an average of three segments per patient. The computed tomography scans immediately after surgery showed an average segmental correction of -18° and 12.9% (16 segments) of 124 segments showed a correction angle of >30°.

CONCLUSIONS

Multilevel OLIF with PCO using a stiff rod to treat severe sagittal imbalance resulted in similar levels of sagittal balance and lordosis correction as obtained by PSO. Multilevel OLIF with PCO using a stiff rod can be an effective alternative to PSO for patients with severe sagittal imbalance.

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.

The MISDEF2 algorithm: an updated algorithm for patient selection in minimally invasive deformity surgery

OBJECTIVE

Minimally invasive surgery (MIS) can be used as an alternative or adjunct to traditional open techniques for the treatment of patients with adult spinal deformity. Recent advances in MIS techniques, including advanced anterior approaches, have increased the range of candidates for MIS deformity surgery. The minimally invasive spinal deformity surgery (MISDEF2) algorithm was created to provide an updated framework for decision-making when considering MIS techniques in correction of adult spinal deformity.

METHODS

A modified algorithm was developed that incorporates a patient's preoperative radiographic parameters and leads to one of 4 general plans ranging from basic to advanced MIS techniques to open deformity surgery with osteotomies. The authors surveyed 14 fellowship-trained spine surgeons experienced with spinal deformity surgery to validate the algorithm using a set of 24 cases to establish interobserver reliability. They then re-surveyed the same surgeons 2 months later with the same cases presented in a different sequence to establish intraobserver reliability. Responses were collected and analyzed. Correlation values were determined using SPSS software.

RESULTS

Over a 3-month period, 14 fellowship-trained deformity surgeons completed the surveys. Responses for MISDEF2 algorithm case review demonstrated an interobserver kappa of 0.85 for the first round of surveys and an interobserver kappa of 0.82 for the second round of surveys, consistent with substantial agreement. In at least 7 cases, there was perfect agreement between the reviewing surgeons. The mean intraobserver kappa for the 2 surveys was 0.8.

CONCLUSIONS

The MISDEF2 algorithm was found to have substantial inter- and intraobserver agreement. The MISDEF2 algorithm incorporates recent advances in MIS surgery. The use of the MISDEF2 algorithm provides reliable guidance for surgeons who are considering either an MIS or an open approach for the treatment of patients with adult spinal deformity.

Analysis of the Relationship Between Modic Change and Spinopelvic Parameters in the Sagittal Plane

Background

This study explored relationship between Modic change and spinopelvic parameters in the sagittal plane.

Material/Methods

We divided 80 patients into 4 groups: 60 subjects diagnosed with Modic changes (MC) were enrolled in the MC groups (MC1, MC2, and MC3) with each MC type consisting of 20 subjects, and 60 healthy subjects were enrolled in the control group. Spinopelvic parameters in the sagittal plane were calculated to assess their associations with MC. Multivariate logistic regression was used to explore possible risk factors for MC.

Results

PI and LL in the MC groups were significant smaller than in the control group (p<0.05). PI, SS, and PT were significantly correlated with LL with a correlation coefficient of 0.75_PI, 0.71_SS and 0.69_PT (p<0.05). Multivariate logistic regression of the significant variables showed that PI (less than 43.2°) is an independent significant risk factor for MC. ROC analysis showed that moderate diagnostic value was obtained for the significant variable, with an area under the curve (AUC) of 0.80 (p>0.05).

Conclusions

We concluded that PI is risk factor for MC, and smaller PI is associated with higher incidence of MC.

MIS lateral ACR for spinal deformity correction: technique and complication avoidance

Deformity correction using minimally invasive surgical (MIS) techniques can be challenging. Here the authors present a case in which an anterior column resection was performed using an MIS lateral approach to restore lumbar lordosis and improve sagittal balance. The authors demonstrate the technique and discuss potential complications and how they may be avoided.

The video can be found here: https://youtu.be/XjOdDeKrKEE.

Minimally Invasive Lateral Lumbar Interbody Fusion for Clinical Adjacent Segment Pathology: A Comparative Study With Conventional Posterior Lumbar Interbody Fusion

STUDY DESIGN

This was a retrospective comparative study.

OBJECTIVE

The main objective of this article was to evaluate the clinical and radiologic efficacies of minimally invasive lateral lumbar interbody fusion (LLIF) for clinical adjacent segment pathology (ASP).

SUMMARY OF BACKGROUND DATA

Minimally invasive techniques have been increasingly applied for spinal surgery. No report has compared LLIF with conventional posterior lumbar interbody fusion for clinical ASP.

METHODS

Forty patients undergoing LLIF with posterior fusion (hybrid surgery) were compared with 40 patients undergoing conventional posterior lumbar interbody fusion (posterior surgery). The radiologic outcomes including indirect decompression in hybrid surgery group, and clinical outcomes such as the Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) were assessed. Postoperative major complications and reoperations were also compared between the 2 groups.

RESULTS

Correction of coronal Cobb's angle and segmental lordosis in the hybrid surgery were significantly greater postoperatively (2.8 vs. 0.9 degrees, P=0.012; 7.4 vs. 2.5 degrees, P=0.009) and at the last follow-up (2.4 vs. 0.5 degrees, P=0.026; 4.8 vs. 0.8 degrees, P=0.016) compared with posterior surgery. As regards indirect decompression of the LLIF, significant increases in thecal sac (83.4 vs. 113.8 mm) and foraminal height (17.8 vs. 20.9 mm) were noted on postoperative magnetic resonance imaging. Although postoperative back VAS (4.1 vs. 5.6, P=0.011) and ODI (48.9% vs. 59.6%, P=0.007) were significantly better in hybrid surgery, clinical outcomes at the last follow-up were similar. Moreover, intraoperative endplate fractures developed in 17.7% and lower leg symptoms occurred in 30.0% of patients undergoing hybrid surgery.

CONCLUSIONS

Hybrid surgery for clinical ASP has advantages of segmental coronal and sagittal correction, and indirect decompression compared with conventional posterior surgery. However, LLIF-related complications such as endplate fracture and lower leg symptoms also developed. LLIF should be performed considering advantages and approach-related complications for the clinical ASP.

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.

Biomechanical evaluation of four surgical scenarios of lumbar fusion with hyperlordotic interbody cage: A finite element study

BACKGROUND

Lumbar spinal fusion in the interbody space is augmented with interbody fusion cages to provide structural support while arthrodesis occurs. Subsidence is a serious complication of interbody fusion. However, the biomechanical influence of anterior longitudinal ligament (ALL) and pedicle screws on subsidence has not been fully understood.

OBJECTIVE

To investigate biomechanical effects of the hyperlordotic cages in different surgical conditions using finite element analysis.

METHODS

Four surgical finite element (FE) models were constructed by inserting 15 degree lordosis cage at the L3-L4 disc space. The four surgical conditions were ALL intact (M1), ALL resected (M2), ALL intact and bilateral pedicle screws (M3), and ALL resected and bilateral pedicle screws (M4). Follow loads were applied at the L2 vertebral body while the inferior surface of L5 was fixed. FEA was implemented to simulate the four motion modes and biomechanical properties of four fusion scenarios with hyperlordotic interbody cage were compared.

RESULTS

The range of motion (ROM) and facet joint force (FJF) at L3-L4 decreased significantly after fusion during all the motion modes. The cage stress and endplate stress at L3-L4 increased significantly after fusion during all the motion modes. The cage stress and endplate stress at L3-L4 for M3 and M4 were smaller than that for M1 and M2 during all the motion modes. The FJF at L3-L4 for M3 and M4 were smaller than that for M1 and M2 during extension, bending, and rotation.

CONCLUSIONS

ALL has little effect on the biomechanics after lumbar fusion with hyperlordotic interbody cage. The bilateral pedicle screws significantly decreased the stress in cage, stress in endplate at L3-L4, and lowered facet contact force except for flexion mode. The implication is that the supplemental bilateral pedicle screws are recommended whether or not the ALL is resected.

Anterior lumbar interbody fusions combined with posterior column osteotomy in patients who had sagittal imbalance associated with degenerative lumbar flat-back deformity: a retrospective case series

Anterior lumbar interbody fusion (ALIF) combined with posterior column osteotomy (PCO) may be effective to achieve ideal lumbar curve correction in lumbar flat-back deformity (LFD). We aimed to investigate the radiographic and clinical outcomes of patients with primary degenerative LFD treated with multi-level ALIFs combined with PCOs. Seventy patients with primary degenerative LFD who underwent corrective surgery were divided into three groups according to the 1-month postoperative pelvic incidence/lumbar lordosis (PI-LL) angles (≤ - 10°, from - 9° to 9°, and ≥ 10°). The spinopelvic parameters, including thoracic kyphosis, LL, pelvic tilt, T1 pelvic angle, and sagittal vertical axis, were analyzed at the preoperative, postoperative follow-up periods. The clinical outcomes, including the Oswestry disability index (ODI), visual analog scale (VAS), and Scoliosis Research Society (SRS)-22r, were also evaluated. Further, the paraspinal muscles were qualitatively and quantitatively examined, preoperatively. All spinopelvic parameters were corrected as close to the normal values at the 1-month postoperative period. The spinopelvic parameters in the PI-LL ≤ - 10° group were better corrected and maintained than those in the other groups. The ODI, VAS, and SRS-22r scores improved at the final follow-up in all groups. The PI-LL ≤ - 10° group showed better clinical outcomes than the other groups. In the paraspinal muscle examination, the mean lumbar muscularity value and fatty degeneration ratio were 236.7% and 20.7%, respectively. Multi-level ALIFs with PCOs in patients with LFD are effective in restoring sagittal balance and improving clinical symptoms. In addition, the postoperative LL angles should be larger than PI + 10° to achieve good overall outcomes in patients with severe degenerative back muscle.

Retrospective Multicenter Assessment of Rod Fracture After Anterior Column Realignment in Minimally Invasive Adult Spinal Deformity Correction

BACKGROUND

Anterior column realignment (ACR) was developed as a minimally invasive method for treating sagittal imbalance. However, rod fracture (RF) rates associated with ACR are not known. Our objective was to assess the rate of and risk factors for RF following ACR in deformity correction surgery.

METHODS

We conducted a retrospective multicenter review of patients with adult spinal deformity (ASD) who underwent ACR for deformity correction. ASD was defined as coronal Cobb angle ≥20°, pelvic incidence-lumbar lordosis >10°, sagittal vertical axis ≥5 cm, pelvic tilt ≥25°, or thoracic kyphosis ≥60°. Inclusion criteria were ASD, age >18 years, use of ACR, and development of RF or full radiographs obtained at least 1 year after surgery that did not demonstrate RF.

RESULTS

Ninety patients were identified, with mean follow-up of 2.3 ± 1.4 years (age, 64.1 ± 9.4; 54 [60%] women). The most common ACR location was L3/4 (42 cases; 47%). Mean fusion length was 7.5 ± 3.6 levels. Four (4.4%) of 90 patients developed RF within 12 months of surgery. RF occurred adjacent to ACR in all cases; RF was not associated with focal correction (P = 0.49), rod material (P = 0.8), degree of correction (P > 0.07), or interbody at L5/S1 (P = 0.06). RF was associated with longer fusion constructs in univariate (P = 0.002) and multivariate (P = 0.03) analyses.

CONCLUSIONS

RF occurred in 4.4% of patients with ASD who underwent ACR with a minimum of 1-year follow-up. RF was not associated with focal correction but appears to be associated with global correction and extent of fixation.

Precautions for Combined Anterior and Posterior Long-Level Fusion for Adult Spinal Deformity: Perioperative Surgical Complications Related to the Anterior Procedure (Oblique Lumbar Interbody Fusion)

Study Design

Retrospective, single-center study.

Purpose

We aimed to determine the perioperative complications of oblique lumbar interbody fusion (OLIF) as a first-stage procedure in combined anterior and posterior operation for adult spinal deformity (ASD) along with sagittal imbalance. Specifically, we aimed to identify the radiological and clinical types of perioperative surgical complications and the factors affecting these complications.

Overview of Literature

OLIF has recently gained popularity, and there are several reports of good outcomes and only a few of complications with OLIF; however, a few studies have focused on the perioperative surgical complications of ASD along with sagittal imbalance.

Methods

The perioperative period was a 1-week interval between the anterior and posterior procedures. All patients underwent simple radiography and magnetic resonance imaging preoperatively and postoperatively. Cage placement was evaluated for displacement (i.e., subsidence and migration) and vertebral body fracture. Clinical patient complaints were evaluated perioperatively. Student t-test was used for data analysis.

Results

A total of 46 patients were included, totaling 138 fusion segments. A week after OLIF, 14 patients/33 segments (30.4%/23.9%) demonstrated endplate injury-associated cage placement change. Subsidence was the most common cage placement-related complication. As compared with patients without endplate injury, those with endplate injuries showed significantly larger correction angles and a higher proportion of them had larger height cages than the disk height in the full-extension lateral view. Although 32.6% of the patients experienced perioperative clinical complications, they were relatively minor and transient. The most common complication was severe postoperative pain (Visual Analog Scale score of >7), and hip flexor weakness spontaneously resolved within 1 week.

Conclusions

OLIF yielded more than expected endplate injuries from treatment modalities for ASD along with sagittal imbalance. Therefore, surgeons should be cautious about endplate injury during OLIF procedures. It is difficult to accomplish lordosis correction via OLIF alone; therefore, surgeons should not attempt this impractical correction goal and insert an immoderate cage.

How Does Cage Lordosis Influence Postoperative Segmental Lordosis in Lumbar Interbody Fusion

BACKGROUND

Consideration of sagittal alignment is an integral part of spinal fusion surgery correlating with superior outcomes. Segmental lordosis is an important contributor to sagittal alignment. This study assessed surgical factors influencing segmental lordosis in a 360° fusion model, including cage dimensions, anterior longitudinal ligament resection, facetectomy, and posterior compression.

METHODS

Six L3-4 synthetic spinal motion segments were used in a repeated measures design. Each sample was sequentially instrumented with lateral cages of increasing height and angle. Lordosis was assessed from lateral radiographs of intact and each instrumented condition. The effect of anterior longitudinal ligament resection, posterior compression with pedicle screws, and bilateral facetectomy was additionally examined.

RESULTS

A linear relationship between segmental lordosis and cage height was found. This effect was greater with the anterior longitudinal ligament divided. In cages of the same anterior height, increased intrinsic cage lordosis did not result in increased segmental lordosis; cages with no intrinsic lordosis resulted in the highest segmental lordosis. In examining this finding, it was shown that posterior cage height had a larger influence on segmental lordosis. Posterior compression with pedicle screws and bilateral facetectomy increased the segmental lordosis by a further 3.4° and 2.6°, respectively.

CONCLUSIONS

Cage height was a key factor, with posterior compression further increasing lordosis. The finding that 0° cages results in the most segmental lordosis was an unexpected finding and highlights the importance of appropriate sizing on resulting lordosis. These findings are relevant to cage selection but require further study prior to applying to clinical practice and may influence future cage design.

Radiographic and Clinical Outcomes following Combined Oblique Lumbar Interbody Fusion and Lateral Instrumentation for the Treatment of Degenerative Spine Deformity: A Preliminary Retrospective Study

Objective

The authors recently used a combination of minimally invasive oblique lumbar interbody fusion (OLIF) and lateral fixation for the treatment of degenerative spine deformity. The early results were promising. Radiographic and clinical results as well as complications were retrospectively assessed in the current study.

Methods

Eleven patients with degenerative spine deformity underwent combined OLIF and lateral instrumentation without real-time electromyography (EMG) monitoring. Radiographic measurements including coronal Cobb angle, central sacral vertebral line (CSVL), lumbar lordosis (LL), sagittal vertebral axis (SVA), pelvic tilt (PT), and LL-PI (pelvic incidence) mismatch were taken preoperatively and at last follow-up postoperatively in all patients. Concurrently, the visual analog score (VAS) for back pain and the Oswestry Disability Index (ODI) score were used to assess clinical outcomes. The fusion rate of OLIF cage, total blood loss, operation time, hospital stay, and complications were also evaluated.

Results

At last follow-up, all patients who underwent combined OLIF and lateral instrumentation achieved statistically significant improvement in coronal Cobb angle (from 15.3±4.7° to 5.9±3.1°, p < 0.01), LL (from 34.3±9.0° to 48.2±8.5°, p < 0.01), PT (from 24.2±9.6° to 16.2±6.0°, p < 0.01), LL-PI mismatch (from 15.4±8.7° to 7.0±3.7°, p < 0.01), CSVL (from 2.1±2.2cm to 0.7±0.9cm, p = 0.01), and SVA (from 7.0±3.9cm to 2.9±1.8cm, p < 0.01). VAS for back pain (from 6.9±1.4 to 2.0±0.9, p < 0.05) and ODI (from 39.5±3.1 to 21.9±3.6, p < 0.01) improved significantly after surgery.

Conclusions

A combination of OLIF and lateral instrumentation is an effective and safety means of achieving correction of both coronal and sagittal deformity, resulting in improvement of quality of life in patients with degenerative spine deformity. It is a promising way to treat patients with moderate degenerative spine deformity.

The Radiologic and Clinical Outcomes of Oblique Lateral Interbody Fusion for Correction of Adult Degenerative Lumbar Deformity

BACKGROUND

Osteotomies aimed at correcting adult spinal deformity are associated with higher complications and perioperative morbidity. Recently, oblique lumbar interbody fusion (OLIF) was introduced for degenerative lumbar diseases. The aim of our study is to demonstrate the effectiveness of OLIF on the management of adult degenerative lumbar deformity (ADLD).

MATERIALS AND METHODS

Patients with ADLD who underwent deformity correction and decompression using OLIF and posterior instrumentation were enrolled. For radiologic evaluation, Cobb's angle (CA), sagittal vertical axis (SVA), lumbar lordosis (LL), thoracic kyphosis (TK), pelvic tilt (PT), sacral slope (SS), and pelvic incidence (PI) were evaluated. Visual analog scale (VAS), Oswestry disability index (ODI), and perioperative parameters were recorded for clinical evaluation.

RESULTS

Fifteen patients with a mean age of 67 years (63-74 years) were enrolled prospectively and an average of 3 OLIFs (range 1-4) was performed. Posterior instrumentations were done at average of six levels (range 4-8). The mean operative blood loss was 863 ml (range 500-1400 ml) with a mean surgical duration of 7 h (range 3-11 h). SVA, TK, LL, CA, PT, and SS showed significant correction (P < 0.05) in immediate postoperative period and all parameters except TK were maintained at final followup. At the end of 24 months of average followup, 86% (13/15) showed fusion. VAS (leg pain), VAS (back pain), and ODI improved by 74% (range 40-100), 58% (range 20%-80%), and 69.5% (range 4%-90%), respectively. There were two major complications requiring revision (1 infection and 1 adjacent vertebral body fracture). Transient hip weakness present in two patients (13%) recovered within 6 weeks.

CONCLUSIONS

OLIF gives favorable short term clinical and radiological outcomes in patients of ADLD. It could potentially reduce the need for morbid pelvic fixation and posterior osteotomies in patients with degenerative lumbar deformity.

Efficacy of Oblique Lateral Interbody Fusion in Treatment of Degenerative Lumbar Disease

OBJECTIVE

This study aimed to analyze the efficacy of oblique lumbar interbody fusion (OLIF) in the treatment of degenerative lumbar disease.

METHODS

Twenty-two patients with degenerative lumbar disease who underwent OLIF between October 2016 and January 2017 were included. Radiography, computed tomography, and magnetic resonance imaging were performed preoperatively and postoperatively. The cross-sectional area (CSA) of the dural sac, disk height, cross-sectional height of the intervertebral foramina, and intervertebral foramina CSA were measured. Scores from the visual analog scale, Oswestry Disability Index, and Medical Outcome Study 36-Item Short-Form Health Survey, obtained preoperatively, 1 week and 3 months postoperatively, and at the final follow-up, were compared.

RESULTS

Forty-five segments were fused in 22 patients using OLIF. Postoperatively, CSA increased from 0.79 ± 0.32 cm2 to 1.40 ± 0.37 cm2, disk height increased from 0.67 ± 0.24 cm to 1.15 ± 0.31 cm, cross-sectional height increased from 1.51 ± 0.25 cm to 2.01 ± 0.31 cm, and intervertebral foramina increased from 1.11 ± 0.28 cm2 to 1.86 ± 0.38 cm2 (P <0.01). The visual analog scale, Oswestry Disability Index, and 36-Item Short-Form Health Survey scores of all patients significantly improved postoperatively (P < 0.05). There were no complications involving injuries to spinal nerves, great vessels, abdominal viscera, or ureters. Only 1 patient experienced injury to the psoas major.

CONCLUSIONS

OLIF is a safe and effective minimally invasive procedure for the treatment of degenerative lumbar disease.

Does approach matter? A comparative radiographic analysis of spinopelvic parameters in single-level lumbar fusion

BACKGROUND CONTEXT

Lumbar fusion is a popular and effective surgical option to provide stability and restore anatomy. Particular attention has recently been focused on sagittal alignment and radiographic spinopelvic parameters that apply to lumbar fusion as well as spinal deformity cases. Current literature has demonstrated the effectiveness of various techniques of lumbar fusion; however, comparative data of these techniques are limited.

PURPOSE

This study aimed to directly compare the impact of various lumbar fusion techniques (anterior lumbar interbody fusion [ALIF], lateral lumbar interbody fusion [LLIF], transforaminal lumbar interbody fusion [TLIF], and posterolateral fusion [PLF]) based on radiographic parameters.

STUDY DESIGN/SETTING

A single-center retrospective study examining preoperative and postoperative radiographs was carried out.

PATIENT SAMPLE

A consecutive list of lumbar fusion surgeries performed by multiple spine surgeons at a single institution from 2013 to 2016 was identified.

OUTCOME MEASURES

Radiographic measurements used included segmental lordosis (SL), lumbar lordosis (LL), pelvic incidence (PI), pelvic incidence-lumbar lordosis (PI-LL) mismatch, anterior and posterior disc height (DH-A, DH-P, respectively), and foraminal height (FH).

METHODS

Radiographic measurements were performed on preoperative and postoperative lateral lumbar radiographs on all single-level lumbar fusion cases. Demographic data were collected including age, gender, approach, diagnosis, surgical level, and implant lordosis. Paired sample t test, one-way analysis of variance (ANOVA), McNemar test, and independent sample t test were used to establish significant differences in the outcome measures. Multiple linear regression was performed to determine a predictive model for lordosis from implant lordosis, fusion technique, and surgical level.

RESULTS

There were 164 patients (78 men, 86 women) with a mean age of 60.1 years and average radiographic follow-up time of 9.3 months. These included 34 ALIF, 23 LLIF, 63 TLIF, and 44 PLF surgeries. ALIF and LLIF significantly improved SL (7.9° and 4.4°), LL (5.5° and 7.7°), DH-A (8.8 mm and 5.8 mm), DH-P (3.4 mm and 2.3 mm), and FH (2.8 mm and 2.5 mm), respectively (p≤.003). TLIF significantly improved these parameters, albeit to a lesser extent: SL (1.7°), LL (2.7°), DH-A (1.1 mm), DH-P (0.8 mm), and FH (1.1 mm) (p≤.02). PLF did not significantly alter any of these parameters while significantly reducing FH (-1.3 mm, p=.01). One-way ANOVA showed no significant differences between ALIF and LLIF other than ALIF with greater ΔDH-A (3.0 mm, p=.02). Both ALIF and LLIF significantly outperformed PLF in preoperative to postoperative changes in all parameters p≤.001. Additionally, ALIF significantly outperformed TLIF in the change in SL (6.2°, p<.001), and LLIF significantly outperformed TLIF in the change in LL (5.0°, p=.02). Both outperformed TLIF in ΔDH-A (7.7 mm and 4.7 mm) and ΔDH-P (2.6 mm and 1.5 mm), respectively (p≤.02). ALIF was the only fusion technique that significantly improved the proportion of patients with a PI-LL<10° (0.410.66, p=.02). Lordotic cages had superior improvement of all parameters compared with non-lordotic cages (p<.001). Implant lordosis (m=1.1), fusion technique (m=6.8), and surgical level (m=6.9) significantly predicted postoperative SL (p<.001, R²=0.56).

CONCLUSIONS

This study demonstrated that these four lumbar fusion techniques yield divergent radiographic results. ALIF and LLIF produced greater improvements in radiographic measurements postoperatively compared with TLIF and PLF. ALIF was the most successful in improving PI-LL mismatch, an important parameter relating to sagittal alignment. Lordotic implants provided better sagittal correction and surgeons should be cognizant of the impact that these differing implants and techniques produce after surgery. Surgical technique is an important determinant of postoperative alignment and has ramifications upon sagittal alignment in lumbar fusion surgery.

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.

Trends in Nonoperative Treatment Modalities Prior to Cervical Surgery and Impact on Patient-Derived Outcomes: Two-Year Analysis of 1522 Patients From the Prospective Spine Treatment Outcome Study

Background

Effects of nonoperative treatments on surgical outcomes for patients who failed conservative management for cervical spine pathologies remain unknown. The objective is to describe conservative modality use in patients indicated for surgery for degenerative cervical spine conditions and its impact on perioperative outcomes.

Methods

The current study comprises a retrospective review of a prospective multicenter database. A total of 1522 patients with 1- to 2-level degenerative cervical pathology who were undergoing surgical intervention were included. Outcome measures used were health-related quality-of-life scores, length of hospitalization, estimated blood loss, length of surgery, and return-to-work status at 2 weeks, 6 months, 1 year, and 2 years postoperatively. Patients were grouped by diagnosis (radiculopathy vs. myelopathy), then divided based on epidural injection(s), physical therapy (PT), or opioid use prior to enrollment. Univariate t-tests and χ² tests were performed to determine differences between groups and impact on outcomes.

Results

Among 1319 radiculopathy patients, 25.7% received preoperative epidural injections, 35.3% received PT, and 35.5% received opioids. Radiculopathy patients who received epidurals and PT had higher 1-year postoperative return-to-work rates (P < .05). Radiculopathy patients without preoperative PT had longer hospitalization times, whereas those who received PT had higher 36-Item Short Form Health Survey (SF-36) physical functioning and physical component scores, lower 2-year visual analog scale (VAS) neck/arm pain scores, and higher 2-year return-to-work incidence (P < .05). Of myelopathy patients (n = 203), 14.8% received epidural injections, 25.1% received opioids, and 41.5% received PT. Myelopathy patients with preoperative PT had worse VAS arm pain scores 2 years postoperatively (P < .05). Patients receiving opioids were younger and had greater baseline-2-year Neck Disability Index improvement (P < .05).

Conclusions

Radiculopathy patients receiving epidurals returned to work after 1 year more frequently. PT was associated with shorter hospitalizations, greater SF-36 bodily pain norm and physical component score improvements, and increased return-to-work rates after 1 and 2 years. No statistically significant nonoperative treatment was associated with return-to-work rate in myelopathy patients.

Clinical Relevance

These findings suggest certain preoperative conservative treatment modalities are associated with improved outcomes in radiculopathy patients.

Lumbar Lordosis Correction With Interbody Hyperlordotic Cages: Initial Experience, Learning Curve, Technical Aspects, and Complication Incidence

Background

Analysis of the initial experience on learning curve, technical differences and perioperative or early postoperative complications using lumbar hyperlordotic anterior and lateral interbody cages for the correction of lumbar lordosis as compared with the usage of regular lordotic cages.

Methods

Initial 21 consecutive patients were treated with 13 hyperlordotic anterior lumbar interbody fusion (ALIF) cages and 8 hyperlordotic extreme lateral interbody fusion (XLIF) cages. The mean patient age was 64 years, and the mean lumbar hypolordosis was 23°.

Results

No significant procedure-related technical differences were found between the hyperlordotic and nonhyperlordotic ALIF cages. Slightly significant procedure-related technical differences were found between hyperlordotic and nonhyperlordotic XLIF cages. The complication type and occurrence were comparable.

Conclusions

Sagittal balance correction of lumbar lordosis using hyperlordotic ALIF and XLIF cages is a relatively safe surgical procedure with a short learning curve for those surgeons already familiar with anterior and lateral retroperitoneal procedures.

Minimally Invasive Lateral Lumbar Interbody Fusion for Adult Spinal Deformity: Clinical and Radiological Efficacy With Minimum Two Years Follow-up

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

To evaluate the clinical and radiological efficacies of supplementing minimally invasive lateral lumbar interbody fusion (LLIF) with open posterior spinal fusion (PSF) in adult spinal deformity (ASD).

SUMMARY OF BACKGROUND DATA

Minimally invasive techniques have been increasingly applied for surgery of ASD. Few reports have been published that directly compare LLIF combined with PSF to conventional PSF for ASD.

METHODS

To evaluate the advantages of minimally invasive LLIF for ASD, patients who underwent minimally invasive LLIF followed by open PSF (combined group) were compared with patients who only underwent PSF (only PSF group). The clinical and radiological outcomes for deformity correction and indirect decompression were assessed. The occurrence of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) were also evaluated.

RESULTS

No significant differences were observed in the clinical outcomes of the Oswestry Disability Index (ODI), visual analog scale, and major complications including reoperations between the groups. No additional advantage was found for coronal deformity correction, but the restoration of lumbar lordosis in the combined group was significantly higher postoperatively (15.3° vs. 8.87°, P = 0.003) and last follow-up (6.69° vs. 1.02°, P = 0.029) compared to that of the only PSF group. In the subgroup analysis for indirect decompression for the combined group, a significant increase of canal area (104 vs. 122 mm) and foraminal height (16.2 vs. 18.5 mm) was noted. The occurrence of PJK or PJF was significantly higher in the combined group than in the only PSF group (P = 0.039).

CONCLUSION

LLIF has advantages of indirect decompression and greater improvements of sagittal correction compared to only posterior surgery. LLIF should be conducted considering the above-mentioned benefits and complications including PJK or PJF in ASD.

LEVEL OF EVIDENCE

4.

Recent Advances in Technique and Clinical Outcomes of Minimally Invasive Spine Surgery in Adult Scoliosis

Objective:

Conventional open spinal surgery of adult scoliosis can be performed from anterior, posterior, or combined approach. Minimally invasive spine surgery (MISS) was developed for the purpose of reducing the undesirable effects and complications. This review aimed to make a brief summary of recent studies of the approach and clinical outcomes of MISS in adult scoliosis.

Data Sources:

We conducted a systematic search from PubMed, Medline, EMBASE, and other literature databases to collect reports of surgical methods and clinical outcomes of MISS in treatment of adult scoliosis. Those reports were published up to March 2017 with the following key terms: “minimally invasive,” “spine,” “surgery,” and “scoliosis.”

Study Selection:

The inclusion criteria of the articles were as followings: diagnosed with adult degenerative scoliosis (DS) or adult idiopathic scoliosis; underwent MISS or open surgery; with follow-up data. The articles involving patients with congenital scoliosis or unknown type were excluded and those without any follow-up data were also excluded from the study. The initial search yielded 233 articles. After title and abstract extraction, 29 English articles were selected for full-text review. Of those, 20 studies with 831 patients diagnosed with adult DS or adult idiopathic scoliosis were reviewed. Seventeen were retrospective studies, and three were prospective studies.

Results:

The surgical technique reported in these articles was direct or extreme lateral interbody fusion, axial lumbar interbody fusion, and transforaminal lumbar interbody fusion. Among the clinical outcomes of these studies, the operated levels was 3–7, operative time was 2.3–8.5 h. Both the Cobb angle of coronal major curve and evaluation of Oswestry Disability Index and Visual Analog Scale decreased after surgery. There were 323 complications reported in the 831 (38.9%) patients, including 150 (18.1%) motor or sensory deficits, and 111 (13.4%) implant-related complications.

Conclusions:

MISS can provide good radiological and self-evaluation improvement in treatment of adult scoliosis. More prospective studies will be needed before it is widely used.

Limitations and complications of minimally invasive spinal surgery in adult deformity

Minimally invasive spine (MIS) surgery has rapidly progressed from simple short segment fusions to large adult deformity corrections, with radiographic and clinical outcomes as good as those of open surgery. Anterior longitudinal ligament release (ALLR) and anterior column realignment (ACR) have been key advancements in the ability to correct deformity using MIS techniques. However, patient selection and appropriate preoperative workup is critical to obtain good outcomes and for complication avoidance. Despite favorable outcomes in spinal deformity surgery, MIS techniques are limited in (I) pronounced cervical or thoracic deformity; (II) patients with prior fusion mass; and (III) severe sagittal imbalance necessitating Schwab 5 osteotomy or higher. Guidelines for proper patient selection are needed to guide MIS spine surgeons in choosing the right candidate.

Complication rates associated with open versus percutaneous pedicle screw instrumentation among patients undergoing minimally invasive interbody fusion for adult spinal deformity

OBJECTIVE

High-quality studies that compare outcomes of open and minimally invasively placed pedicle screws for adult spinal deformity are needed. Therefore, the authors compared differences in complications from a circumferential minimally invasive spine (MIS) surgery and those from a hybrid surgery.

METHODS

A retrospective review of a multicenter database of patients with spinal deformity who were treated with an MIS surgery was performed. Database inclusion criteria included an age of ≥ 18 years and at least 1 of the following: a coronal Cobb angle of > 20°, a sagittal vertical axis of > 5 cm, a pelvic incidence–lumbar lordosis angle of > 10°, and/or a pelvic tilt of > 20°. Patients were propensity matched according to the levels instrumented.

RESULTS

In this database, a complete data set was available for 165 patients, and after those who underwent 3-column osteotomy were excluded, 137 patients were available for analysis; 76 patients remained after propensity matching (MIS surgery group 38 patients, hybrid surgery group 38 patients). The authors found no difference in demographics, number of levels instrumented, or preoperative and postoperative radiographic results. At least 1 complication was suffered by 55.3% of patients in the hybrid surgery group and 44.7% of those in the MIS surgery group (p = 0.359). Patients in the MIS surgery group had significantly fewer neurological, operative, and minor complications than those in the hybrid surgery group. The reoperation rates in both groups were similar. The most common complication category for the MIS surgery group was radiographic and for the hybrid surgery group was neurological. Patients in both groups experienced postoperative improvement in their Oswestry Disability Index and visual analog scale (VAS) back and leg pain scores (all p < 0.05); however, MIS surgery provided a greater reduction in leg pain according to VAS scores.

CONCLUSIONS

Overall complication rates in the MIS and hybrid surgery groups were similar. MIS surgery resulted in significantly fewer neurological, operative, and minor complications. Reoperation rates in the 2 groups were similar, and despite complications, the patients reported significant improvement in their pain and function.

Minimally invasive techniques for lumbar decompressions and fusions

PURPOSE OF REVIEW

The purpose of this study is to summarize the recent literature investigating the use of minimally invasive (MIS) techniques in the treatment of lumbar degenerative stenosis, spondylolisthesis, and scoliosis.

RECENT FINDINGS

MIS lumbar decompression and fusion techniques for degenerative pathology are associated with reduced operative morbidity, shortened length of hospital stay, and reduced postoperative pain and narcotics utilization. Recent studies with long-term clinical follow-up have demonstrated equivalence in clinical outcomes between open and MIS surgical procedures. Radiographically, MIS procedures provide adequate postoperative correction of coronal alignment. Correction of sagittal alignment, however, is more variable based on current reports. MIS techniques are both safe and effective in the treatment of lumbar degenerative pathologies. While some studies have reported on long-term outcomes and costs associated with MIS procedures, more investigation into these topics is still necessary. Additionally, further work is required to analyze the training requirements and learning curves of MIS procedures to better promote adoption amongst surgeons.

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.

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.

S2-AI screw placement with the aide of electronic conductivity device monitoring: a retrospective analysis

STUDY DESIGN

A retrospective analysis of two consecutive patients who underwent a novel surgical technique.

OBJECTIVE

A report of a novel surgical technique utilizing an electronic conductivity device guidance to aide placement of S2-Alar-Iliac (S2-AI) instrumentation. Electronic conductivity guidance for instrumentation of the thoracolumbar spine is an accepted means of improving intraoperative accuracy. Although commercially available for percutaneous techniques, there is a paucity of literature regarding its use. Percutaneous implantation of S2-AI screws has been previously described as another technique surgeons can avail, primarily employing fluoroscopy as a means of intraoperative feedback. We describe a novel technique that utilizes electronic conductivity as an added feedback measure to increase accuracy of percutaneous S2-AI fixation.

METHODS

Two patients were treated by the senior author (FAS) who underwent surgery employing S2-AI fixation utilizing an electronic conductivity device (Pediguard cannulated probe, Spineguard, Paris, France). The surgical technique, case illustrations, and radiographic outcomes are discussed.

RESULTS

Stable and accurate fixation was attained in both patients. There were no peri-operative complications related to hardware placement.

CONCLUSION

To the authors' knowledge, this is the first reported literature combining S2-AI screws with electronic conductivity for immediate intraoperative feedback. This technique has the opportunity to provide surgeons with increased accuracy for placement of S2-AI screws while improving overall radiation safety. This feedback can be particularly helpful when surgeons are learning new techniques such as placement of S2AI screws.