The prevalence of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) in patients undergoing circumferential minimally invasive surgical (cMIS) correction for adult spinal deformity: long-term 2- to 13-year follow-up

Proximal Junctional Kyphosis and Failure Prophylaxis Improves Cost Efficacy, While Maintaining Optimal Alignment, in Adult Spinal Deformity Surgery

BACKGROUND AND OBJECTIVES

To investigate the cost-effectiveness and impact of prophylactic techniques on the development of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) in the context of postoperative alignment.

METHODS

Adult spinal deformity patients with fusion to pelvis and 2-year data were included. Patients receiving PJK prophylaxis (hook, tether, cement, minimally-invasive surgery approach) were compared to those who did not. These cohorts were further stratified into "Matched" and "Unmatched" groups based on achievement of age-adjusted alignment criteria. Costs were calculated using the Diagnosis-Related Group costs accounting for PJK prophylaxis, postoperative complications, outpatient health care encounters, revisions, and medical-related readmissions. Quality-adjusted life years were calculated using Short Form-36 converted to Short-Form Six-Dimension (SF-6D) and used an annual 3% discount rate. Multivariate analysis controlling for age, sex, levels fused, and baseline deformity severity assessed outcomes of developing PJK/PJF if matched and/or with use of PJK prophylaxis.

RESULTS

A total of 738 adult spinal deformity patients met inclusion criteria (age: 63.9 ± 9.9, body mass index: 28.5 ± 5.7, Charlson comorbidity index: 2.0 ± 1.7). Multivariate analysis revealed patients corrected to age-adjusted criteria postoperatively had lower rates of developing PJK or PJF (odds ratio [OR]: 0.4, [0.2-0.8]; P = .011) with the use of prophylaxis. Among those unmatched in T1 pelvic angle, pelvic incidence lumbar lordosis mismatch, and pelvic tilt, prophylaxis reduced the likelihood of developing PJK (OR: 0.5, [0.3-0.9]; P = .023) and PJF (OR: 0.1, [0.03-0.5]; P = .004). Analysis of covariance analysis revealed patients matched in age-adjusted alignment had better cost-utility at 2 years compared with those without prophylaxis ($361 539.25 vs $419 919.43; P < .001). Patients unmatched in age-adjusted criteria also generated better cost ($88 348.61 vs $101 318.07; P = .005) and cost-utility ($450 190.80 vs $564 108.86; P < .001) with use of prophylaxis.

CONCLUSION

Despite additional surgical cost, the optimization of radiographic realignment in conjunction with prophylaxis of the proximal junction appeared to be a more cost-effective strategy, primarily because of the minimization of reoperations secondary to mechanical failure. Even among those not achieving optimal alignment, junctional prophylactic measures were shown to improve cost efficiency.

Minimally Invasive Versus Open Surgery for Thoracolumbar Fractures Treatment : A Meta-analysis of Randomized Controlled Trials and Prospective Studies

STUDY DESIGN

Meta-analysis.

OBJECTIVE

The purpose of this systematic review and meta-analysis was to pool the available data comparing MIS to open surgery for thoracolumbar fractures and provide a more comprehensive assessment of this topic.

BACKGROUND

There remains a debate over whether minimally invasive surgery (MIS) or open fixation provides superior outcomes for patients with thoracolumbar fractures. While several randomized controlled trials and prospective studies have compared these two approaches, the published studies are limited by sample size.

METHODS

Following PRISMA guidelines, a systematic review of the PubMed, Cochrane, and Google Scholar (pages 1-20) databases was performed on October 1, 2024. The extracted data consisted of complications, surgery-related parameters, early and late postoperative back pain, and postoperative regional kyphosis.

RESULTS

Five RCTs and five prospective studies were included in the meta-analysis, including 584 patients, with 299 in the MIS group and 285 in the open group. MIS patients were shown to have less EBL (MD=-155.86; 95% CI: -217.97 to -93.76, P <0.001), a shorter LOS (MD=-3.34; 95% CI: -4.62 to -2.06, P <0.001), lower pain scores during the early postoperative period (MD=-1.14; 95% CI: -1.56 to -0.71, P <0.001), and less regional kyphosis (MD=-5.17; 95% CI: -7.17 to -3.16, P <0.001), even when stratifying by study type. In addition, fluoroscopy time was longer in the MIS group (MD=0.60; 95% CI: 0.21-0.98, P =0.003), although this difference was not seen when looking at RCTs only.

CONCLUSIONS

Among patients with thoracolumbar fractures, treatment with MIS was associated with decreased EBL, shorter LOS, earlier pain reduction, and less regional kyphosis compared with treatment with open fixation. In addition, higher radiation exposure was seen among patients treated with MIS. While MIS offers several potential benefits, both MIS and open fixation remain safe and reliable options for the treatment of thoracolumbar fractures.

Impact of Paraspinal Muscle Degeneration on Surgical Outcomes and Radiographical Sagittal Alignment in Adult Spinal Deformity: A Multicenter Study

OBJECTIVE

This multicenter study aimed to evaluate the impact of paravertebral muscles (PVMs) degeneration, particularly fat infiltration, on preoperative sagittal imbalance, and postoperative complications and sagittal alignment change in patients with adult spinal deformity (ASD).

METHODS

A retrospective analysis was conducted on 454 patients who underwent ASD surgery across 5 institutions. Patients were classified into 2 groups based on paraspinal muscle fat infiltration on MRI: those with significant infiltration (FI-PVM(+)) and those with minimal or no infiltration (FI-PVM(-)). Propensity score matching was performed to adjust for demographic factors and preoperative radiographical parameters. Spinopelvic parameters were assessed preoperatively, postoperatively, and at a 2-year follow-up. Mechanical complications were compared between the groups.

RESULTS

The FI-PVM(+) group showed greater sagittal vertical axis (86.4 ± 57.5 vs. 51.8 ± 59.2, p < 0.001) preoperatively and required more extensive surgical correction with a significantly greater number of fused vertebral levels (7.3 ± 3.7 vs. 6.7 ± 3.7, p < 0.039). After propensity score matching, both groups showed significant improvement in spinopelvic alignment postoperatively, maintained throughout the 2-year follow-up. However, the FI-PVM(+) group demonstrated a trend toward a higher incidence of distal junctional kyphosis (6.3% vs. 0.9%, p = 0.070) and exhibited significantly greater decrease in pelvic tilt postoperatively (4.3° ± 7.6° vs. 1.3° ± 8.2°, p = 0.006).

CONCLUSION

Fat infiltration in PVM is associated with increased surgical complexity and a higher risk of mechanical complications. Preoperative assessment of muscle quality, along with targeted rehabilitation and closer postoperative monitoring, may be crucial for improving long-term outcomes in ASD surgery.

Segmental Interbody, Muscle-Preserving, Ligamentotaxis-Enabled Reduction: "SIMPLER" Technique for cMIS Correction of ASD

BACKGROUND

Correction of adult spinal deformity (ASD) through minimally invasive techniques is a challenging endeavor and has typically been reserved for experienced surgeons. This publication aims to be the first high-resolution technique guide to demonstrate a reproducible technique for ASD correction utilizing circumferential minimally invasive surgery (cMIS) without an osteotomy. The Segmental Interbody, Muscle-Preserving, Ligamentotaxis-Enabled Reduction (SIMPLER) technique is a novel ligamentotaxis-based scoliosis surgery that represents a paradigm shift from traditional osteotomies toward patient-specific correction.

METHODS

The senior author's (N.A.) cMIS technique for ASD correction without an osteotomy is described using high-resolution photographs, computer-generated imagery (CGI), and a case example. Step-by-step intraoperative photographs document a novel muscle-preserving posterior spinal exposure, spinal robotic safety protocol for instrumentation, dedicated deformity instrumentation system, rod reduction sequence, and minimally invasive fusion technique. CGI assists to reinforce technical considerations described by intraoperative photographs.

RESULTS

The SIMPLER technique is documented from incision to closure with high-resolution pictures including CGI to highlight concepts documented in photographs. Technical considerations were detailed for all aspects involved in the planning and execution of an osteotomy-free deformity correction.

CONCLUSION

This represents the first in-depth technical description of ligamentotaxis-based, osteotomy-free, ASD scoliosis correction. The SIMPLER approach is reproducible and minimally invasive and can be done routinely for appropriately selected deformity candidates. This technique serves as a foundation to externally validate previously described cMIS ASD deformity correction outcomes.

CLINICAL RELEVANCE

Circumferential minimally invasive spinal deformity correction is reproducible and can be achieved reliably through the use of the SIMPLER technique, without the use of an osteotomy.

LEVEL OF EVIDENCE: 5

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.

Hardware failure following multilevel posterior percutaneous fixation using the minimally invasive antepsoas (MIS-ATP) approach in adult spine deformity

Background

Adult spinal deformities (ASDs) requiring long fusions to the lumbosacral junction are notorious for L5-S1 pseudarthrosis and hardware-related complications. The minimally invasive surgery antepsoas (MIS-ATP) technique allows for substantial anterior column reconstruction thereby reducing the risk of posterior hardware-related complications. This study investigates the incidence of posterior hardware-related complications following long-segment fusion (seven or more vertebrae) using MIS-ATP and posterior percutaneous fixation (PPF).

Methods

This is a retrospective review of patients who underwent long spinal fusion (MIS-ATP + PPF) to the sacrum and pelvis for the management of ASD between 2008 and 2019. Postoperative clinical complications and radiographic parameters were collected and analyzed. The following postoperative variables were collected: surgical site infections, neuro-vascular injuries, implant fracture, implant displacement, hardware prominence and related pain, pseudarthrosis, junctional disease (proximal and distal), and need for surgical revision.

Results

A total of 143 patients were included in this study. The most common indications for fusion included: degenerative scoliosis (76.9%) and degenerative spondylolisthesis (17.5%). The average number of fused vertebrae per individual was 8.7. The most common levels fused were: T12-S1 anterior/T10-S1 posterior (53.1%). Forty-four patients (30.8%) experienced a total of 48 complications: pseudarthrosis (2.1%), deep infections (4.2%), painful iliac hardware (5.6%), pedicle screw complications (6.3%), and proximal junctional disease (PJD) (9.8%). Of these, 30 patients (21%) required revision surgery, mostly due to PJD (8 patients; 5.6%).

Conclusions

Long spinal fusions to the sacrum and pelvis are technically challenging and notorious for hardware failure (HF) and revision surgeries. The use of MIS-ATP fusion coupled with PPF could provide a safe and effective strategy against posterior HF. Furthermore, additional benefits of the MIS-ATP technique are inherent to its relatively safe approach-related profile.

The Impact of Spine Pathology on Posterior Ligamentous Complex Structure and Function

PURPOSE OF REVIEW

Spinal ligament is an important component of the spinal column in mitigating biomechanical stress. Particularly the posterior ligamentous complex, which is composed of the ligamentum flavum, interspinous, and supraspinous ligaments. However, research characterizing the biomechanics and role of ligament health in spinal pathology and clinical context are scarce. This article provides a comprehensive review of the implications of spinal pathology on the structure, function, and biomechanical properties of the posterior ligamentous complex.

RECENT FINDINGS

Current research characterizing biomechanical properties of the posterior ligamentous complex is primarily composed of cadaveric studies and finite element modeling, and more recently incorporating patient-specific anatomy into finite element models. The ultimate goal of current research is to understand the relative contributions of these ligamentous structures in healthy and pathological spine, and whether preserving ligaments may play an important role in spinal surgical techniques. At baseline, posterior ligamentous complex structures account for 30-40% of spinal stability, which is highly dependent on the intrinsic biomechanical properties of each ligament. Biomechanics vary widely with pathology and following rigid surgical fixation techniques and are generally maladaptive. Often secondary to morphological changes in the setting of spinal pathology, but morphological changes in ligament may also serve as a primary pathology. Biomechanical maladaptations of the spinal ligament adversely influence overall spinal column integrity and ultimately predispose to increased risk for surgical failure and poor clinical outcomes. Future research is needed, particularly in living subjects, to better characterize adaptations in ligaments that can provide targets for improved treatment of spinal pathology.

Minimally Invasive Surgery Strategies to Prevent Proximal Junctional Kyphosis

Proximal junctional kyphosis (PJK) is a common complication following long-segment thoracolumbar fusions for patients with adult spinal deformities. PJK is described as a progressive kyphosis at the upper instrumented vertebra or 1 or 2 segments adjacent to the instrumented vertebra. This condition can lead to proximal junction failure, which results in vertebral body fractures, screw pullouts, and neurological deficits. Revision surgery is necessary to address symptomatic PJK. Research efforts have been dedicated to elucidating risk factors and prevention strategies. It has been postulated that minimally invasive surgery (MIS) techniques may help prevent PJK because these techniques aim to preserve the soft tissue integrity at the top of the construct and maintain posterior element support. In this article, the authors define PJK, describe MIS strategies to prevent PJK, and compare PJK rates after MIS with PJK rates after open approaches for long-segment thoracolumbar fusion.

Scoliosis

Scoliosis is a three-dimensional spinal deformity that can occur at any age. It may be idiopathic or secondary in children, idiopathic and degenerative in adults. Management of patients with scoliosis is multidisciplinary, involving rheumatologists, radiologists, orthopaedic surgeons, and prosthetists. Imaging plays a central role in diagnosis, including the search for secondary causes, follow-up, and preoperative work-up if surgery is required. Evaluating scoliosis involves obtaining frontal and lateral full-spine radiographs in the standing position, with analysis of coronal and sagittal alignment. For adolescent idiopathic scoliosis, imaging follow-up is often required, accomplished using low-dose stereoradiography such as EOS imaging. For adult degenerative scoliosis, the crucial characteristic is rotatory subluxation, also well detected on radiographs. Magnetic resonance imaging is usually more informative than computed tomography for visualizing associated canal and foraminal stenoses. Radiologists must also have a thorough understanding of postoperative features and complications of scoliosis surgery because aspects can be misleading.

Proximal Junctional Kyphosis or Failure After Adult Spinal Deformity Surgery - Review of Risk Factors and Its Prevention

Proximal junction kyphosis (PJK) is a common imaging finding after long-level fusion, and proximal junctional failure (PJF) is an aggravated form of the progressive disease spectrum of PJK. This includes vertebral fracture of upper instrumented vertebra (UIV) or UIV+1, instability between UIV and UIV+1, neurological deterioration requiring surgery. Many studies have reported on PJK and PJF after long segment instrumentation for adult spinal deformity (ASD). In particular, for spine deformity surgeons, risk factors and prevention strategies of PJK and PJF are very important to minimize reoperation. Therefore, this review aims to help reduce the occurrence of PJK and PJF by updating the latest contents of PJK and PJF by 2023, focusing on the risk factors and prevention strategies of PJK and PJF. We conducted a search on multiple database for articles published until February 2023 using the search keywords "proximal junctional kyphosis," "proximal junctional failure," "proximal junctional disease," and "adult spinal deformity." Finally, 103 papers were included in this study. Numerous factors have been suggested as potential risks for the development of PJK and PJF, including a high body mass index, inadequate postoperative sagittal balance and overcorrection, advanced age, pelvic instrumentation, and osteoporosis. Recently, with the increasing elderly population, sarcopenia has been emphasized. The quality and quantity of muscle in the surgical site have been suggested as new risk factor. Therefore, spine surgeon should understand the pathophysiology of PJK and PJF, as well as individual risk factors, in order to develop appropriate prevention strategies for each patient.

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.

Management of severe adult spinal deformity with circumferential minimally invasive surgical strategies without posterior column osteotomies: a 13-year experience

OBJECTIVE

To evaluate the mid- to long-term clinical outcomes of circumferential minimally invasive surgery (CMIS) without posterior column osteotomies for severe adult spine deformity (ASD) correction.

METHODS

All patients with a minimum of 2-year follow-up undergoing staged CMIS correction of ASD from January 2007 to July 2018 were identified. All included patients had fusion of 3 or more interbody levels that spanned the L5-S1 junction. Only patients with severe deformity, Coronal Cobb > 50° or at least one SRS-Schwab ++ sagittal modifier (SVA > 95 mm, or PI-LL > 20, or PT > 30) were included. All complications were noted.

RESULT

136 patients met inclusion criteria; mean age of patients was 63.6 years (21-85, SD 13.7). The mean follow-up was 82.8 months (24-159, SD 36.6). The mean number of levels fused was 7 (3-16, SD 3). A total of 40 (29.4%) major complications were noted at final follow-ups: 2 (1.4%) intra-operative, 12 (8.9%) peri-operative (≤ 6 weeks from index), 26 (19.1%) post-operative (> 6 weeks from index). There was a total of 53 (40.0%) minor complications. Seven (5.1%) patients who developed radiographic proximal junctional kyphosis. Three patients (2.2%) developed proximal junctional failure. There were 8 (5.9%) cases of pseudarthrosis. Five of these occurred in patients undergoing AxiaLIF. All patients experienced improvements in patient-perceived outcomes (VAS, TIS, ODI, and SRS-22) and radiographic parameters at last follow-up when compared to pre-op (p < 0.05).

CONCLUSION

Rates of complications with CMIS correction of severe ASD are lower than published rates of complications seen with open ASD correction. Specifically, the incidence of catastrophic complications is lower. Furthermore, CMIS is associated with significant improvements in clinical and functional outcomes, low rates of pseudarthrosis and proximal junctional kyphosis. Therefore, in the appropriately selected patient, CMIS may be an excellent alternative approach to addressing severe ASD.

Biomechanical Evaluation of Semi-rigid Junctional Fixation Using a Novel Cable Anchor System to Prevent Proximal Junctional Failure in Adult Spinal Deformity Surgery

STUDY DESIGN

A porcine cadaveric biomechanical study.

OBJECTIVE

To biomechanically evaluate a novel Cable Anchor System as semi-rigid junctional fixation technique for the prevention of proximal junctional failure after adult spinal deformity surgery and to make a comparison to alternative promising prophylactic techniques.

SUMMARY OF BACKGROUND DATA

The abrupt change of stiffness at the proximal end of a pedicle screw construct is a major risk factor for the development of proximal junctional failure after adult spinal deformity surgery. A number of techniques that aim to provide a gradual transition zone in range of motion (ROM) at the proximal junction have previously been studied. In this study, the design of a novel Cable Anchor System, which comprises a polyethylene cable for rod fixation, is assessed.

METHODS

Ten T6-T13 porcine spine segments were subjected to cyclic 4 Nm pure-moment loading. The following conditions were tested: uninstrumented, 3 level pedicle screw fixation (PSF), and PSF with supplementary Cable Anchors applied proximally at 1-level (Anchor1) or 2-levels (Anchor2), transverse process hooks (TPH), and 2-level sublaminar tapes (Tape2). The normalized segmental range of motion in the junctional zone was compared using one-way analysis of variance and linear regression.

RESULTS

Statistical comparison at the level proximal to PSF showed significantly lower ROMs for all techniques compared to PSF fixation alone in all movement directions. Linear regression demonstrated a higher linearity for Anchor1 (0.820) and Anchor2 (0.923) in the junctional zone in comparison to PSF (1-level: 0.529 and 2-level: 0.421). This linearity was similar to the compared techniques (TPH and Tape2).

CONCLUSION

The Cable Anchor System presented in this study demonstrated a gradual ROM transition zone at the proximal end of a rigid pedicle screw construct similar to TPH and 2-level sublaminar tape semi-rigid junctional fixation constructs, while providing the benefit of preserving the posterior ligament complex.Level of Evidence: 5.