Radiological outcomes of static vs expandable titanium cages after corpectomy: a retrospective cohort analysis of subsidence

Physiologic Osseous Remodeling of the Anterior Wall of the Spinal Canal after Anterior Cervical Corpectomy and Fusion: A Retrospective Observational Study

BACKGROUND

 Anterior cervical corpectomy and fusion (ACCF) has been widely used in the treatment of cervical spondylotic myelopathy (CSM), ossification of posterior longitudinal ligament (OPLL), cervical trauma, and other cervical diseases, but few studies have reported the osseous and physiologic remodeling of the anterior wall of the spinal canal following ACCF. In this study, we analyze that remodeling process and its influence on titanium mesh cage (TMC) subsidence.

METHODS

 We performed a clinical and radiologic analysis of consecutive patients treated with ACCF. Growth rates (GRs) reflecting the extent of remodeling of the remnants of the resected vertebral bodies were measured. We compared the computed tomography (CT) scans taken immediately and at least 1 year after surgery, and a literature review was conducted.

RESULTS

 In all, 48 patients underwent ACCF at a mean age of 61.5 ± 12.0 years. The median follow-up was 36 months, and 159 CT images were analyzed. The GR values of the remnants of the vertebral bodies on CT images immediately and 1 year after surgery were 0.505 ± 0.077 and 0.650 ± 0.022 (p < 0.001), respectively, and the GR value at ≥4 years was 1. Axial CT scans showed that remodeling starts from the lateral remnants of the resected vertebral bodies, finally reaching the center. When fusion of the vertebral bodies and the titanium cage was complete during the first year after ACCF, osteogenesis and remodeling were initiated in the osseous anterior wall of the spinal canal. The remodeling of the osseous anterior wall of the spinal canal was completed at the fourth year after surgery, without recompressing the spinal cord, as seen on both axial and lateral CT scans. According to the literature review, there was no TMC subsidence at more than 4 years after surgery.

CONCLUSION

 The anterior wall of the spinal canal undergoes osseous remodeling after ACCF. The process is complete in the fourth year after surgery and prevents TMC subsidence.

A novel nanohydroxyapatite/polyamide 66 strut for reducing subsidence after one-level anterior cervical corpectomy and fusion: a finite-element study

BACKGROUND

The aim of this study is to introduce a novel nanohydroxyapatite/polyamide 66(n-HA/PA66)n strut to improve biomechanical performance and reduce subsidence.

METHODS

One validated intact and 2 ACCF-simulated C3-C7 cervical spine models were developed (old strut: Group A, new strut: Group B). In the ACCF models, C5 underwent corpectomy and was fixed by an anterior cervical plate. Screw angles were categorized as 1 (0 ) and 2 (45 ) and divided into 4 groups, A1, A2, B1 and B2, for each model. An axial force of 74 N and a moment couple of 1.0 Nm were imposed on the C3 vertebra. The range of motion (ROM) of each segment and the stress distribution on the screw-vertebra interface, strut, and strut-endplate interface were recorded and analysed.

RESULTS

There was no significant difference in ROM between Group A and Group B during bending, extension and rotation under 74 N axial pressure. The stress concentration on the strut body in Group A was higher than that in Group B. The peak stress values at the screw-vertebral interface in Groups A1 and A2 were higher than those in Groups B1 and B2, except for during extension and lateral bending. Under axial pressure, the peak stress values at the strut body-endplate interface during bending, extension and rotation were lower in the A1 and A2 groups than in the B1 and B2 groups. The Group B model showed much higher graft stress than the Group A model.

CONCLUSIONS

Based on finite-element analysis, compared with the old strut, the novel strut showed better biomechanical performance at the screw-vertebra interface.

Customized 3-dimensional-printed Vertebral Implants for Spinal Reconstruction After Tumor Resection: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVE

To examine the outcomes of customized 3-dimensional (3D) printed implants for spinal reconstruction after tumor resection.

SUMMARY OF BACKGROUND DATA

Various techniques exist for spinal reconstruction after tumor resection. Currently, there is no consensus regarding the utility of customized 3D-printed implants for spinal reconstruction after tumor resection.

MATERIALS AND METHODS

A systematic review was registered with PROSPERO and performed according to "Preferred Reporting Items for Systematic Reviews and Meta-analyses" guidelines. All level I-V evidence studies reporting the use of 3D-printed implants for spinal reconstruction after tumor resection were included.

RESULTS

Eleven studies (65 patients; mean age, 40.9 ± 18.1 y) were included. Eleven patients (16.9%) underwent intralesional resections with positive margins and 54 patients (83.1%) underwent en bloc spondylectomy with negative margins. All patients underwent vertebral reconstruction with 3D-printed titanium implants. Tumor involvement was in the cervical spine in 21 patients (32.3%), thoracic spine in 29 patients (44.6%), thoracolumbar junction in 2 patients (3.1%), and lumbar spine in 13 patients (20.0%). Ten studies with 62 patients reported perioperative outcomes radiologic/oncologic status at final follow-up. At the mean final follow-up of 18.5 ± 9.8 months, 47 patients (75.8%) had no evidence of disease, 9 patients (14.5%) were alive with recurrence, and 6 patients (9.7%) had died of disease. One patient who underwent C3-C5 en bloc spondylectomy had an asymptomatic subsidence of 2.7 mm at the final follow-up. Twenty patients that underwent thoracic and/or lumbar reconstruction had a mean subsidence of 3.8 ± 4.7 mm at the final follow-up; however, only 1 patient had a symptomatic subsidence that required revision surgery. Eleven patients (17.7%) had one or more major complications.

CONCLUSION

There is some evidence to suggest that using customized 3D-printed titanium or titanium alloy implants is an effective technique for spinal reconstruction after tumor resection. There is a high incidence of asymptomatic subsidence and major complications that are similar to other methods of reconstruction.

LEVEL OF EVIDENCE

Level V, systematic review of level I-V studies.

Myth or fact: 3D-printed off-the-shelf prosthesis is superior to titanium mesh cage in anterior cervical corpectomy and fusion?

BACKGROUND

To find out if three-dimensional printing (3DP) off-the-shelf (OTS) prosthesis is superior to titanium mesh cages in anterior cervical corpectomy and fusion (ACCF) when treating single-segment degenerative cervical spondylotic myelopathy (DCSM).

METHODS

DCSM patients underwent ACCF from January 2016 to January 2019 in a single center were included. Patients were divided into the 3DP group (28) and the TMC group (23). The hospital stays, operation time, intraoperative blood loss, and the cost of hospitalization were compared. The Japanese Orthopedic Association (JOA) scores and Neck Disability Index (NDI) were recorded pre-operatively, 1 day, 3, 6, 12, and 24 months post-operatively. Radiological data was measured to evaluate fusion, subsidence, and cervical lordosis. Patients were sent with SF-36 to assess their health-related quality of life (HRQoL).

RESULTS

The differences in operative time, intraoperative blood loss, and hospital stay were not statistically significant between groups (p > 0.05). Postoperative dysphagia occurred in 2 cases in the 3DP group and 3 cases in the TMC group, which all relieved one week later. The difference in improvement of JOA and NDI between the two groups was not statistically significant (p > 0.05). No hardware failure was found and bony fusion was achieved in all cases except one in the 3DP group. The difference in cervical lordosis (CL), fused segmental angle (FSA), mean vertebral height (MVH), and subsidence rates between groups at each follow-up time point was not statistically significant and the results of the SF-36 were similar (p > 0.05). The total cost was higher in the 3DP group with its higher graft cost (p < 0.05).

CONCLUSION

In treating single-segment DCSM with ACCF, both 3DP OTS prosthesis and TMC achieved satisfactory outcomes. However, the more costly 3DP OTS prosthesis was not able to reduce subsidence as it claimed.

Anterior cervical X-shape-corpectomy and fusion vs. anterior cervical corpectomy and fusion for two-level cervical spondylosis

PURPOSE

Anterior cervical X-shape-corpectomy and fusion (ACXF) is a novel cervical surgery, designed as partial alternative to the classic technique, anterior cervical corpectomy and fusion (ACCF). The aim of this study was to evaluate the early-stage outcomes of ACXF in treating two-level cervical spondylosis (CS) through comparisons with ACCF.

METHODS

A retrospectively comparative study was conducted in two cohorts of patients who underwent single-vertebral ACXF or ACCF to treat two-level CS during September 2019 and October 2021. Clinical and radiological data of all the patients were collected from pre-operation to 1 year after the surgery, following by intra- and intergroup analyses and comparisons.

RESULTS

Fifty-seven patients were included, with 24 undergoing ACXF and 33 undergoing ACCF. ACXF group had significantly shorter drainage duration (2.13 ± 0.61 days vs. 3.48 ± 1.30 days, P < 0.001) and less drainage volume (30.21 ± 26.88 ml vs. 69.30 ± 37.65 ml, P < 0.001) than ACCF group. Both techniques significantly improved all the clinical parameters (P < 0.01) with comparable effects (P > 0.05). Each complication rate in ACXF group was lower than that in ACCF group without significant difference (P > 0.05). ACXF showed a significantly smaller transverse decompression range than ACCF (11.93 ± 1.27 mm vs. 16.29 ± 1.88 mm, P < 0.001). Postoperatively, ACXF yielded a comparable fusion rate (P > 0.05) and a significantly lower subsidence rate (P < 0.01) than ACCF technique at all time points.

CONCLUSIONS

ACXF is a potential surgical alternative for certain patients with two-level CS, as it provides both adequate decompression range and fewer adverse events than ACCF. The further modifications on ACXF worth exploration.

Predictors of Subsidence and its Clinical Impact After Expandable Cage Insertion in Minimally Invasive Transforaminal Interbody Fusion

STUDY DESIGN

Retrospective review of prospectively collected multisurgeon data.

OBJECTIVE

Examine the rate, clinical impact, and predictors of subsidence after expandable minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) cage.

SUMMARY OF BACKGROUND DATA

Expandable cage technology has been adopted in MI-TLIF to reduce the risks and optimize outcomes. Although subsidence is of particular concern when using expandable technology as the force required to expand the cage can weaken the endplates, its rates, predictors, and outcomes lack evidence.

MATERIALS AND METHODS

Patients who underwent 1 or 2-level MI-TLIF using expandable cages for degenerative lumbar conditions and had a follow-up of >1 year were included. Preoperative and immediate, early, and late postoperative radiographs were reviewed. Subsidence was determined if the average anterior/posterior disc height decreased by >25% compared with the immediate postoperative value. Patient-reported outcomes were collected and analyzed for differences at the early (<6 mo) and late (>6 mo) time points. Fusion was assessed by 1-year postoperative computed tomography.

RESULTS

One hundred forty-eight patients were included (mean age, 61 yr, 86% 1-level, 14% 2-level). Twenty-two (14.9%) demonstrated subsidence. Although statistically not significant, patients with subsidence were older, had lower bone mineral density, and had higher body mass index and comorbidity burden. Operative time was significantly higher ( P = 0.02) and implant width was lower ( P < 0.01) for subsided patients. Visual analog scale-leg was significantly lower for subsided patients compared with nonsubsided patients at a >6 months time point. Long-term (>6 mo) patient-acceptable symptom state achievement rate was lower for subsided patients (53% vs . 77%), although statistically not significant ( P = 0.065). No differences existed in complication, reoperation, or fusion rates.

CONCLUSIONS

Of the patients, 14.9% experienced subsidence predicted by narrower implants. Although subsidence did not have a significant impact on most patient-reported outcome measures and complication, reoperation, or fusion rates, patients had lower visual analog scale-leg and patient-acceptable symptom state achievement rates at the >6-month time point.

LEVEL OF EVIDENCE

Level 4.

Evaluation of Radiological and Neurological Outcomes after Anterior Cervical Corpectomy with Fusion using Expandable Cage Alone and Expandable Cage with Anterior Cervical Plating

Objective After anterior cervical corpectomy expandable cage were used with or without using anterior cervical plate for structural support are being preferred over autologous bone graft and other types of cages. Nowadays, the preferable type of cages and application of anterior cervical plate remain a debatable topic with studies giving divergent results. The purpose of this study is to evaluate the outcomes of expandable cages used alone or expandable cage used with anterior cervical plate following anterior cervical corpectomy.

Materials and Methods This study was conducted on 100 patients from January 2019 to December 2021 and all patients were undergone anterior cervical corpectomy and fusion and divided in two groups with expandable cage only (Group A) and expandable cage with anterior cervical plate (Group B). Various long-term benefits and radiological outcomes were studied in both groups.

Statistical Analysis and Results In this study, 100 patients were included and all patients underwent corpectomy followed by insertion of expandable cage alone or with anterior cervical plate. There was an improvement in C2–C7 Cobb's angle in group B was significantly higher than group A (p < 0.05) and decrease in Nurick's scale score in group B was significantly higher than group A (p < 0.05). The outcomes were measured with fusion rate (94%), subsidence rate (15%) and change in C2–C7 Cobb's angle was 4 degrees in this study.

Conclusion Expandable cage with or without anterior cervical plate was used after anterior cervical corpectomy for various cervical pathological conditions. In this study, we conclude the long-term benefits and radiological outcomes of two groups as expandable cage was used alone or with additional application of anterior cervical plate. In this study, the results were more in favor of additional application of anterior cervical plate as compared with expandable cage alone and more studies were required in future for more established long-term benefits and drawbacks.

Characteristics and risk factors of instrumentation failure following total en bloc spondylectomy

AIMS

The aim of this study was to investigate the incidence and characteristics of instrumentation failure (IF) after total en bloc spondylectomy (TES), and to analyze risk factors for IF.

METHODS

The medical records from 136 patients (65 male, 71 female) with a mean age of 52.7 years (14 to 80) who underwent TES were retrospectively reviewed. The mean follow-up period was 101 months (36 to 232). Analyzed factors included incidence of IF, age, sex, BMI, history of chemotherapy or radiotherapy, tumour histology (primary or metastasis; benign or malignant), surgical approach (posterior or combined), tumour location (thoracic or lumbar; junctional or non-junctional), number of resected vertebrae (single or multilevel), anterior resection line (disc-to-disc or intravertebra), type of bone graft (autograft or frozen autograft), cage subsidence (CS), and local alignment (LA). A survival analysis of the instrumentation was performed, and relationships between IF and other factors were investigated using the Cox regression model.

RESULTS

A total of 44 patients (32.4%) developed IF at a median of 31 months (interquartile range 23 to 74) following TES. Most IFs were rod fractures preceded by a mean CS of 6.1 mm (2 to 18) and LA kyphotic enhancement of 10.8° (-1 to 36). IF-free survival rates were 75.8% at five years and 56.9% at ten years. The interval from TES to IF peaked at two to three years postoperatively and continued to occur over a period of time thereafter; the early IF-developing group had greater CS at one month postoperatively (CS1M) and more lumbar TES. CS1M ≥ 3 mm and sole use of frozen autografts were identified as independent risk factors for IF.

CONCLUSION

IF is a common complication following TES. We have demonstrated that robust spinal reconstruction preventing CS, and high-quality bone grafting are necessary for successful reconstruction.Cite this article: Bone Joint J 2023;105-B(2):172-179.

Posterior unilateral approach with 270° spinal canal decompression and three-column reconstruction using double titanium mesh cage for thoracic and lumbar burst fractures

Objective

To evaluate the clinical effects of the posterior unilateral approach with 270° spinal canal decompression and three-column reconstruction using double titanium mesh cage (TMC) for thoracic and lumbar burst fractures.

Materials and methods

From May 2013 to May 2018, 27 patients with single-level thoracic and lumbar burst fractures were enrolled. Every patient was followed for at least 18 months. Demographic data, neurologic status, back pain, canal compromise, anterior body compression, operative time, estimated blood loss and surgical-related complications were evaluated. Radiographs were reviewed to assess deformity correction, anterior body height correction, bony fusion and TMC subsidence.

Results

The average preoperative percentages of canal compromise and anterior body height compression were 58.4% and 50.5%, respectively. All surgeries were successfully completed in one phase, the operative time was 151.5 ± 25.5 min (range: 115-220 min), the estimated blood loss was 590.7 ± 169.9 ml (range: 400-1,000 ml). Neurological function recovery was significantly improved except for 3 grade A patients. The preoperative visual analog scale (VAS) scores for back pain were significantly decreased compared with the values at the last follow-up (P = 0.000). The correct deformity angle was 12.4 ± 4.7° (range: 3.9-23.3°), and the anterior body height recovery was 96.7%. The TMC subsidence at the last follow-up was 1.3 ± 0.7 mm (range: 0.3-3.1 mm). Bony fusion was achieved in all patients.

Conclusion

The posterior unilateral approach with 270° spinal canal decompression and three-column reconstruction using double TMC is a clinically feasible, safe and alternative treatment for thoracic and lumbar burst fractures.

The predictive value of Hounsfield units for titanium mesh cage subsidence after anterior cervical corpectomy and fusion

Objective

To investigate whether bone mineral density (BMD) measured in Hounsfield units (HUs) correlates with titanium mesh cage (TMC) subsidence after anterior cervical corpectomy and fusion (ACCF).

Methods

A total of 64 patients who underwent one or two levels of ACCF with TMC with a mean follow-up of 19.34 ± 7.86 months were analysed. HU values were measured three times in 3 different planes in the upper and lower vertebrae according to published methods. Subsidence was defined as segmental height loss of more than 3 mm. Pearson correlation analysis was performed. Receiver operating characteristic (ROC) curve analysis was used to obtain optimal thresholds. A multivariate logistic regression analysis was also conducted.

Results

Twenty-two patients (34.38%) had evidence of TMC subsidence on follow-up x-ray. The mean HU values in the subsidence group (317.34 ± 32.32, n = 22) were significantly lower than those in the nonsubsidence group (363.07 ± 25.23 n = 42, p < 0.001, t test). At last follow-up, mean disc height loss was 4.80 ± 1.16 mm in the subsidence group and 1.85 ± 1.14 mm in the nonsubsidence group (p < 0.001). There was a negative correlation between HU values and disc height loss (Pearson's coefficient -0.494, p < 0.001). HU values decreased gradually from the C3 vertebra to the C7 vertebra, and the HU values of the C5, C6, and C7 vertebrae in the nonsubsidence group were significantly higher than those in the subsidence group (p < 0.05). Furthermore, there were significant differences between the groups in the segmental angle at the last follow-up and the mean changes in segmental angle (p < 0.05). The area under the ROC curve was 0.859, and the most appropriate threshold of the HU value was 330.5 (sensitivity 100%, specificity 72.7%). The multivariate logistic regression analysis showed that older age (p = 0.033, OR = 0.879), lower LIV HU value (p < 0.001, OR = 1.053) and a greater segmental angle change (p = 0.002, OR 6.442) were significantly associated with a higher incidence of TMC subsidence after ACCF.

Conclusion

There are strong correlations between a lower HU value and TMC subsidence after ACCF. More accurate assessment of bone quality may be obtained if HU measurement can be used as a routine preoperative screening method together with DXA. For patients with HU values <330.5, a more comprehensive and cautious preoperative plan should be implemented to reduce TMC subsidence.

Factors affecting titanium mesh cage subsidence in single-level anterior cervical corpectomy and fusion for ossification of the posterior longitudinal ligament

PURPOSE

To analyze risk factors of titanium mesh cage (TMC) subsidence in single-level anterior cervical corpectomy and fusion (ACCF) for cervical ossification of the posterior longitudinal ligament (OPLL).

METHODS

TMC subsidence is defined as the reduction of the adjacent vertebral bodies by ≥ 2 mm. Patients with cervical OPLL who were treated with single-level ACCF between January 2019 and May 2021 were retrospectively analyzed in two groups: patients with TMC subsidence as Group S and patients with no TMC subsidence as Group N during the one-year follow-up period. The degree of distraction of surgical segment and correction of the cervical curvature was measured to analyze their relationship with TMC subsidence.

RESULTS

A total of 128 patients were included in Group S, and 138 patients were included in Group N. There was no significant difference in patient demographics and complications between the two groups. The degree of distraction in Group S was significantly higher than that in Group N (11.4% ± 7.6% vs. 4.7% ± 9.7%, P < 0.01). The change of C2 to C7 Cobb angle (α) in Group S was significantly greater than that in Group N (5.7 ± 2.7 vs. 1.4 ± 4.7, P < 0.01), and the change of interspinous process distance (SPD) in Group S was also significantly greater than that in Group N (7.0 ± 4.2 vs. 4.1 ± 2.7, P < 0.01). The JOA score and JOA recovery rate were not statistically different between the two groups.

CONCLUSIONS

Intraoperative selection of overlength TMC in single-level ACCF for OPLL, over-distraction and excessive correction of the cervical curvature may cause TMC subsidence after surgery. No significant impact of TMC subsidence on the surgical outcome was observed during the 1-year follow-up period.

Anterior Cervical Corpectomy and Fusion for Degenerative Cervical Spondylotic Myelopathy: Case Presentation With Surgical Technique Demonstration and Review of Literature

Anterior cervical corpectomy and fusion (ACCF) provides an extensive decompression and provides a large surface area for fusion in patients presenting with cervical spondylotic myelopathy. Unfortunately, this procedure is a more difficult spinal surgery to perform (compared with a traditional anterior cervical discectomy and fusion) and has a higher incidence of overall complications. In literature, ACCF has functional outcomes that seem clinically equivalent to those for multilevel anterior cervical discectomy and fusion, especially when contained to 1 vertebral body level, and in cases, for which both posterior and anterior procedures would be appropriate surgical options, may provide greater long-term clinical benefit than posterior fusion or laminoplasty. In this manuscript, we summarize the indications and outcomes following ACCF for degenerative cervical spondylotic myelopathy. We then describe a case presentation and associated surgical technique with a discussion of complication avoidance with this procedure.

The Efficiency and Reliability of Minimally Invasive Anterior Corpectomy and Percutaneous Posterior Stabilization for the Treatment of Unstable Thoracolumbar Burst Fractures

OBJECTIVE

The purpose of this study was to evaluate the radiological and clinical outcomes of minimally invasive anterior corpectomy and percutaneous posterior stabilization for treating unstable thoracolumbar burst fractures.

METHODS

Patients with unstable thoracolumbar burst fractures who underwent minimally invasive anterior corpectomy and percutaneous posterior stabilization between 2012 and 2019 at a tertiary hospital were enrolled. Radiological outcomes such as endplate subsidence and fusion status were identified on preoperative and postoperative plain radiographs and computed tomography images. Preoperative and postoperative neurological statuses were evaluated using the American Spinal Injury Association impairment scale. Furthermore, operation-related parameters were analyzed.

RESULTS

In total, 21 patients (mean follow-up period, 21.7 months) were included in this study. Of them, 17 (80.95%) patients exhibited complete fusion according to the Bridwell's criteria at the final follow-up, and only 1 patient exhibited nonunion at the surgical level. Endplate subsidence was observed in 6 (28.57%) patients; however, there were no definite symptoms that would have necessitated a revision surgery. Of 15 patients with preoperative neurological impairment, 7 exhibited neurological improvement during follow-up. None of the patients experienced postoperative neurological deterioration. Regarding operation-related parameters, the mean operative time and intraoperative blood loss were 266.19 ± 51.54 min and 520.71 ± 190.86 ml, respectively. The mean length of hospital stays and days to postoperative ambulation were 12.14 and 4.20 days, respectively.

CONCLUSIONS

Minimally invasive anterolateral corpectomy with percutaneous pedicle screw fixation is a reliable surgical treatment option for unstable thoracolumbar burst fractures.

Customized Multilevel 3D Printing Implant for Reconstructing Spine Tumor: A Retrospective Case Series Study in a Single Center

Objective

To investigate the clinical efficacy and safety of 3D printed artificial vertebral body for patients who underwent multilevel total en bloc spondylectomy (TES) and analyze whether it could reduce the incidence of implant subsidence.

Methods

This is a retrospective study. From January 2017 to May 2018, eight consecutive cases with spine tumor undergoing multilevel TES were analyzed. All patients underwent X‐ray and CT examinations to evaluate the stability of internal fixation during the postoperative follow‐up. Demographic, surgical details, clinical data, and perioperative complications was collected. Visual analog scale, Frankel score, and spinal instability neoplastic score (SINS) classification were also recorded.

Results

There were six cases of primary spinal tumor and two cases of metastatic spinal tumor. All patients achieved remarkable pain relief and improvement in neurological function. Five patients underwent operation through the posterior approach, one patient underwent operation through the anterior approach and the remaining two patients through a combined anterior and posterior approach. At the last follow‐up period, X‐rays showed that the 3D printed artificial vertebral body of all cases matched well, and the fixation was reliable. Hardware failure such as loosening, sinking, breaking, and displacement wasn't observed during the follow‐up period.

Conclusion

3D printed customized artificial vertebral body can provide satisfying good clinical and radiological outcomes for patients who have undergone multilevel TES.

Subsidence and fusion performance of a 3D-printed porous interbody cage with stress-optimized body lattice and microporous endplates - a comprehensive mechanical and biological analysis

BACKGROUND CONTEXT

Cage subsidence remains a serious complication after spinal fusion surgery. Novel porous designs in the cage body or endplate offer attractive options to improve subsidence and osseointegration performance.

PURPOSE

To elucidate the relative contribution of a porous design in each of the two major domains (body and endplates) to cage stiffness and subsidence performance, using standardized mechanical testing methods, and to analyze the fusion progression via an established ovine interbody fusion model to support the mechanical testing findings.

STUDY DESIGN/SETTING

A comparative preclinical study using standardized mechanical testing and established animal model.

METHODS

To isolate the subsidence performance contributed by each porous cage design feature, namely the stress-optimized body lattice (vs. a solid body) and microporous endplates (vs. smooth endplates), four groups of cages (two-by-two combination of these two features) were tested in: (1) static axial compression of the cage (per ASTM F2077) and (2) static subsidence (per ASTM F2267). To evaluate the progression of fusion, titanium cages were created with a microporous endplate and internal lattice architecture analogous to commercial implants used in subsidence testing and implanted in an endplate-sparing, ovine intervertebral body fusion model.

RESULTS

The cage stiffness was reduced by 16.7% by the porous body lattice, and by 16.6% by the microporous endplates. The porous titanium cage with both porous features showed the lowest stiffness with a value of 40.4±0.3 kN/mm (Mean±SEM) and a block stiffness of 1976.8±27.4 N/mm for subsidence. The body lattice showed no significant impact on the block stiffness (1.4% reduction), while the microporous endplates decreased the block stiffness significantly by 24.9% (p<.0001). All segments implanted with porous titanium cages were deemed rigidly fused by manual palpation, except one at 12 weeks, consistent with robotic ROM testing and radiographic and histologic observations. A reduction in ROM was noted from 12 to 26 weeks (4.1±1.6° to 2.2±1.4° in lateral bending, p<.05; 2.1±0.6° to 1.5±0.3° in axial rotation, p<.05); and 3.3±1.6° to 1.9±1.2° in flexion extension, p=.07). Bone in the available void improved with time in the central aperture (54±35% to 83±13%, p<.05) and porous cage structure (19±26% to 37±21%, p=.15).

CONCLUSIONS

Body lattice and microporous endplates features can effectively reduce the cage stiffness, therefore reducing the risk of stress shielding and promoting early fusion. While body lattice showed no impact on block stiffness and the microporous endplates reduced the block stiffness, a titanium cage with microporous endplates and internal lattice supported bone ingrowth and segmental mechanical stability as early as 12 weeks in ovine interbody fusion.

CLINICAL SIGNIFICANCE

Porous titanium cage architecture can offer an attractive solution to increase the available space for bone ingrowth and bridging to support successful spinal fusion while mitigating risks of increased subsidence.

Comparison of Navigated Expandable Vertebral Cage with Conventional Expandable Vertebral Cage for Minimally Invasive Lumbar/Thoracolumbar Corpectomy

Background and Objectives: The thoracolumbar burst fracture is one of the most common spinal injuries. If the patient has severe symptoms, corpectomy is indicated. Currently, minimally invasive corpectomy with a navigated expandable vertebral cage is available thanks to spinal surgical technology. The aim of this study is to retrospectively compare clinical and radiographic outcomes of conventional and navigational minimally invasive corpectomy techniques. Materials and Methods: We retrospectively evaluated 21 patients who underwent thoracolumbar minimally invasive corpectomy between October 2016 and January 2021. Eleven patients had a navigated expandable cage (group N) and 10 patients had a conventional expandable cage (group C). Mean follow-up period was 31.9 months for group N and 34.7 months for group C, ranging from 12 to 42 months in both groups. Clinical and radiographic outcomes are assessed using values including visual analogue scale (VAS) for back pain and Oswestry disability index (ODI). This data was collected preoperatively and at 6, 12, and 24 months postoperatively. Results: Surgical time and intraoperative blood loss of both groups were not significantly different (234 min vs. 267 min, 656 mL vs. 786 mL). Changes in VAS and ODI were similar in both groups. However, lateral cage mal-position ratio in group N was lower than that of group C (relative risk 1.64, Odds ratio 4.5) and postoperative cage sinking was significantly lower in group N (p = 0.033). Conclusions: Clinical outcomes are not significantly different, but radiographic outcomes of lateral cage mal-position and postoperative cage sinking were significantly lower in the navigation group.

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.

Application of an Expandable Cage for Reconstruction of the Cervical Spine in a Consecutive Series of Eighty-Six Patients

Background and objectives: Expandable cages are frequently used to reconstruct the anterior spinal column after a corpectomy. In this retrospective study, we evaluated the perioperative advantages and disadvantages of corpectomy reconstruction with an expandable cage. Materials and Methods: Eighty-six patients (45 male and 41 female patients, medium age of 61.3 years) were treated with an expandable titanium cage for a variety of indications from January 2012 to December 2019 and analyzed retrospectively. The mean follow-up was 30.7 months. Outcome was measured by clinical examination and visual analogue scale (VAS); myelopathy was classified according to the EMS (European Myelopathy Scale) and gait disturbances with the Nurick score. Radiographic analysis comprised measurement of fusion, subsidence and the C2–C7 angle. Results: Indications included spinal canal stenosis with myelopathy (46 or 53.5%), metastasis (24 or 27.9%), spondylodiscitis (12 or 14%), and fracture (4 or 4.6%). In 39 patients (45.3%), additional dorsal stabilization (360° fusion) was performed. In 13 patients, hardware failure occurred, and in 8 patients, adjacent segment disease occurred. Improvement of pain symptoms, myelopathy, and gait following surgery were statistically significant (p < 0.05), with a medium preoperative VAS of 8, a postoperative score of 3.2, and medium EMS scores of 11.3 preoperatively vs. 14.3 postoperatively. Radiographic analysis showed successful fusion in 74 patients (86%). As shown in previous studies, correction of the C2–C7 angle did not correlate with improvement of neurological symptoms. Conclusion: Our results show that expandable titanium cages are a safe and useful tool in anterior cervical corpectomies for providing adequate anterior column support and stability.

A prospective randomized cohort study on 3D-printed artificial vertebral body in single-level anterior cervical corpectomy for cervical spondylotic myelopathy

Background

This was a prospective randomized cohort study aiming at examining the safety and efficacy of artificial vertebral body (AVB) fabricated by electron beam melting (EBM) in comparison to conventional titanium mesh cage (TMC) used in single-level anterior cervical corpectomy and fusion (SL-ACCF).

Methods

Forty patients with cervical spondylotic myelopathy (CSM) underwent SL-ACCF using either the EBM-AVB or the TMC. Patients were evaluated for their demographics, radiological characteristics, neurologic function [using the Japanese Orthopaedic Association (JOA) scale], and health-related quality-of-life (HRQoL) aspects [using the Short Form 36 (SF-36)] before and after the surgery and comparison was made between the two groups both at baseline and the last follow-up. The Student t-text, paired-sample t-text, and Fisher's exact test were used when appropriate to detect any statistical significance at the level of α=0.05.

Results

Post-operative recovery was uneventful for all patients and no revision surgery was required. There were no significant differences between the EBM-AVB group and the TMC group at baseline. Patients in both groups demonstrated significant improvement in cervical alignment, JOA score, and SF-36 score after the surgery. Six months post-operatively, patients in the EBM-AVB group were found to have significantly less loss of fusion height and lower incidence for severe implant subsidence compared with the TMC group. Patients in the two groups were comparable at the last follow-up regarding their rate of fusion, cervical alignment, JOA recovery rate, SF-36 score, and by Odom's criteria.

Conclusions

For CSM patients undergoing SL-ACCF, the EBM-AVB group demonstrated comparable outcomes regarding patient cervical alignment, neurologic function, and HRQoL in comparison with the TMC group. Furthermore, the use of EBM-AVB was associated with decreased loss of the height of the fusion mass and a lower rate for severe implant subsidence.

Expandable Interbody Fusion Cages: An Editorial on the Surgeon's Perspective on Recent Technological Advances and Their Biomechanical Implications

BACKGROUND

Expandable cages have gone through several iterations since they first appeared on the market in the early 2000s. Their development was prompted by some common problems associated with static interbody cages, including migration, expulsion, dural or neural traction injury, and pseudarthrosis.

OBJECTIVE

To summarize current technological advances from earlier expandable lumbar interbody fusion devices to implants with vertical and medial-to-lateral expansion mechanisms.

METHODS

The authors review the currently available expandable cage designs, the incremental technological advances, and how these devices impact minimally invasive surgery interbody procedures and clinical outcomes. The strategic concepts intended to improve the minimally invasive application of expandable interbody fusion implants are reviewed from a surgeon's perspective in a clinical context to discuss how their use may improve patient outcomes.

CONCLUSIONS

The geometrical configuration, effective stiffness of composite multi-material cage designs may impact the bone-implant contact area with the endplates. Hybridization strategies of expandable cage technology with modern minimally invasive and endoscopic spinal surgery techniques are presented by outlining their advantages and disadvantages.

LEVEL OF EVIDENCE

1 CLINICAL RELEVANCE: Systematic review.

Endoscopic Transforaminal Lumbar Interbody Fusion With a Single Oblique PEEK Cage and Posterior Supplemental Fixation

BACKGROUND

To demonstrate the feasibility of an endoscopically assisted minimally invasive surgery transforaminal lumbar interbody fusion (MIS-TLIF) and to study clinical outcomes with the use of a static oblique bullet-shaped cannulated poly-ether-ether-ketone (PEEK) lumbar interbody fusion cage in conjunction with platelet enriched plasma infused allograft cancellous chips and posterior supplemental fixation.

METHODS

In this retrospective study of 43 patients who underwent endoscopically assisted MIS-TLIF for spondylolisthesis (53.5%) and stenosis (46.3%), the Oswestry Disability Index, the visual analog scale (VAS) for back and leg pain, and the modified Macnab criteria were used as primary clinical outcome measures. Clinical outcomes were cross-tabulated against fusion grade using the Bridwell classification of interbody fusion.

RESULTS

The majority of patients (90.7%) had excellent (8/43; 18.6%) and good (31/43; 72.1%) Macnab outcomes. There were significant VAS back score reductions from an average preoperative values of 8.9070 to a postoperative VAS score of 3.8605, and a score of 2.7674 at final follow-up (P < .0001). The reductions in the VAS leg scores were also significant from preoperative score of 5.58 to a postoperative value of 2.16, and a final follow-up score of 1.67 (P < .0001); the Oswestry Disability Index score went from a preoperative value of 54.4 to 23.3 postoperatively and 18.5 at the final follow-up (P < .0001). The vast majority of patients (92.9%) with Bridwell grade I fusion had excellent and good Macnab outcomes (P = .027).

CONCLUSIONS

The authors recommend the use of an endoscope as an adjunct to MIS-TLIF, a minimally invasive spinal surgery technique in which many surgeons may be well versed and have a great deal of experience. Clinical outcomes with the endoscopic interbody fusion procedure with a static PEEK cage in conjunction with platelet-enriched bone allograft were favorable.

LEVEL OF EVIDENCE

3.

CLINICAL RELEVANCE

Feasibility study.

Transfacet Minimally Invasive Transforaminal Lumbar Interbody Fusion With an Expandable Interbody Device-Part II: Consecutive Case Series

BACKGROUND

Advances in operative techniques and instrumentation technology have evolved to maximize patient outcomes following minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). The transfacet MIS-TLIF is a modified approach to the standard MIS-TLIF that leverages a bony working corridor to access the disc space for discectomy and interbody device placement.

OBJECTIVE

To evaluate clinical and radiographic results following transfacet MIS-TLIF using an expandable interbody device.

METHODS

We performed a retrospective review of consecutive patients who underwent transfacet MIS-TLIF for degenerative lumbar spondylolisthesis. Patient-reported outcome measures for pain and disability were assessed. Sagittal lumbar segmental parameters and regional lumbopelvic parameters were assessed on upright lateral radiographs obtained preoperatively and during follow-up.

RESULTS

A total of 68 patients (61.8% male) underwent transfacet MIS-TLIF at 74 levels. The mean age was 63.4 yr and the mean follow-up 15.2 mo. Patients experienced significant short- and long-term postoperative improvements on the numeric rating scale for low back pain (-2.3/10) and Oswestry Disability Index (-12.0/50). Transfacet MIS-TLIF was associated with an immediate and sustained reduction of spondylolisthesis, and an increase in index-level disc height (+0.71 cm), foraminal height (+0.28 cm), and segmental lordosis (+6.83°). Patients with preoperative hypolordosis (<40°) experienced significant increases in segmental (+9.10°) and overall lumbar lordosis (+8.65°). Pelvic parameters were not significantly changed, regardless of preoperative alignment. Device subsidence was observed in 6/74 (8.1%) levels, and fusion in 50/53 (94.3%) levels after 12 mo.

CONCLUSION

Transfacet MIS-TLIF was associated with clinical improvements and restoration of radiographic sagittal segmental parameters. Regional alignment correction was observed among patients with hypolordosis at baseline.

Imaging evaluation of nano-hydroxyapatite/polyamide 66 strut in cervical construction after 1-level corpectomy: a retrospective study of 520 patients

BACKGROUND

The application of nano-hydroxyapatite/polyamide 66(n-HA/PA66) struts has become reliable in anterior cervical corpectomy and fusion (ACCF) as a source of sufficient segmental stability. This was a retrospective and long-term imaging evaluation of the n-HA/PA66 strut in 1-level ACCF.

METHODS

The patients between June 2006 and December 2014, who underwent 1-level ACCF using an n-HA/PA66 strut, were reviewed. The neurological status was assessed using the Japanese Orthopedic Association (JOA) score and axial pain was evaluated using a Visual Analogue Scale (VAS) score and the radiographic parameters were determined by X-ray and 3-D CT examinations when necessary for the evaluation of bone fusion using the Brantigan scale and imaging characteristics.

RESULTS

A total of 520 patients underwent one-level ACCF, with a mean follow-up (FU) duration of 72.38 ± 24.56 months. The level of surgery was C4 in 58 cases, C5 in 173 cases, C6 in 208 cases, and C7 in 81 cases. According to the Brantigan scale, on X-ray examination, the bony fusion rate was observed to be 40%, 70%, 93%, and 98% at 3 months, 6 months, 1 year and the final FU. An interesting radiographic appearance of the bone graft growth pattern was classified into three types. 95% of the patients accounted for types a and b. No significant differences were observed in age, hospitalization duration, surgical haemorrhage volume, or fusion rate among the types except in the percentage and sex of the patients among the types. Type a had better cervical lordosis, and less subsidence than types b and c (P < 0.05). No significant difference was found in segment angle between type a and type b. Type c was more often observed with subsidence rate, segmental angle loss and cervical alignment loss than types a and b (P < 0.05). Type a also had a slightly higher fusion rate, than types b and c, but there were no significant differences. The overall mean JOA score at the final follow-up among the groups were significantly improved comparing that preoperatively and no significant differences were found among the groups, no matter pre-operation or final follow-up. The overall mean VAS score at the final follow-up among the groups were significantly improved comparing that preoperatively and no significant differences in preoperative VAS score were found among the groups. However, the VAS score at the final follow-up of type a or type b was better than type c. No patients received revision surgery.

CONCLUSIONS

The type a bone graft growth pattern could allow a lower incidence of subsidence and better maintenance of local and global alignment to be achieved and is thus proposed for surgeons.

Additive Manufacturing for Metal Applications in Orthopaedic Surgery

Metallic additive manufacturing, a process by which metal structures are created in a layered fashion, is poised to revolutionize orthopaedic implants and instruments. It allows for the design and manufacture of devices, which not only macroscopically more closely match patient-specific anatomy but also have improved microscopic detail for more rapid and durable host integration. In addition, additive manufacturing-designed implants have improved biomechanical properties and fixation systems allowing use in areas where current implants are not well suited. This review provides an overview of the technology and both its current and future use in orthopaedic surgery.

Risk factors for subsidence of titanium mesh cage following single-level anterior cervical corpectomy and fusion

Background

To clarify the risk factors for subsidence of titanium mesh cage (TMC) following single-level anterior cervical corpectomy and fusion (ACCF) to reduce subsidence.

Methods

The present retrospective cohort study included 73 consecutive patients who underwent single-level ACCF. Patients were divided into subsidence (n = 31) and non-subsidence groups (n = 42). Medical records and radiological parameters such as age, sex, operation level, segmental angle (SA), cervical sagittal angle (CSA), height of anterior (HAE) and posterior endplate (HPE), ratio of anterior (RAE) and posterior endplate (RPE), the alignment of TMC, the global cervical Hounsfield Units (HU) were analyzed. Clinical results were evaluated using the Japanese Orthopedic Association (JOA) scoring system and the Visual Analog Scale (VAS).

Results

Subsidence occurred in 31 of 73 (42.5%) patients. Comparison between the groups showed significant differences in the value of RAE, the alignment of TMC and the global cervical HU value (p < 0.001, p = 0.002, p < 0.001). In multivariate logistic regression analysis, RAE > 1.18 (OR = 6.116, 95%CI = 1.613–23.192, p = 0.008), alignment of TMC > 3° (OR = 5.355, 95%CI = 1.474–19.454, p = 0.011) and the global cervical HU value< 333 (OR = 11.238, 95%CI = 2.844–44.413, p = 0.001) were independently associated with subsidence. Linear regression analysis revealed that RAE is significantly positive related to the extent of subsidence (r = − 0.502, p = 0.006).

Conclusion

Our findings suggest that the value of RAE more than 1.18, alignment of TMC and poor bone mineral density are the risk factors for subsidence. TMC subsidence does not negatively affect the clinical outcomes after operation. Avoiding over expansion of intervertebral height, optimizing placing of TMC and initiation of anti-osteoporosis treatments 6 months prior to surgery might help surgeons to reduce subsidence after ACCF.

Biomechanical analysis of a novel height-adjustable nano-hydroxyapatite/polyamide-66 vertebral body: a finite element study

Background

To compare the biomechanical properties of a novel height-adjustable nano-hydroxyapatite/polyamide-66 vertebral body (HAVB) with the titanium mesh cage (TMC) and artificial vertebral body (AVB), and evaluate its biomechanical efficacy in spinal stability reconstruction.

Methods

A 3D nonliner FE model of the intact L1-sacrum was established and validated. Three FE models which instrumented HAVB, TMC, and AVB were constructed for surgical simulation. A pure moment of 7.5 Nm and a 400-N preload were applied to the three FE models in 3D motion. The peak von Mises stress upon each prosthesis and the interfaced endplate was recorded for analysis. In addition, the overall and intersegmental range of motion (ROM) of each model was investigated to assess the efficacy of each model in spinal stability reconstruction.

Results

AVB had the greatest stress concentration compared with TMC and HAVB in all motions (25.6–101.8 times of HAVB, 0.8–8.1 times of TMC). The peak stress on HAVB was 3.1–10.3% of TMC and 1.6–3.9% of AVB. The maximum stress values on L2 caudal and L4 cranial endplates are different between the three FE models: 0.9–1.9, 1.3–12.1, and 31.3–117.9 times of the intact model on L2 caudal endplates and 0.9–3.5, 7.2–31.5, and 10.3–56.4 times of the intact model on L4 cranial endplates in HAVB, TMC, and AVB, respectively, while the overall and segmental ROM reduction was similar between the three models, with AVB providing a relatively higher ROM reduction in all loading conditions (88.1–84.7% of intact model for overall ROM and 69.5–82.1% for L1/2, 87.0–91.7% for L2/4, and 71.1–87.2% for L4/5, respectively).

Conclusions

HAVB had similar biomechanical efficacy in spinal stability reconstruction as compared with TMC and AVB. The material used and the anatomic design of HAVB can help avoid stress concentration and the stress shielding effect, thus greatly reducing the implant-associated complications. HAVB exhibited some advantageous biomechanical properties over TMC and AVB and may prove to be a potentially viable option for spinal stability reconstruction. Further in vivo and vitro studies are still required to validate our findings and conclusions.

Influence of additional cement augmentation on endplate stability in circumferential stabilisation of osteoporotic spine fractures

BACKGROUND

Anterior stabilisation of osteoporotic spine fractures is uncommon but necessary in the case of complex vertebral body comminution. The purpose of this study was to investigate the effect of additional cement-augmentation on the endplate stability.

METHODS

Twelve human cadaveric lumbar spines were divided in two groups: (A) posterior cement-augmented pedicle screw/rod-based instrumentation of L3 to L5, posterior decompression of L4/5 and partial corpectomy of L4 and (B) same experimental setup with additional cement-augmentation of the adjacent endplates. A cyclic loading test was performed at a frequency of 3 Hz, starting with a peak of 500 N for the first 2.000 cycles, up to 950 N for 100.000 cycles under a general preload with 50 N. All specimens were evaluated with regard to a potential collapse of the adjacent endplates. Subsequently, the maximum zero-time failure load of all specimens was determined using a universal testing machine.

FINDINGS

The median T-score of bone density was -4.32 (range -2.97 to -5.59), distributed equally in the two groups (average age 83 years). The specimen of the endplate-augmented group showed a significant higher failure load compared to non-endplate-augmented cadavers (group A: 2038 N, group B: 2990 N, p = 0.03). All specimens passed the full cyclic loading protocol with 100.000 cycles. No significant difference was observable regarding the adjacent endplate subsidence.

INTERPRETATION

Additional cement augmentation in circumferential stabilisation resulted in a significant enhancement of the endplate stability regarding the maximum axial load, while the cyclic loading did not significantly enhance the fatigue endurance of the vertebral endplates over the 100,000 cycles tested.

Subsidence Rates After Lateral Lumbar Interbody Fusion: A Systematic Review

OBJECTIVE

The evidence regarding the consequences of subsidence with lateral lumbar interbody fusion (LLIF) has been sparse. The objective of this study is to calculate the incidence of subsidence and reoperation for subsidence after LLIF. A secondary outcome examined the quantitative degree of subsidence by calculating the percent change in the height of the intervertebral space secondary to interbody subsidence at various postoperative follow-up times.

METHODS

Following the MOOSE (Meta-analysis [and Systematic Review] Of Observational Studies in Epidemiology) guidelines, a systematic review searched for all cohort studies that focused on subsidence rates after LLIF, including extreme lateral interbody fusions (XLIFs) and direct lateral interbody fusion. Neoplastic, infectious, and/or metabolic indications for LLIF were similarly excluded because these diseases may compromise bone quality and, thus, confound the rate of cage subsidence. Corpectomies were removed from the systematic review because 1) indications for removal of vertebral body typically reflect those excluded diseases and 2) subsidence refers to a different biomechanical process.

RESULTS

This systematic review identified a subsidence incidence with LLIF of 10.3% (N = 141/1362 patients in 14 articles) and reoperation rate for subsidence of 2.7% (N = 41/1470 patients in 16 articles). In the secondary outcome measure, the disc height decreased from 5.6% after 3 months, 6.0% after 6 months, and 10.2% after 12 months, to 8.9% after 24 months (P < 0.001).

CONCLUSIONS

Subsidence after LLIF carries a nonnegligible risk that may be incorporated in surgical consent discussions in selected patients.

A Novel Height-Adjustable Nano-Hydroxyapatite/Polyamide-66 Vertebral Body for Reconstruction of Thoracolumbar Structural Stability After Spinal Tumor Resection

BACKGROUND

Reconstruction of thoracolumbar structural stability is a formidable challenge for spine surgeons after vertebral body tumor resection. Various disadvantages of the currently used expandable or nonexpandable cages have limited their clinical applications. We sought to develop a novel prosthesis for clinical use and assess its preliminary clinical outcome in reconstruction of thoracolumbar structural stability after spinal tumor resection.

METHODS

Using data obtained from a retrospective analysis of the morphological characteristics of the thoracolumbar vertebrae and endplates in previously reported studies, we modified the nano-hydroxyapatite/polyamide-66 (n-HA/PA66) strut into a novel height-adjustable vertebral body. A retrospective study was performed of 7 patients who had undergone reconstruction of thoracolumbar structural stability with this novel prosthesis from August 2016 to January 2017.

RESULTS

A novel height-adjustable vertebral body (AHVB) composed of n-HA/PA66 with 2 separate components with a 163° contact surface at each end was manufactured. The height-adjustable range was 28-37 mm. No significant implant-related complications were observed in the process of operation. All patients experienced a significant reduction in pain, with the visual analog scale score decreasing from 7.9 to 4.0. Neurological improvement was assessed using the Frankel grading system after surgery. Postoperative radiographic and computed tomography/magnetic resonance imaging findings indicated that the operated segment was stable, the outcome of kyphosis correction was good, and no prosthesis subsidence or dislocation was observed.

CONCLUSION

This novel prosthesis has many advantages in the reconstruction of height, lordosis, and alignment after thoracolumbar spinal tumor resection and has a favorable prospect for clinical application.

Nanohydroxyapatite/polyamide 66 strut subsidence after one-level corpectomy: underlying mechanism and effect on cervical neurological function

The aim of this study was to investigate n-HA/PA66 strut subsidence after one-level in Anterior cervical corpectomy decompression and fusion (ACCF) and its effect on treatment outcomes to better understand the underlying mechanism and related risk factors. In total, 56 patients undergoing ACCF using n-HA/PA66 struts were analysed retrospectively. After a 12-month follow-up, the height of the fused segments and fused intervertebral heights were measured, the neurological findings were evaluated using the Japanese Orthopedic Association (JOA) and axial pain was assessed using a Visual Analogue Scale(VAS). Subsidence was defined as a decrease in the height of the fused segments or the fused intervertebral body greater than 3 mm compared with that on postoperative day one, and all patients were assigned to the n-HA/PA66 strut subsidence and control groups. In total, 45 patients experienced n-HA/PA66 strut subsidence during the postoperative (3 ± 2.42/3.11 ± 2.01) months. No significant differences were observed in sex, age, hospitalization time, surgical haemorrhage,bone mineral density (BMD), or height in the n-HA/PA66 strut group. The JOA and VAS of neck pain in the control group improved more than those in the subsidence group, suggesting that subsidence might be correlated with poor improvement of neurological function. In conclusion, n-HA/PA66 strut subsidence is a common complication after ACCF, and the reduced height of the postoperative fused segments and the height reduction in the postoperative fused intervertebral bodies are independent risk factors of n-HA/PA66 strut subsidence.

[A classification of implants for reconstruction of the anterior and middle supporting columns of the spine]

OBJECTIVE

The study objective was to classify implants for anterior interbody fusion, depending on their design features and functional capabilities, to optimize the choice of endoprosthesis designs for reconstructive surgery of the spin.

MATERIAL AND METHODS

We analyzed information provided in advertising brochures, annotations, and communications describing the designs of vertebral body endoprostheses. To study the design features of various implants, we selected 25 implant types with the structural designs of major units typical of vertebral body replacement systems. We performed static tests of mechanical features of anterior interbody fusion systems using special equipment and mathematical modeling based on the finite element technique to determine features of the stressed-deformed state in replacement of the vertebral bodies with artificial implants of various designs.

RESULTS AND DISCUSSION

The analysis results define the prerogative of combined telescopic designs with axisymmetric accommodation of compression stresses, which enable reconstruction and stabilization of the spinal motion segment without additional fixation by a ventral plate. The classification of endoprostheses enables evaluation of advantages and disadvantages of various implants to objectively assess the mechanisms of potential postoperative complications and to prevent them. The presented data may facilitate the optimal choice of an implant with allowance for the peculiarities of a clinical situation in each particular case.

The Impact of Cage Dimensions, Positioning, and Side of Approach in Extreme Lateral Interbody Fusion

STUDY DESIGN

This is a retrospective single-center study.

OBJECTIVE

The aim of the study was to evaluate the impact of cage characteristics and position toward clinical and radiographic outcome measures in patients undergoing extreme lateral interbody fusion (ELIF).

SUMMARY OF BACKGROUND DATA

ELIF is utilized for indirect decompression and minimally invasive surgical treatment for various degenerative spinal disorders. However, evidence regarding the influence of cage characteristics in patient outcome is minimal.

MATERIALS AND METHODS

Patients undergoing ELIF between 2007 and 2011 were included in a retrospective study. Demographic and perioperative data, as well as cage characteristics and side of approach were extracted. Radiographic parameters including lumbar lordosis, foraminal height, and disc height as well as clinical outcome parameters (Oswestry Disability Index and Visual Analog Scale) were measured preoperatively, postoperatively, and at the latest follow-up examination. Cage dimensions, in situ position, and type were correlated with radiographic and clinical outcome parameters.

RESULTS

In total, 84 patients with a total of 145 functional spinal units were analyzed. At the last follow-up of 17.7 months, radiographic and clinical outcome measures revealed significant improvement compared with before surgery with both, 18 and 22 mm cage anterior-posterior diameter subgroups (P≤0.05). Among cage characteristics, 22 mm cages presented superior restoration of foraminal and disc heights compared with 18 mm cages (P≤0.05). Neither position of the cage (anterior vs. posterior), nor the type (parallel vs. lordotic) had a significant impact on restoration of foraminal height and lumbar lordosis. Moreover, the side of surgical approach did not influence the amount of foraminal height increase.

CONCLUSIONS

Cage anterior-posterior diameter is the determining factor in restoration of foraminal height in ELIF. Cage height, type, positioning, and side of approach do not have a determining role in radiographic outcome in the present study. Sustainable foraminal height restoration is achieved by implantation of wider cages.

LEVEL OF EVIDENCE

Level 3.

Anterior Lumbar Corpectomy with Expandable Titanium Cage Reconstruction: A Case Series of 42 Patients

BACKGROUND

Burst fractures involve the anterior and middle columns with an intact posterior column. Deforming forces are magnified at areas of transition, making the thoracolumbar junction highly susceptible to injury.

METHODS

This is a retrospective review of 42 consecutive patients who underwent single-level anterior lumbar corpectomy using an obelisc expandable titanium cage and lateral fixation for traumatic lumbar burst fractures.

RESULTS

Myelopathy and sensory dysfunction were the most frequent neurologic deficits initially, occurring in 16 (38%) and 15 (36%) patients, respectively, which both decreased to 5 (13%). At follow-up, 26 patients (68%) were able to ambulate independently. No patient had significant cage displacement or needed cage replacement. Subsidence was minimal in 32 of 39 patients (82%). There were no hardware infections or surgical site infections. Options for stabilization include posterior instrumentation and fusion, anterior corpectomy with interbody fusion, and combination procedures. We believe anterior stabilization is superior because the aim is structural restoration of anterior and middle columns. The aim of posterior fixation is to replace the posterior tension band, which is not affected. There are 3 major surgical components to consider. First is anterior versus posterior decompression of the spinal canal. Second is the choice of autograft or titanium graft. Third is whether to stabilize posteriorly or anterolateral.

CONCLUSIONS

Anterior corpectomy with an expandable titanium cage and lateral rod fixation is safe and effective with minimal complications. It is a viable alternative to posterior decompression and instrumentation.

Single-Level Anterior Cervical Corpectomy and Fusion Using a New 3D-Printed Anatomy-Adaptive Titanium Mesh Cage for Treatment of Cervical Spondylotic Myelopathy and Ossification of the Posterior Longitudinal Ligament: A Retrospective Case Series Study

BACKGROUND The aim of this study was to evaluate the clinical and radiological outcomes of the use of a new 3D-printed anatomy-adaptive titanium mesh cage (AA-TMC) for single-level anterior cervical corpectomy and fusion (ACCF) in patients with cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL). MATERIAL AND METHODS We retrospectively reviewed the records of 15 consecutive patients who underwent ACCF surgeries with AA-TMC implantation. The Japanese Orthopedic Association (JOA) scoring system, a visual analogue scale (VAS), the mean intervertebral height (MIBH) of the surgical segments, and the surgical segmental angle (SSA) were recorded preoperatively, immediately after surgery and at the final follow-up visit. The outcomes of these parameters at different time points were compared. RESULTS Six months after ACCF surgery, solid bony fusions of the surgical level were achieved in all patients. The mean MIBH was 21.05±1.99 mm preoperatively, 27.51±1.44 mm immediately after surgery (P<0.05), and 26.85±1.25 mm at the last follow-up visit (P<0.05). At the last follow-up visit, none of the AA-TMCs exhibited severe subsidence (>3 mm). The mean SSA was 6.66±7.08° preoperatively, 14.03±2.3° immediately after surgery (P<0.05), and 15.09±2.1° at the final follow-up visit (P>0.05). The mean VAS and JOA scores were 6.6±1.26 and 10.47±2.07, respectively, preoperatively and 2.47±1.3 and 13.6±1.96 immediately after surgery, respectively (P<0.05). At the last follow-up visit, the mean VAS and JOA were further restored to 1.67±1.18 and 14.9±1.39, respectively (P<0.05). CONCLUSIONS The application of the AA-TMC in single-level ACCF significantly relieved symptoms of CSM and OPLL. The rational design of the AA-TMC restores the surgical segmental curvature, maintains the intervertebral height, and prevents postoperative subsidence-related complications.

Effects of Titanium Mesh Cage End Structures on the Compressive Load at the Endplate Interface: A Cadaveric Biomechanical Study

Background

This study aimed to evaluate whether obliquely angled and ring-shaped titanium mesh cage (TMC) end structures can improve the compressive load on the endplate interface in anterior cervical corpectomy and fusion (ACCF).

Material/Methods

A total of 23 volunteers underwent cervical lateral x-ray. The oblique angle of the superior endplate was measured, which was used to construct the gradient of the TMC end. Forty-two fresh cadaveric vertebral bodies were harvested and randomly distributed among four TMC groups with different ends. The baseline indicators of bone mineral density and anteroposterior and transverse dimensions were recorded. The superior endplate was placed at an angle of 12° when performing uniaxial compression testing. The maximum loads of the four TMCs were assessed.

Results

There were no significant differences among the groups regarding the baseline indicators. The conventional TMC had the lowest maximum load (1362.3±221.78 N, p<0.05), whereas the TMC with an obliquely end ring had the highest maximum load (2095.82±285.64 N, p<0.05). The maximum loads of the TMCs with oblique footprints and flat end ring were much higher than that of the conventional TMC (p<0.05) but significantly lower than that of the TMC with the obliquely end ring (p<0.05), with average values of 1806.91±246.98 N and 1725.3±213.33 N, respectively.

Conclusions

Both the ring shape and oblique angle of the TMC end contributed to an increase in compressive force and are advocated for use in TMC structure optimization to decrease the incidence of TMC subsidence in ACCF.

A Novel Anterior Transpedicular Screw Artificial Vertebral Body System for Lower Cervical Spine Fixation: A Finite Element Study

A finite element model was used to compare the biomechanical properties of a novel anterior transpedicular screw artificial vertebral body system (AVBS) with a conventional anterior screw plate system (ASPS) for fixation in the lower cervical spine. A model of the intact cervical spine (C3–C7) was established. AVBS or ASPS constructs were implanted between C4 and C6. The models were loaded in three-dimensional (3D) motion. The Von Mises stress distribution in the internal fixators was evaluated, as well as the range of motion (ROM) and facet joint force. The models were generated and analyzed by mimics, geomagic studio, and ansys software. The intact model of the lower cervical spine consisted of 286,382 elements. The model was validated against previously reported cadaveric experimental data. In the ASPS model, stress was concentrated at the connection between the screw and plate and the connection between the titanium mesh and adjacent vertebral body. In the AVBS model, stress was evenly distributed. Compared to the intact cervical spine model, the ROM of the whole specimen after fixation with both constructs is decreased by approximately 3 deg. ROM of adjacent segments is increased by approximately 5 deg. Facet joint force of the ASPS and AVBS models was higher than those of the intact cervical spine model, especially in extension and lateral bending. AVBS fixation represents a novel reconstruction approach for the lower cervical spine. AVBS provides better stability and lower risk for internal fixator failure compared with traditional ASPS fixation.

A New Vertebral Body Replacement Strategy Using Expandable Polymeric Cages

We have developed a novel polymeric expandable cage that can be delivered via a posterior-only surgical approach for the treatment of noncontained vertebral defects. This approach is less invasive than an anterior-only or combined approach and much more cost-effective than currently used expandable metal cages. The polymeric expandable cage is composed of oligo poly(ethylene glycol) fumarate (OPF), a hydrogel that has been previously shown to have excellent nerve and bone tissue biocompatibility. OPF hydrogel cages can expand to twice their original diameter and length within a surgical time frame following hydration. Modulation of parameters such as polymeric network crosslink density or the introduction of charge to the network allowed for precise expansion kinetics. To meet specific requirements due to size variations in patient vertebral bodies, we fabricated a series of molds with varied diameters and explored the expansion kinetics of the OPF cages. Results showed a stable expansion ratio of approximately twofold to the original size within 20 min, regardless of the absolute value of the cage size. Following implantation of a dried OPF cage into a noncontained vertebral defect and its in situ expansion with normal saline, other augmentation biomaterials, such as poly(propylene fumarate) (PPF), can be injected to the lumen of the OPF cage and allowed to crosslink in situ. The OPF/PPF composite scaffold can provide the necessary rigidity and stability to the augmented spine.

Bioactivity of sol-gel-derived TiO2 coating on polyetheretherketone: In vitro and in vivo studies

A polyetheretherketone (PEEK) surface was modified using a sol-gel-derived TiO2 coating in order to confer bone-bonding ability. To enhance the bonding strength of the coating layer, pretreatment with either O2 plasma or sandblasting was performed prior to sol-gel coating. Additionally, post-treatment with acid was carried out to confer apatite (calcium phosphate)-forming ability to the surface. Biomechanical and histological analyses performed using an in vivo rabbit tibia model showed that PEEK surfaces modified with sol-gel-derived TiO2 and acid post-treatment had better bone-bonding properties than uncoated PEEK surfaces. These modified surfaces also performed well in terms of their in vitro cell responses due to their modified surface chemistries and topographies. Although O2 plasma or sandblasting treatment were, for the most part, equivocal in terms of performance, we conclude that sol-gel-derived TiO2 coating followed by acid post-treatment significantly improves the bone bonding ability of PEEK surfaces, thus rendering them optimal for their use in surgical implants.

STATEMENT OF SIGNIFICANCE

The role of polyetheretherketone (PEEK) as an alternative biomaterial to conventional metallic implant materials has become increasingly important. However, its low bone bonding ability is yet to be resolved. This in vivo and in vitro investigation on the functionalization of PEEK surfaces highlights the utility of this material in clinical interventions that require implants, and may extend range of applications of PEEK.

Spondylectomy for Giant Cell Tumor After Denosumab Therapy

STUDY DESIGN

A case report.

OBJECTIVE

To report a case of the lumbar giant cell tumor (GCT) utilizing a new clinical treatment modality (denosumab therapy), which showed a massive tumor reduction combined with the L4 spondylectomy.

SUMMARY OF BACKGROUND DATA

There are some controversies about spinal GCT treatments. Denosumab has provided good clinical results in terms of tumor shrinkage, and local control in a short-time follow-up clinical study phase 2, although for spinal lesions, it has not been described. Nonetheless, "en bloc" spondylectomy has been accepted as being the best treatments modalities in terms of oncological control.

METHODS

A case study with follow-up examination and series radiological assessments 6 months after therapy started, followed by a complex spine surgery.

RESULTS

The denosumab therapy showed on the lumbar computed tomography scans follow-up 6 months later, a marked tumor regression around 90% associated to vertebral body calcification, facilitating a successful L4 spondylectomy with an anterior and posterior reconstruction. The patient recovered without neurological deficits.

CONCLUSION

A new therapeutic modality for spinal GCT is available and showing striking clinical results; however, it is necessary for well-designed studies to answer the real role of denosumab therapy avoiding or facilitating complex spine surgeries as spondylectomies for spinal GCT.

LEVEL OF EVIDENCE

5.

A controlled anterior sequential interbody dilation technique for correction of cervical kyphosis

OBJECT

Cervical kyphosis can lead to spinal instability, spinal cord injury, and disability. The correction of cervical kyphosis is technically challenging, especially in severe cases. The authors describe the anterior sequential interbody dilation technique for the treatment of cervical kyphosis and evaluate perioperative outcomes, degree of correction, and long-term follow-up outcomes associated with the technique.

METHODS

In the period from 2006 to 2011, a consecutive cohort of adults with cervical kyphosis (Cobb angles ≥ 0°) underwent sequential interbody dilation, a technique entailing incrementally increased interbody distraction with the sequential placement of larger spacers (at least 1 mm) in the discectomy and/or corpectomy spaces. The authors retrospectively reviewed these patients, and primary outcomes of interest included kyphosis correction, blood loss, hospital stay, complications, Nurick grade, pain, reoperation, and pseudarthrosis. A subgroup analysis among patients with preoperative kyphosis of 0°–9° (mild), 10°–19° (moderate), and ≥ 20° (severe) was performed.

RESULTS

One hundred patients were included in the study: 74 with mild preoperative cervical kyphosis, 19 with moderate, and 7 with severe. The mean patient age was 53.1 years, and 54.0% of the patients were male. Mean estimated blood loss was 305.6 ml, and the mean length of hospital stay was 5.2 days. The overall complication rate was 9.0%, and there were no deaths. Sixteen percent of patients underwent supplemental posterior fusion. There was significant correction in cervical alignment (p < 0.001), and the mean overall kyphosis correction was 12.4°. Patients with severe preoperative kyphosis gained a correction of 24.7°, those with moderate kyphosis gained 17.8°, and those with mild kyphosis gained 10.1°. A mean correction of 32.0° was obtained if 5 levels were addressed. The mean follow-up was 26.8 months. The reoperation rate was 4.7%. At follow-up, there was significant improvement in visual analog scale neck pain (p = 0.020) and Nurick grade (p = 0.037). The pseudarthrosis rate was 6.3%.

CONCLUSIONS

Sequential interbody dilation is a feasible and effective method of correcting cervical kyphosis. Complications and reoperation rates are low. Similar benefits are seen among all severities of kyphosis, and greater correction can be achieved in more severe cases.

Expandable Polyaryl-Ether-Ether-Ketone Spacers for Interbody Distraction in the Lumbar Spine

Study Design Retrospective case series. Objective StaXx XD (Spine Wave, Inc., Shelton, CT, United States) is an expandable polyaryl-ether-ether-ketone (PEEK) wafer implant utilized in the treatment of lumbar degenerative disease. PEEK implants have been successfully used as interbody devices. Few studies have focused on expandable PEEK devices. The aim of the current study is to determine the radiographic and clinical outcome of expandable PEEK cages utilized for transforaminal lumbar interbody fusion in patients with lumbar degenerative diseases. Methods Forty-nine patients who underwent lumbar interbody fusion with implantation of expandable PEEK cages and posterior instrumentation were included. The clinical outcome was evaluated using the visual analog scale (VAS) and the Oswestry Disability Index (ODI). Radiographic parameters including disk height, foraminal height, listhesis, local disk angle of the index level/levels, regional lumbar lordosis, and graft subsidence were measured preoperatively, postoperatively, and at latest follow-up. Results At an average follow-up of 19.3 months, the minimum clinically important difference for the ODI and VAS back, buttock, and leg were achieved in 64, 52, 58, and 52% of the patients, respectively. There was statistically significant improvement in VAS back (6.42 versus 3.11, p < 0.001), VAS buttock (4.66 versus 1.97, p = 0.002), VAS leg (4.55 versus 1.96, p < 0.001), and ODI (21.7 versus 12.1, p < 0.001) scores. There was a significant increase in the average disk height (6.49 versus 8.18 mm, p = 0.037) and foraminal height (15.6 versus 18.53 mm, p = 0.0001), and a significant reduction in the listhesis (5.13 versus 3.15 mm, p = 0.005). The subsidence of 0.66 mm (7.4%) observed at the latest follow-up was not significant (p = 0.35). Conclusions Midterm results indicate that expandable PEEK spacers can effectively and durably restore disk and foraminal height and improve the outcome without significant subsidence.

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.

Extended costotransversectomy to achieve circumferential fusion for pathologies causing thoracic instability

BACKGROUND CONTEXT

Conventional circumferential stabilization for pathologies causing instability of the thoracic spine requires a two or even a three-staged procedure. The authors present their tertiary care center experience of single-staged procedure to establish a circumferential fusion through an extended costotransversectomy approach.

OBJECTIVE

To demonstrate neural canal decompression, removal of the pathology, achieve circumferential fusion, and correcting the deformity through a single procedure.

STUDY DESIGN

Prospective and observational.

PATIENT SAMPLE

Forty-six patients with pan thoracic column instability due to various pathologies.

OUTCOME MEASURES

Neurologic condition was evaluated using American Spinal Injury Association and Eastern Cooperative Oncology Group grading systems. Outcome was evaluated with regard to the decompression of neural canal, correction of deformity, and neurologic improvement. All patients were evaluated for neural canal compromise and degree of kyphosis preoperatively, early, and late postoperatively.

METHODS

All patients had severe spinal canal compromise (mean, 59%±9%) and loss of vertebral body height (mean, 55%±10%). A single-stage circumferential fusion was performed (four-level pedicle screw fixation along with a ventral cage fixation after a vertebrectomy or corpectomy) through an extended costotransversectomy approach.

RESULTS

The pathologies included trauma (21), tuberculosis (18), hemangioma (2), aneurysmal bone cyst (1), recurrent hemangioendothelioma (1), solitary metastasis (1) and plasmacytoma (1), and neurofibromatosis (1). Thirty-five of 46 patients (76%) demonstrated improvement in the performance status. The major complications included pneumonitis (3), pneumothorax (3) and neurologic deterioration (3; improved in two), deep venous thrombosis (2), and recurrent hemoptysis (1). No implant failures were noted on last radiology follow-up. There were two mortalities; one because of myocardial infarction and another because of respiratory complications.

CONCLUSIONS

The following study demonstrated that extended costotrasversectomy approach is a good option for achieving single-staged circumferential fusion for correcting unstable thoracic spine due to both traumatic and nontraumatic pathologies.

Assessment of long-term kyphosis following transthoracic corpectomy with single adjacent level posterior instrumentation

Anterior thoracic spinal instrumentation has traditionally been supported by a posterior thoracic construct spanning from at least two levels above to two levels below; however, instrumentation at a single-level above and below may be adequate to support such a construct. We report two cases of transthoracic corpectomy with short-segment posterior fixation with success in long-term stabilization. Two patients with thoracic vertebral malignancy resulting in spinal deformity and spinal cord compression underwent transthoracic corpectomy with placement of an expandable cage proceeded by posterior fixation one level above and one level below. Using the Cobb angle, the degree of kyphosis was measured at 3, 6, and 12 months postoperatively. Long-term spinal stabilization was achieved in both patients. There was no significant increase in kyphosis and no evidence of hardware failure in either patient during the follow-up period. Transthoracic corpectomy with supplementary posterior fixation one level above and below may be adequate to stabilize the spine.

Comparison of Clinical and Radiologic Results between Expandable Cages and Titanium Mesh Cages for Thoracolumbar Burst Fracture

Objective

A thoracolumbar burst fracture is usually unstable and can cause neurological deficits and angular deformity. Patients with unstable thoracolumbar burst fracture usually need surgery for decompression of the spinal canal, correction of the angular deformity, and stabilization of the spinal column. We compared two struts, titanium mesh cages (TMCs) and expandable cages.

Methods

33 patients, who underwent anterior thoracolumbar reconstruction using either TMCs (n=16) or expandable cages (n=17) between June 2000 and September 2011 were included in this study. Clinical outcome was measured by visual analogue scale (VAS), American Spinal Injury Association (ASIA) scale and Low Back Outcome Score (LBOS) for functional neurological evaluation. The Cobb angle, body height of the fractured vertebra, the operation time and amount of intra-operative bleeding were measured in both groups.

Results

In the expandable cage group, operation time and amount of intraoperative blood loss were lower than that in the TMC group. The mean VAS scores and LBOS in both groups were improved, but no significant difference. Cobb angle was corrected higher than that in expandable cage group from postoperative to the last follow-up. The change in Cobb angles between preoperative, postoperative, and the last follow-up did not show any significant difference. There was no difference in the subsidence of anterior body height between both groups.

Conclusion

There was no significant difference in the change in Cobb angles with an inter-group comparison, the expandable cage group showed better results in loss of kyphosis correction, operation time, and amount of intraoperative blood loss.