Progressive junctional kyphosis at the caudal end of lumbar instrumented fusion: etiology, predictors, and treatment

Distal Junctional Failures in Degenerative Thoracolumbar Hyperkyphosis

OBJECTIVE

Degenerative thoracolumbar hyperkyphosis (DTH) is a disease that negatively affects individual health and requires surgical intervention, yet the ideal surgical approach and complications, especially distal junctional failures (DJF), remain poorly understood. This study aims to investigate DJF in DTH and to identify the risk factors for DJF so that we can improve surgical decision-making, and advance our knowledge in the field of spinal surgery to enhance patient outcomes.

METHODS

This study retrospectively reviewed 78 cases (late osteoporotic vertebral compression fracture [OVCF], 51; Scheuermann's kyphosis [SK], 17; and degenerative disc diseases [DDD], 10) who underwent corrective surgery in our institute from 2008 to 2019. Clinical outcomes were assessed using health-related quality of life (HRQOL) measures, including the visual analogue scale (VAS) scores for back and leg pain, the Oswestry disability index (ODI), and the Japanese Orthopaedic Association (JOA) scoring system. Multiple radiographic parameters, such as global kyphosis (GK) and thoracolumbar kyphosis (TLK), were assessed to determine radiographic outcomes. Multivariate logistic regression analysis was employed to identify the risk factors associated with DJF.

RESULTS

HRQOL improved, and GK, TLK decreased at the final follow-up, with a correction rate of 67.7% and 68.5%, respectively. DJF was found in 13 of 78 cases (16.7%), two cases had wedging in the disc (L3-4) below the instrumentation, one case had a fracture of the lowest instrumented vertebrae (LIV), one case had osteoporotic fracture below the fixation, nine cases had pull-out or loosening of the screws at the LIV and three cases (23.1%) required revision surgery. The DJF group had older age, lower computed tomography Hounsfield unit (CT HU), longer follow-up, more blood loss, greater preoperative sagittal vertical axis (SVA), and poorer postoperative JOA and VAS scores (back). The change in TLK level was larger in the non-DJF group. Post-sagittal stable vertebrae (SSV) moved cranially compared with pre-SSV.

CONCLUSION

Age, CT HU, length of follow-up, estimated blood loss, and preoperative SVA were independent risk factors for DJF. We recommend fixation of the two vertebrae below the apex vertebrae for DTH to minimize surgical trauma.

Short-Term Risk Factors for Distal Junctional Kyphosis after Spinal Reconstruction Surgery in Patients with Osteoporotic Vertebrae

STUDY DESIGN

Level 3 retrospective cohort case-control study.

PURPOSE

This study aimed to investigate the risk factors for distal junctional kyphosis (DJK) caused by osteoporotic vertebral fractures following spinal reconstruction surgery, with a focus on the sagittal stable vertebra.

OVERVIEW OF LITERATURE

Despite the rarity of reports on DJK in this setting, DJK was reported to reduce when the lower instrumented vertebra (LIV) was extended to the sagittal stable vertebra in the posterior corrective fixation for Scheuermann's disease.

METHODS

This study included 46 patients who underwent spinal reconstruction surgery for thoracolumbar osteoporotic vertebral fractures and kyphosis and were followed up for 1 year postoperatively. DJK was defined as an advanced kyphosis angle >10° between the LIV and one lower vertebra. The patients were divided into groups with and without DJK. The risk factors of the two groups, such as patient background, surgery-related factors, radiographic parameters, and clinical outcomes, were analyzed.

RESULTS

The DJK and non-DJK groups included 14 and 32 patients, respectively, without significant differences in patient background. Those with instability in the distal adjacent LIV disc had a significantly higher risk of DJK occurrence (28.6% vs. 3.2%, p=0.027). DJK occurrence significantly increased in those with the sagittal stable vertebra not included in the fixation range (57.1% vs. 18.8%, p=0.020). Other preoperative radiographic parameters were not significantly different. Instability in the distal adjacent LIV disc (adjusted odds ratio, 14.50; p=0.029) and the exclusion of the sagittal stable vertebra from the fixation range (adjusted odds ratio, 5.29; p=0.020) were significant risk factors for DJK occurrence.

CONCLUSIONS

Regarding spinal reconstruction surgery in patients with osteoporotic vertebral fractures, instability in the distal adjacent LIV disc and the exclusion of the sagittal stable vertebra from the fixation range were risk factors for DJK occurrence in the short term.

Risk Factors for Distal Junctional Problems Following Long Instrumented Fusion for Degenerative Lumbar Scoliosis: Are they Related to the Paraspinal Muscles

PURPOSE

Although the incidence of distal junctional problems (DJPs) following long construct-based treatment for degenerative lumbar scoliosis (DLS) is lower, affected patients are more likely to require revision surgery when they occur. So the aim of this study is to identify risk factors associated with DJPs to avoid its occurrence by at least 1-year follow-up.

METHODS

A total of 182 DLS patients undergoing long instrumented fusion surgery (≥4 levels) between February 2011 and March 2022 were retrospectively analyzed. Patients were placed into the DJP group if a DJP occurred at the final follow-up; patients without mechanical complications were matched 1:2 according to age, sex and BMI as the control group. Patient characteristics, surgical variables, radiographic parameters, lumbar muscularity and fatty degeneration were analyzed statistically. The statistical differences in the results between the two groups (p values <0.05) and other variables selected by experts were entered into a multivariate logistic regression model, and the forwards likelihood ratio method was used to analyze the independent risk factors for DJPs.

RESULTS

Twenty-four (13.2%) patients suffered a DJP in the postoperative period and the reoperation rate was 8.8%. On univariate analysis, the lowest instrumented vertebra (LIV) CT value (p = 0.042); instrumented levels (p = 0.030); preoperative coronal vertical axis (CVA) (p = 0.046), thoracolumbar kyphosis (TLK) (p = 0.006), L4-S1 lordosis (p = 0.013), sacral slop (SS) (p = 0.030), pelvic tilt (PT) classification (p = 0.004), and sagittal vertical axis (SVA) (p = 0.021); TLK correction (p = 0.049); post-operative CVA (p = 0.029); Overall, There was no significant difference in the paraspinal muscle parameters between the two groups. On multivariate analysis, instrumented levels (OR = 1.595; p = 0.035), preoperative SVA (OR = 1.016; p = 0.022) and preoperative PT (OR = 0.873; p = 0.001) were identified as significant independent risk factors for DJP.

CONCLUSION

Longer instrumented levels, a greater preoperative SVA and a smaller PT were found to be strongly associated with the presence of DJPs in patients treated for DLS. The degeneration of the paraspinal muscles may not be related to the occurrence of DJPs. For DLS patients, the occurrence of DJP can be reduced by selecting reasonable fusion segments and evaluating the patient's sagittal balance and spino-pelvic parameters before operation.

Correlation Between Sagittal Balance and Mechanical Distal Junctional Failure in Degenerative Pathology of the Spine: A Retrospective Analysis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

This study aimed to investigate the failure of the caudal end of lumbar posterior fixation in terms of pre-operative and post-operative spinopelvic parameters, correction performed, demographic and clinical data.

METHODS

The lumbar, thoraco-lumbar and lumbo-sacral posterior fixations performed with pedicle screws and rods in 2017-2019 were retrospectively analyzed. As 81% failures occurred within 4 years, an observational period of 4 years was chosen. The revision surgeries due to the failure in the caudal end were collected in the junctional group. Fixations which have not failed were gathered in the control group. The main spinopelvic parameters were measured for each patient on standing lateral radiographs with the software Surgimap. Demographic and clinical data were extracted for both groups.

RESULTS

Among the 457 patients who met the inclusion criteria, the junctional group included 101 patients, who required a revision surgery. The control group collected 356 primary fixations. The two most common causes of revision surgeries were screws pullout (57 cases) and rod breakage (53 cases). SVA, PT, LL, PI-LL and TPA differed significantly between the two groups (P = .021 for LL, P < .0001 for all the others). The interaction between the two groups and the pre-operative and post-operative conditions was significant for PT, SS, LL, TK, PI-LL and TPA (P < .005). Sex and BMI did not affect the failure onset.

CONCLUSIONS

Mechanical failure is more likely to occur in patients older than 40 years with a thoraco-lumbar fixation where PT, PI-LL and TPA were not properly restored.

Avoiding Spinal Implant Failures in Osteoporotic Patients: A Narrative Review

STUDY DESIGN

Narrative review.

OBJECTIVES

With an aging population, the prevalence of osteoporosis is continuously rising. As osseous integrity is crucial for bony fusion and implant stability, previous studies have shown osteoporosis to be associated with an increased risk for implant failure and higher reoperation rates after spine surgery. Thus, our review's purpose was to provide an update of evidence-based solutions in the surgical treatment of osteoporosis patients.

METHODS

We summarize the existing literature regarding changes associated with decreased bone mineral density (BMD) and resulting biomechanical implications for the spine as well as multidisciplinary treatment strategies to avoid implant failures in osteoporotic patients.

RESULTS

Osteoporosis is caused by an uncoupling of the bone remodeling cycle based on an unbalancing of bone resorption and formation and resulting reduced BMD. The reduction in trabecular structure, increased porosity of cancellous bone and decreased cross-linking between trabeculae cause a higher risk of complications after spinal implant-based surgeries. Thus, patients with osteoporosis require special planning considerations, including adequate preoperative evaluation and optimization. Surgical strategies aim towards maximizing screw pull-out strength, toggle resistance, as well as primary and secondary construct stability.

CONCLUSIONS

As osteoporosis plays a crucial role in the fate of patients undergoing spine surgery, surgeons need to be aware of the specific implications of low BMD. While there still is no consensus on the best course of treatment, multidisciplinary preoperative assessment and adherence to specific surgical principles help reduce the rate of implant-related complications.

Biomechanical comparative analysis of conventional pedicle screws and cortical bone trajectory fixation in the lumbar spine: An in vitro and finite element study

Numerous screw fixation systems have evolved in clinical practice as a result of advances in screw insertion technology. Currently, pedicle screw (PS) fixation technology is recognized as the gold standard of posterior lumbar fusion, but it can also have some negative complications, such as screw loosening, pullout, and breakage. To address these concerns, cortical bone trajectory (CBT) has been proposed and gradually developed. However, it is still unclear whether cortical bone trajectory can achieve similar mechanical stability to pedicle screw and whether the combination of pedicle screw + cortical bone trajectory fixation can provide a suitable mechanical environment in the intervertebral space. The present study aimed to investigate the biomechanical responses of the lumbar spine with pedicle screw and cortical bone trajectory fixation. Accordingly, finite element analysis (FEA) and in vitro specimen biomechanical experiment (IVE) were performed to analyze the stiffness, range of motion (ROM), and stress distribution of the lumbar spine with various combinations of pedicle screw and cortical bone trajectory screws under single-segment and dual-segment fixation. The results show that dual-segment fixation and hybrid screw placement can provide greater stiffness, which is beneficial for maintaining the biomechanical stability of the spine. Meanwhile, each segment's range of motion is reduced after fusion, and the loss of adjacent segments' range of motion is more obvious with longer fusion segments, thereby leading to adjacent-segment disease (ASD). Long-segment internal fixation can equalize total spinal stresses. Additionally, cortical bone trajectory screws perform better in terms of the rotation resistance of fusion segments, while pedicle screw screws perform better in terms of flexion-extension resistance, as well as lateral bending. Moreover, the maximum screw stress of L4 cortical bone trajectory/L5 pedicle screw is the highest, followed by L45 cortical bone trajectory. This biomechanical analysis can accordingly provide inspiration for the choice of intervertebral fusion strategy.

[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.

Risk factors for L5 pedicle fractures after single-level posterior spinal fusion

BACKGROUND CONTEXT

Pedicle fractures are a rare but potentially devastating complication of posterior instrumented spinal fusion (PSF). Preoperative awareness of the possible risk factors may help prevent these fractures by modifying the surgical plan. However, the risk factors have not yet been identified.

PURPOSE

To determine the preoperative parameters associated with postoperative L5 pedicle fracture after L4/5 PSF.

STUDY DESIGN

Case control study.

PATIENT SAMPLE

Patients undergoing L4/5 PSF at a single academic institution between 2014 and 2020.

OUTCOME MEASURES

Occurrence of postoperative L5 pedicle fracture.

METHODS

Of 253 patients (female:male, 145:108) undergoing L4/5 PSF from 2014 to 2020, patients with postoperative L5 pedicle fractures were identified retrospectively as "cases" (n = 8, all female, age: 70 ± 10.7 years). As a control group all remaining patients with a follow-up of more than 12 months were allocated (n = 184, 104 females, age: 64.27 ± 13.00 years). In all but 16 cases, anterior support with transforaminal or posterior interbody fusion was performed. Demographic and clinical data (body mass index (BMI)), surgical factors, and comorbidities) were compared. Radiological assessment of spinopelvic parameters was performed using pre- and postoperative standing lateral radiographs.

RESULTS

The overall incidence of L5 pedicle fractures after L4/5 spinal fusion was 3.16%, with a median time from index surgery to diagnosis of 25 days (range, 6-199 days) (75% within the first 32 days postoperatively). Patients with L5 pedicle fractures had higher pelvic incidence (PI) (71° ± 9° vs. 56° ± 11°; p=.001), sacral slope (SS) (45° ± 7° vs. 35° ± 8°; p=.002), L5 slope (30° ± 11° vs. 15° ± 10°, p=.001), L5 incidence (42° ± 14° vs. 26° ± 11°; p= .003), L1-S1 lumbar lordosis (LL) postop (57° ± 10° vs. 45° ± 11°; p=.006), and L4 -S1 LL postop (33° ± 7° vs. 28° ± 7°; p=.049) compared with the control group. Pelvic tilt and PI- LL mismatch were not significantly different. Female gender was a significant risk factor for L5 pedicle fractures (p=.015). BMI (kg/m²) was statistically equal in patients with or without pedicle fractures (28.37 ± 5.96 vs. 28.53 ± 16.32; p=.857). There was no significant difference between the groups for approximative bone mineral density assessment (Hounsfield units; 113 ± 60 vs. 120 ± 43; p=.396) using the L3 trabecular region of interest (ROI) measurement. The correlation analysis demonstrated that most of the identified risk factors except for the postoperative L4-S1 lordosis show significant positive associations among each other. All eight patients in the fracture group underwent revision surgery, and the instrumented fusion was extended to the sacrum, with the addition of sacral-alar-iliac or iliac screws, in six cases.

CONCLUSIONS

L5 pedicle fractures occurred in 3% of the patients after single level L4/5 PSF. Risk factors are female gender, higher PI, SS, L5 slope, L5 incidence, and LL postop but not high BMI. These findings can be used for surgical planning and decision of fusion levels.

Validity of the Roussouly classification system for assessing distal junctional problems after long instrumented spinal fusion in degenerative scoliosis

PURPOSE

To evaluate the validity of the Roussouly classification system for assessing distal junctional problems (DJP) after long instrumented spinal fusion in degenerative scoliosis.

METHODS

Sixty-four patients with degenerative scoliosis and long-segment fixation receiving treatment at our hospital between December 2012 and December 2018 were retrospectively analyzed. Patients were classified preoperatively and postoperatively (Roussouly classification) and divided into DJP and control groups. We observed whether patients restored to their preoperative Roussouly classification (based on pelvic incidence [PI]) postoperatively.

RESULTS

The incidences of DJP were 11.11% and 50% in patients who did and did not match their sagittal Roussouly classification immediately postoperatively, respectively. The adjusted Chi-square test that showed whether the sagittal profile matched the Roussouly classification immediately after surgery was statistically significant (P = 0.012). PIs were 55.83 ± 4.94 and 47.21 ± 10.81 in the DJP and non-DJP groups, respectively (t' = 4.367, P < 0.001). Distal junctional kyphosis angles were 6.33 ± 4.19° and 11.56 ± 5.02° in the DJP and non-DJP groups, respectively (t = - 2.595, P = 0.015). Preoperative PI-lumbar lordosis values were 29.14 ± 13.82 and 16.67 ± 11.39 in the DJP and non-DJP groups, respectively (t = - 2.626, P = 0.013). The logistic regression model showed that patients whose Roussouly classification did not match the postoperative PI value were more likely to have DJP (odds ratio [OR] = 4.01, 95% confidence interval [CI]: 0.51-31.61) and preoperative distal junctional kyphotic changes.

CONCLUSION

If the postoperative sagittal profile can be restored to match the patient's own PI value, use of the Roussouly classification can greatly reduce the possibility of postoperative DJP.

Distal Junctional Kyphosis after Posterior Spinal Fusion in Lenke 1 and 2 Adolescent Idiopathic Scoliosis-Exploring Detailed Features of the Sagittal Stable Vertebra Concept

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

To investigate the factors contributing to the development of postoperative distal junctional kyphosis (DJK) in adolescent idiopathic scoliosis (AIS) patients who underwent posterior spinal fusion (PSF) with lowest instrumented vertebrae (LIV) at or above L1.

METHODS

Patients with Lenke type 1 or 2 curves who underwent PSF with LIV at or above L1 with a minimum follow-up of 2 years were evaluated. The primary outcome measure was the occurrence of postoperative DJK. Radiographic parameters of sagittal alignment and inclusion/exclusion of sagittal stable vertebra (SSV) in PSF were analyzed to determine their associations with the occurrence of postoperative DJK.

RESULTS

Overall, 122 patients (mean age: 15.1 ± 3.2 years) were included. The overall incidence of postoperative DJK was 6.6%. DJK was observed in 19.0% (8/42) of patients whose SSV was not included in PSF and not in patients with SSV included in PSF (n = 80). In the SSV-excluded group, univariate analysis found two significant risk factors for DJK: postoperative thoracic kyphosis (TK, T5-12) and postoperative thoracolumbar kyphosis (TLK, T11-L2). The ROC curve revealed that postoperative TK ≥ 25° and TLK ≥ 10° best predicted the occurrence of postoperative DJK in the SSV-excluded group. The incidence was significantly higher in cases with postoperative TK ≥ 25° or TLK ≥ 10° (7/13 = 53.8%) than in those with postoperative TK < 25° and TLK < 10° (1/29 = 3.4%).

CONCLUSIONS

The current study revealed that postoperative TK ≥ 25° or postoperative TLK ≥ 10° with SSV excluded from PSF were related to DJK after PSF for Lenke type 1 and type 2 AIS. When the SSV is intended to be spared from PSF to save more motion segments, TK and TLK should be carefully evaluated and attained in a lesser magnitude (TK < 25°, TLK < 10°) after surgery.

Impact of Spinal Correction Surgeries with Osteotomy and Pelvic Fixation in Patients with Kyphosis Due to Osteoporotic Vertebral Fractures

Study Design

Combination of retrospective and prospective study.

Purpose

We aimed to compare the clinical outcomes between local fixation surgery and spinopelvic fixation surgery for the treatment of kyphosis secondary to osteoporotic vertebral fractures with spinopelvic malalignment.

Overview of Literature

The clinical characteristics of patients with rigid kyphosis due to osteoporotic vertebral fracture differ from that of middle-aged patients with vertebral fractures in terms of bone fragility and presence of spinopelvic malalignment. Little is known about the surgical strategies for these deformities, most especially the extent of fusion of vertebra involved.

Methods

We analyzed 24 patients with vertebral osteotomy at the level of the fracture and spinal fixation without pelvic fixation (local group), and 22 patients with vertebral osteotomy and pelvic fixation (pelvic group). Radiographic parameters, the incidence of proximal junctional kyphosis (PJK), distal junctional kyphosis (DJK), rod fractures, and the Oswestry Disability Index (ODI) were compared between the two groups over a 2-year follow-up period.

Results

In the pelvic group, postoperative spinopelvic parameters significantly improved, with the improvements maintained. No remarkable changes in spinopelvic parameters were seen in the local group. The mean ODI scores 2 years after surgery were 45.3 and 33.0 in the local and pelvic group, respectively (p-value <0.05). There was no significant difference in the incidence of PJK in the local and pelvic groups, but there was a higher rate of DJK (41.7%) in the local group. In contrast, rod fractures were more common in the pelvic group (45.5%). Patients with DJK had higher ODI scores 2 years after surgery (52.0 in DJK patients vs. 34.8 in non-DJK patients; p-value <0.05).

Conclusions

For patients with rigid kyphosis due to osteoporotic vertebral fractures, better spinopelvic alignment and health-related quality of life can be achieved through extensive corrective surgery with pelvic fixation.

Asymmetrical vertebral column decancellation for the management of rigid congenital kyphoscoliosis

Background

Congenital kyphoscoliosis is a disease that often requires surgical treatment. Wedge osteotomies, such as pedicle subtraction osteotomy, are insufficient to correct this complicated rigid deformity. Vertebral column resection yields sufficient correction, but it is an exhaustively lengthy operation with a high risk of major complications. There are few effective and safe techniques for treating rigid congenital kyphoscoliosis. We aimed to investigate the technique of asymmetrical vertebral column decancellation (AVCD) for the treatment of rigid congenital kyphoscoliosis and evaluate the clinical and radiographic results of patients treated with the technique.

Methods

Between January 2013 to June 2017, the data of 31 patients with congenital kyphoscoliosis who underwent single level AVCD were reviewed. Preoperative and postoperative radiographical parameters and the visual analogue scale, Asia Spinal Injury Association, and Scoliosis Research Society-22 scores were documented. The patients were followed up for an average period of 29 months.

Results

The average operative time was 273.9 ± 46.1 min. The average volume of blood loss was 782.3 ± 162.6 ml. The main coronal curve improved from a mean of 81.4° preoperatively to 24.7° at the final follow-up, and the coronal balance improved from 28.9 to 7.6 mm. The degree of local kyphosis improved from a mean of 86.5° to 29.2°, and the sagittal balance improved from 72.3 to 16.9 mm. All clinical outcomes also improved significantly from preoperatively to the final follow-up. No permanent postoperative neurologic complications occurred.

Conclusion

The AVCD surgical procedure corrects spinal deformities in both the coronal and sagittal planes by way of a convex-sided Y shape osteotomy, achieves satisfactory realignment without additional neurological complications, and can be considered an alternative treatment for rigid congenital kyphoscoliosis.

Can L5 Be Trusted During Proximal Extension of Fusion? A Case Series and a Review of the Literature

Background

Debate on whether to stop fusion at L5 or to extend fusion to S1 in a long spinal construct has been a controversial topic in spine surgery. Fewer data are available to support whether to include a prior solid fusion at L4-L5 or to extend to S1 during a proximal extension of fusion to T10. The purpose of this review is to report and discuss 2 cases of L5 vertebra fracture after proximal extension of solid L4-L5 fusion to T10 and to provide a guideline to surgeons based on the available literature.

Methods

Case report and literature review.

Results

Literature review identified multiple publications with levels of evidence from level 2 to level 4. Advanced L5-S1 degeneration with long-segment fusion to L5 is reported to be greater than 60% with a new rate of symptom development approaching 20%-25%. There is no prior literature specific to L5 fracture development after thoracic lumbar fusion with the lowest instrumented level at a fused L4-L5 segment. Reoperation rate is not consistently affected by the lowest instrumented vertebral level L5 versus sacrum/ilium.

Conclusions

Literature review is inconclusive as to the need to include the lumbosacral junction when performing a proximal extension of fusion from L5 to the thoracic spine, especially during a revision adult deformity surgery. Stress of the long lever arm of a long-segment thoracolumbar fusion above a prior solid L4-L5 fusion could cause the L5 vertebra to split in the coronal plane, resulting in vertebral body fracture even with a mildly degenerated disc at L5-S1 prior to surgery.

Level of Evidence

4.

Factors Impacting Outcomes and Health Care Utilization in Osteoporotic Patients Undergoing Lumbar Spine Fusions: A MarketScan Database Analysis

OBJECTIVE

To identify factors impacting long-term complications, reoperations, readmission rates, and health care utilization in patients with osteoporosis (OP) following lumbar fusions.

METHODS

We used International Classification of Disease, Ninth Revision, International Classification of Disease, Tenth Revision , and Current Procedural Terminology codes to extract data from MarketScan (2000-2016). Patients undergoing lumbar spine fusion were divided into 2 groups based on preoperative diagnosis: OP or non-OP. We used multivariable generalized linear regression models to analyze outcomes of interest (reoperation rates, readmissions, complications, health care utilization) at 1, 6, 12, and 24 months after discharge.

RESULTS

MarketScan identified 116,749 patients who underwent lumbar fusion with ≥24 months of follow-up; 6% had OP. OP patients had a higher incidence of complications (14% vs. 9%); were less likely to be discharged home (77% vs. 86%, P < 0.05); had more new fusions or refusions at 6 months (2.9% vs. 2.1%), 12 months (5% vs. 3.8%), and 24 months (8.5% vs. 7.4%); incurred more outpatient services at 12 months (80 vs. 61) and 24 months (148 vs. 115); and incurred higher overall costs at 12 months ($22,932 vs. $17,017) and 24 months ($48,379 vs. $35,888). Elderly OP patients (>65 years old) who underwent multilevel lumbar fusions had longer hospitalization, had higher complication rates, and incurred lower costs at 6, 12, and 24 months compared with young non-OP patients who underwent single-level lumbar fusion.

CONCLUSIONS

Patients of all ages with OP had higher complication rates and required revision surgeries at 6, 12, and 24 months compared with non-OP patients. Elderly OP patients having multilevel lumbar fusions were twice as likely to have complications and lower health care utilization compared with younger non-OP patients who underwent single-level fusion.

Effects of menopausal state on lumbar decompression and fusion surgery

Menopause leads to fluctuations in androgenic hormones which directly affect bone metabolism. Bone resorption, mineralization, and remodeling at fusion sites are essential in order to obtain a solid and biomechanically stable fusion mass. Bone metabolic imbalance seen in the postmenopausal state may predispose to fusion related complications. The aim of this study was to investigate fusion outcomes in lumbar spinal fusion surgery in women based on menopausal status. A retrospective analysis of all female patients who underwent posterior lumbar decompression and fusion at a single institution from 2013 to 2017 was performed. A total of 112 patients were identified and stratified into premenopausal (n = 25) and postmenopausal (n = 87) groups. Clinical and radiographic data was assessed at 1 year follow up. Postmenopausal patients had a higher rates of pseudarthrosis (11.63% vs 0%, p = 0.08), PJK (15.1% vs 4%, p = 0.14), and revision surgery (3.5% vs 0%, p = 0.35). The number of levels fused was associated with increased risk of pseudarthrosis (OR 1.4, p = 0.02); however, there was no association between age, hormonal use, prior tobacco use, or T-score. Age was associated with increased risk of developing PJK (OR = 1.11, p = 0.01); however, PJK was not associated with menopause, hormonal use, prior tobacco use, or T-score. Revision surgery was not associated with age, hormonal use, prior tobacco use, or T-score. This study suggests that postmenopausal women may be prone to have higher rates of pseudarthrosis, PJK and revision surgery, although our results were not statistically significant. Larger studies with longer follow up will help elucidate the true effects of menopause in spine surgery.

Advancements in osteoporotic spine fixation

With the global rise in the population of elderly along with other risk factors, spine surgeons have to encounter osteoporotic spine more often. Osteoporotic spine, however, causes problems in management, particularly where instrumentation is involved, resulting in screw loosening, pull out, pseudoarthroses or adjacent segment kyphosis. Osteoporosis alters the bio mechanics at the bone implant interface resulting in various degrees of fixation failure. Various advancements have been made in this field to deal with such issues in addition to modification of basic surgical techniques such as increasing the diameter and length of the screw, smaller pilot hole, under tapping, longer constructs, supplemental anterior fixation, sublaminar wires or laminar hooks, use of transverse connectors and triangulation techniques, among others. They include novel surgical techniques such as cortical bone trajectory, superior cortical trajectory, double screw technique, cross trajectory technique, bicortical screw technique or prophylactic vertebroplasty. Advances in the screw design include expandable screws, fenestrated screws, conical screws and coated screws. In addition to PMMA cement augmentation, other biodegradable cements have been introduced to mitigate the side effects of PMMA such as calcium phosphate, calcium apatite and hydroxyapatite. Pharmacotherapy with teriparatide can aid fusion and lower the rate of pedicle screw loosening. Many of these strategies have only bio mechanical evidence and require well designed clinical trials to establish their clinical efficacy. Though no single technique is fool proof, little modifications in the existing techniques or utilizing a combination of techniques without adding to the cost of the surgery may help to achieve a near-ideal result. Surgeons have to equip their armamentarium with all the recent advances, and should be open to novel thoughts and techniques.

Comparison of long fusion terminating at L5 versus the sacrum in treating adult spinal deformity: a meta-analysis

Purpose

Choosing an optimal distal fusion level for adult spinal deformity (ASD) is still controversial. To compare the radiographic and clinical outcomes of distal fusion to L5 versus the sacrum in ASD, we conducted a meta-analysis.

Methods

Relevant studies on long fusion terminating at L5 or the sacrum in ASD were retrieved from the PubMed, Embase, Cochrane, and Google Scholar databases. Then, studies were manually selected for inclusion based on predefined criteria. The meta-analysis was performed by RevMan 5.3.

Results

Eleven retrospective studies with 1211 patients were included in meta-analysis. No significant difference was found in overall complication rate (95% CI 0.60 to 1.30) and revision rate (95% CI 0.59 to 1.99) between fusion to L5 group (L group) and fusion to the sacrum group (S group). Significant lower rate of pseudarthrosis and implant-related complications (95% CI 0.29 to 0.64) as well as proximal adjacent segment disease (95% CI 0.35 to 0.92) was found in L group. Patients in S group obtained a better correction of lumbar lordosis (95% CI − 7.85 to − 0.38) and less loss of sagittal balance (95% CI − 1.80 to − 0.50).

Conclusion

Our meta-analysis suggested that long fusion terminating at L5 or the sacrum was similar in scoliosis correction, overall complication rate, revision rate, and improvement in pain and disability. However, fusion to L5 had advantages in lower rate of pseudarthrosis, implant-related complications, and proximal adjacent segment disease, while fusion to the sacrum had advantages in the restoration of lumbar lordosis, maintenance of sagittal balance, and absence of distal adjacent segment disease.

Graphic abstract

These slides can be retrieved under Electronic Supplementary Material.

A Review and Clinical Perspective of the Impact of Osteoporosis on the Spine

Introduction

Osteopenia and osteoporosis are common conditions in the United States. The health consequences of low bone density can be dire, from poor surgical outcomes to increased mortality rates following a fracture.

Significance

This article highlights the impact low bone density has on spine health in terms of vertebral fragility fractures and its adverse effects on elective spine surgery. It also reviews the clinical importance of bone health assessment and optimization.

Results

Vertebral fractures are the most common fragility fractures with significant consequences related to patient morbidity and mortality. Additionally, a vertebral fracture is the best predictor of a subsequent fracture. These fractures constitute sentinel events in osteoporosis that require further evaluation and treatment of the patient's underlying bone disease. In addition to fractures, osteopenia and osteoporosis have deleterious effects on elective spine surgery from screw pullout to fusion rates. Adequate evaluation and treatment of a patient's underlying bone disease in these situations have been shown to improve patient outcomes.

Conclusion

With an increased understanding of the prevalence of low bone mass and its consequences as well an understanding of how to identify these patients and appropriately intervene, spine surgeons can effectively decrease the rates of adverse health outcomes related to low bone mass.

Preliminary report on the flexible rod technique for prevention of proximal junctional kyphosis following long-segment fusion to the sacrum in adult spinal deformity

OBJECTIVE

The incidence of proximal junctional kyphosis (PJK) after long-segment fixation in patients with adult spinal deformity (ASD) has been reported to range from 17% to 61.7%. Recent studies have reported using "hybrid" techniques in which semirigid fixation is introduced between the fused and flexible segments at the proximal level to allow a more gradual transition. The authors used these hybrid techniques in a clinical setting and analyzed PJK to evaluate the usefulness of the flexible rod (FR) technique.

METHODS

The authors retrospectively selected 77 patients with lumbar degenerative kyphosis (LDK) who underwent sagittal correction and long-segment fixation and had follow-up for > 1 year. An FR was used in 30 of the 77 patients. PJK development and spinal sagittal changes were analyzed in the FR and non-FR groups, and the predictive factors of PJK between a PJK group and a non-PJK group were compared.

RESULTS

The patient population comprised 77 patients (75 females and 2 males) with a mean (± SD) follow-up of 32.0 ± 12.7 months (36.7 ± 9.8 months in the non-FR group and 16.8 ± 4.7 months in the FR group) and mean (± SD) age of 71.7 ± 5.1 years. Sagittal balance was well maintained at final follow-up (10.5 and 1.5 mm) in the non-FR and FR groups, respectively. Thoracic kyphosis (TK) and lumbar lordosis (LL) were improved in both groups, without significant differences between the two (p > 0.05). PJK occurred in 28 cases (36.4%) in total, 3 (10%) in the FR and 25 (53.2%) in the non-FR group (p < 0.001). Postoperatively, PJK was observed at an average of 8.9 months in the non-FR group and 1 month in the FR group. No significant differences in the incidence of PJK regarding patient factors or radiological parameters were found between the PJK group and non-PJK group (p > 0.05). However, FR (vs non-FR) and interbody fusion except L5-S1 using oblique lumbar interbody fusion (vs non-oblique lumbar interbody fusion), demonstrated a significantly lower PJK prevalence (p < 0.001 and p = 0.044) among the surgical factors.

CONCLUSIONS

PJK was reduced after surgical treatment with the FR in the patients with LDK. Solid long-segment fixation and the use of the FR may become another surgical option for spine surgeons who plan and make decisions regarding spine reconstruction surgery for patients with ASD.

Distal Junctional Failure Following Pediatric Spinal Fusion

BACKGROUND

Adjacent segment pathology is a known complication after spinal fusion, but little has been reported on junctional failure. A series of adolescent patients presented with acute distal junctional failure (DJF). We sought to determine any common features of these patients to develop a prevention strategy.

METHODS

A retrospective review was conducted of pediatric patients who developed DJF after instrumented spinal fusion performed at 2 institutions from 1999 to 2013. Patients with proximal junctional failure or junctional kyphosis without failure were excluded.

RESULTS

Fifteen subjects were identified with mean follow-up of 38 months. Distal failure occurred a mean of 60 days after index surgery, with history of minor trauma in 4 patients. Failures included 3-column Chance fracture (11) or instrumentation failure (4). Thirteen patients presented with back pain and/or acute kyphosis, whereas 2 asymptomatic patients presented with healed fractures. Two patients also developed new onset of severe lower extremity neurological deficit after fracture, which improved but never resolved after revision. A total of 13/15 subjects required revision surgery, typically within 1 week. Complications associated with revision surgery were encountered in 8 patients (62%). Major complications that required return to the operating room included 2 deep infections, 2 instrumentation failures, and dense lower extremity paralysis that improved after medial screw revision and decompression. At final follow-up, 10 patients are asymptomatic, 2 have persistent neurological deficit, 2 have chronic pain, and 1 has altered gait with gait aid requirement.

CONCLUSIONS

This study analyzes a heterogenous cohort of spinal fusion patients who developed DJF from 3-column Chance fracture or instrumentation failure. Revision surgery is typically required, but has a high complication rate and can result in severe neurological deficit, highlighting the morbidity of this complication. It is unclear whether level of the lowest instrumented vertebra contributes to DJF. Increased awareness of junctional failure in children may prompt additional studies to further characterize risk factors and preventative strategies.

LEVEL OF EVIDENCE

Level IV-study-type case series.

Multi-Rod Constructs Can Increase the Incidence of Iliac Screw Loosening after Surgery for Adult Spinal Deformity

Study Design

A retrospective study.

Purpose

To investigate the incidence of iliac screw loosening with a two-rod vs. multi-rod construct and the effect on clinical and radiographic outcomes after surgery for adult spinal deformity (ASD).

Overview of Literature

Multi-rod construct is useful for preventing rod fracture in ASD surgery. However, limited information is available regarding the incidence of iliac screw loosening after corrective fusion surgery using a multi-rod construct.

Methods

Total 106 patients with ASD (24 men and 82 women; mean age, 68 years) who underwent corrective fusion surgery using bilateral iliac screws and were followed up for at least 1 year were reviewed. The following variables were compared between patients who underwent surgery with a two-rod and multi-rod construct: age, sex, bone mineral density (BMD), fusion level, high-grade osteotomy, L5/S interbody fusion, screw loosening (upper instrumented vertebra [UIV], S1, and iliac), rod fracture, proximal junctional kyphosis, spinopelvic parameters, and Oswestry Disability Index (ODI) score. We also compared patients with and without iliac screw loosening in the multi-rod construct group.

Results

Of the 106 patients, 55 underwent surgery with a conventional two-rod construct and 51 with a multi-rod construct (three rods in 16, four rods in 35). Iliac and UIV screw loosening was observed in 24 patients (21%) and 35 patients (33%), respectively. The multi-rod group showed significantly higher incidence of iliac and UIV screw loosening and lower incidence of rod fracture. Patients with iliac screw loosening had a lower BMD than those without screw loosening; however, no significant differences were observed in the spinopelvic parameters or the ODI score.

Conclusions

The use of multi-rod constructs led to a higher incidence of junctional screw loosening than the use of conventional two-rod constructs, especially in patients with osteoporosis. Iliac screw loosening did not affect sagittal alignment or clinical outcome in the short term.

Biomechanical Analysis of a Long-Segment Fusion in a Lumbar Spine—A Finite Element Model Study

Examine the biomechanical effect of material properties, geometric variables, and anchoring arrangements in a segmental pedicle screw with connecting rods spanning the entire lumbar spine using finite element models (FEMs). The objectives of this study are (1) to understand how different variables associated with posterior instrumentation affect the lumbar spine kinematics and stresses in instrumentation, (2) to compare the multidirectional stability of the spinal instrumentation, and (3) to determine how these variables contribute to the rigidity of the long-segment fusion in a lumbar spine. A lumbar spine FEM was used to analyze the biomechanical effects of different materials used for spinal rods (TNTZ or Ti or CoCr), varying diameters of the screws and rods (5 mm and 6 mm), and different fixation techniques (multilevel or intermittent). The results based on the range of motion and stress distribution in the rods and screws revealed that differences in properties and variations in geometry of the screw-rod moderately affect the biomechanics of the spine. Further, the spinal screw-rod system was least stable under the lateral bending mode. Stress analyzes of the screws and rods revealed that the caudal section of the posterior spinal instrumentation was more susceptible to high stresses and hence possible failure. Although CoCr screws and rods provided the greatest spinal stabilization, these constructs were susceptible to fatigue failure. The findings of the present study suggest that a posterior instrumentation system with a 5-mm screw-rod diameter made of Ti or TNTZ is advantageous over CoCr instrumentation system.

Medical optimization of lumbar fusion in the osteoporotic patient

PURPOSE

In patients undergoing lumbar fusion, osteoporosis has been shown to lead to poorer outcomes and greater incidence of fusion-related complications. Given the undesirable effect of osteoporosis on lumbar fusion surgery, a number of medications have been proposed for use in the peri- and postoperative period to mitigate risks and enhance outcomes. The purpose of this review was to summarize and synthesize the current literature regarding medical management of osteoporosis in the context of lumbar fusion surgery.

METHODS

A literature search of PubMed, Embase, and Web of Science was conducted in October 2016, using permutations of various search terms related to osteoporosis, medications, and lumbar fusion.

RESULTS

Teriparatide injections may lead to faster, more successful fusion, and may reduce fusion-related complications. Bisphosphonate therapy likely does not hinder fusion outcomes and may be useful in reducing certain complications of fusion in osteoporotic patients. Calcitonin and selective estrogen receptor modulator therapy show mixed results, but more research is necessary to make a recommendation. Vitamin D deficiency is associated with poor fusion outcomes, but evidence for supplementation in patients with normal serum levels is weak.

CONCLUSIONS

Overall, the current body of research appears to support the use of teriparatide therapy to enhance lumbar fusion outcomes in the osteoporotic patient, although the extent of research on this topic is limited. Additionally, very little evidence exists to cease any of the mentioned osteoporosis treatments prior to lumbar fusion.

Clinical and radiographic outcomes of upper thoracic versus lower thoracic upper instrumented vertebrae for adult scoliosis: a meta-analysis

The aim of this study was to evaluate the clinical and radiographic outcomes of upper thoracic (UT) versus lower thoracic (LT) upper instrumented vertebrae (UIV) for adult scoliosis by meta-analysis. We conducted a literature search in three databases to retrieve related studies up to March 15, 2017. The preliminary screened studies were assessed by two reviewers according to the selection criteria. All analyses were carried out using the statistical software package R version 2.31. Odds ratios (OR) with 95% confidence intervals (CI) were used to describe the results. The I² statistic and Q statistic test were used for heterogeneity assessment. Egger's test was performed to detect publication bias. To assess the effect of each study on the overall pooled OR or standardized mean difference (SMD), sensitive analysis was conducted. Ten trials published between 2007 and 2015 were eligible and included in our study. Meta-analysis revealed that the UT group was associated with more blood loss (SMD=0.4779, 95%CI=0.3349-0.6209, Z=6.55, P<0.0001) and longer operating time (SMD=0.5780, 95%CI=0.1971-0.958, Z=2.97, P=0.0029) than the LT group. However, there was no significant difference in Oswestry Disability Index, Scoliosis Research Society (SRS) function subscores, radiographic outcomes including sagittal vertical axis, lumbar lordosis, and thoracic kyphosis, length of hospital stay, and revision rates between the two groups. No evidence of publication bias was found between the two groups. Fusion from the lower thoracic spine (below T10) has as advantages a shorter operation time and less blood loss than upper thoracic spine (above T10) in posterior long-segment fixation for degenerative lumbar scoliosis.

Distal junctional failure secondary to L5 vertebral fracture-a report of two rare cases

Distal junctional failure (DJF) with fracture at the last instrumented vertebra is a rare occurrence. In this case report, we present two patients with L5 vertebral fracture post-instrumented fusion of the lumbar spine. The first patient is a 78-year-old female who had multi-level degenerative disc disease, spinal stenosis and degenerative scoliosis involving levels T12 to L5. She underwent instrumented posterolateral fusion (PLF) from T12 to L5, and transforaminal lumbar interbody fusion (TLIF) at L2/3 and L4/5. Six months after her operation, she presented with a fracture of the L5 vertebral body necessitating revision of the L5 pedicle screws, with additional TLIF of L5/S1. The second patient is a 71-year-old female who underwent decompression and TLIF of L3/4 and L4/5 for degenerative spondylolisthesis. Six months after the surgery, she developed a fracture of the L5 vertebral body with loosening of the L5 screws. The patient declined revision surgery despite being symptomatic. DJF remains poorly understood as its rare incidence precludes sufficiently powered studies within a single institution. This report aims to contribute to the currently scarce literature on DJF.

Perioperative complications associated with spine surgery in patients with established spinal cord injury

BACKGROUND CONTEXT

Only a small percentage of patients with spinal cord injury (SCI) require consideration for reconstructive surgery after their initial injury. For those who do, perioperative complications can be frequent and significant. There has been very little published literature examining treatment of these patients and essentially nothing to guide the surgeon in perioperative decision making and management.

PURPOSE

To identify some of the common challenges associated with surgery in this patient population and review the literature to highlight the perioperative concerns in patients with chronic SCI.

STUDY DESIGN

Review article.

METHODS

A primary PubMed literature search was performed and reviewed for patients with chronic SCI with emphasis on the complications and difficulties encountered during surgical treatment of patients with chronic SCI.

RESULTS

For those who do proceed with surgery in this patient population, preoperative nutrition, bone density, and skin should be evaluated and optimized. Preoperative inferior vena cava filters should be considered. The integrity of the reconstruction will be extensively challenged. In addition, augmented fixation and bracing should be contemplated.

CONCLUSIONS

Patients with chronic SCI who require spinal reconstruction provide many unique challenges. Indications for surgery must be strong as perioperative complications can be frequent and long-term outcomes unpredictable. Close monitoring for postoperative complications is essential.

Multilevel Noncontiguous Spinal Fractures: Surgical Approach towards Clinical Characteristics

Study Design

The study retrospectively investigated 15 cases with multilevel noncontiguous spinal fractures (MNSF).

Purpose

To clarify the evaluation of true diagnosis and to plane the surgical treatment.

Overview of Literature

MNSF are defined as fractures of the vertebral column at more than one level. High-energy injuries caused MNSF, with an incidence ranging from 1.6% to 16.7%. MNSF may be misdiagnosed due to lack of detailed neurological and radiological examinations.

Methods

Patients with metabolic, rheumatologic diseases and neoplasms were excluded. Despite the presence of a spinal fracture associated clearly with the clinical picture, all patients were scanned within spinal column by direct X-rays, computed tomography and magnetic resonance imaging. When there were ≥5 intact vertebrae between two fractured vertebral segments, each fracture region was managed with a separated stabilization. In cases with ≤4 intact segments between two fractured levels, both fractures were fixed with the same rod and screw system.

Results

There were 32 vertebra fractures in 15 patients. Eleven (73.3%) patients were male and age ranged from 20 to 64 years (35.9±13.7 years). Eleven cases were the American Spinal Injury Association (ASIA) E, 3 were ASIA A, and one was ASIA D. Ten of the 15 (66.7%) patients returned to previous social status without additional deficit or morbidity. The remaining 5 (33.3%) patients had mild or moderate improvement after surgery.

Conclusions

The spinal column should always be scanned to rule out a secondary or tertiary vertebra fracture in vertebral fractures associated with high-energy trauma. In MNSF, each fracture should be separately evaluated for decision of surgery and planned approach needs particular care. In MNSF with ≤4 intact vertebra in between, stabilization of one segment should prompt the involvement of the secondary fracture into the system.

Lumbopelvic fixation: a surgical alternative for lumbar stability

OBJECTIVE: Lumbopelvic fixation is a valid surgical option to achieving great stability in cases where it is particularly demanded, such as in patients with poor quality bone, degenerative scoliosis, and revision surgeries with modern materials and techniques. It enables simple integration of the iliopelvic systems with the rest of the spinal structure, maintaining hemorrhagia at acceptable levels, as well as surgery time. METHODS: We analyzed a case series of 15 patients of our center, who required major construction and/or presented poor quality bone. RESULTS: A total of 15 patients was studied, of which 12 (80%) were women and three (20%), men. Nine (60%) of these were revision surgeries, maintaining a surgery time of 5 hours (±1 h), with average blood loss of 1380 ml (±178 ml). All the patients received six to eight transpedicular screws, including iliac screws, and in all cases, a bone graft was inserted. CONCLUSION: Lumbopelvic fixation in patients with characteristics associated with osteopenia and osteoporosis, and in major instrumentations, particularly revision surgeries, three-dimensional correction is achieved, constructing a strong, stable pelvic base that is very useful, in patients with fragile surgical anatomy, for changes of implant or extensive decompression, provided the arthrodesis technique is adequate and with the insertion of a sufficient bone graft, and obviously, taking care to maintain the sagittal balance.

Sagittal plane correction in pedicle subtraction osteotomy using the Xia 3 SUK Direct Vertebral Rotation System: technical note

The Xia 3 SUK Direct Vertebral Rotation (DVR) System was developed for performing the vertebral derotation maneuver in scoliosis surgery. The author applied this device to sagittal plane correction in pedicle subtraction osteotomy for adult spinal deformity. The surgical procedure included 1) preparing secure proximal and distal foundations for correction using mutisegmental pedicle screw-rod fixation (to avoid stress concentration to a specific screw-bone interface), 2) decancellating only the posterior two-thirds of the vertebral column, 3) providing supplemental interbody fusion above and below the osteotomy site (the anterior one-third of the vertebral column and interbody cages serve as an anterior column support and a pivot of correction), 4) closing the osteotomy by gradual approximation of SUK tubes secured to the proximal- and distal-most screw heads, and 5) connecting rods between the proximal and distal screw-rod constructs. Eight consecutive patients with fixed sagittal imbalance were treated using this surgical procedure. No patient required distal fixation points extending to the sacrum and/or pelvis. The sagittal plane correction was 43°. The mean anterior deviation of the C-7 plumb line was improved from 12.7 cm to 4.0 cm immediately after surgery, and it was 6.0 cm at the final follow-up. A pedicle subtraction osteotomy using the Xia 3 SUK DVR System ensures a safe and secure sagittal plane correction in adult spinal deformity.

Junctional spinal disorders in operated adult spinal deformities: present understanding and future perspectives

INTRODUCTION

Junctional spinal disorders have become one of the greatest challenges in spinal deformity surgery. They can occur at any age but are mostly seen in adult deformity surgery and are most often observed as the patient gets older.

DEFINITIONS

Different forms can be individualized according to their types and location: one can observe simple segmental degeneration above or below instrumentation with or without spinal stenosis. Or the situation may be more complex with proximal junctional kyphosis, distal junctional kyphosis and intercalary junctional kyphosis where the junctional kyphosis occurs between two instrumented segments of the spine. Junctional scoliosis may also be observed as a new curve that did not exist after the index surgery.

PATHOPHYSIOLOGY

Many different factors have been described being associated or the cause of junctional problems: old age, increased BMI, osteoporosis, etc. The role of pre-existing and postoperative sagittal imbalance plays a definitive role in their pathogenesis. As well the weakened posterior elements and or fatty degeneration of the posterior muscles are key factors in the occurrence of these problems. Multiple different radiologic parameters to describe and achieve perfect sagittal balance have been described knowing that the pelvic incidence of the patients is the key element that governs lumbar lordosis of the patient and hence the sagittal balance. Away from the spine one has to integrate the issues of the knees and the hips in the presentation of these junctional problems whether they are the cause or one of the consequences of the sagittal malalignment. Likewise the non-instrumented part of the spine (thoracic and or cervical spine) will also play a role in the pathogenesis or prevention of these junctional problems if they are stiff and or autofused along with their respective deformity.

TREATMENT

To prevent the occurrence of such junctional problems some basic surgical rules must be observed, but still lots remain unknown such as how much restoration of lordosis is really necessary, how to create a smoother transition between the instrumented and non-instrumented spine, which metal and where to use it, which implants to use as our widely used pedicle screw system may be one of the causes of these problems. Clinically these junctional problems can be asymptomatic and require only observation, or require revision surgery. Revision will require in most cases decompression of the neural elements, extension of the instrumentation and spinal osteotomies.

CONCLUSION

Definitively the issue of junctional spinal disorder after deformity surgery will require further extensive research to minimize this problem especially in our aging population.

Effects of rod stiffness and fusion mass on the adjacent segments after floating mono-segmental fusion: a study using finite element analysis

PURPOSE

The aims of the present study were to compare the biomechanical effects on the adjacent segments after mono-segmental floating fusion with posterior semi-rigid or rigid stabilization, and to evaluate the effect of the amount of fusion mass on the biomechanical differences.

METHODS

A detailed, nonlinear L1-S1 finite element model had been developed and validated. Then five models were reconstructed by different fixation techniques on the L3-L4 level: rigid fixation with an interbody spacer (Ti + IS), rigid fixation with a large interbody spacer (Ti + IS_all), semi-rigid fixation with an interbody spacer (PEEK + IS), semi-rigid fixation with a large interbody spacer (PEEK + IS_all), and semi-rigid fixation only (PEEK). Analyses were conducted for the case of erect standing position, flexion, and extension motion.

RESULTS

At L1-L2 and L2-L3, PEEK + IS demonstrated less inter-segmental rotation and nucleus pressure increments from the intact model compared with Ti + IS. The L4-L5 and L5-S1 levels showed slightly higher values with PEEK + IS, but these differences among the instrumented models were not significant. The motion difference based on the fusion mass at the adjacent levels was at most 3%. All instrumentation cases generated a 55% higher facet contact force at the lower adjacent level (L4-L5) compared to that of the intact model during 26° extension and the largest increment was detected at the upper adjacent level (L2-L3) in the Ti + IS. Instrumentation with Ti + IS markedly increased the stress in the intervertebral disk at the upper adjacent level, while the stress with PEEK + IS appeared largest at the lower adjacent level.

CONCLUSIONS

Posterior instrumentation with semi-rigid rods may lower the incidence of disk and facet degeneration in the upper adjacent segment compared to rigid rods. On the other hand, the possibility of facet degeneration will be similar for all instrumentation devices in the lower adjacent segment in the long-term. The stiffness difference between rigid and semi-rigid rods on the changes in the adjacent motion segments was more crucial than amount of fusion mass.

Análise radiográfica comparativa da cifose juncional entre instrumentação híbrida, ganchos e parafusos na escoliose idiopática do adolescente

OBJETIVO: Avaliação radiográfica das cifoses juncionais proximal e distal em pacientes submetidos a artrodese e diferentes tipos de instrumentação posterior no tratamento cirúrgico da escoliose idiopática do adolescente (EIA). MÉTODO: Foi realizado estudo retrospectivo com avaliação radiográfica de 34 pacientes submetidos à artrodese da coluna vertebral com instrumentação posterior, sendo 10 com ganchos (Grupo I), 13 com ganchos e parafusos (Grupo II) e 11 com parafusos (Grupo III), entre junho de 1997 e dezembro de 2009. Foi avaliada a ocorrência de cifose juncional proximal (CJP) e cifose juncional distal (CJD) à artrodese, no pré-operatório, no pós-operatório imediato e no final do seguimento, pós-operatório tardio, que foi de, no mínimo, 12 meses. RESULTADOS: Os pacientes do grupo I apresentaram cifose torácica de menor valor no pré-operatório, porém a lordose lombar permaneceu inalterada ao longo da evolução. Os pacientes do grupo II e grupo III apresentaram aumento do valor aferido da lordose lombar no pós-operatório. Não houve diferença significativa para a ocorrência de cifose juncional proximal entre os três grupos estudados. Com relação à cifose juncional distal, houve aumento estatisticamente significativo do valor entre pré é pós-operatório, para os grupos II e III. CONCLUSÃO: A avaliação radiográfica das cifoses juncionais proximal e distal em pacientes submetidos à artrodese e diferentes tipos de instrumentação no tratamento cirúrgico da EIA revelou a presença de cifoses juncionais proximais pré-operatórias, que não evoluíram para a deformidade juncional pós-operatória, além de ausência completa da anormalidade juncional distal.

Frequency, risk factors, and treatment of distal adjacent segment pathology after long thoracolumbar fusion: a systematic review

STUDY DESIGN

Systematic review.

OBJECTIVE

To systematically review the literature related to distal adjacent segment pathology (ASP) after long thoracolumbar fusions for deformity including frequency, risk factors, frequency differences between adolescents and adults, surgical approach for revision, and revision complications.

SUMMARY OF BACKGROUND DATA

Spinal deformity surgery complications include ASP. Although ASP at the rostral end of instrumented fusions has been well described, substantially less has been documented about distal ASP.

METHODS

A systematic search was conducted in Medline and the Cochrane Collaboration Library for articles published between January 1, 1983, and March 15, 2012. We included all articles that described distal ASP after long thoracolumbar fusion for deformity. Radiographical ASP (RASP) was defined as evidence of ASP based on imaging, and clinical ASP (CASP) was defined as symptomatic ASP.

RESULTS

Seven retrospective cohort studies met inclusion criteria. Distal CASP developed in 17.7% at 2- 6-year follow-up and 19.8% at 9-year follow-up, whereas reoperation due to CASP was reported in 15.6% at 2 to 6 years and 14.4% at 9 years. Distal RASP was more frequent (44.7%-65.5%). Preoperative sagittal imbalance was associated with increased risk of distal ASP. There was increased risk of CASP in patients with higher postoperative fractional curve and increased risk of RASP in younger patients and those with preoperative disc degeneration, longer fusions, circumferential procedures, and postoperative L5-S1 disc space narrowing. No studies meeting inclusion criteria compared distal ASP in adults and adolescents or defined the best approach or complications for distal ASP revision.

CONCLUSION

Low-quality evidence suggests a cumulative rate of 18% to 20% for CASP and 45% to 65% for RASP after long thoracolumbar fusion for spinal deformity during 9-year follow-up. Low-quality evidence suggests an association between preoperative sagittal imbalance and distal ASP, with greater risk of distal ASP in patients with sagittal imbalance. Low-quality evidence suggests increased risk of CASP in patients with higher postoperative fractional curve and increased risk of RASP in younger patients and those with preoperative disc degeneration, longer fusions, circumferential procedures, and postoperative L5-S1 disc space narrowing.

CONSENSUS STATEMENT

1. The risk of developing new symptoms secondary to distal adjacent segment pathology following long thoracolumbar fusion for deformity is approximately 18–20% during a period of 9 years follow up, and most of these patients will require revision surgery. Strength of Statement: Weak. 2. The risk of developing distal adjacent segment pathology may be higher in those with preoperative sagittal imbalance, preoperative disc degeneration, longer fusions, circumferential procedures, and postoperative L5–S1 disc space narrowing. Strength of Statement: Weak.

Hip-spine syndrome

The incidence of symptomatic osteoarthritis of the hip and degenerative lumbar spinal stenosis is increasing in our aging population. Because the subjective complaints can be similar, it is often difficult to differentiate intra- and extra-articular hip pathology from degenerative lumbar spinal stenosis. These conditions can present concurrently, which makes it challenging to determine the predominant underlying pain generator. A thorough history and physical examination, coupled with selective diagnostic testing, can be performed to differentiate between these clinical entities and help prioritize management. Determining the potential benefit from surgical intervention and the order in which to address these conditions are of utmost importance for patient satisfaction and adequate relief of symptoms.

Factors affecting clinical outcomes in treating patients with grade 1 degenerative spondylolisthesis using interspinous soft stabilization with a tension band system: a minimum 5-year follow-up

STUDY DESIGN

Retrospective clinical study.

OBJECTIVE

To explore the factors influencing the clinical outcomes and motion-preserving stabilization after interspinous soft stabilization (ISS) with a tension band system for grade 1 degenerative spondylolisthesis (DS).

SUMMARY OF BACKGROUND DATA

Despite increasing recognition of the benefits of dynamic stabilization systems for treating lumbar degenerative disorders, the factors affecting the clinical and radiological outcomes of these systems have rarely been identified.

METHODS

Sixty-five patients (mean age, 60.3 years) who underwent ISS with a tension band system between 2002 and 2004 were analyzed. The mean follow-up period was 72.5 months. The patients were divided according to the postsurgical clinical improvements into the optimal (n = 44) and suboptimal groups (n = 21), and the radiological intergroup differences were analyzed. Multiple linear regression analysis was performed to determine the impact of the radiological factors on the clinical outcomes.

RESULTS

Significant intergroup differences were observed on the follow-up clinical examination. Radiologically, total lumbar lordosis (TLL) and segmental lumbar lordosis (SLL) were significantly improved only in the optimal group, resulting in significant intergroup differences in TLL (P = 0.023), SLL (P = 0.001), and the L1 tilt (P = 0.002). All these measures were closely associated with postoperative segmental lumbar lordosis, which also was the most influential radiological variable for the clinical parameters.

CONCLUSION

In the patients with grade 1 DS, the back pain relief and functional improvement following ISS were affected by the improvements in the sagittal spinal alignment through the achievement of segmental lumbar lordosis. ISS can be an alternative treatment to fusion surgery for grade 1 DS in patients who do not require fixation or reduction.

Acute reciprocal changes distant from the site of spinal osteotomies affect global postoperative alignment

Introduction. Three-column vertebral resections are frequently applied to correct sagittal malalignment; their effects on distant unfused levels need to be understood. Methods. 134 consecutive adult PSO patients were included (29 thoracic, 105 lumbar). Radiographic analysis included pre- and postoperative regional curvatures and pelvic parameters, with paired independent t-tests to evaluate changes. Results. A thoracic osteotomy with limited fusion leads to a correction of the kyphosis and to a spontaneous decrease of the unfused lumbar lordosis (−8°). When the fusion was extended, the lumbar lordosis increased (+8°). A lumbar osteotomy with limited fusion leads to a correction of the lumbar lordosis and to a spontaneous increase of the unfused thoracic kyphosis (+13°). When the fusion was extended, the thoracic kyphosis increased by 6°. Conclusion. Data from this study suggest that lumbar and thoracic resection leads to reciprocal changes in unfused segments and requires consideration beyond focal corrections.

Risk factors of sagittal decompensation after long posterior instrumentation and fusion for degenerative lumbar scoliosis

STUDY DESIGN

A retrospective study of clinical results of operative treatment for degenerative lumbar scoliosis.

OBJECTIVE

To determine the risk factors of sagittal decompensation after long instrumentation and fusion to L5 or S1.

SUMMARY OF BACKGROUND DATA

Little is known about the risk factors for sagittal decompensation, which was defined in this study as sagittal C7 plumb falling anterior >8 cm from the posterosuperior corner of the sacrum.

METHODS

Forty-five patients (mean age: 64.4 year) with adult degenerative lumbar scoliosis were reviewed retrospectively with a minimum 2 years. The mean number of levels fused was 6.1 +/- 1.6 segments. The upper instrumented vertebra ranged from T9 to L2. The lower instrumented vertebra was L5 and S1 in 24 and 21 patients, respectively.

RESULTS

Sagittal decompensation (SD) developed in 19 patients. The most significant risk factors of SD were preoperative sagittal imbalance and high pelvic incidence. The preoperative sagittal C7 plumb was more positive (67.9 mm) in the decompensation group than in the balance group (37.0 mm) (P = 0.002). There was a significant difference in pelvic incidence between 61.7 degrees in the decompensation and 54.9 degrees in the balance group (P = 0.01). The preoperative lumbar lordosis was hypolordotic in the decompensation group, however, it was not found to be a risk factor. Pseudarthrosis was identified at the lumbosacral junction in 5 patients, and 4 of them (80%) had SD. SD developed in 55% of patients who had loosening of the distal screws and 50% of patients with hypolordotic lumbar fusion. Distal adjacent segment disease was more likely to cause SD than proximal adjacent segment disease.

CONCLUSION

Sagittal decompensation is common after long posterior instrumentation and fusion for degenerative lumbar scoliosis. It is mostly associated with complications at the distal segments, including pseudarthrosis and implant failure at the lumbosacral junction. Restoration of optimal lumbar lordosis and secure lumbosacral fixation is necessary especially in patients with preoperative sagittal imbalance and high pelvic incidence in order to prevent sagittal decompensation after surgery.

Arthrodesis to L5 versus S1 in long instrumentation and fusion for degenerative lumbar scoliosis

There is a debate regarding the distal fusion level for degenerative lumbar scoliosis. Whether a healthy L5-S1 motion segment should be included or not in the fusion remains controversial. The purpose of this study was to determine the optimal indication for the fusion to the sacrum, and to compare the results of distal fusion to L5 versus the sacrum in the long instrumented fusion for degenerative lumbar scoliosis. A total of 45 patients who had undergone long instrumentation and fusion for degenerative lumbar scoliosis were evaluated with a minimum 2 year follow-up. Twenty-four patients (mean age 63.6) underwent fusion to L5 and 21 patients (mean age 65.6) underwent fusion to the sacrum. Supplemental interbody fusion was performed in 12 patients in the L5 group and eleven patients in the sacrum group. The number of levels fused was 6.08 segments (range 4-8) in the L5 group and 6.09 (range 4-9) in the sacrum group. Intraoperative blood loss (2,754 ml versus 2,938 ml) and operative time (220 min versus 229 min) were similar in both groups. The Cobb angle changed from 24.7 degrees before surgery to 6.8 degrees after surgery in the L5 group, and from 22.8 degrees to 7.7 degrees in the sacrum group without statistical difference. Correction of lumbar lordosis was statistically better in the sacrum group (P = 0.03). Less correction of lumbar lordosis in the L5 group seemed to be associated with subsequent advanced L5-S1 disc degeneration. The change of coronal and sagittal imbalance was not different in both groups. Subsequent advanced L5-S1 disc degeneration occurred in 58% of the patients in the L5 group. Symptomatic adjacent segment disease at L5-S1 developed in five patients. Interestingly, the development of adjacent segment disease was not related to the preoperative grade of disc degeneration, which proved minimal degeneration in the five patients. In the L5 group, there were nine patients of complications at L5-S1 segment, including adjacent segment disease at L5-S1 and loosening of L5 screws. Seven of the nine patients showed preoperative sagittal imbalance and/or lumbar hypolordosis, which might be risk factors of complications at L5-S1. For the patients with sagittal imbalance and lumbar hypolordosis, L5-S1 should be included in the fusion even if L5-S1 disc was minimal degeneration.

PEDICLE SUBTRACTION OSTEOTOMY

OBJECTIVE

Pedicle subtraction osteotomy (PSO) is an effective tool for the correction of fixed sagittal plane deformity. However, there is potentially significant perioperative morbidity associated with this technique. We report our perioperative morbidity rate in recently performed PSO cases treated with our present surgical, anesthetic, and monitoring techniques and discuss complication-avoidance strategies.

METHODS

We conducted a retrospective study of 10 patients (mean age, 56 yr; range, 7–77 yr) undergoing thoracolumbar PSO at a single institution in the past 3 years. Two patients underwent PSO at T12, seven patients underwent PSO at L3, and one patient underwent PSO at L2. Eight of the patients had undergone at least one previous spine surgery in the region of the PSO, and nine of the patients had comorbidities that increased their surgical risk stratification. We identified all causes of perioperative morbidity.

RESULTS

We classified perioperative complications into two categories: intraoperative and early postoperative. Intraoperative complications included dural tears in two patients, cardiovascular instability in one patient, and coagulopathy in two patients. Early postoperative complications included neurological deficit (one patient), wound infection (two patients), urinary tract infection (one patient), and delirium (two patients). All patients recovered fully from these complications. There was no mortality in this series.

CONCLUSION

In this series, most patients undergoing PSO had multiple previous spine surgeries and comorbidities. The risk of perioperative morbidity for revision cases undergoing PSO was in excess of 50%. We discuss complication-avoidance strategies.

A single posterior approach for multilevel modified vertebral column resection in adults with severe rigid congenital kyphoscoliosis: a retrospective study of 13 cases

We report a multilevel modified vertebral column resection (MVCR) through a single posterior approach and clinical outcomes for treatment of severe congenital rigid kyphoscoliosis in adults. Transpedicular eggshell osteotomies and vertebral column resection are two techniques for the surgical treatment of rigid severe spine deformities. The authors developed a new technique combining the two surgical methods as a MVCR, through a single posterior approach, for surgical treatment of severe congenital rigid kyphoscoliosis in adults. Thirteen adult patients with severe rigid congenital kyphoscoliosis deformity were treated by a single posterior approach using a MVCR technique. The surgery processes included a one-stage posterior transpedicular eggshell technique first, and then expanded the eggshell technique to adjacent intervertebra space through abrasive reduction of the vertebral cortices from inside out. All posterior vertebral elements were removed including the cortical vertebral bone around the neural canal. Range of resection of the vertebral column at the apex of the deformity included apical vertebra and both cephalic and/or caudal adjacent wedged vertebrae. Totally, 32 vertebrae had been removed in 13 patients, with 2.42 vertebrae being removed on average in each case. The average fusion extent was 7.69 vertebrae. Mean operation time was 266 min with average blood loss of 2,411.54 ml during operation. Patients were followed up for an average duration of 2.54 years. Deformity correction was 59% in the coronal plane (from 79.7 degrees to 32.4 degrees ) postoperatively and 33.7 degrees (57% correction) at 2 years follow-up. In the sagittal plane, correction was from preoperative 85.9 degrees to 27.5 degrees immediately after operation, and 32.0 degrees at 2 years follow-up. Postoperative pain was reduced from preoperative 1.77 to 0.54 at 2 years follow-up in visual analog scale. SRS-24 scale was from 38.2 preoperatively to 76.9 at 2 years follow-up postoperative. Complications were encountered in four patients (30.7%) with transient neurology that spontaneously improved without further treatment within 3 months. MVCR technique through a single posterior approach is an effective procedure for the surgical treatment of severe congenital rigid kyphoscoliosis in adults.

Classification of posterior dynamic stabilization devices

✓Numerous new posterior dynamic stabilization (PDS) devices have been developed for the treatment of disorders of the lumbar spine. In this report the authors provide a classification scheme for these devices and describe several clinical situations in which the instrumentation may be expected to play a role. By using this classification, the PDSs that are now available and those developed in the future can be uniformly categorized.