Review of mechanisms of expandable spine surgery devices

INTRODUCTION

Expandable devices such as interbody cages, vertebral body reconstruction cages, and intravertebral body expansion devices are frequently utilized in spine surgery. Since the introduction of expandable implants in the early 2000s, the variety of mechanisms that drive expansion and implant materials have steadily increased. By examining expandable devices that have achieved commercial success and exploring emerging innovations, we aim to offer an in-depth evaluation of the different types of expandable cages used in spine surgery and the underlying mechanisms that drive their functionality.

AREAS COVERED

We performed a review of expandable spinal implants and devices by querying the National Library of Medicine MEDLINE database and Google Patents database from 1933 to 2024. Five major types of mechanical jacks that drive expansion were identified: scissor, pneumatic, screw, ratchet, and insertion-expansion.

EXPERT OPINION

We identified a trend of screw jack mechanism being the predominant machinery in vertebral body reconstruction cages and scissor jack mechanism predominating in interbody cages. Pneumatic jacks were most commonly found in kyphoplasty devices. Critically reviewing the mechanisms of expansion and identifying trends among effective and successful cages allows both surgeons and medical device companies to properly identify future areas of development.

Transpedicular Intravertebral Cage Augmentation Using Expandable Cage in Kummell Disease: Technical Note and Case Series

OBJECTIVE

To demonstrate the surgical techniques for transpedicular intravertebral cage augmentation (TPICA) using an expandable cage for Kummell disease, which requires posterior surgical stabilization, and provide the preliminary surgical outcomes.

METHODS

Six consecutive patients undergoing TPICA surgery using an expandable cage with a minimum 6-month follow-up were evaluated. Radiographic analysis to evaluate the local kyphosis angle, restoration ratio of anterior vertebral height of the index vertebra, and clinical outcomes including the Oswestry Disability Index, EuroQol 5-dimension instrument, and visual analog scale for back and leg pain, were compared between the preoperative and final follow-ups.

RESULTS

All patients showed improvements in all clinical outcomes and were able to walk independently without support at the last follow-up. In radiographic evaluation, the mean preoperative restoration ratio of anterior vertebral height was 41.2 ± 15.6%, which increased postoperatively to 70.3 ± 20.5% (1.70 times) and 62.4 ± 20.0% at the last follow-up (1.51 times). The mean preoperative local kyphosis angle was 10.5 ± 14.8 and was corrected to 6.0 ± 10.0 at the last follow-up. A slight loss of correction was observed between the postoperative period and the last follow-up; however, there was no clinical significance.

CONCLUSIONS

Expandable cages in TPICA may allow easier surgical manipulation for cage insertion around the pedicle entrance, minimizing damage to the fractured vertebral body's end plates while achieving satisfactory height restoration compared to static cages, and may also provide wider indications for TPICA surgery.

Transforaminal lumbar interbody fusion with an expandable interbody device: Two-year clinical and radiographic outcomes

Background

The use of interbody cages as an adjunct to lumbar spinal fusion remains an important technique to enhance segmental stability, promote solid arthrodesis, maintain neuroforaminal decompression, and preserve/improve segmental lordosis. Appropriate segmental lumbar lordosis and sagittal balance is well-known to be critical for long-term patient outcomes. This study sought to evaluate the radiographic and clinical results of TLIF in patients using an articulating, expandable cage. Primary endpoint was clinical and radiographic outcomes, including complications, at 12 and 24 months.

Methods

A total of 37 patients underwent open single-level or 2-level TLIF by a single surgeon using an expandable cage with concomitant bilateral pedicle screws and posterolateral arthrodesis. Clinical outcomes included ODI and VAS for back and legs. Radiographic outcomes included pelvic incidence and tilt, lumbar and segmental lordoses, and disc height at the operative level(s). All outcomes were collected at baseline, 2-weeks, 6-weeks, 3-months, 6-months, 12-months, and 24-months postop.

Results

A total of 28 patients were available for analysis. Nine patients failed to follow-up at 24 months. Mean ODI scores showed significant improvement, from pre-to-postoperative at 24 months (55%; p<.0001). VAS for back and legs was significantly lower at 24 months on average by 72 and 79%, respectively (p<.0001 for both). Both segmental and lumbar lordoses significantly improved by 5.3° and 4.2° (p<.0001 and p=.049), respectively. Average disc height improved by 49% or 6.1 mm (p<.001). No device-related complications nor instances of measured subsidence. One patient had a superficial infection, and another had an intraoperatively repaired incidental durotomy.

Conclusions

The use of an expandable cage contributed to improvement in both segmental and lumbar lordosis with no reported complications at 24-month follow-up. All clinical measures significantly improved as well. The expandable cage design represents an effective and safe option to increase cage size and allow significant segmental lordosis correction.

Comparison of surgical outcomes between lumbar interbody fusions using expandable and static cages: a systematic review and meta-analysis

BACKGROUND

The use of static cages for lumbar interbody fusion (LIF) can cause complications such as end plate violation, graft subsidence, and nerve injury. Therefore, expandable cages that allow for in-situ expansion have been developed to overcome these problems. However, it remains uncertain whether expandable cages have better surgical outcomes than static cages do.

PURPOSE

We aimed to determine the effectiveness of expandable cages by analyzing studies that compared the surgical outcomes between the use of expandable cages and static cages.

STUDY DESIGN

A systematic review and meta-analysis.

METHODS

The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were used to conduct this meta-analysis and systematic review. The primary outcomes of this study were anterior disc height, posterior disc height, segmental lordosis (SL), lumbar lordosis (LL), subsidence rate, numeric rating scale (NRS) scores for back and leg pain, and Oswestry Disability Index (ODI).

RESULTS

Thirteen studies with 1,700 patients were included in the meta-analysis. Compared with static cages for LIFs, expandable cages significantly increased the anterior disc height (standardized mean difference 0.478, 95% confidence interval [CI] 0.088-0.867, p=.0162) and segmental lordosis (sMD 0.307, 95% CI 0.159-0.454, p<.0001). There were no significant differences in the posterior disc height, lumbar lordosis, subsidence rate, back pain, leg pain, or ODI between the two groups.

CONCLUSION

Expandable cages show no clear clinical benefit over static cages.

Early Radiological Assessment of Static and Expandable Cages in Lateral Single Position for Indirect Decompression- Lateral Lumbar Interbody Fusion

OBJECTIVE

This study aimed to compare the postoperative alignment of static and expandable cages in lateral single-position (LSP) for indirect decompression in lateral lumbar interbody fusion (LLIF).

METHODS

We included sixty-seven patients who underwent LSP-LLIF for lumbar degenerative disease. We performed radiological assessments preoperatively and two weeks postoperatively using computed tomography and magnetic resonance imaging. We divided the patients into the expandable cage group (23 patients) and the static cage group (44 patients). We measured disc height (DH), segmental lordosis (SL), and foraminal area (FA) from computed tomography images and the area of the dural sac from magnetic resonance imaging. We recorded surgical outcomes and complications.

RESULTS

Both static and expandable cages demonstrated improvements in DH, SL, FA, and dural sac expansion. However, we found no statistically significant differences in the average change in DH (4.4 ± 2.1 mm vs. 4.2 ± 1.8 mm, P = 0.685), the average change in SL (1.0 ± 4.4° vs. 1.9 ± 3.6°, P = 0.310), or FA change (32.5 ± 31.7 mm2 vs. 34.9 ± 29.5 mm2, P = 0.966) between the expandable and static cage groups. We also found no statistically significant difference in dural sac enlargement between the two groups. We observed no significant differences in operation time, estimated blood loss, or length of hospital stay between the two groups. No severe adverse events or additional surgeries were reported.

CONCLUSIONS

In LSP-LLIF without facet joint resection or other posterior techniques, static and expandable cages showed comparable effectiveness in achieving increased DH, SL, FA, and indirect decompression.

Minimally Invasive Transforaminal Lumbar Interbody Fusion Using Expandable Cages: Increased Risk of Late Postoperative Subsidence Without a Real Improvement of Perioperative Outcomes: A Clinical Monocentric Study

BACKGROUND

Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is one of several approaches to lumbar interbody fusion that has proven to be a safe and effective treatment for symptomatic lumbar degenerative disease The clinical outcomes of MIS-TLIF are generally favorable, but there is still controversy regarding its ability to restore sagittal alignment. For this reason, expandable transforaminal lumbar interbody fusion cages have been developed and designed to improve ability to restore disc height and segmental lordosis. The use of expandable cages in transforaminal lumbar interbody fusion has increased drastically; however, it is not clear how effective cage expansion is in regard to disc space lordosis, distraction, and long-term outcome.

METHODS

We reviewed a cohort of patients with symptomatic lumbar degenerative disc pathology who underwent MIS-TLIF at our institution. We compared clinical and radiographic outcomes of expandable versus nonexpandable cage use in MIS-TLIF focusing on mean changes in segmental lordosis, disc height, and postoperative complications. The results were compared with other studies reported in the international literature.

RESULTS

Mean change in segmental lordosis was not significantly different between the 2 groups. A significantly higher rate of postoperative subsidence was demonstrated in the expandable cage group.

CONCLUSION

This study established that expandable cage use in single-level transforaminal lumbar interbody fusion did not reduce the rate of postoperative complications, but rather significantly increased a patient's risk of postoperative subsidence. Expandable cages do not presently demonstrate improved clinical outcomes or improved sagittal alignment compared with static cages.

Expandable Cage Technology-Transforaminal, Anterior, and Lateral Lumbar Interbody Fusion

This review of the literature will focus on the indications, surgical techniques, and outcomes for expandable transforaminal lumbar interbody fusion (TLIF), anterior lumbar interbody fusion (ALIF), and lateral lumbar interbody fusion (LLIF) operations. The expandable TLIF cage has become a workhorse for common degenerative pathology, whereas expandable ALIF cages carry the promise of greater lordotic correction while evading the diseased posterior elements. Expandable LLIF cages call upon minimally invasive techniques for a retroperitoneal, transpsoas approach to the disc space, obviating the need for an access surgeon and decreasing risk of injury to the critical neurovascular structures. Nuances between expandable and static cages for all 3 TLIF, ALIF, and LLIF operations are discussed in this review.

Static Versus Expandable Polyether Ether Ketone (PEEK) Interbody Cages: A Comparison of One-Year Clinical and Radiographic Outcomes for One-Level Transforaminal Lumbar Interbody Fusion

OBJECTIVE

To examine the effect of static versus expandable polyether ether ketone (PEEK) cages on both clinical and radiographic outcomes.

METHODS

A retrospective cohort study was conducted on patients who underwent one-level transforaminal lumbar interbody fusion with either a static or expandable PEEK cage. Patient outcomes were obtained from chart review and radiographic outcomes were measured using standing, lateral radiographs. Recovery ratios and the proportion of patients achieving the minimally clinically important difference were calculated for Oswestry Disability Index (ODI), Physical Component Score-12, Mental Component Score-12, visual analogue scale for back, and visual analogue scale for leg at 1 year and compared between groups. Multivariate linear regression analysis was performed to determine the effect of cage type on the change in patient-reported outcome measures, controlling for demographic factors.

RESULTS

A total of 240 patients (137 static, 103 expandable) were included in the final analysis. ΔPhysical Component Score-12 scores at 3 months were significantly greater for the static group (16.0 vs. 10.0, P = 0.043) compared with the expandable group. Multivariate regression demonstrated that use of an expandable cage was associated with greater improvements in ΔODI (β: -7.82, P = 0.048) at 1 year. No differences were found in the perioperative change in sagittal spinal alignment within or between groups at 1 year. Subsidence rates failed to show any statistically significant difference between the 2 groups.

CONCLUSIONS

Transforaminal lumbar interbody fusion with an expandable PEEK cage is an independent predictor of improved ODI scores at 1 year. Our study showed no significant differences in subsidence rates or changes in sagittal spinal alignment between static and expandable PEEK cages.

Translocation of Cervical Vertebral Body Replacement Device into the Esophagus

Expandable vertebrectomy devices are a key technology that has facilitated the adoption of minimally invasive approaches to spine oncology surgery. However, advanced technology still requires proper attention to surgical fundamentals. Here we illustrate a cage of a misplaced expandable vertebrectomy device causing esophageal perforation. Examination of the postoperative radiographs suggests that haptic feedback from the expandable technology may have given the false impression of bony engagement. This case highlights the need for proper mortise work and complete visualization of the segments to be instrumented even during minimally invasive surgery.

Expandable cages increase the risk of intraoperative subsidence but do not improve perioperative outcomes in single level transforaminal lumbar interbody fusion

BACKGROUND CONTEXT

Expandable cages (EXP) are being more frequently utilized in transforaminal lumbar interbody fusions (TLIF). EXP were designed to reduce complications related to neurological retraction, enable better lordosis restoration, and improve ease of insertion, particularly in the advent of minimally invasive surgical (MIS) techniques, however they are exponentially more expensive than the nonexpandable (NE) alternative.

PURPOSE

To investigate the clinical results of expandable cages in single level TLIF.

STUDY DESIGN/SETTING

Retrospective review at a single institution.

PATIENT SAMPLE

Two hundred and fifty-two single level TLIFs from 2012 to 2018 were included.

OUTCOME MEASURES

Clinical characteristics, perioperative and neurologic complication rates, and radiographic measures.

METHODS

Patients ≥18 years of age who underwent single level TLIF with minimum 1 year follow-up were included.

OUTCOME MEASURES

clinical characteristics, perioperative and neurologic complications. Radiographic analysis included pelvic incidence-lumbar lordosis (PI-LL) mismatch, segmental lumbar lordosis (LL) mismatch, disc height restoration, and subsidence ≥2 mm. Statistical analysis included independent t tests and chi-square analysis. For nonparametric variables, Mann-Whitney U test and Spearman partial correlation were utilized. Multivariate regression was performed to assess relationships between surgical variables and recorded outcomes. For univariate analysis significance was set at p<.05. Due to the multiple comparisons being made, significance for regressions was set at p<.025 utilizing Bonferroni correction.

RESULTS

Two hundred and fifty-two TLIFs between 2012 and 2018 were included, with 152 NE (54.6% female, mean age 59.28±14.19, mean body mass index (BMI) 28.65±5.38, mean Charlson Comorbidity Index (CCI) 2.20±1.89) and 100 EXP (48% female, mean age 58.81±11.70, mean BMI 28.68±6.06, mean CCI 1.99±1.66) with no significant differences in demographics. Patients instrumented with EXP cages had a shorter length of stay (3.11±2.06 days EXP vs. 4.01±2.64 days NE; Z=-4.189, p<.001) and a lower estimated blood loss (201.31±189.41 mL EXP vs. 377.82±364.06 mL NE; Z=-6.449, p<.001). There were significantly more MIS-TLIF cases and bone morphogenic protein (BMP) use in the EXP group (88% MIS, p<.001 and 60% BMP, p<.001) as illustrated in Table 1. There were no significant differences between the EXP and NE groups in rates of radiculitis and neuropraxia. In multivariate regression analysis, EXP were not associated with a difference in perioperative outcomes or complications. Radiographic analyses demonstrated that the EXP group had a lower PI-LL mismatch than the NE cage group at baseline (3.75±13.81° EXP vs. 12.75±15.81° NE; p=.001) and at 1 year follow-up (3.81±12.84° EXP vs. 8.23±12.73° NE; p=.046), but change in regional and segmental alignment was not significantly different between groups. Multivariate regression demonstrated that EXP use was a risk factor for intraoperative subsidence (2.729[1.185-6.281]; p=.018).

CONCLUSIONS

Once technique was controlled for, TLIFs utilizing EXP do not have significantly improved neurologic or radiographic outcomes compared with NE. EXP increase risk of intraoperative subsidence. These results question the value of the EXP given the higher cost.

Isolated unstable burst fractures of the fifth lumbar vertebra: functional and radiological outcome after posterior stabilization with reconstruction of the anterior column: About 6 cases and literature review

INTRODUCTION

L5 burst fractures represent a small percentage of all spine fractures. Treatment strategy has not yet been standardized. Anatomical features and their biomechanical characteristics create fracture patterns which differ from those at the thoracolumbar junction. The objective of this study was to evaluate L5 burst fracture surgical treatment outcomes after posterior stabilization and reconstruction of the anterior column.

PATIENTS AND METHODS

Six patients with fifth lumbar isolated unstable burst fractures were analyzed. Medical records, radiographs, and clinical scores were obtained. The results were evaluated based on restoration of vertebral body height, spinal lordosis/kyphosis, canal compromise and sagittal alignment at several phases of treatment.

RESULTS

No patient showed neurologic deterioration, regardless of treatment. The median preoperative anterior vertebral height was 41mm and postoperative was 48mm. The median preoperative kyphotic angle as measured by Cobb angle (local and regional) was 21.5 degrees and 33 degrees which improved respectively by 7.5 and 5.5 degrees following instrumentation. The median amount of backward protrusion of bony fragment into the canal was measured at 67% preoperatively and at 35% postoperatively. There were no pseudarthrosis and anterior arthrodesis solid fusion was visible in all cases. There were a sagittal alignment restoration. At one year of follow up, fusion was obtained in all the cases, all patients had minimal to moderate disability using Oswestry Disability Index. The ability to return to work revealed a good-to-excellent long-term result.

DISCUSSION

The results of treatment of 5th lumbar unstable burst fractures with posterior stabilization and reconstruction of the anterior column show benefit on durable functional outcome, spine stabilization and radiologic parameters.

LEVEL OF EVIDENCE

IV, retrospective study.

Single-Stage Posterior Circumferential Stabilization Using Double Small Cages for the Treatment of Thoracic and Lumbar Spine Fractures

OBJECTIVE

Controversy remains regarding the optimal methods for resection of the vertebral body, reconstruction of the anterior column, and decompression of the spinal cord in patients who have severe vertebral body destruction of the thoracic or lumbar spine with associated neurologic impairment. We report an alternative technique for primary treatment and salvage involving single-stage corpectomy followed by reconstruction of the anterior column using double small mesh cages via the posterior-only approach.

METHODS

Plain radiographs and computed tomography scans, taken at different intervals, were used to measure local kyphosis, segmental height, and fusion grade. Pain was evaluated using the visual analog scale (VAS), and neurologic symptoms were classified according to Frankel grade.

RESULTS

The mean kyphotic deformity improved by 14.47 ± 9.06 degrees (P < 0.001), and the mean segmental height improved by 7.17 mm ± 6.11 mm (P < 0.001) after surgery. Fusion was achieved at 84% of patients, within a median interval of 12 months. Kyphotic recurrence was observed in 2 patients (11%), segmental height loss occurred in 1 patient (5%), and both kyphotic recurrence and segmental height loss occurred in 1 patient (5%). None of the patients reported worsening pain or neurologic symptoms after surgery, and there were no surgery-related complications such as neural injury, cerebrospinal fluid leakage, cage dislocation, surgical site infection, or cardiopulmonary complications.

CONCLUSIONS

Single-stage corpectomy followed by reconstruction of the anterior column using double small mesh cages via the posterior-only approach is a reliable and less invasive single-stage treatment and salvage option in selected cases.

Less Opioid Consumption With Enhanced Recovery After Surgery Transforaminal Lumbar Interbody Fusion (TLIF): A Comparison to Standard Minimally-Invasive TLIF

Objective

The concept of enhanced recovery after surgery (ERAS) is relatively new to the neurosurgical field. The introduction of an ERAS protocol in lumbar fusion surgery has aimed to accelerate patient recovery from surgery by reducing in-hospital opioid consumption.

Methods

Patients with 1- or 2-level degenerative lumbar spine disease and who underwent ERAS transforaminal lumbar interbody fusion (TLIF) were retrospectively reviewed. Patients’ general demographic data, in-hospital opioid dosage (converted to morphine equivalents), and hospital stay were compared to those who underwent standard minimally-invasive (MIS)-TLIF.

Results

Twenty-four patients who received ERAS TLIF (the ERAS group) were compared to a series of 24 patients who received standard MIS-TLIF (the MIS group). The demographic data were similar. The operation time and blood loss significantly favored ERAS TLIF. The average daily opioid consumption was remarkably lower in the ERAS group than the MIS group. Average opioid dosage throughout the entire in-hospital period was also significantly reduced in the ERAS group compared to the MIS group. The average length of hospital stay was substantially shorter in the ERAS group (1.4 ± 1.13 days vs. 4.0±1.98 days, p <0.001).

Conclusion

The present study demonstrated a significant decline in the consumption of opioids and in the hospital length of stay for patients undergoing ERAS TLIF for 1- or 2-level degenerative lumbar spine disease.

Assessing the Difference in Clinical and Radiologic Outcomes Between Expandable Cage and Nonexpandable Cage Among Patients Undergoing Minimally Invasive Transforaminal Interbody Fusion: A Systematic Review and Meta-Analysis

BACKGROUND

Minimally invasive transforaminal interbody fusion (MIS-TLIF) has been shown to have excellent outcomes for surgical management of degenerative disc disease. However, the challenge is in addressing coronal imbalance and restoring lumbar lordosis and sagittal alignment. Use of expandable cages in MIS-TLIF has been hypothesized to circumvent this disadvantage. An indirect meta-analysis of the evidence is presented comparing outcomes from expandable cages with those from nonexpandable cages, in patients undergoing MIS-TLIF.

METHODS

PRISMA guidelines were used to conduct a systematic review and meta-analysis to compare the clinical and radiologic outcomes of expandable cages and nonexpandable cages in patients undergoing MIS-TLIF.

RESULTS

Twelve studies (706 patients) were included in the meta-analysis. The mean increase in disc height was found to be significantly greater for the nonexpandable cages group than for the expandable cages group (1.33 mm; 95% confidence interval [CI], 1.28-1.38 vs. 1.14 mm,; 95% CI, 1.06-1.23; P < 0.001). No significant difference was found regarding change in lumbar lordosis at last follow-up between the 2 groups (P = 0.34). The mean change in segmental lordosis was found to be significantly higher for the expandable cage group (5.04°, 95% CI, 3.89-6.20 vs. 2.08°, 95% CI, 1.93-2.22; P < 0.001). We did not detect any significant difference in fusion rate (P = 0.33), subsidence rate (P = 0.41) or in reoperations (P = 0.56) at last follow-up between the 2 groups.

CONCLUSIONS

Our results indicate that there may not be a significant difference in clinical and radiologic parameters between expandable cages and nonexpandable cages among patients undergoing MIS-TLIF, and it is unclear if the higher cost of the expandable cages is justified.

Palliative Posterior Instrumentation versus Corpectomy with Cage Reconstruction Treatment for Thoracolumbar Pathological Fracture

Study Design

Single-center, retrospective cohort study.

Purpose

We aimed to evaluate and compare the clinical outcomes in patients who underwent palliative posterior instrumentation (PPI) versus those who underwent corpectomy with cage reconstruction (CCR) for thoracolumbar pathological fracture.

Overview of Literature

The requirement for anterior support after corpectomy has been emphasized in the treatment of pathological fractures of the vertebrae. However, for patients with a relatively short life expectancy, anterior reconstruction may not be required and posterior instrumentation alone may provide adequate stabilization.

Methods

A total of 43 patients with metastases of the thoracolumbar spine underwent surgery in the department of orthopaedic and traumatology of Istanbul University Faculty of Medicine from 2003 to 2016. Surgical outcomes were assessed on the basis of survival status, pre- and postoperative pain, complication rate, and operation time.

Results

PPI was performed for 22 patients and CCR was performed for 21 patients. In the PPI group, the follow-up period of the five surviving patients was 32 months. The remaining 17 patients died with a mean survival duration of 12.3 months postoperatively. In the CCR group, the five surviving patients were followed up for an average of 14.1 months. The remaining 16 patients died with a mean survival duration of 18.7 months postoperatively. No statistically significant difference (p=0.812) was noted in the survival duration. The Visual Analog Scale scores of the patients were significantly reduced after both procedures, with no significant difference noted on the basis of the type of surgical intervention (p>0.05). The complication rate in the CCR group (33.3%) was higher compared with that in the PPI group (22.7%); however, this difference was not noted to be statistically significant (p=0.379). The average operation time in the PPI group (149 minutes) was significantly shorter (p=0.04) than that in the CCR group (192 minutes).

Conclusions

The PPI technique can decompress the tumor for functional improvement and can stabilize the spinal structure to provide pain relief.

Three-dimensional thoracoscopic vertebral body replacement at the thoracolumbar junction

OBJECTIVE

The aim is to stabilize the thoracolumbar spine with a thoracoscopically implanted vertebral body replacement (VBR). To improve intraoperative depth perception and orientation, implantation is performed under three-dimensional (3D) thoracoscopic vision.

INDICATIONS

Vertebral burst fractures at the thoracolumbar junction (A4 AOSpine classification), pseudarthrosis, and posttraumatic instability with increasing kyphosis.

CONTRAINDICATIONS

Severe pulmonary dysfunctions, pulmonary or thoracic infections, previous thoracic surgery, and pulmonary adhesions.

SURGICAL TECHNIQUE

The patient is lying in a right lateral decubitus position. Localization of the fractured vertebra. Minimally invasive transthoracic approach. Perform single lung ventilation and insert the 3D thoracoscope two intercostal spaces above the working portal. Utilization of special binocular glasses for 3D vision of the operation field and secure resection of the fractured vertebra. Measurement of the bony defect and insertion of the expandable cage. Control of correct cage position under fluoroscopy. Insertion of a chest tube and inflate the left lung.

POSTOPERATIVE MANAGEMENT

Chest × ray Remove chest tube when output is <500 ml/24 h Early mobilization on the ward 6 weeks no weight-bearing >5 kg RESULTS: Between 2012 and 2017, 12 patients received a VBR under 3D thoracoscopic vision. After a mean follow up of 26 months, no cage dislocation was noticed and all patients recovered from the initial back pain. Complications were notable in two cases (17%) with a small pneumothorax after removal of the chest tube and postoperative pneumonia in one patient (8%). All responded to conservative treatment. Revision surgery was not necessary.

Instrumented Circumferential Fusion in Two Stages for Instable Lumbar Fracture: Long-Term Results of a Series of 74 Patients on Sagittal Balance and Functional Outcomes

OBJECTIVE

To report the radiologic and functional results of a multicenter, prospective case series of patients with comminuted lumbar fractures treated with 2-stage circumferential arthrodesis.

METHODS

A multicenter prospective case series of 74 patients with comminuted lumbar fractures was analyzed. The strategy entailed initial posterior osteosynthesis, followed by physical replacement with an expandable titanium cage filled with autologous bone via retroperitoneal lumbotomy. The mechanism of lesion formation and epidemiologic characteristics were recorded. Clinical and quality-of-life analyses (visual analog scale [VAS], Oswesty Disability Index [ODI], Short Form 12 [SF-12]) were performed over a minimum observation period of 1 year. Radiologic parameters, including deformity measurements, were recorded at each evaluation. Fusion was analyzed by means of a 1-year monitoring scan.

RESULTS

The mean patient age was 38.1 years, and median duration of follow-up was 2.1 years (interquartile range, 1.3-2.9). The distribution of fractures according to the Magerl classification scheme was as follows: A, 64.8%; B, 16.7%; C, 18.5%. At the last follow-up, fusion was considered certain in 57 cases (77%). The mean VAS score was 2.1 ± 1.3, mean ODI was 14.7 ± 8.0, mean SF-12 Physical Component Summary score was 43.2 ± 9.3, and mean SF-12 Mental Component Summary score was 50.8 ± 5.9. Correction of the regional sagittal deformity was significant during the postoperative period, with a mean increase in lordosis of 9.0° (P < 0.0001). The loss of mean correction at the last follow-up (-2.9°) was not significant.

CONCLUSIONS

Circumferential arthrodesis, including posterior osteosynthesis and physical replacement with an expandable cage and autologous graft, is applicable to the treatment of comminuted lumbar fractures. A high rate of fusion was obtained with significant and long-lasting correction of the sagittal deformity. Functional scores measured at 1 year suggest mild disability. The ODI, SF-12, and VAS scores were positively correlated with fusion at the last follow-up.

Analysis of the spinal nerve roots in relation to the adjacent vertebral bodies with respect to a posterolateral vertebral body replacement procedure

OBJECTIVE

This study aims to improve the understanding of the anatomic variations along the thoracic and lumbar spine encountered during an all-posterior vertebrectomy, and reconstruction procedure. This information will help improve our understanding of human spine anatomy and will allow better planning for a vertebral body replacement (VBR) through either a transpedicular or costotransversectomy approach.

SUMMARY OF BACKGROUND DATA

The major challenge to a total posterior approach vertebrectomy and VBR in the thoracolumbar spine lies in the preservation of important neural structures.

METHODS

This was a retrospective analysis. Hundred normal magnetic resonance imaging (MRI) spinal studies (T1-L5) on sagittal T2-weighted MRI images were studied to quantify: (1) mid-sagittal vertebral body (VB) dimensions (anterior, midline, and posterior VB height), (2) midline VB and associated intervertebral discs height, (3) mean distance between adjacent spinal nerve roots (DNN) and mean distance between the inferior endplate of the superior vertebrae to its respective spinal nerve root (DNE), and (4) posterior approach expansion ratio (PAER).

RESULTS

(1) The mean anterior VB height gradually increased craniocaudally from T1 to L5. The mean midline and posterior VB height showed a similar pattern up to L2. Mean posterior VB height was larger than the mean anterior VB height from T1 to L2, consistent with anterior wedging, and then measured less than the mean anterior VB height, indicating posterior wedging. (2) Midline VB and intervertebral disc height gradually increased from T1 to L4. (3) DNN and DNE were similar, whereby they gradually increased from T1 to L3. (5) Mean PAER varied between 1.69 (T12) and 2.27 (L5) depending on anatomic level.

CONCLUSIONS

The dimensions of the thoracic and lumbar vertebrae and discs vary greatly. Thus, any attempt at carrying out a VBR from a posterior approach should take into account the specifications at each spinal level.

Novel reconstruction of the anterior craniocervical junction using an expandable cage with integrated fixation after total C2 spondylectomy for chordoma

Chordoma is a locally aggressive malignant tumor that generally occurs in the clivus, mobile spine and sacrum. While en bloc resection with wide margins has been advocated as the only cure for chordomas, tumor characteristics and violation of critical anatomical boundaries may preclude pursuing this treatment option in the cervical spine. We present a C2 chordoma in a 35-year-old man with epidural and prevertebral extension that was treated with a single stage anterior-posterior total C2 spondylectomy with novel reconstruction using an expandable cage with integrated fixation followed by stereotactic radiosurgery. Single stage intralesional total C2 spondylectomy via anterior transoral and posterior approaches was performed. The anterior column was reconstructed using an expandable cage with integrated fixation from the clivus to C3. The patient maintained his intact neurological status at 6 month follow-up with full resumption of activities of daily living without any significant morbidity.

Anterior cervical corpectomy for cervical spondylotic myelopathy: Reconstruction with expandable cylindrical cage versus iliac crest autograft. A retrospective study

OBJECTIVES

To compare retrospectively the clinical and radiographic outcomes between cervical reconstruction with expandable cylindrical cage (ECC) and iliac crest autograft after one- or two-level anterior cervical corpectomy for spondylotic myelopathy.

PATIENTS AND METHODS

Forty-two patients underwent cervical reconstruction with either iliac crest autograft and plating (20 patients) or ECC and plating (22 patients). The average clinical and radiological follow-up period was 77.54 ± 44.28 months (range 14-155 months). The authors compared clinical parameters (Nurick Myelopathy Grade, modified Japanese Orthopedic Association (mJOA) scores), perioperative parameters (hospital stays, complications) and radiological parameters (Cobb's angles of the fused segments and C2-C7 segments, cervical subsidence, fusion rate). Fusion was assessed on flexion-extension X-ray films.

RESULTS

No significant differences between the two groups were found in demographics, neurological presentation, preoperative sagittal alignment, clinical improvement and length of hospitalization. Patients of the autograft group experienced more postoperative complications, although the difference between the two treatment groups was not statistically significant (15 versus 4.5%, p=0.232). The fusion rate was 100% in both groups. The average lordotic increase of the segmental angle was significantly greater in the ECC group (p<0.05). Other radiological parameters were not significantly different in the two groups.

CONCLUSION

Cervical reconstruction either with iliac crest autograft and plating or ECC and plating provides good clinical results and similar fusion rates after one- or two-level corpectomy for spondylotic myelopathy. However, the use of ECC obviates donor site complications and provides a more significant increase of lordosis in segmental angle.

Minimally Invasive Muscle Sparing Posterior-Only Approach for Lumbar Circumferential Decompression and Stabilization to Treat Spine Metastasis--Technical Report

OBJECTIVE

Palliative tumor resection and subsequent stabilization are important for maximizing function and quality of life for patients suffering from spinal metastases. However, traditional operative techniques for spinal metastases with vertebral body destruction involve extensive soft tissue dissection. In the lumbar spine, open 2-staged spine procedures are routinely required with an anterior retroperitoneal approach for corpectomy and cage insertion and posterior decompression and stabilization with pedicle screws and rods. Both stages require extensive soft tissue dissection that results in significant surgical morbidity, long recovery time, and subsequent delay in initiating postoperative chemoradiotherapy, as well as initially hampering patients' overall quality of life. A minimally invasive approach is desirable for achieving spinal stability, pain control, functional recovery, rapid initiation of adjuvant therapies, and overall patient satisfaction, especially in patients whose medical and surgical therapies are aimed at palliation rather than cure.

PRESENTATION

A 59-year-old man with renal cell carcinoma and a known L1 vertebral body metastasis presented with severe progressive low back pain and was found to have a pathologic L1 vertebral body fracture with focal kyphosis.

INTERVENTION

Here, we describe a minimally invasive muscle-sparing, posterior-only approach for L1 transpedicular hemicorpectomy and expandable cage placement, L1 laminectomy, and T11-L3 posterior instrumented stabilization. The surgical corridor was achieved through the Wiltse muscle plane between the multifidus and longissimus muscles so that minimal muscle detachment was required to achieve transpedicular access to the anterior and middle spinal columns. The L1 nerve root was completely skeletonized to allow adequate lumbar hemicorpectomy, tumor resection, and expandable titanium cage insertion. Lastly, percutaneous pedicle screws and rods were inserted from T11 to L3 for stabilization.

RESULT

The patient tolerated the procedure well with no complications and less than 200 mL estimated blood loss. Postoperative computed tomography revealed restoration of intervertebral height and adequate tumor resection with excellent placement of the expandable cage and posterior construct. The patient was discharged on postoperative day 4 and had nearly no back pain 3 weeks after surgery. Adjuvant therapies were started soon after. At the 6-month follow-up, the patient required minimal narcotic pain medication. Computed tomography scan demonstrated stable hardware with no evidence of failure.

CONCLUSION

A minimally invasive muscle-sparing, posterior-only approach is a promising surgical strategy for 360-degree decompression and stabilization for the treatment of lumbar spinal metastases with minimized blood loss, muscle detachment and postoperative pain, and fast postoperative recovery and initiation of adjuvant therapy.

Safety of instrumentation and fusion at the time of surgical debridement for spinal infection

The present study aims to assess the results of single-stage instrumentation and fusion at the time of surgical debridement of spinal infections; vertebral osteomyelitis or epidural abscess. Nine patients with spinal infection were treated with instrumentation and fusion after radical debridement in a single-stage operation. Predisposing factors and comorbidities, pain, American Spinal Injury Association motor scores, primary pathologies, microbiology and perioperative markers were recorded. Seven patients with pyogenic and two with tuberculous spinal infection were encountered; the most common pathogen was Staphylococcus aureus. Five patients were predisposed to infection because of diabetes mellitus. Duration of antibiotic therapy lasted up to 12 months. Six patients had thoracic infection, two lumbar and one cervical. No post-operative complications were encountered. There was a significant reduction in pain scores compared to pre-operatively. All patients with neurological deficits improved post-operatively. Despite introduction of hardware, no patients had a recurrence of their infection in the 12 month follow up period. Single-stage debridement and instrumentation appeared to be a safe and effective method of managing spinal infections. The combination of debridement and fusion has the dual benefit of removing a focus of infection and stabilising the spine. The current series confirms that placing titanium cages into an infected space is safe in a majority of patients. Stabilisation and correction of spinal deformity reduces pain, aids neurologic recovery and improves quality of life. The small patient population and retrospective nature limit the present study.

Thoracic lateral extracavitary corpectomy for anterior column reconstruction with expandable and static titanium cages: clinical outcomes and surgical considerations in a consecutive case series

OBJECTIVE

Many surgical interventions have emerged as effective means of restoring mechanical stability of the anterior column of the spine. The lateral extracavitary approach (LECA) allows for broad visualization and circumferential reconstruction of the spinal column. However, early reports demonstrated significant complication rates, protracted operative times, and prolonged hospitalizations. More recent reports have highlighted concerns for subsidence, particularly with expandable cages. Our work seeks to describe a single-surgeon consecutive series of patients undergoing LECA for thoracic corpectomy. Specifically, the objective was to explore the surgical considerations, clinical and radiographic outcomes, and complication profile of this approach.

METHODS

A retrospective study examined data from 17 consecutive patients in whom single or multi-level corpectomy was performed via a LECA by a single surgeon. Vertebral body replacement was achieved with either a static or expandable titanium cage. The Karnofsky Performance Scale (KPS) was utilized to assess patient functional status before and after surgery. Radiographic outcomes, particularly footplate-to-body ratio and subsidence, were assessed on CT imaging at 6 weeks after surgery and at follow-up of at least 6 months.

RESULTS

The majority of patients had post-operative KPS scores consistent with functional independence (≥70, 12/17 patients, 71%). Fourteen patients had improved or maintained function by last follow-up. In both groups, all patients had a favorable footplate-to-body ratio, and rates of subsidence were similar at both time points. Notably, the overall complication rate (24%) was significantly lower than that published in the literature, and no patient suffered a pneumothorax that required placement of a thoracostomy tube.

CONCLUSION

The LECA approach for anterior column reconstruction with static or expandable cages is an important surgical consideration with favorable surgical parameters and complication rates. Further, use of expandable cages may allow for reconstruction over a larger segment without increased risk of subsidence.

Corpectomy cage subsidence with rectangular versus round endcaps

Corpectomy cages with rectangular endcaps utilize the stronger peripheral part of the endplate, potentially decreasing subsidence risk. The authors evaluated cage subsidence during cyclic biomechanical testing, comparing rectangular versus round endcaps. Fourteen cadaveric spinal segments (T12-L2) were dissected and potted at T12 and L2, then assigned to a rectangular (n=7) or round (n=7) endcap group. An L1 corpectomy was performed and under uniform conditions a cage/plate construct was cyclically tested in a servo-hydraulic frame with increasing load magnitude. Testing was terminated if the test machine actuator displacement exceeded 6mm, or the specimen completed cyclic loading at 2400 N. Number of cycles, compressive force and force-cycles product at test completion were all greater in the rectangular endcap group compared with the round endcap group (cycles: 3027 versus 2092 cycles; force: 1943 N versus 1533 N; force-cycles product: 6162kN·cycles versus 3973 kN·cycles), however these differences were not statistically significant (p ⩾ 0.076). After normalizing for individual specimen bone mineral density, the same measures increased to a greater extent with the rectangular endcaps (cycles: 3014 versus 1855 cycles; force: 1944 N versus 1444 N; force-cycles product: 6040 kN·cycles versus 2980 kN·cycles), and all differences were significant (p⩽0.030). The rectangular endcap expandable corpectomy cage displayed increased resistance to subsidence over the round endcap cage under cyclic loading as demonstrated by the larger number of cycles, maximum load and force-cycles product at test completion. This suggests rectangular endcaps will be less susceptible to subsidence than the round endcap design.

Mini-open transpedicular lumbar vertebrectomy reconstructed with double cages and short segment fixation

Background:

The purpose of this study was to assess the feasibility of using dual expandable cages plus short segment posterior fixation for reconstruction of vertebral bodies following a mini-open transpedicular approach.

Methods:

A single posterior incision was used to perform a laminectomy of L2, a partial laminectomy of L1 and bilateral transpedicular approaches for a piecemeal vertebrectomy in a patient with spinal compression secondary to metastatic cancer. Subsequently, bilateral cages were placed through the transpedicular corridors and percutaneous pedicle screws were inserted a single level above and below the level of the vertebral column resection.

Results:

The bilateral transpedicular approach facilitated the use of a mini-open incision (6.0 cm) compared with the extensive dissection normally employed for a lateral extracavitary type approach in the lumbar region. The bilateral transpedicular approach at L2 allowed for a vertebrectomy and complete decompression of neurological elements. The use of expandable cages allowed the nerve roots to be preserved. Placement of the cages in the lateral position was straightforward despite minimal exposure. The reconstruction with double expandable cages appeared robust.

Conclusions:

In select patients requiring circumferential decompression of the lumbar spine, dual cage reconstruction decreases the technical difficulty of the operation and facilitates a mini-open approach. The durability of this construct will need biomechanical assessment and long-term clinical follow-up.

Clinical and radiological outcomes of unilateral facetectomy and interbody fusion using expandable cages for lumbosacral foraminal stenosis

OBJECTIVE

Surgical treatment of lumbosacral foraminal stenosis requires an understanding of the anatomy of the lumbosacral area in individual patients. Unilateral facetectomy has been used to completely decompress entrapment of the L5 nerve root, followed in some patients by posterior lumbar interbody fusion (PLIF) with stand-alone cages.

METHODS

We assessed 34 patients with lumbosacral foraminal stenosis who were treated with unilateral facetectomy and PLIF using stand-alone cages in our center from January 2004 to September 2007. All the patients underwent follow-up X-rays, including a dynamic view, at 3, 6, 12, 24 months, and computed tomography (CT) at 24 months postoperatively. Clinical outcomes were analyzed with the mean numeric rating scale (NRS), Oswestry Disability Index (ODI) and Odom's criteria. Radiological outcomes were assessed with change of disc height, defined as the average of anterior, middle, and posterior height in plain X-rays. In addition, lumbosacral fusion was also assessed with dynamic X-ray and CT.

RESULTS

Mean NRS score, which was 9.29 prior to surgery, was 1.5 at 18 months after surgery. The decrease in NRS was statistically significant. Excellent and good groups with regard to Odom's criteria were 31 cases (91%) and three cases (9%) were fair. Pre-operative mean ODI of 28.4 decreased to 14.2 at post-operative 24 months. In 30 patients, a bone bridge on CT scan was identified. The change in disc height was 8.11 mm, 10.02 mm and 9.63 mm preoperatively, immediate postoperatively and at 24 months after surgery, respectively.

CONCLUSION

In the treatment of lumbosacral foraminal stenosis, unilateral facetectomy and interbody fusion using expandable stand-alone cages may be considered as one treatment option to maintain post-operative alignment and to obtain satisfactory clinical outcomes.

Secondary Collapse of an Expandable Cage After Vertebral Corpectomy

Expandable vertebral body replacement systems have been increasingly used for anterior stabilization of spine. We report a secondary collapse of an expandable vertebral body replacement system. This specific complication has not been reported in the literature so far. The most obvious reason for failure was insufficient tightening of a locking screw. This paper emphasizes the importance of correct technical application.

A Multi-center Clinical Study of Posterior Lumbar Interbody Fusion with the Expandable Stand-alone Cage (Tyche(R) Cage) for Degenerative Lumbar Spinal Disorders

OBJECTIVE

This multi-center clinical study was designed to determine the long-term results of patients who received a one-level posterior lumbar interbody fusion with expandable cage (Tyche(R) cage) for degenerative spinal diseases during the same period in each hospital.

METHODS

Fifty-seven patients with low back pain who had a one-level posterior lumbar interbody fusion using a newly designed expandable cage were enrolled in this study at five centers from June 2003 to December 2004 and followed up for 24 months. Pain improvement was checked with a Visual Analogue Scale (VAS) and their disability was evaluated with the Oswestry Disability Index. Radiographs were obtained before and after surgery. At the final follow-up, dynamic stability, quality of bone fusion, interveretebral disc height, and lumbar lordosis were assessed. In some cases, a lumbar computed tomography scan was also obtained.

RESULTS

The mean VAS score of back pain was improved from 6.44 points preoperatively to 0.44 at the final visit and the score of sciatica was reduced from 4.84 to 0.26. Also, the Oswestry Disability Index was improved from 32.62 points preoperatively to 18.25 at the final visit. The fusion rate was 92.5%. Intervertebral disc height, recorded as 9.94+/-2.69 mm before surgery was increased to 12.23+/-3.31 mm at postoperative 1 month and was stabilized at 11.43+/-2.23 mm on final visit. The segmental angle of lordosis was changed significantly from 3.54+/-3.70 degrees before surgery to 6.37+/-3.97 degrees by 24 months postoperative, and total lumbar lordosis was 20.37+/-11.30 degrees preoperatively and 24.71+/-11.70 degrees at 24 months postoperative.

CONCLUSION

There have been no special complications regarding the expandable cage during the follow-up period and the results of this study demonstrates a high fusion rate and clinical success.