Proximal junctional kyphosis in adult spinal deformity with long spinal fusion from T9/T10 to the ilium

An evidence based conceptual framework for the multifactorial understanding of proximal junctional kyphosis

Introduction

Adult spinal deformity (ASD) is a debilitating pathology that arises from a variety of etiologies. Spinal fusion surgery is the mainstay of treatment for those who do not achieve symptom relief with conservative interventions. Fusion surgery can be complicated by a secondary deformity termed proximal junctional kyphosis (PJK).

Research question

This scoping review evaluates the modern body of literature analyzing risk factors for PJK development and organizes these factors according to a multifactorial framework based on mechanical, tissue or demographic components.

Materials and methods

An extensive search of the literature was performed in PubMed and Embase back to the year 2010. Articles were assessed for quality. All risk factors that were evaluated and those that significantly predicted the development of PJK were compiled. The frequency that a risk factor was predictive compared to the number of times it was evaluated was calculated.

Results

150 articles were reviewed. 57.3% of papers were of low quality. 76% of risk factors analyzed were focusing on the mechanical contribution to development of PJK versus only 5% were focusing on the tissue-based contribution. Risk factors that were most frequently predictive compared to how often they were analyzed were Hounsfield Units of vertebrae, UIV disc degeneration, paraspinal muscle cross sectional area and fatty infiltration, ligament augmentation, instrument characteristics, postoperative hip and lower extremity radiographic metrics, and postoperative teriparatide supplementation.

Discussion and conclusion

This review finds a multifactorial framework accounting for mechanical, patient and tissue-based risk factors will improve the understanding of PJK development.

Global Sagittal Angle and T9-tilt seem to be the most clinically and functionally relevant global alignment parameters in patients with Adult Spinal Deformity

Introduction

Radiographic analysis is necessary for the assessment and the surgical planning in adults with spinal deformity (ASD). Restoration of global alignment is key to improving patient's quality of life. However, the large number of existing global alignment parameters can be confusing for surgeons.

Research question

To determine the most clinically and functionally relevant global alignment parameters in ASD.

Material and methods

ASD and controls underwent full body biplanar X-ray to calculate global alignment parameters: odontoid to hip axis angle (OD-HA), global sagittal angle (GSA), global tilt (GT), SVA, center of auditory meatus to hip axis (CAM-HA), SSA, T1-tilt and T9-tilt. All subjects filled HRQoL questionnaires: ODI, SF-36, VAS for pain and BDI (Beck's Depression Inventory). 3D gait analysis was performed to calculate kinematic and spatio-temporal parameters. A machine learning model predicted gait parameters and HRQoL scores from global alignment parameters.

Results

124 primary ASD and 47 controls were enrolled. T9 tilt predicted the most BDI (31%), hip flexion/extension during gait (36%), and double support time (39%). GSA predicted the most ODI (26%), thorax flexion/extension during gait (33%), and cadence (36%).

Discussion and conclusion

Among all global alignment parameters, GSA, evaluating both trunk shift and knee flexion, and T9 tilt, evaluating the shift of the center of mass, were the best predictors for most of HRQoL scores and gait kinematics. Therefore, we recommend using GSA and T9 tilt in clinical practice when evaluating ASD because they represent the most quality of life and functional kinematic of these patients.

Effect of overcorrection on proximal junctional kyphosis in adult spinal deformity: analysis by age-adjusted ideal sagittal alignment

BACKGROUND CONTEXT

The effect of the degree of lumbar lordosis (LL) correction on proximal junctional kyphosis (PJK) has not been analyzed in context of the age-adjusted sagittal alignment goal.

PURPOSE

To determine the effect of sagittal correction on the incidence of PJK after an age-adjusted analysis in patients with adult spinal deformity (ASD).

STUDY DESIGN/SETTING

Retrospective comparative study.

PATIENT SAMPLE

Seventy-eight ASD patients who underwent deformity correction.

OUTCOME MEASURES

Visual analog scale (VAS), Oswestry Disability Index (ODI), and imaging.

METHODS

This study included 78 ASD patients who underwent deformity correction and were followed-up more than 2 years. Patients were grouped according to the degree of LL correction relative to pelvic incidence (PI) by adjusting for age using the following formula: (age-adjusted ideal PI - LL) - (postoperative PI - LL). These were group U (undercorrection; <-10˚, N=15), group I (ideal correction; -10˚-10˚, N=34), and group O (over correction, >10˚, N=29). Various clinical and radiological parameters were compared among groups. The risk factors for PJK were also evaluated.

RESULTS

The overall incidence of PJK was 32.1% (25/78), with significantly higher PJK rate in group O (48.3%) compared with groups U (13.3%) and I (26.5%) (p=.041). The degree of postoperative LL correction relative to the PI by adjusting for age was a risk factor for the development of PJK (11.4° for PJK vs. 0.2° for non-PJK, p=.033). In addition, 2-year postoperative VAS (7.0 vs. 3.4, p<.001) and ODI (28.9 vs. 24.8, p=.040) scores were significantly higher in the PJK group than in the non-PJK group. A small PI (PI < 45°) was associated with a tendency of overcorrection (73.3%, P < 0.001) and thereby with the high incidence of PJK (53.3%, p=.005).

CONCLUSIONS

Overcorrection of LL relative to PI considering age-adjusted ideal sagittal alignment tends to increase the incidence of PJK. The incidence of PJK is expected to be high in patients with low PI (<45°) because of the tendency of overcorrection. To reduce the risk of PJK, surgeons should take age-adjusted parameters into account and exercise caution not to overcorrect patients with low PI, since this can result in suboptimal clinical outcomes.

Surgical Restoration of Sagittal Alignment of the Spine: Correlation with Improved Patient-Reported Outcomes: A Systematic Review and Meta-Analysis

BACKGROUND

The sagittal-plane curvatures of the human spine are the consequence of evolution from quadrupedalism to bipedalism and are needed to maintain the center of mass of the body within the base of support in the bipedal position. Lumbar degenerative disorders can lead to a decrease in lumbar lordosis and thereby affect overall alignment of the spine. However, there is not yet enough direct evidence that surgical restoration of spinal malalignment would lead to a better clinical outcome. Therefore, the aim of this study was to assess the correlation between patient-reported outcomes and actual obtained spinal sagittal alignment in adult patients with lumbar degenerative disorders who underwent surgical treatment.

METHODS

A comprehensive literature search was conducted through databases (PubMed, Cochrane, Web of Science, and Embase). The last search was in November 2018. Risk of bias was assessed with the Newcastle-Ottawa quality assessment scale. A meta-regression analysis was performed.

RESULTS

Of 2,024 unique articles in the original search, 34 articles with 973 patients were included. All studies were either retrospective or prospective cohort studies; no randomized controlled trials were available. A total of 54 relations between preoperative-to-postoperative improvement in patient-reported outcome measures (PROMs) and radiographic spinopelvic parameters were found, of which 20 were eligible for meta-regression analysis. Of these, 2 correlations were significant: pelvic tilt (PT) versus Oswestry Disability Index (ODI) (p = 0.009) and PT versus visual analog scale (VAS) pain (p = 0.008).

CONCLUSIONS

On the basis of the current literature, lower PT was significantly correlated with improved ODI and VAS pain in patients with sagittal malalignment caused by lumbar degenerative disorders that were treated with surgical correction of the sagittal balance.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Posterior Polyethylene Tethers Reduce Occurrence of Proximal Junctional Kyphosis After Multilevel Spinal Instrumentation for Adult Spinal Deformity: A Retrospective Analysis

BACKGROUND

Proximal junctional kyphosis (PJK) is a common postoperative complication after adult spinal deformity (ASD) surgery and may manifest with neurological decline, worsening spinal deformity, and spinal instability, which warrant reoperation. Rates of PJK may be as high as 69.4% after ASD surgery.

OBJECTIVE

To evaluate the efficacy of junctional tethers for PJK prophylaxis after multilevel instrumented surgery for ASD with minimum 2-yr follow-up.

METHODS

Single-center retrospective analysis of adult patients (age ≥18 yr) who underwent ASD surgery with index operations performed between November 2010 and June 2016 and achieved minimum 2-yr follow-up. Patients with ASD were subdivided into 3 treatment cohorts based on institutional protocol: no tether (NT), polyethylene tether-only (TO), and tether with crosslink (TC). PJK was defined as a proximal junctional angle (PJA) >10° and 10° greater than the corresponding preoperative measurement. Patient demographics, operative details, standard radiographic scoliosis measurements (including PJA and assessment of PJK), and complications were analyzed.

RESULTS

Of 184 patients, 146 (79.3%) achieved minimum 2-yr follow-up (mean = 45 mo; mean age = 67 yr; 67.8% women). PJK rates reported for the NT, TO, and TC cohorts were 60.7% (37/61), 35.7% (15/42), and 23.3% (10/43), respectively. PJK rates among TC patients were significantly lower than NT (P = .01601).

CONCLUSION

Junctional tethers with crosslink significantly reduced the incidence of PJK and revisions for PJK among ASD patients treated with long-segment posterior instrumented fusions who achieved minimum 2-yr follow-up.

The Hybrid Open Muscle-Sparing Approach in Adult Spinal Deformity Patients Undergoing Lower Thoracic Fusion to the Pelvis

Proximal junctional kyphosis (PJK) is a difficult complication to manage following adult spinal deformity surgery. Particularly in spinal fusions from the lower thoracic spine down to pelvis, PJK is a major consideration. While the open posterior approach allows for excellent visualization and preparation of bony surfaces for fusion, disruption of posterior soft tissue structures increases risk of PJK postoperatively. Minimally invasive approaches, on the other hand, preserve posterior ligamentous structures and musculature at the proximal fusion levels however prevent the access afforded by an open approach. We describe here the hybrid open muscle-sparing approach—a technique that allows for decortication of bony surfaces as well as clear exposure of anatomic landmarks for freehand pedicle screw placement, while protecting the posterior soft tissue structures to reduce risk of PJK.

Incidence and risk factors of proximal junctional kyphosis after internal fixation for adult spinal deformity: a systematic evaluation and meta-analysis

To investigate the factors associated with proximal junctional kyphosis (PJK). A systematic search was performed. The weighted mean difference (WMD) was pooled for continuous variables, and the odds ratio (OR) was calculated for dichotomous variables. The PJK group had higher values for age (WMD = 2.53, 95%CI = 1.38 ~ 3.68, P < 0.001), female gender (OR = 1.56, 95%CI = 1.29 ~ 1.87, P < 0.001), and diagnosed osteoporosis (OR = 1.58, 95%CI = 1.11 ~ 2.26, P = 0.01). Preoperatively, significant differences were detected in sagittal vertical axis (SVA) (WMD = 19.29, 95%CI = 16.60 ~ 21.98, P < 0.001), pelvic incidence minus lumbar lordosis (PI-LL) (WMD = 2.71, 95%CI = 0.25 ~ 5.18, P = 0.03), pelvic tilt (PT) (WMD = 2.64, 95%CI = 1.38 ~ 3.90, P < 0.001), lumbar lordosis (LL) (WMD = - 1.76, 95%CI = - 2.73 ~ -0.79, P < 0.001), and sacral slope (SS) (WMD = - 2.80, 95%CI = - 5.57 ~ -0.04, P = 0.001). At follow-up, the following were higher in the PJK group: thoracic kyphosis (TK) (WMD = 5.51, 95%CI = 2.23 ~ 8.80, P < 0.001), proximal junctional angle (PJA) (WMD = 9.07, 95%CI = 4.21 ~ 13.92, P < 0.001), and PT (WMD = 1.51, 95%CI = 0.31 ~ 2.72, P = 0.01). However, there was no significant difference in SS (P = 0.49), and SVA (P = 0.11) between groups. Fusion to S1 or pelvis significantly increased the risk of PJK (OR = 2.08, P < 0.001). Ligament augmentation reduced the risk of PJK (OR = 0.34, 95%CI = 0.21 ~ 0.53, P < 0.001) better than the use of laminar hook (OR = 0.46, P < 0.001). Although no difference was detected for preoperative SRS-22 score (P = 0.056), a lower score (WMD = - 0.24, 95%CI = - 0.35 ~ -0.14, P < 0.001) was detected in PJK group at follow-up. The elderly female ASD patients were more susceptible to PJK, especially for those with osteoporosis, high preoperative SVA, low LL, large PT, and LIV extended to pelvis. The use of laminar hook and ligament reinforcement at the proximal end might prevent PJK.

Changes in Thoracic Kyphosis and Thoracolumbar Kyphosis in Asymptomatic Korean Male Subjects Aged >50 Years: Do They Progress Above T5, T10, T12, or L2?

Study Design

Retrospective analysis of prospectively collected data.

Purpose

To evaluate the natural progression of segmental kyphosis in thoracic and thoracolumbar spine with advancing age.

Overview of Literature

To our knowledge, the evolution of segmental thoracic kyphosis (TK) in individuals aged >50 years has not been reported.

Methods

Total 179 normal, asymptomatic Korean men were divided in to three groups (6th, 7th, and 8th decade) according to their age. Standard sagittal spinopelvic parameters, including TK and thoracolumbar kyphosis, were measured and subdivided into the following four segments: A (C7 upper end plate [UEP]–T5 UEP), B (T5 UEP–T10 UEP), C (T10 UEP–T12 lower end plate [LEP]), and D (T12 LEP–L2 LEP). These segments of the three study groups were analyzed.

Results

In segment B, the segmental kyphosis of group 3 (20.2°±8.0°) showed a statistically larger value than that of group 1 (15.6°±6.8°) and group 2 (16.7°±8.8°) (p=0.017). In segment C, the segmental kyphosis of group 2 (12.9°±6.5°) and group 3 (12.2°±7.1°) showed statistically larger values than that of group 1 (9.5°±6.2°) (p=0.016). The A and D segments of the three groups were not significantly different.

Conclusions

Increased TK was observed in the middle (segment B) and lower (segment C) thoracic segments in normal asymptomatic male subjects with age. The results from the natural progression of segmental kyphosis with age would provide baseline reference data to help surgeons choose the optimal point of the upper instrumented vertebra level for preventing proximal junctional kyphosis.

Clinical and Radiological Outcomes of Corrective Surgery on Adult Spinal Deformity Patients: Comparison of Short and Long Fusion

Despite the accumulated knowledge of spinal alignment and clinical outcomes the full corrective surgery cannot be applied to all the deformity patients as it requires considerable surgical burden to the patients. The aim of this study was to investigate the clinical and radiological outcomes of the patients who have received short and long fusion for ASD. A total of 21 patients who received surgical reconstructive spinal fusion procedures and were followed up for at least one year were retrospectively reviewed. Sixteen cases have received spinal corrective surgery that upper instrumented vertebrate (UIV) was thoracic level (group T), or 5 cases were with UIV in lumbar level (group L). Group L had shorter operation time, smaller intraoperative estimated blood loss, and shorter postoperative hospitalization days. Group T tends to improve more in the magnitude of VAS of lumbar pain compared to group L. Improvement of spinal alignment revealed the advantage of long fusion compared to short fusion, in Cobb angle, sagittal vertical axis (SVA), lumbar lordosis (LL), PI-LL C7 plum line (C7PL), and center sacral vertebral line (CSVL). Pelvic tilt (PT) did not differ between the groups. Disc lordosis was the most acquired in XLIF compared to TLIF and PLF and maintained one year. There were 9 adverse events, 3 cases of pulmonary embolism (PE), one case of delirium, and 6 cases of proximal junctional kyphosis. Current study elucidated that long fusion, UIV, is thoracic and can achieve better spinal alignment compared to short fusion, UIV, in lumbar. XLIF demonstrated strong ability to reconstruct the deformity on intervertebral space that is better to apply as much intervertebral space as possible. For the ASD patients with complications, short fusion can be one of the options.