Minimally invasive surgery in adult degenerative scoliosis: a systematic review and meta-analysis of decompression, anterior/lateral and posterior lumbar approaches

Static Versus Expandable Cages in Minimally Invasive Lateral Lumbar Interbody Fusion: A Systematic Review and Meta-Analysis

STUDY DESIGN

A meta-analysis approach to a systematic review.

OBJECTIVE

Perform a systematic review to identify all reports directly comparing outcomes of lateral lumbar interbody fusion (LLIF) using static versus expandable interbody cages. Specifically focusing on periprocedural complications, intraoperative morbidity, and fusion outcomes.

SUMMARY OF BACKGROUND DATA

Minimally invasive surgical techniques, particularly LLIF, have gained popularity for their potential to reduce muscle and soft tissue dissection, leading to faster postoperative recovery. LLIF has been associated with fewer complications compared with open posterior approaches. The introduction of expandable lumbar interbody devices aims to further reduce surgical difficulty and potential complications. However, concerns include a small graft window due to the expansion mechanism and higher costs.

METHODS

The Web of Science, Scopus, and PubMed databases were systematically queried in accordance with PRISMA guidelines to identify articles comparing outcomes following LLIF using static and expandable interbodies. The Newcastle-Ottawa Scale (NOS) was employed to assess the risk of bias (ROB) in the selected studies. Extracted data underwent effect-size meta-analysis with the PyMARE library, using P<0.05 to define statistical significance.

RESULTS

Of the 77 identified articles, 4 studies comprising 283 patients (mean age: 67.1 y, 55.8% female) met the inclusion and exclusion criteria. A total of 150 patients (53%) were treated with static interbodies compared with 133 (47%) receiving expandable interbodies. The groups did not differ significantly with respect to operative time (P=0.59), blood loss (P=0.89), length of stay (P=0.78), subsidence (P=0.49), 24-month mean disc height (P=0.11), 24-month mean ODI (P=0.58), or 24-month mean visual analog scale (VAS) back pain (P=0.81). The expandable group saw a trend toward improved fusion rates (97% vs. 92%, P=0.06).

CONCLUSIONS

The present meta-analysis suggests the use of expandable (vs. static) interbodies in LLIF surgery may result in similar surgical morbidity, subsidence, and decompression. Further prospective comparative studies are merited to validate these results.

Deformity Correction with Interbody Fusion Using Lateral versus Posterior Approach in Adult Degenerative Scoliosis: A Systematic Review and Observational Meta-analysis

This study was designed to systematically review and meta-analyze the functional and radiological outcomes between lateral and posterior approaches in adult degenerative scoliosis (ADS). Both lateral (lumbar, extreme, and oblique) and posterior interbody fusion (posterior lumbar and transforaminal) are used for deformity correction in patients with ADS with unclear comparison in this cohort of patients in the existing literature. A literature search using three electronic databases was performed to identify studies that reported outcomes of lateral (group L) and posterior interbody fusion (group P) in patients with ADS with curves of 10°-40°. Group P was further subdivided into minimally invasive surgery (MIS-P) and open posterior (Op-P) subgroups. Data on functional, radiological, and operative outcomes, length of hospital stay (LOHS), fusion rates, and complications were extracted and meta-analyzed using the random-effects model. A total of 18 studies (732 patients) met the inclusion criteria. No significant difference was found in functional and radiological outcomes between the two groups on data pooling. Total operative time in the MIS-P subgroup was less than that of group L (233.86 minutes vs. 401 minutes, p <0.05). The total blood loss in group L was less than that in the Op-P subgroup(477 mL vs. 1,325.6 mL, p <0.05). Group L had significantly less LOHS than the Op-P subgroup (4.15 days vs. 13.5 days, p <0.05). No significant difference was seen in fusion rates, but complications were seen except for transient sensorimotor weakness (group L: 24.3%, group P: 5.6%; p <0.05). Complications, such as postoperative thigh pain (7.7%), visceral injuries (2%), and retrograde ejaculation (3.7%), were seen only in group L while adjacent segment degeneration was seen only in group P (8.6%). Lateral approach has an advantage in blood loss and LOHS over the Op-P subgroup. The MIS-P subgroup has less operative time than group L, but with comparable blood loss and LOHS. No significant difference was found in functional, radiological, fusion rates, pseudoarthrosis, and complications, except for transient sensorimotor deficits. Few complications were approach-specific in each group.

What Are the Benefits of Lateral Lumbar Interbody Fusion on the Treatment of Adult Spinal Deformity: A Systematic Review and Meta-Analysis Deformity

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVE

The purpose of this systematic review and meta-analysis was to compare the efficacy of lateral lumbar interbody fusion (LLIF) combined with posterior spinal fusion (PSF) with that of conventional PSF in the treatment of adult spinal deformity (ASD).

METHODS

A comprehensive literature search was performed for relevant studies in PubMed, EMBASE, Web of Science, and the Cochrane Library. Spinopelvic parameters, surgical data, complications, and clinical outcomes at the last follow-up were compared between patients with ASD who underwent LLIF combined with PSF (LLIF+PSF group) and those who underwent conventional PSF (only-PSF group).

RESULTS

Ten studies, comprising 621 patients with ASD (313 in the LLIF+PSF group and 308 in the only-PSF group), were included. The level of evidence was III for 7 studies and IV for 3 studies. There was no significant difference in the improvement in the visual analog scale score, systemic complication rate, and revision rate between groups. In the LLIF+PSF group, we noted a superior restoration of lumbar lordosis (weighted mean difference [WMD], 9.77; 95% confidence interval [CI] 7.10 to 12.44, P < .001), pelvic tilt (WMD, -2.50; 95% CI -4.25 to -.75, P = .005), sagittal vertical axis (WMD, -21.92; 95% CI -30.73 to -13.11, P < .001), and C7 plumb line-center sacral vertical line (WMD, -4.03; 95% CI -7.52 to -.54, P = .024); a lower estimated blood loss (WMD, -719.99; 95% CI -1105.02 to -334.96, P < .001) while a prolonged operating time (WMD, 104.89; 95% CI 49.36 to 160.43, P < .001); lower incidence of pseudarthrosis (risk ratio [RR], .26; 95% CI .08 to .79, P = .017) while higher incidence of neurologic deficits (RR, 2.04; 95% CI 1.27 to 3.25, P = .003); and a better improvement in Oswestry Disability Index score (WMD, -7.04; 95% CI -10.155 to -3.93, P < .001) and Scoliosis Research Society-22 total score (WMD, .27; 95% CI .11 to .42, P = .001). The level of evidence in this systematic review and meta-analysis was II.

CONCLUSION

Compared with conventional PSF, LLIF combined with PSF was associated with superior restoration of sagittal and coronal alignment, lower incidence of pseudarthrosis, better improvement in quality of life, and less surgical invasiveness in the treatment of ASD, albeit at the cost of prolonged surgical times and substantially high incidence of lower extremity symptoms. Surgeons should weigh the advantages and disadvantages of this procedure, and inform patients about its side effects.

[Selection of upper instrumented vertebra for long-segment fixation in adult degenerative scoliosis]

Objective

To review the research progress of upper instrumented vertebra (UIV) selection strategy for long-segment fixation (LSF) in adult degenerative scoliosis (ADS).

Methods

The relevant domestic and foreign literature in recent years was reviewed, and the selection strategy of sagittal and coronal UIV for LSF in ADS patients, the relationship between UIV selection and proximal junctional kyphosis (PJK) and proximal junctional failure (PJF), the impact of minimally invasive spine surgery on the selection strategy of UIV were summarized.

Results

LSF can restore the biomechanical balance of the spine and reconstruct the physiological curve of the spine for ADS patients. LSF should be selected for ADS patients with severe scoliosis, vertebral rotation, and severe sagittal imbalance. For patients with poor general condition, UIV can choose the thoracic and lumbar vertebrae to reduce the operation time and intraoperative bleeding, which is conducive to early mobilization and reduce complications; for patients with good general condition, the upper thoracic vertebrae can be considered if necessary, in order to achieve satisfactory long-term effectiveness. However, the lower thoracic vertebra (T 9、10) should be selected as much as possible to reduce postoperative complications such as PJK and PJF. In recent years, a new reference marker, the first coronal reverse vertebra was proposed, to guide the selection of UIV. But a large-sample multicenter randomized controlled study is needed to further verify its reliability. Studies have shown that different races and different living habits would lead to different parameters of the spine and pelvis, which would affect the selection of UIV. Minimally invasive surgeries have achieved satisfactory results in the treatment of ADS, but the UIV selection strategy in specific applications needs to be further studied.

Conclusion

The selection strategy of UIV in LSF has not yet been unified. The selection of UIV in the sagittal plane of the upper thoracic spine, the lower thoracic spine, or the thoracolumbar spine should comprehensively consider the biomechanical balance of the spine and the general condition of the patient, as well as the relationship between the upper horizontal vertebra, the upper neutral vertebra, and the upper end vertebra on the coronal plane.

Comparison of Patient Preference, Understanding, and Sentiment for Minimally Invasive Versus Open Spine Surgery

STUDY DESIGN

Retrospective questionnaire analysis.

OBJECTIVE

The goal of this study was to analyze patients' understanding and preferences for minimally invasive spine (MIS) versus open spine surgery.

SUMMARY OF BACKGROUND DATA

MIS surgery is increasing in prevalence. However, there is insufficient literature to evaluate how the availability of MIS surgery influences the patients' decision-making process and perceptions of spine procedures.

METHODS

A survey was administered to patients who received a microdiscectomy or transforaminal lumbar interbody fusion between 2016 and 2020. All eligible patients were stratified into two cohorts based on the use of minimally invasive techniques. Each cohort was administered a survey that evaluated patient preferences, perceptions, and understanding of their surgery.

RESULTS

One hundred fifty two patients completed surveys (MIS: 88, Open: 64). There was no difference in time from surgery to survey (MIS: 2.1 ± 1.4 yrs, Open: 1.9 ± 1.4 yrs; P = 0.36) or sex (MIS: 56.8% male, Open: 53.1% male; P = 0.65). The MIS group was younger (MIS: 53.0 ± 16.9 yrs, Open: 58.2 ± 14.6 yrs; P = 0.05). More MIS patients reported that their technique influenced their surgeon choice (MIS: 64.0%, Open: 37.5%; P  < 0.00001) and increased their preoperative confidence (MIS: 77.9%, Open: 38.1%; P  < 0.00001). There was a trend towards the MIS group being less informed about the intraoperative specifics of their technique (MIS: 35.2%, Open: 23.4%; P = 0.12). More of the MIS cohort reported perceived advantages to their surgical technique (MIS: 98.8%, Open: 69.4%; P < 0.00001) and less reported disadvantages (MIS: 12.9%, Open: 68.8%; P < 0.00001). 98.9% and 87.1% of the MIS and open surgery cohorts reported a preference for MIS surgery in the future.

CONCLUSION

Patients who received a MIS approach more frequently sought out their surgeons, were more confident in their procedure, and reported less perceived disadvantages following their surgery compared with the open surgery cohort. Both cohorts would prefer MIS surgery in the future. Overall, patients have positive perceptions of MIS surgery.Level of Evidence: 3.

Correction of adult spinal deformity with a minimally invasive fusionless bipolar construct: Preliminary results

INTRODUCTION

Fusion in adult spinal deformity has a high rate of complications. Fusionless constructs in children and percutaneous fixation in adults are now being used routinely. The aim of this study was to evaluate the preliminary results of a minimally invasive fusionless surgical technique used to correct adult spinal deformity.

MATERIALS AND METHODS

Thirty-eight patients with an average age of 45 years (15-76) with major spinal deformity requiring extensive arthrodesis from the upper thoracic region to the pelvis were operated consecutively and followed prospectively. Two hooks were implanted at the top and two iliosacral screws at the bottom. Two large rods connected by dominos to two small rods joined the upper hooks to the lower screws. The surgical data (operative time and bleeding), the radiological findings (Cobb angle, sagittal parameters, C7-plumbline AP and lateral), the complication rate and the morbidity were evaluated at the last follow-up visit.

RESULTS

The primary curvature was reduced by 40% from a mean of 58.5° (26-146) to 35.2° (3-109) (p<0.001). A clear decrease in operating time (270min) and blood loss (50cc/level) were observed. The length of hospitalization averaged 18 days (6-66), including an 8-15 day long preoperative traction period for 11 patients. We found 7 infectious complications, 11 early mechanical complications and one case of paraplegia due to severe kyphoscoliosis.

CONCLUSION

The corrections obtained are comparable to those reported in the literature for standard constructs. Most patients had an uneventful postoperative course. The early complications observed led us to very carefully select the indications. Long-term follow-up is essential.

Posterior instrumented fusion surgery for adult spinal deformity: Correction rate and total balance

Background:

The primary radiological goal of surgery for adult spinal deformity (ASD) is the restoration of lumbar lordosis (LL). Radiological parameters were analyzed to determine the surgical indications for ASD using posterior side-loading spinal instrumentation system.

Materials and Methods:

This retrospective study included 31 patients of ASD who underwent posterior instrumented fusion surgery. Imaging parameters included spinal tilt angle (STA), LL, and thoracic kyphosis (TK). The ideal LL was estimated based on the normal value.

Results:

Of 16 patients with sagittal imbalance, 10 patients demonstrated sagittal balance postoperatively. All six patients with frontal imbalance showed frontal balance postoperatively. STA improvement well correlated with change of LL. On univariate analysis, preoperative TK was significantly associated with preoperative sagittal imbalance and postoperative lack of LL with postoperative sagittal imbalance.

Conclusions:

The surgical concept of ASD focusing on correction of LL was demonstrated. Although the surgery of ASD is still challenging, posterior instrumented fusion surgery using posterior side-loading system may be well applied for mild or moderate ASD without hyper-TK. The posterior side-loading system is practical and can be one of the surgical choices.

Nonunion of Transpsoas Lateral Lumbar Interbody Fusion Using an Allograft: Clinical Assessment and Risk Factors

Introduction

This retrospective study was performed to evaluate the clinical influence of - and to identify the risk factors for nonunion of transpsoas lateral lumbar interbody fusion (LLIF) with use of allograft.

Methods

Sixty-three patients who underwent transpsoas LLIF (69.8 ± 8.9 years, 21 males and 42 females, 125 segments) were followed for a minimum 2 years postoperatively. For all LLIF segments, polyetheretherketone (PEEK) cages packed with allogenic bone were applied with supplemental bilateral pedicle screws (PSs). Bone bridge formation was evaluated by computed tomography (CT) 2 years postoperative, and a segment without any bridge formation was determined to be a nonunion. Sixty-one participants (96.8%) were classified into two groups for clinical evacuation: Group N that contained one or more nonunion segments and Group F that contained no nonunion segment. Visual analogue scales (VAS) scores and the effective rates of the five domains of the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) were compared between Groups N and F. The risk factors for nonunion were determined by univariate and multivariate analyses.

Results

Twenty segments (16%) were diagnosed as nonunion. There were no significant differences in all VAS scores, and the ratio of effective cases in all domains of JOABPEQ between Group N (n = 14) and F (n = 47). Multivariate analysis identified percutaneous PS (PPS) usage (odds ratio [OR]: 3.14, 95% confidence interval: 1.13-8.68, p = 0.028) as a positive risk factor for nonunion.

Conclusions

We should be aware of the higher nonunion rate in the LLIF segments supplemented with PPS, though nonunion does not affect significantly clinical outcomes at 2 years postoperative.

Learning curves for minimally invasive spine surgeries: Are they worth it?

Background:

Minimally invasive surgery (MIS) spine procedures were developed to limit operative time, the extent of dissection, and reduce perioperative morbidity. Here, we asked what are the “learning curves” for these MIS spine procedures?

Methods:

We reviewed studies in the literature that discussed the “learning curves” attributed to performing different MIS spine surgical procedures. Of interest, the majority were single-surgeon series.

Results:

Very few articles assessed the learning curves for different MIS spine procedures. One study reported no learning curve for open vs. MIS discectomy/laminotomy. Another study indicated that 20–30 cases were required for a surgeon to become proficient in performing a variety of MIS spine fusions [e.g., cervical MIS fusions, MIS anterior lumbar interbody fusions (ALIF), MIS transforaminal lumbar interbody fusions (TLIF), and MIS pedicle/screw placement in the thoracic/lumbar spine]. Several other studies specifically cited that, to become proficient in the performance of TLIF, surgeons had to have performed between 10, to 32, to 40, to 44 such cases.

Conclusions:

There is a very limited literature available that focuses on the “learning curves” associated with the performance of different types of MIS spine procedures. The number of cases required to satisfy the “learning curves” for different operations varied from 0 for MIS vs. open discectomy/laminotomy, to 20-30 for a variety of cervical-thoracic-lumbar procedures, and up to 44 cases for TLIF. Shouldn’t we ask whether better oversight measures and/or mentoring programs could limit the morbidity/AE occurring during these “learning curves” in the future?