Indirect decompression in spinal surgery

Novel Combination of Lateral Interbody Fusion and Endoscopic Ipsi-Contra Decompression for Severe Stenosis From Lumbar Spondylolisthesis: A Case Report

Minimally invasive surgical approaches to the spine that leverage indirect decompression are gaining increasing popularity. While there is excellent literature on the value of indirect decompression, there are limitations to this procedure. Specifically, in patients with severe stenosis and neurogenic claudication, there is a concern among many surgeons regarding the adequacy of indirect decompression alone. In these cases, the lateral approach is often abandoned in favor of an open posterior or posterior minimally invasive approach. Unfortunately, some of the distinct benefits of the direct lateral approach are then lost. Here, we present the case of a 58-year-old male who underwent an L4-L5 lateral interbody fusion with an endoscopic ipsi-contra decompression to achieve both direct and indirect treatment of severe neuroforaminal and central stenosis. From this strategy, this patient had complete pre-operative symptom resolution and was able to return to work immediately after surgery without significant restriction. Combining the benefits of direct and indirect using an ultra-minimally invasive decompressive approach offers a potential solution.

Characterizing utilization patterns and reoperation risk factors of interspinous process devices: analysis of a national claims database

INTRODUCTION

Interspinous process devices (IPDs) were developed as minimally invasive alternatives to open decompression surgery for spinal stenosis. However, given high treatment failure and reoperation rates, there has been minimal adoption by spine surgeons. This study leveraged a national claims database to characterize national IPD usage patterns and postoperative outcomes after IPD implantation.

METHOD

Using the PearlDiver database, we identified all patients who underwent 1- or 2-level IPD implantation between 2010 and 2018. Univariate and multivariable logistic regression was performed to identify predictors of the number of IPD levels implanted and reoperation up to 3 years after the index surgery. Right-censored Kaplan-Meier curves were plotted for duration of reoperation-free survival and compared with log-rank tests.

RESULTS

Patients (n = 4865) received 1-level (n = 3246) or 2-level (n = 1619) IPDs. Patients who were older (adjusted odds ratio [aOR] 1.02, 95% confidence interval [CI] 1.01-1.03, P < .001), male (aOR 1.31, 95% CI 116-1.50, P < .001), and obese (aOR 1.19, 95% CI 1.05-1.36, P < .01) were significantly more likely to receive a 2-level IPD than to receive a 1-level IPD. The 3-year reoperation rate was 9.3% of patients when mortality was accounted for during the follow-up period. Older age decreased (aOR 0.97, 95% CI 0.97-0.99, P = .0039) likelihood of reoperation, whereas 1-level IPD (aOR 1.37, 95% CI 1.01-1.89, P = .048), Charlson Comorbidity Index (aOR 1.07, 95% CI 1.01-1.14, P = .018), and performing concomitant open decompression increased the likelihood of reoperation (aOR 1.68, 95% CI 1.35-2.09, P = .0014).

CONCLUSION

Compared with 1-level IPDs, 2-level IPDs were implanted more frequently in older, male, and obese patients. The 3-year reoperation rate was 9.3%. Concomitant open decompression with IPD placement was identified as a significant risk factor for subsequent reoperation and warrants future investigation.

Resolution of Radiculopathy Following Indirect Versus Direct Decompression in Single Level Lumbar Fusion

STUDY DESIGN

Retrospective analysis.

OBJECTIVES

To evaluate resolution of radiculopathy in one-level lumbar fusion with indirect or direct decompression techniques.

METHODS

Patients ≥18 years of age with preoperative radiculopathy undergoing single-level lumbar fusion with up to 2-year follow-up were grouped by indirect and direct decompression. Direct decompression (DD) group included ALIF and LLIF with posterior DD procedure as well as all TLIF. Indirect decompression (ID) group included ALIF and LLIF without posterior DD procedure. Propensity score matching was used to control for intergroup differences in age. Intergroup outcomes were compared using means comparison tests. Logistic regressions were used to correlate decompression type with symptom resolution over time. Significance set at P < .05.

RESULTS

116 patients were included: 58 direct decompression (DD) (mean 53.9y, 67.2% female) and 58 indirect decompression (ID) (mean 54.6y, 61.4% female). DD patients experienced greater blood loss than ID. Additionally, DD patients were 4.7 times more likely than ID patients to experience full resolution of radiculopathy at 3 months post-op. By 6 months, DD patients demonstrated larger reductions in VAS score. With regard to motor function, DD patients had improved motor score associated with the L5 dermatome at 6 months relative to ID patients.

CONCLUSIONS

Direct decompression was associated with greater resolution of radiculopathy in the near post-operative term, with no differences at long term follow-up when compared with indirect decompression. In particularly debilitated patients, these findings may influence surgeons to perform a direct decompression to achieve more rapid resolution of radiculopathy symptoms.

Effects of indirect foraminal decompression during anterior cervical disc fusion procedure: preliminary results of a prospective study with clinical and radiological outcomes

INTRODUCTION

The respective effects of direct and indirect decompression in the clinical outcome after anterior cervical disc fusion (ACDF) is still debated. The main purpose of this study was to analyze the effects of indirect decompression on foraminal volumes during ACDF performed in patients suffering from cervico-brachial neuralgias due to degenerative foraminal stenosis, i.e. to determine whether implant height was associated with increased postoperative foraminal height and volume.

METHODS

A prospective follow-up of patients who underwent ACDF for cervicobrachial neuralgias due to degenerative foraminal stenosis was conducted. Patient had performed a CT-scan pre and post-operatively. Disc height, foraminal heights and foraminal volumes were measured pre and post operatively.

RESULTS

37 cervical disc fusions were successfully performed in 20 patients, with a total of 148 foramina studied. Foraminal height and volume were measured bilaterally on the pre- and post-operative CT scans (148 foramina studied). After univariate analysis, it was found a significant improvement for every radiological parameter, with a significant increase in disc height, foraminal height and foraminal volume being respectively +3,22 mm (p < 0,001), +2,12 mm (p < 0,001) and +54 mm3 (p < 0,001). Increase in disc height was significantly associated with increase in foraminal height (p < 0,001) and foraminal volume (p < 0,001). At the same time, increase in foraminal height was significantly correlated with foraminal volume (p < 0,001), and seems to be the major component affecting increasing in foraminal volume.

CONCLUSION

Indirect decompression plays an important part in the postoperative foraminal volume increase after ACDF performed for cervicobrachial neuralgias.

Spinal Canal Remodeling and Indirect Decompression of Contralateral Foraminal Stenosis After Endoscopic Posterolateral Transforaminal Lumbar Interbody Fusion

Objective: There is a lack of literature on indirect decompression in uniportal endoscopic posterolateral transforaminal lumbar interbody fusion (EPTLIF). Our aim is to evaluate the dimensions of the spinal canal and contralateral foramen before and after EPTLIF.Methods: This is a retrospective study of patients who underwent EPTLIF in a tertiary spine centre over a 2-year period. The cross-sectional area of the spinal canal and the contralateral foramen at the level of fusion were measured on magnetic resonance imaging scan at 1-day postoperation and at the final follow-up. Patients were grouped according to the decompression performed as per the clinician’s judgement.Results: One hundred fifty-two levels of fusion were performed in 120 patients. There was a statistically significant clinical improvement in visual analogue scale and Oswestry Disability Index scores postoperation. The measurements of the spinal canal area were 106.0 mm², 138.8 mm², and 195.5 mm²; while contralateral foraminal area were 73.2 mm², 104.4 mm², and 120.7 mm² at preoperation, 1-day postoperation, and at the final follow-up, respectively (p < 0.001). For the subgroup analyses, spinal canal area measurements for the bilateral decompression cohort (n = 35) were 57.0 mm², 123.9 mm², and 191.8 mm²; for the ipsilateral decompression cohort (n = 42) were 89.3 mm², 128.9 mm², 183.3 mm²; and for the cohort without any decompression and only cage inserted (n = 75) were 138.3 mm², 151.2 mm², and 204.1 mm² (p < 0.001). Contralateral foraminal area measurements were 73.3 mm², 106.4 mm² and 120.4 mm² in the bilateral decompression cohort; 69.5 mm², 99.0 mm², 116.9 mm² in the ipsilateral decompression cohort; and 75.1 mm², 106.5 mm², 122.9 mm² in the cohort without any decompression (p < 0.001).Conclusion: Indirect decompression of both the spinal canal and the contralateral foramen can be achieved via EPTLIF. Decompression on an asymptomatic contralateral side is not necessary.

The Gantry Crane Technique: A Novel Technique for Treating Severe Thoracic Spinal Stenosis and Myelopathy Caused by Ossification of the Ligamentum Flavum and Preliminary Clinical Results

STUDY DESIGN

Retrospective single-arm study.

OBJECTIVE

To propose a novel technique named the gantry crane technique for treating severe thoracic spinal stenosis and myelopathy caused by thoracic ossification of the ligamentum flavum (TOLF) and investigate its clinical results.

METHODS

From June 2017 to January 2019, 18 patients presenting with severe spinal stenosis and myelopathy caused by TOLF were included in our study. All patients were treated with gantry crane technique, pre-operative JOA score, as well as 3 days-, 3 months-, 6 months-, 12 months-, 24 months after operation, and Hirabayashi recovery rate were reported. Pre- and post-operative image were utilized for the assessment of post-operative effect. Peri-operative complications were recorded to assess the safety of the gantry crane technique.

RESULTS

The JOA score increased from 10.56 ± 3.76 preoperatively to 12.94 ± 3.33, 13.56 ± 3.48, 13.94 ± 3.32, 14.17 ± 3.70 and 14.06 ± 3.54 in 3 days, 3 months, 6 months, 12 months and 24 months after surgery, respectively. The post-operative JOA scores were improved with statistical significance at the level of P < 0.05. The recovery rate was (39.09 ± 33.85) %, (51.35 ± 42.60) %, (55.79 ± 36.10) %, (64.98 ± 29.24) % and (60.98 ± 35.96) % for 3 days, 3 months, 6 months, 12 months and 24 months after surgery, respectively. There were 2 cases of SSI (surgical site infection), 1 case of NI (neurovascular injury) and 1 case of cerebrospinal fluid (CSF) leakage.

CONCLUSIONS

This study highlights a safe and effective technique, the gantry crane technique, for treating severe thoracic spinal stenosis and myelopathy caused by TOLF.

OLIF versus ALIF: Which is the better surgical approach for degenerative lumbar disease? A systematic review

PURPOSE

The aim of this study was to compare the clinical and radiographical outcomes between OLIF and ALIF in treating lumbar degenerative diseases.

METHODS

We searched PubMed, Embase, Web of Science, and Cochrane Library for relevant studies. Changes in disc height (DH), segmental lordosis angle (SLA), lumbar lordosis (LL), visual analogue scale (VAS) score, and Oswestry disability index (ODI) between baseline and final follow-up, along with other important surgical outcomes, were assessed and analysed. Data on the global fusion rate and main complications were collected and compared.

RESULTS

Approximately, 2041 patients from 36 studies were included, consisting of 1057 patients who underwent OLIF and 984 patients who underwent ALIF. The results reveal no significant difference in DH, SLA, VAS score, and ODI between the two groups (all P > 0.05). The operation time, estimated blood loss, and length of hospital stay were also comparable between the two groups. Over 90% of the fusion rate was achieved in both groups. The OLIF group showed a higher complication rate than the ALIF group (OLIF 18.83% vs ALIF 7.32%).

CONCLUSIONS

OLIF leads to a higher complication rate, with the most notable complication being cage subsidence. Both OLIF and ALIF are effective treatments for degenerative lumbar diseases and have similar therapeutic effects. ALIF was expected to be more expensive for patients because of the necessity of involving vascular surgeons.

Outcomes Following Direct Versus Indirect Decompression Techniques for Lumbar Spondylolisthesis: A Propensity-Matched Analysis

STUDY DESIGN

Retrospective review.

OBJECTIVE

The aim was to compare outcomes at 3 and 12 months for patients with lumbar spondylolisthesis treated with direct decompression (DD) versus indirect decompression (ID) techniques.

SUMMARY OF BACKGROUND DATA

Debate persists regarding the optimal surgical strategy to treat lumbar spondylolisthesis. Novel techniques relying on ID have shown superior radiographic outcomes compared to DD, however, doubt remains regarding their effectiveness in achieving adequate decompression. Currently, there is a paucity of data comparing the clinical efficacy of DD to ID.

METHODS

The Quality Outcomes Database (QOD), a national, multicenter prospective spine registry, was queried for patients who underwent DD and ID between April 2013 and January 2019. Propensity scores for each treatment were estimated using logistic regression dependent on baseline covariates potentially associated with outcomes. The propensity scores were used to exclude nonsimilar patients. Multivariable regression analysis was performed with the treatment and covariate as independent variables and outcomes as dependent variables.

RESULTS

A total of 4163 patients were included in the DD group and 86 in the ID group. The ID group had significantly lower odds of having a longer hospital stay and for achieving 30% improvement in back and leg pain at 3 months. These trends were not statistically significant at 12 months. There were no differences in ED5D scores or Oswestry disability index 30% improvement scores at 3 or 12 months. ID patient had a significantly higher rate of undergoing a repeat operation at 3 months (4.9% vs. 1.5%, P =0.015).

CONCLUSION

Our study suggests that both DD and ID for the treatment of lumbar spondylolisthesis result in similar clinical outcomes, with the exception that those treated with ID experienced a lower reduction in back and leg pain at 3 months and a higher 3-month reoperation rate. This data can provide surgeons with additional information when counseling patients on the pros and cons of ID versus DD surgery.

Obesity and Spine Surgery: A Qualitative Review About Outcomes and Complications. Is It Time for New Perspectives on Future Researches?

STUDY DESIGN

Literature review.

OBJECTIVES

An increasing number of obese patients requires operative care for degenerative spinal disorders. The aim of this review is to analyze the available evidence regarding the role of obesity on outcomes after spine surgery. Peri-operative complications and clinical results are evaluated for both cervical and lumbar surgery. Furthermore, the contribution of MIS techniques for lumbar surgery to play a role in reducing risks has been analyzed.

METHODS

Only articles published in English in the last 10 years were reviewed. Inclusion criteria of the references were based on the scope of this review, according to PRISMA guidelines. Moreover, only paper analyzing obesity-related complications in spine surgery have been selected and thoroughly reviewed. Each article was classified according to its rating of evidence using the Sacket Grading System.

RESULTS

A total number of 1636 articles were found, but only 130 of them were considered to be relevant after thorough evaluation and according to PRISMA checklist. The majority of the included papers were classified according to the Sacket Grading System as Level 2 (Retrospective Studies).

CONCLUSION

Evidence suggest that obese patients could benefit from spine surgery and outcomes be satisfactory. A higher rate of peri-operative complications is reported among obese patients, especially in posterior approaches. The use of MIS techniques plays a key role in order to reduce surgical risks. Further studies should evaluate the role of multidisciplinary counseling between spine surgeons, nutritionists and bariatric surgeons, in order to plan proper weight loss before elective spine surgery.

Indirect Lumbar Decompression Combined With or Without Additional Direct Posterior Decompression: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVE

Indirect decompression via lateral lumbar interbody fusion (LLIF) can ameliorate central and foraminal lumbar stenosis. In severe central stenosis, additional posterior direct decompression is utilized. The aim of this review is to synthesize existing literature on these 2 techniques and identify significant differences in outcomes between isolated indirect decompression via LLIF and combined indirect decompression supplemented with direct posterior decompression.

METHODS

A database search algorithm was utilized to query MEDLINE, COCHRANE, and EMBASE to identify literature reporting adult decompression study groups that involved an oblique or lateral fusion approach through September 2020. Improvement in outcomes measures and complication rates were pooled and tested for significance.

RESULTS

A total of 110 publications were assessed with 15 studies meeting inclusion criteria, including 557 patients and 1008 levels. Mean age was 63.1 years with BMI of 27.5 kg/m². For the combined indirect and direct decompression cohort, lumbar lordosis (LL) increased 133.9%, from 22.8^o to 48.7^o, while the indirect decompression cohort LL increased 8.9%, from 41.9^o to 45.5^o. Difference in LL improvement between cohorts was insignificant (P > .05). Oswestry Disability Index (ODI) decreased from 36.5 to 19.4 in the combined indirect and direct decompression cohort, and from 44.4 to 23.1 in the indirect decompression cohort. ODI reduction was insignificant (P = .053).

CONCLUSIONS

Prior studies of both indirect decompression as well as combined indirect and direct decompression of lumbar spine stenosis are limited by small samples, heterogeneous populations, and lack of direct comparisons. Both procedures result in improved function and pain postoperatively with direct decompression restoring more lordosis in patients with worse preoperative alignment.

Best Practices for Minimally Invasive Lumbar Spinal Stenosis Treatment 2.0 (MIST): Consensus Guidance from the American Society of Pain and Neuroscience (ASPN)

Introduction

Methods

Results

Discussion

Conclusion

Tomodensitometric bone anatomy of the intervertebral foramen of the lower cervical spine: measurements and comparison of foraminal volume in healthy individuals and patients suffering from cervicobrachial neuralgia due to foraminal stenosis

PURPOSE

Degenerative foraminal stenosis of the cervical spine can lead to cervicobrachial neuralgias. Computed tomography (CT)-scan assists in the diagnosis and evaluation of foraminal stenosis. The main objective of this study is to determine the bony dimensions of the cervical intervertebral foramen and to identify which foraminal measurements are most affected by degenerative disorders of the cervical spine. These data could be applied to the surgical treatment of this pathology, helping surgeons to focus on specific areas during decompression procedures.

METHODS

A descriptive study was conducted between two groups: an asymptomatic one (young people with no evidence of degenerative cervical spine disorders) and a symptomatic one (experiencing cervicobrachial neuralgia due to degenerative foraminal stenosis). Using CT scans, we determined a method allowing measurements of the following foraminal dimensions: foraminal height (FH), foraminal length (FL), foraminal width in its lateral part ((UWPP, MWPP and IWPP (respectively Upper, Medial and Inferior Width of Pedicle Part)) and medial part (UWMP, MWMP and IWMP (respectively Upper, Medial and Inferior Width of Medial Part)), and disk height (DH). Foraminal volume (FV) was calculated considering the above data. Mean volumes were measured in the asymptomatic group and compared to the values obtained in the symptomatic group.

RESULTS

Both groups were made up of 10 patients, and a total of 50 intervertebral discs (100 intervertebral foramina) were analyzed in each group. Comparison of C4C5, C5C6 and C6C7 levels between both groups showed several significant decreases in foraminal dimensions (p < 0.05) as well as in foraminal volume (p < 0.001) in the symptomatic group. The most affected dimensions were UWPP, MWPP, UWMP, MWMP and FV. The most stenotic foraminal areas were the top of the uncus and the posterior edge of the lower plate of the overlying vertebra.

CONCLUSION

Using a new protocol for measuring foraminal volume, the present study refines the current knowledge of the normal and pathological anatomy of the lower cervical spine and allows us to understand the foraminal sites most affected by degenerative stenosis. Those findings can be applied to foraminal stenosis surgeries. According to our results, decompression of the foramen in regard of both uncus osteophytic spurs and inferior plate of the overlying vertebra might be an important step for spinal nerves release.

Evolution of Complex Spine Surgery in Neurosurgery: From Big to Minimally Invasive Surgery for the Treatment of Spinal Deformity

Spinal instrumentation for adult spinal deformity dates back to the surgical correction of secondary complications from infectious processes, such as Pott's disease and poliomyelitis [1]. With the population aging at a longer life expectancy today, advanced degenerative spinal diseases and idiopathic scoliosis supersede as the most common causes of adult spinal deformity. Correction of the thoracolumbar malignment, specifically, has rapidly evolved with the burgeoning success of spinal instrumentation. The objective of this chapter is to review the metamorphosis of operative principles for adult thoracolumbar deformity, from aggressive osteotomies in the posterior bony elements to minimally invasive surgery (MIS) at the intervertebral disc space.

Radiological Assessment of the Effects of Anterior Cervical Discectomy and Fusion on Distraction of the Posterior Ligamentum Flavum in Patients with Degenerative Cervical Spines

Background

This study aimed to assess the effects of anterior cervical discectomy and fusion (ACDF) on distraction of the posterior ligamentum flavum (LF) by increasing the intervertebral disc height and positioning a graft in patients with degenerative cervical spine disease.

Methods

Sixty-eight patients with degenerative cervical diseases who underwent single-level ACDF were included in the analysis. The intervertebral disc height, Cobb angle, and transverse thickness of the LF were measured, and magnetic resonance imaging was performed both preoperatively and 6 weeks postoperatively on each patient. Correlation analyses were performed to evaluate the relationships between age, sex, change in intervertebral disc height, Cobb angle, and position of the intervertebral implant according to the postoperative change in LF thickness. The position of the intervertebral implant was categorized as anterior, middle, or posterior. We also evaluated radiological effects according to the implant position.

Results

The mean intervertebral disc height increased from 5.88 mm preoperatively to 7.49 mm postoperatively. The Cobb angle was 0.88° preoperatively and 1.43° postoperatively. Age (p = 0.551), sex (p = 0.348), position of cage (p = 0.312), pre- and postoperative intervertebral disc height (p = 0.850, p = 0.900), Cobb angle (p = 0.977, p = 0.460), and LF thickness (p = 0.060, p = 1.00) were not related to changes in postoperative LF thickness. Postoperative increase in disc height was related to Cobb angle (r = 0.351, p = 0.038). No other factors were significantly related. The position of the cage was not related with the change of Cobb angle (p = 0.91), LF thickness (p = 0.31), or disc height (p = 0.54).

Conclusions

Change in the intervertebral disc height and the position of the intervertebral implant after ACDF did not affect the thickness of the LF after surgery in patients with degenerative cervical spine disease.

Decompression Using Minimally Invasive Surgery for Lumbar Spinal Stenosis Associated with Degenerative Spondylolisthesis: A Review

Lumbar spinal stenosis (LSS), which often occurs concurrently with degenerative spondylolisthesis (DS), is a common disease in the elderly population, affecting the quality of life of aged people significantly. Notwithstanding the frequently good effect of conservative therapy on LSS, a minority of the patients ultimately require surgery. Surgery for LSS aims to decompress the narrowed spinal canals with preservation of spinal stability. Traditional open surgery, either pure decompression or decompression with fusion, was considered effective for the treatment of LSS with or without DS. However, the long-term clinical outcomes of traditional open surgery are still unclear. Moreover, the disadvantages of conventional open surgery are extensive, examples including tissue injuries or secondary instability, with limited outcomes and significant reoperation rates. With the development and improvement of surgical tools, various minimally invasive spine surgery (MISS) methods, including indirect decompression techniques of interspinous process devices (IPDs) and direct decompression techniques such as microscopic spine surgery or endoscopic spine surgery (ESS), have been updated with enhancement. IPDs, such as Superion devices, were reported to behave with comparable physical function, disability, and symptoms outcomes to laminectomy decompression. As an emerging technique of MISS, ESS has beneficial hallmarks including minimal tissue injuries, reduced complication rates, and shortened recovery periods, thus gaining popularity in recent years. ESS can be classified in terms of endoscopic hallmarks and approaches. Predictably, with the continuous development and gradual maturity, MISS is expected to replace traditional open surgery widely in the surgical treatment of LSS associated with DS in the future.

Use of L5-S1 transdiscal screws in the treatment of isthmic spondylolisthesis: a technical note

Surgical treatment of L5-S1 isthmic spondylolisthesis consists of a combination of decompression and fusion. One previously discussed mode of fusion is via transdiscal screws. Biomechanical studies of transdiscal screws have demonstrated greater rigidity than traditional pedicle screw fixation, which theoretically translates to a higher fusion rate. Furthermore, when compared to pedicle screw fixation, transdiscal screw fixation also demonstrates improved functional and radiographic outcomes. However, transdiscal screw placement can be technically difficult. At this time, a detailed surgical technique has yet to be reported in the literature. Our surgical technique for transdiscal screw placement using intraoperative C-arm at L5-S1 is described. We include considerations for preoperative planning including necessary imaging and appropriate patient selection. We also discuss intraoperative concerns such as setup, surgical approach, proper screw trajectory, and our method for achieving indirect decompression. The results of thirteen consecutive patients treated with transdiscal screw fixation are described. One patient had subcutaneous seroma requiring reoperation (7.7%), three patients had implant failure (23.1%), and one patient had nonunion (7.7%). Our results suggest that transdiscal screw fixation is a safe and acceptable alternative for stabilization and indirect decompression of L5-S1 isthmic spondylolisthesis. Recent innovation in intraoperative navigation and robotic surgery may lessen the technical difficulty of transdiscal screw placement and make it even more effective.

Decompression of Lumbar Central Spinal Canal Stenosis Following Minimally Invasive Transforaminal Lumbar Interbody Fusion

STUDY DESIGN

This was a retrospective clinical series.

OBJECTIVE

The objective of this study was to evaluate radiologic changes in central spinal canal dimensions following minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with placement of a static or an expandable interbody device.

SUMMARY OF BACKGROUND DATA

MIS-TLIF is used to treat lumbar degenerative diseases and low-grade spondylolisthesis. MIS-TLIF enables direct and indirect decompression of lumbar spinal stenosis, with patients experiencing relief from radiculopathy and neurogenic claudication. However, the effects of MIS-TLIF on the central spinal canal are not well-characterized.

MATERIALS AND METHODS

We identified patients who underwent MIS-TLIF for degenerative lumbar spondylolisthesis and concurrent moderate to severe spinal stenosis. We selected patients who had both preoperative and postoperative magnetic resonance imaging (MRI) and upright lateral radiographs of the lumbar spine. Measurements on axial T2-weighted MRI scans include anteroposterior and transverse dimensions of the dural sac and osseous spinal canal. Measurements on radiographs include disk height, neural foraminal height, segmental lordosis, and spondylolisthesis. We made pairwise comparisons between each of the central canal dimensions and lumbar sagittal segmental radiologic outcome measures relative to their corresponding preoperative values. Correlation coefficients were used to quantify the association between changes in lumbar sagittal segmental parameters relative to changes in radiologic outcomes of central canal dimensions. Statistical analysis was performed for "all patients" and further stratified by interbody device subgroups (static and expandable).

RESULTS

Fifty-one patients (age 60.4 y, 68.6% female) who underwent MIS-TLIF at 55 levels (65.5% at L4-L5) were included in the analysis. Expandable interbody devices were used in 45/55 (81.8%) levels. Mean duration from surgery to postoperative MRI scan was 16.5 months (SD 11.9). MIS-TLIF was associated with significant improvements in dural sac dimensions (anteroposterior +0.31 cm, transverse +0.38 cm) and osseous spinal canal dimensions (anteroposterior +0.16 cm, transverse +0.32 cm). Sagittal lumbar segmental parameters of disk height (+0.56 cm), neural foraminal height (+0.35 cm), segmental lordosis (+4.26 degrees), and spondylolisthesis (-7.5%) were also improved following MIS-TLIF. We did not find meaningful associations between the changes in central canal dimensions relative to the corresponding changes in any of the sagittal lumbar segmental parameters. Stratified analysis by interbody device type (static and expandable) revealed similar within-group changes as in the overall cohort and minimal between-group differences.

CONCLUSIONS

MIS-TLIF is associated with radiologic decompression of neural foraminal and central spinal canal stenosis. The mechanism for neural foraminal and central canal decompression is likely driven by a combination of direct and indirect corrective techniques.

Clinical and radiographic performance of indirect foraminal decompression with anterior retroperitoneal lumbar approach for interbody fusion (ALIF)

STUDY DESIGN

Retrospective study BACKGROUND: Indirect decompression with ALIF allows the restoration of the disk and foraminal height with limited soft tissue damage. However, it does not offer a direct view of the neural structure and a direct intraoperative assessment of the results of the decompression is not possible. For this reason, ALIF is often accompanied by posterior, direct decompression. So far, there is no consensus on the effects of indirect decompression alone for L5-S1 foraminal stenosis.

OBJECTIVE

Evaluation of the clinical and mechanical performance of indirect decompression with anterior lumbar interbody fusion (ALIF) in L5-S1 foraminal stenosis.

METHODS

All patients who underwent ALIF at our institution and had a minimum follow-up of six months were assessed for inclusion. Radiographic parameters (anterior and posterior disc height, foraminal height and surface, L5-S1 angle, pelvic incidence, pelvic tilt and lumbar lordosis) and clinical data (Oswestry Disability Index - ODI and Numeric Rating Scale - NRS) before ALIF and at the last follow-up were compared. A regression analysis was performed to investigate the correlation between radiographic and clinical outcomes.

RESULTS

Thirty-four patients were available for the study (55.9% female, mean age 53.4±11.5 years), mean follow-up was 26.4±11.1 months. At the last follow-up, a significant increase in foraminal height (14.6±4.0 vs. 17.9±3.9 mm, p<0.001), posterior disc height (6.5±2 vs. 9.1±2 mm, p<0.001) was observed. ODI and NRS back and leg improved significantly. The NRS leg correlated with foraminal height (r=-0.45), foraminal surface (r=-0.36) and anterior (r=-0.41) and posterior disc height (r=-0.43).

CONCLUSION

ALIF provided significant indirect foraminal decompression and improvement of radicular pain. The increase of foraminal height, surface, and posterior disc height is directly associated with radicular pain improvement.

LEVEL OF EVIDENCE

IV AVAILABILITY OF DATA AND MATERIAL: The datasets used and/or analyzed in the present study are available from the corresponding author on reasonable request.

Reasons for revision following stand-alone anterior lumbar interbody fusion and lateral lumbar interbody fusion

OBJECTIVE

Anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF) are alternative and less invasive techniques to stabilize the spine and indirectly decompress the neural elements compared with open posterior approaches. While reoperation rates have been described for open posterior lumbar surgery, there are sparse data on reoperation rates following these less invasive procedures without direct posterior decompression. This study aimed to evaluate the overall rate, cause, and timing of reoperation procedures following anterior or lateral lumbar interbody fusions without direct posterior decompression.

METHODS

This was a retrospective cohort study of all consecutive patients indicated for an ALIF or LLIF for lumbar spine at a single academic institution. Patients who underwent concomitant posterior fusion or direct decompression surgeries were excluded. Rates, causes, and timing of reoperations were analyzed. Patients who underwent a revision decompression were matched with patients who did not require a reoperation, and preoperative imaging characteristics were analyzed to assess for risk factors for the reoperation.

RESULTS

The study cohort consisted of 529 patients with an average follow-up of 2.37 years; 40.3% (213/529) and 67.3% (356/529) of patients had a minimum of 2 years and 1 year of follow-up, respectively. The total revision rate was 5.7% (30/529), with same-level revision in 3.8% (20/529) and adjacent-level revision in 1.9% (10/529) of patients. Same-level revision patients had significantly shorter time to revision (7.14 months) than adjacent-level revision patients (31.91 months) (p < 0.0001). Fifty percent of same-level revisions were for a posterior decompression. After further analysis of decompression revisions, an increased preoperative canal area was significantly associated with a lower risk of further decompression revision compared to the control group (p = 0.015; OR 0.977, 95% CI 0.959-0.995).

CONCLUSIONS

There was a low reoperation rate after anterior or lateral lumbar interbody fusions without direct posterior decompression. The majority of same-level reoperations were due to a need for further decompression. Smaller preoperative canal diameters were associated with the need for revision decompression.

A novel three-dimensional volumetric method to measure indirect decompression after percutaneous cement discoplasty

PURPOSE

Percutaneous cement discoplasty (PCD) is a minimally invasive surgical option to treat patients who suffer from the consequences of advanced disc degeneration. As the current two-dimensional methods can inappropriately measure the difference in the complex 3D anatomy of the spinal segment, our aim was to develop and apply a volumetric method to measure the geometrical change in the surgically treated segments.

METHODS

Prospective clinical and radiological data of 10 patients who underwent single- or multilevel PCD was collected. Pre- and postoperative CT scan-based 3D reconstructions were performed. The injected PMMA (Polymethylmethacrylate) induced lifting of the cranial vertebra and the following volumetric change was measured by subtraction of the geometry of the spinal canal from a pre- and postoperatively predefined cylinder. The associations of the PMMA geometry and the volumetric change of the spinal canal with clinical outcome were determined.

RESULTS

Change in the spinal canal volume (ΔV) due to the surgery proved to be significant (mean ΔV = 2266.5 ± 1172.2 mm3, n = 16; p = 0.0004). A significant, positive correlation was found between ΔV, the volume and the surface of the injected PMMA. A strong, significant association between pain intensity (low back and leg pain) and the magnitude of the volumetric increase of the spinal canal was shown (ρ = 0.772, p = 0.009 for LBP and ρ = 0.693, p = 0.026 for LP).

CONCLUSION

The developed method is accurate, reproducible and applicable for the analysis of any other spinal surgical method. The volume and surface area of the injected PMMA have a predictive power on the extent of the indirect spinal canal decompression. The larger the ΔV the higher clinical benefit was achieved with the PCD procedure.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

The developed method has the potential to be integrated into clinical software's to evaluate the efficacy of different surgical procedures based on indirect decompression effect such as PCD, anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (LLIF), oblique lumbar interbody fusion (OLIF), extreme lateral interbody fusion (XLIF). The intraoperative use of the method will allow the surgeon to respond if the decompression does not reach the desired level.

Clinical and radiological results of indirect decompression after anterior lumbar interbody fusion in central spinal canal stenosis

OBJECTIVE

Whereas the benefits of indirect decompression after lateral lumbar interbody fusion are well known, the effects of anterior lumbar interbody fusion (ALIF) have not yet been verified. The purpose of this study was to evaluate the clinical and radiological effects of indirect decompression after ALIF for central spinal canal stenosis. In this report, along with the many advantages of the anterior approach, the authors share cases with good outcomes that they have encountered.

METHODS

The authors performed a retrospective analysis of 64 consecutive patients who underwent ALIF for central spinal canal stenosis with instability and mixed foraminal stenosis between January 2015 and December 2018 at their hospital. Clinical assessments were performed using the visual analog scale score, the Oswestry Disability Index, and the modified Macnab criteria. The radiographic parameters were determined from pre- and postoperative cross-sectional MRI scans of the spinal canal and were compared to evaluate neural decompression after ALIF. The average follow-up period was 23.3 ± 1.3 months.

RESULTS

All clinical parameters, including the visual analog scale score, Oswestry Disability Index, and modified Macnab criteria, improved significantly. The mean operative duration was 254.8 ± 60.8 minutes, and the intraoperative bleeding volume was 179.8 ± 119.3 ml. In the radiological evaluation, radiological parameters of the cross-sections of the spinal canal showed substantial development. The spinal canal size improved by an average of 43.3% (p < 0.001) after surgery. No major complications occurred; however, aspiration guided by ultrasonography was performed in 2 patients because of a pseudocyst and fluid collection.

CONCLUSIONS

ALIF can serve as a suitable alternative to extensive posterior approaches. The authors suggest that ALIF can be used for decompression in central spinal canal stenosis as well as restoration of the foraminal dimensions, thus allowing decompression of the nerve roots.

Physiologic Decompression of Lumbar Spinal Stenosis Through Anatomic Restoration Using Trans-Kambin Oblique Lateral Posterior Lumbar Interbody Fusion (OLLIF): A Retrospective Analysis

Introduction Lumbar spinal stenosis (LSS) is one of the most common indications for spinal surgery. Traditionally, decompression is achieved by removing bony and ligamentous structures through open surgery. However, recent studies have shown that symptomatic relief can be accomplished in many patients by increasing intervertebral and interpedicular height using fusion alone. In this study, we evaluate whether trans-Kambin oblique lateral lumbar interbody fusion (OLLIF) can effectively and safely relieve symptoms of LSS when an indication for fusion is present. Methods This is a retrospective single surgeon cohort study of 187 patients with LSS who underwent 189 OLLIF procedures between 2012 and August 2, 2019. Inclusion criteria for this study were age >18 years with symptoms of LSS, including pain, sensory, and motor deficits, and an additional indication for fusion, which included spondylolisthesis, degenerative disk disease, disk herniation, or scoliosis. Exclusion criteria were the bony obstruction of the approach, osteogenic spinal canal stenosis, large facet hypertrophy, and listhesis grade II or greater. The primary outcome was a change in the Oswestry Disability Index (ODI) one year after surgery. Secondary outcomes were the resolution of radiculopathy at the first follow-up visit and one year after surgery, complication rates, surgery time, blood loss, and hospital stay. Results ODI improved from 52% pre-op to 37% at the one-year follow-up. At the first follow-up, radiculopathy had resolved in 39% of patients, and 72% of patients experienced improvement of 50% or greater. One year after surgery, radiculopathy had resolved in 52% of patients and 74% experienced improvement of 50% or greater. Single-level surgeries required 56.4±21.5 minutes, with a mean hospital stay of 1.6‑±2.4 days. Nerve irritation occurred in 12% of patients at the first postoperative follow-up and persisted in 6.8% of patients one year after surgery. There was one case each of persistent weakness at one year, infection, and cage subsidence. Conclusion Trans-Kambin OLLIF delivers anatomic restoration of intradiscal and interpedicular distance, which results in physiologic decompression of lumbar spinal stenosis in patients undergoing lumbar fusion for degenerative or herniated disk disease, spondylolisthesis, or scoliosis. Amongst patients with LSS, OLLIF results in significant improvement of radiculopathy and patient-reported disability in the majority of patients with low rates of long-term complications. Unlike other minimally invasive surgery (MIS) fusions, OLLIF can be safely used from T12-S1.

Transfacet Minimally Invasive Transforaminal Lumbar Interbody Fusion With an Expandable Interbody Device-Part I: 2-Dimensional Operative Video and Technical Report

BACKGROUND

Advances in operative techniques and minimally invasive technologies have evolved to maximize patient outcomes and radiographic results, while reducing morbidity and recovery time.

OBJECTIVE

To describe the operative technique for a transfacet minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) as a proposed modification to the standard approach MIS-TLIF.

METHODS

We present the case of a 72-yr-old man with left-sided lumbar radiculopathy. Preoperative imaging demonstrated degenerative lumbar anterolisthesis at L4-5, with associated canal and neuroforaminal stenosis. The patient underwent transfacet MIS-TLIF at L4-L5. We describe the preoperative planning, patient positioning, incision and dissection, pedicle screw insertion, transfacet approach to the working access corridor, discectomy, interbody device placement, fixation, and closure.

RESULTS

The transfacet MIS-TLIF utilizes 3 key techniques to safely maximize surgical correction: (1) a limited bony resection based on the superior articular process, leaving the medial inferior articular process, lateral superior articular process, and rostral pars intact, providing a working bony corridor that protects the traversing and exiting nerve roots; (2) decortication and release of the contralateral facet joint to provide additional capacity for indirect decompression and provide the first point of osseous fusion; and (3) placement of an expandable interbody device that provides additional indirect decompression to the working side and contralateral foramen.

CONCLUSION

The transfacet MIS-TLIF uniquely leverages a bony working corridor to access the disc space for discectomy and interbody placement. Transfacet MIS-TLIF is a feasible solution for lumbar spinal reconstruction to maximize direct and indirect decompression of the neuroforamina and central spinal canal in patients with lumbar degenerative diseases and low-grade spondylolisthesis.

Transfacet Minimally Invasive Transforaminal Lumbar Interbody Fusion With an Expandable Interbody Device-Part II: Consecutive Case Series

BACKGROUND

Advances in operative techniques and instrumentation technology have evolved to maximize patient outcomes following minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). The transfacet MIS-TLIF is a modified approach to the standard MIS-TLIF that leverages a bony working corridor to access the disc space for discectomy and interbody device placement.

OBJECTIVE

To evaluate clinical and radiographic results following transfacet MIS-TLIF using an expandable interbody device.

METHODS

We performed a retrospective review of consecutive patients who underwent transfacet MIS-TLIF for degenerative lumbar spondylolisthesis. Patient-reported outcome measures for pain and disability were assessed. Sagittal lumbar segmental parameters and regional lumbopelvic parameters were assessed on upright lateral radiographs obtained preoperatively and during follow-up.

RESULTS

A total of 68 patients (61.8% male) underwent transfacet MIS-TLIF at 74 levels. The mean age was 63.4 yr and the mean follow-up 15.2 mo. Patients experienced significant short- and long-term postoperative improvements on the numeric rating scale for low back pain (-2.3/10) and Oswestry Disability Index (-12.0/50). Transfacet MIS-TLIF was associated with an immediate and sustained reduction of spondylolisthesis, and an increase in index-level disc height (+0.71 cm), foraminal height (+0.28 cm), and segmental lordosis (+6.83°). Patients with preoperative hypolordosis (<40°) experienced significant increases in segmental (+9.10°) and overall lumbar lordosis (+8.65°). Pelvic parameters were not significantly changed, regardless of preoperative alignment. Device subsidence was observed in 6/74 (8.1%) levels, and fusion in 50/53 (94.3%) levels after 12 mo.

CONCLUSION

Transfacet MIS-TLIF was associated with clinical improvements and restoration of radiographic sagittal segmental parameters. Regional alignment correction was observed among patients with hypolordosis at baseline.

Biomechanics and Mechanism of Action of Indirect Lumbar Decompression and the Evolution of a Stand-alone Spinous Process Spacer

Objective

Objective Interspinous process spacers are used in the treatment of lumbar spinal stenosis by preventing extension at the implanted level and reducing claudication, which is a common symptom of lumbar spinal stenosis. This review assessed the current safety and performance of lumbar spinal stenosis treatments and the biomechanical effects of spinal position, range of motion, and the use of interspinous process spacers.

Method

Method EMBASE and PubMed were searched to find studies reporting on the safety and performance of nonsurgical treatment, including physical therapy and pharmacological treatment, and surgical treatment, including direct and indirect lumbar decompression treatment. Results were supplemented with manual searches to include studies reporting on the use of interspinous process spacers and the review of biomechanical testing performed on the Superion device.

Results

Results The effects of spinal position in extension and flexion have been shown to have an impact in the variation in dimensions of the spinal canal and foramina areas. Overall studies have shown that spinal positions from flexion to extension reduce the spinal canal and foramina dimensions and increase ligamentum flavum thickness. Biomechanical test data have shown that the Superion device resists extension and reduces angular movement at the implantation level and provides significant segmental stability.

Conclusions

Conclusions Superion interspinous lumbar decompression is a minimally invasive, low-risk procedure for the treatment of lumbar spinal stenosis, which has been shown to have a low safety profile by maintaining sagittal alignment, limiting the potential for device dislodgment or migration, and to preserve mobility and structural elements.

Factors Influencing Early Disc Height Loss Following Lateral Lumbar Interbody Fusion

Study Design

Retrospective radiological analysis.

Purpose

To analyze the factors influencing early disc height loss following lateral lumbar interbody fusion (LLIF).

Overview of Literature

Postoperative disc height loss can occur naturally as a result of mechanical loading. This phenomenon is enabled by the yielding of the polyaxial screw heads and settling of the cage to the endplates. When coupled with cage subsidence, there can be significant reduction in the foraminal space which ultimately compromises the indirect decompression achieved by LLIF.

Methods

Seventy-two cage levels in 37 patients aged 62±10.2 years who underwent single or multilevel LLIF for degenerative spinal conditions were selected. Their preoperative and postoperative follow-up radiographs were used to measure the anterior disc height (ADH), posterior disc height (PDH), mean disc height (MDH), disc space angle (DSA), and segmental angle. Correlations between the loss of disc height and several factors, including age, construct length, preoperative lordosis, postoperative lordosis, disc height, cage dimensions, and cage position, were analyzed.

Results

We found that the lateral interbody cages significantly increased ADH, PDH, MDH, and DSA after surgery (p <0.0001). However, there was a loss of disc height over time. All postoperative disc height parameters, especially the amount of increase in MDH (r =0.413, p <0.0001) after surgery, showed a significant positive association with early disc height loss. The levels demonstrating a significant (≥25%) height loss were those that exhibited a substantial height increase (128.3%, 4.6±3.0 to 10.5±5.6 mm) postoperatively. However, the levels that showed less than 25% height loss were those that exhibited, on average, only a 57.4% height increase post-operatively.

Conclusions

The greater the postoperative increase in disc height, the greater the disc height loss throughout early follow-up. Therefore, achieving an optimal disc height rather than overcorrection is an important surgical strategy to adopt when performing LLIF.

Segmental coupling effects during correction of three-dimensional lumbar deformity using lateral lumbar interbody fusion

PURPOSE

Lateral lumbar interbody fusion (LLIF) has been performed to correct spinal deformity associated with lumbar degenerative disease. Although its usefulness has been studied, there are no reports of quantitative evaluation in three dimensions. Our purpose is to quantitate 3D deformity of the patients with lumbar degenerative disease and correction of the deformity by LLIF using patient-specific 3D CT models.

METHODS

We measured the disc height and 3D alignment of the lumbar spine in 28 patients with degenerative disease undergoing LLIF using patient-specific 3D CT models created preoperatively and 3 months after surgery. The 3D alignment was calculated as wedge, lordosis and axial rotation angles at each motion segment. The disc height and the rotational angles were compared between before and after LLIF.

RESULTS

A strong positive correlation was found between the wedge angle and the axial rotation angles (r = 0.718, P < 0.001) in the patients with lumbar degenerative disease preoperatively. The wedge and axial rotation angles decreased after surgery (P < 0.001 and P < 0.001, respectively). A positive correlation was found between the corrected wedge angle and the corrected axial rotation angle (r = 0.46, P < 0.001).

CONCLUSION

The present study demonstrated positive correlations between the wedge deformity and the axial rotational deformity in the patients with lumbar degenerative disease. The axial rotational deformity was simultaneously corrected with LLIF only by leveling the intervertebral wedge deformity via cage insertion without additional correction procedure. These slides can be retrieved under Electronic Supplementary Material.

Biomechanical Analysis of Stand-alone Lateral Lumbar Interbody Fusion for Lumbar Adjacent Segment Disease

Study design

Biomechanical cadaveric study 

Objective

To compare biomechanical properties of a single stand-alone interbody fusion and a single-level pedicle screw construct above a previous lumbar pedicle fusion.

Summary of background data

Adjacent segment disease (ASD) is spondylosis of adjacent vertebral segments after previous spinal fusion. Despite the consensus that ASD is clinically significant, the surgical treatment of ASD is controversial.

Methods

Lateral lumbar interbody fusion (LLIF) and posterior spinal fusion (PSF) with pedicle screws were analyzed within a validated cadaveric lumbar fusion model. L3-4 vertebral segment motion was analyzed within the following simulations: without implants (intact), L3-4 LLIF-only, L3-4 LLIF with previous L4-S1 PSF, L3-4 PSF with previous L4-S1 PSF, and L4-S1 PSF alone. L3-4 motion values were measured during flexion/extension with and without axial load, side bending, and axial rotation.

Results

L3-4 motion in the intact model was found to be 4.7 ± 1.2 degrees. L3-4 LLIF-only decreased motion to 1.9 ± 1.1 degrees. L3-4 LLIF with previous L4-S1 fusion demonstrated less motion in all planes with and without loading (p < 0.05) compared to an intact spine. However, L3-4 motion with flexion/extension and lateral bending was noted to be greater compared to the L3-S1 construct (p < 0.5). The L3-S1 PSF construct decreased motion to less than 1° in all planes of motion with or without loading (p < 0.05). The L3-4 PSF with previous L4-S1 PSF constructs decreased the flexion/extension motion by 92.4% compared to the intact spine, whereas the L3-4 LLIF with previous L4-S1 PSF constructs decreased motion by 61.2%.

Conclusions

Stand-alone LLIF above a previous posterolateral fusion significantly decreases motion at the adjacent segment, demonstrating its utility in treating ASD without necessitating revision. The stand-alone LLIF is a biomechanically sound option in the treatment of ASD and is advantageous in patient populations who may benefit from less invasive surgical options.

Anterior lumbar interbody fusion (ALIF): biometrical results and own experiences

Lumbar fusion is a mainstay in the treatment of low back pain resulting from degenerative disc disease. Anterior lumbar interbody fusion (ALIF) has become a reasonable treatment technique to achieve indirect foraminal decompression with high fusion rates. The aim of the study was to analyse the biometrical parameters of the lumbar spine and the clinical outcome. The medical records of 51 patients treated with ALIF between 2012 and 2016 were retrospectively reviewed. Anterior and posterior disc height (DH), lumbar lordosis (LL), local disc angle (LDA) and foraminal dimensions were obtained on pre- and postoperative plain radiographs and computed tomography scans using ImageJ and Surgimap software according to the pedicle–pedicle technique. To evaluate the interbody fusion status on the last follow-up CT scans, we used Bridwell criteria. Preoperative and 12 months postoperative Oswestry Disability Index (ODI) scores were determined for all patients. The average length of hospitalisation was 4 days. Most of the patients had degenerative disc disease with foraminal stenosis. Five patients had early complications like paresthesia of lower limbs, sympathetic dysfunction or wound infections, but there were no major complications. Statistically significant (P < .01) improvement was observed in foraminal dimensions (area = 49%, height = 33% and width = 19%), anterior DH (49%), posterior DH (69%), LDA (47%) and LL (17.5%). Posterior DH correlated significantly with foramen height improvement. Radiographic evidence of fusion according to the modified Bridwell criteria (grade I and grade II) was observed in 96% (49/51) of the patients in the last CT of the lumbar spine. We also observed significant improvement in functional recovery in 94% of patients. The mini-open ALIF approach is a reasonable alternative to the more extensive posterior approaches. ALIF significantly restores the height of the intervertebral disc, indirectly increases foraminal dimensions, increases lordosis angle with significant short and long-term pain relief and functional recovery.

Microscopic Anterior Neural Decompression Combined with Oblique Lumbar Interbody Fusion-A Technical Note

BACKGROUND

Minimally invasive oblique lumbar interbody fusion (OLIF) techniques generally rely on deformity correction to achieve indirect neural decompression. However, indirect neural decompression will not always be sufficient. Thus, a second procedure, such as posterior direct decompression, will be added for full decompression, increasing the surgical morbidity and healthcare costs. We have described a technique of direct anterior microscopic neural decompression combined with OLIF.

METHODS

We report our surgical technique of anterior lumbar neural microscopic decompression with OLIF with patients in the lateral position. We also report the cases of 3 patients treated from March 2018 to June 2018.

RESULTS

Three patients underwent anterior microscopic neural decompression combined with OLIF in the lateral position. All 3 patients achieved clinically and radiologically significant neural decompression and deformity correction. No perioperative complications developed.

CONCLUSION

Direct anterior microscopic neural decompression is feasible and safe in selected patients undergoing OLIF.

The role of diffusion tensor imaging as an objective tool for the assessment of motor function recovery after paraplegia in a naturally-occurring large animal model of spinal cord injury

Background

Traumatic spinal cord injury (SCI) results in sensory and motor function impairment and may cause a substantial social and economic burden. For the implementation of novel treatment strategies, parallel development of objective tools evaluating spinal cord (SC) integrity during motor function recovery (MFR) is needed. Diffusion tensor imaging (DTI) enables in vivo microstructural assessment of SCI.

Methods

In the current study, temporal evolvement of DTI metrics during MFR were examined; therefore, values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured in a population of 17 paraplegic dogs with naturally-occurring acute SCI showing MFR within 4 weeks after surgical decompression and compared to 6 control dogs. MRI scans were performed preoperatively and 12 weeks after MFR was observed. DTI metrics were obtained at the lesion epicentre and one SC segment cranially and caudally. Variance analyses were performed to compare values between evaluated localizations in affected dogs and controls and between time points. Correlations between DTI metrics and clinical scores at follow-up examinations were assessed.

Results

Before surgery, FA values at epicentres were higher than caudally (p = 0.0014) and control values (p = 0.0097); ADC values were lower in the epicentre compared to control values (p = 0.0035) and perilesional (p = 0.0448 cranially and p = 0.0433 caudally). In follow-up examinations, no significant differences could be found between DTI values from dogs showing MFR and control dogs. Lower ADC values at epicentres correlated with neurological deficits at follow-up examinations (r = − 0.705; p = 0.0023).

Conclusions

Findings suggest that a tendency to the return of DTI values to the physiological situation after surgical decompression accompanies MFR after SCI in paraplegic dogs. DTI may represent a useful and objective clinical tool for follow-up studies examining in vivo SC recovery in treatment studies.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1630-4) contains supplementary material, which is available to authorized users.