Titanium mesh cages for cervical spine stabilization after corpectomy: a clinical and radiological study

A novel anatomic titanium mesh cage for reducing the subsidence rate after anterior cervical corpectomy: a finite element study

Fusion with a titanium mesh cage (TMC) has become popular as a conventional method after cervical anterior corpectomy, but postoperative TMC subsidence has often been reported in the literature. We designed a novel anatomic cervical TMC to reduce the postoperative subsidence rate. According to the test process specified in the American Society of Testing Materials (ASTM) F2267 standard, three-dimensional finite element analysis was used to compare the anti-subsidence characteristics of a traditional TMC (TTMC) and novel TMC (NTMC). Through analysis, the relative propensity values of a device to subside (Kp) of the TTMC and NTMC were 665.5 N/mm and 1007.2 N/mm, respectively. A higher Kp measurement is generally expected to indicate that the device is more resistant to subsidence into a vertebral body. The results showed that the novel anatomic titanium mesh cage (NTMC) significantly improved the anti-subsidence performance after anterior cervical corpectomy and fusion (ACCF), which was approximately 51.3% higher than that of the traditional titanium mesh cage.

Comparative Analysis of 3D-Printed Artificial Vertebral Body Versus Titanium Mesh Cage in Repairing Bone Defects Following Single-Level Anterior Cervical Corpectomy and Fusion

Background

The aim of this study was to compare the clinical and radiological outcomes of the 3D-printed artificial vertebral body vs the titanium mesh cage in repairing bone defects for single-level anterior cervical corpectomy and fusion (ACCF).

Material/Methods

A total of 51 consecutive patients who underwent single-level ACCF in Huai’an Second People’s Hospital from July 2017 to August 2020 were retrospectively reviewed. According to the implant materials used, patients were divided into a 3D-printed artificial vertebral body group (3D-printed group) (n=20; 12 males, 8 females) and a titanium mesh cage group (TMC group) (n=31; 15 males, 16 females). General data, radiological parameters, and clinical outcomes were recorded.

Results

The rate of subsidence in the 3D-printed group (0.01, 2/20) was lower than in the TMC group (0.29, 9/31) (P<0.05). HAE and HPE of the patients in the 3D-printed group were significantly higher than those in the TMC group (P<0.05). C2–C7 Cobb angle and SA of the patients in the 3D-printed group were significantly larger than those in the TMC group (P<0.05). All patients in the 2 groups showed significant improvement in VAS, JOA, and NDI scores at 3 months and 1 year after surgery.

Conclusions

3D-printed artificial vertebral body helps maintain intervertebral height and cervical physiological curvature and is a good candidate for ACCF.

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.

Anterior Cervical Corpectomy and Fusion and Anterior Cervical Discectomy and Fusion Using Titanium Mesh Cages for Treatment of Degenerative Cervical Pathologies: A Literature Review

Anterior cervical corpectomy and fusion (ACCF) and anterior cervical discectomy and fusion (ACDF) are 2 effective and safe surgical treatments of degenerative cervical pathologies and are associated with a high percentage of excellent clinical outcomes when a graft or device must be used during the surgery, such as an allograft, autograft, nano-hydroxyapatite/polyamide cages, poly-ether-ether-ketone (PEEK) cages, and titanium mesh cages (TMCs). Although TMCs have been used in cervical surgeries for almost 2 decades, no specific reviews have been performed introducing the state of this material. Thus, in the present review, we discuss the status of using TMCs in anterior cervical surgeries.

Studies that tested the usage of TMCs in treating degenerative cervical pathologies were included in this review. The development and progress of TMCs, the biomechanical analysis of TMCs, the radiological and clinical assessment of TMCs, the advantages and disadvantages of using TMCs, and their prospects for future applications as a device of ACCF and ACDF in treating degenerative cervical pathologies are discussed.

Studies included in this review showed that TMCs can provide sufficient biomechanical stability. Furthermore, the TMCs used in anterior cervical fusion avoid the donor-site morbidity and achieve a solid bony fusion. However, there are some shortcomings. The structural characteristics and the design of TMCs cause the TMC subsidence rate to remain high, thus resulting in multiple related complications.

We believe that due to the virtues of TMCs, they are worthy of application and promotion. However, the structure of TMCs should be further optimized to reduce the TMC subsidence rate and subsidence-related complications, ultimately achieving excellent clinical results.

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.

Preventing Construct Subsidence Following Cervical Corpectomy: The Bump-stop Technique

Cervical corpectomy is a viable technique for the treatment of multilevel cervical spine pathology. Despite multiple advances in both surgical technique and implant technology, the rate of construct subsidence can range from 6% for single-level procedures to 71% for multilevel procedures. In this technical note, we describe a novel technique, the bump-stop technique, for cervical corpectomy. The technique positions the superior and inferior screw holes such that the vertebral bodies bisect them. This allows for fixation in the dense cortical bone of the endplate while providing a buttress to corpectomy cage subsidence. We then discuss a retrospective case review of 24 consecutive patients, who were treated using this approach, demonstrating a lower than previously reported cage subsidence rate.

Sagittal Alignment of a Strut Graft Affects Graft Subsidence and Clinical Outcomes of Anterior Cervical Corpectomy and Fusion

Study Design

Retrospective study.

Purpose

The purpose of this study was to investigate the influence of sagittal alignment of the strut graft on graft subsidence and clinical outcomes after anterior cervical corpectomy and fusion (ACCF).

Overview of Literature

ACCF is a common technique for the treatment of various cervical pathologies. Although graft subsidence sometimes occurs after ACCF, it is one cause for poor clinical results. Malalignment of the strut graft is probably one of the factors associated with graft subsidence. However, to the best of our knowledge, no prior reports have demonstrated correlations between the alignment of the strut graft and clinical outcomes.

Methods

We evaluated 56 patients (33 men and 23 women; mean age, 59 years; range, 33–84 years; 45 with cervical spondylotic myelopathy and 11 with ossification of the posterior longitudinal ligament) who underwent one- or two-level ACCF with an autogenous fibular strut graft and anterior plating. The Japanese Orthopaedic Association (JOA) score recovery ratio for cervical spondylotic myelopathy was used to evaluate clinical outcomes. The JOA score and lateral radiograms were evaluated 1 week and 1 year postoperatively. Patients were divided into two groups (a straight group [group I] and an oblique group [group Z]) based on radiographic assessment of the sagittal alignment of the strut graft.

Results

Group I showed a significantly greater JOA score recovery ratio (p<0.05) and a significantly lower graft subsidence than group Z (p<0.01).

Conclusions

Our findings suggest that a straight alignment of the strut graft provides better clinical outcomes and lower incidence of graft subsidence after ACCF. In contrast, an oblique strut graft can lead to significantly increased strut graft subsidence and poor clinical results.

Only spinal fixation as treatment of prolapsed cervical intervertebral disc in patients presenting with myelopathy

Aim:

An alternative form of surgical treatment of prolapsed cervical intervertebral disc in patients presenting with symptoms related to myelopathy is discussed. The treatment involved fixation of the affected spinal segments and aimed at arthrodesis. No direct manipulation or handling of the disc was done.

Materials and Methods:

During the period August 2010 to June 2017, 16 patients presenting with symptoms attributed to myelopathy and diagnosed to have prolapsed cervical intervertebral disc were surgically treated by spinal stabilization. There were 11 males and 5 females and their ages ranged from 20 to 66 years (average: 40.6 years). Apart from clinical and radiological indicators, the number of spinal segments that were stabilized depended on direct observation of facetal morphology, alignment, and stability. Surgery involved distraction-fixation of facets using Goel facet spacer (8 patients), transarticular facetal fixation (5 patients) using screws or a combination of both facetal spacer, and transarticular screws (3 patients).

Results:

All patients had “remarkable” clinical improvement in the immediate postoperative period as assessed by visual analog scale, Goel's clinical grading, and Japanese Orthopedic Association scores. Follow-up ranged from 3 to 84 months (average: 50 months). The herniated disc regressed or disappeared at follow-up radiological assessment that ranged from 24 h to 3 months after surgery.

Conclusions:

Spinal segmental fixation aiming at arthrodesis with or without distraction of facets and without any direct surgical manipulation in the disc space or removal of the prolapsed portion of the disc can be considered in the armamentarium of the surgeon.

Long-term results of anterior cervical corpectomy and fusion with nano-hydroxyapatite/polyamide 66 strut for cervical spondylotic myelopathy

To assess the long-term clinical and radiographic outcomes of anterior cervical corpectomy and fusion (ACCF) with a neotype nano-hydroxyapatite/polyamide 66 (n-HA/PA66) strut in the treatment of cervical spondylotic myelopathy (CSM). Fifty patients with CSM who underwent 1- or 2-level ACCF with n-HA/PA66 struts were retrospectively investigated. With a mean follow-up of 79.6 months, the overall mean JOA score, VAS and cervical alignment were improved significantly. At last follow-up, the fusion rate was 98%, and the subsidence rate of the n-HA/PA66 strut was 8%. The "radiolucent gap" at the interface between the n-HA/PA66 strut and the vertebra was further noted to evaluate the osteoconductivity and osseointegration of the strut, and the incidence of it was 62% at the last follow-up. Three patients suffered symptomatic adjacent segment degeneration (ASD). No significant difference was detected in the outcomes between 1- and 2-level corpectomy at follow-ups. In conclusion, the satisfactory outcomes in this study indicated that the n-HA/PA66 strut was an effective graft for cervical reconstruction. Moreover, the osteoconductivity and osseointegration of the strut is still need to be optimized for future clinical application owing to the notably presence of "radiolucent gap" in present study.

Comparison of anterior cervical fusion by titanium mesh cage versus nano-hydroxyapatite/polyamide cage following single-level corpectomy

PURPOSE

The titanium mesh cage (TMC) is a typical metal cage device which has been widely used in cervical reconstruction for decades. Nano-hydroxyapatite/polyamide-66 (n-HA/PA66) cage is a novel biomimetic non-metal cage device growing in popularity in many medical centres in recent years. There has been no comparison of the efficacy between these two anterior reconstructing cages. The purpose of this study was to compare the radiographic and clinical outcomes of these two different devices.

METHODS

Sixty-seven eligible patients with single-level ACCF using TMC or n-HA/PA66 cage for cervical degenerative diseases, with four-year minimum follow-up, were included in this prospective non-randomised comparative study. Their radiographic (cage subsidence, fusion status, segmental sagittal alignment [SSA]) and clinical (VAS and JOA scales) data before surgery and at each follow-up was recorded completely.

RESULTS

The fusion rate of the n-HA/PA66 group was higher than TMC at one year after surgery (94% vs. 84%) though their finial fusion rates were similar (97% vs. 94%). Finial n-HA/PA66 cage subsidence was 1.5 mm with 6% of severe subsidence over three millimetres, which was significantly lower than the respective 2.9 mm and 22% of TMC (P < 0.0001). Lastly, SSA, VAS and JOA in TMC group were worse than in the n-HA/PA66 group (P = 0.235, 0.034 and 0.007, respectively).

CONCLUSIONS

The n-HA/PA66 cage is associated with earlier radiographic fusion, less subsidence and better clinical results than TMC within four years after one-level ACCF. With the added benefit of radiolucency, the n-HA/PA66 cage may be superior to TMC in anterior cervical construction.

Hybrid decompression technique and two-level corpectomy are effective treatments for three-level cervical spondylotic myelopathy

The optimal surgical strategy for multilevel cervical spondylotic myelopathy (CSM) has not been defined, and few comparative researches between hybrid decompression and multilevel corpectomy have been conducted. Here, we reported 28 patients of three-level CSM, of whom 12 underwent hybrid decompression and 16 two-level corpectomy, with each type of procedure chosen according to radiologic characteristics of those patients. Clinical and radiologic parameters of both groups showed various degrees of improvement. However, no statistically significant differences in Japanese Orthopedic Association (JOA) score improvement rate, graft fusion rate, post-operative neck disability index (NDI) or segmental lordosis between the two groups were found. We conclude that both hybrid decompression and two-level corpectomy could obtain satisfying clinical efficacy in the management of three-level CSM for appropriate patients.

In vitro study of accuracy of cervical pedicle screw insertion using an electronic conductivity device (ATPS part III)

Reconstruction of the highly unstable, anteriorly decompressed cervical spine poses biomechanical challenges to current stabilization strategies, including circumferential instrumented fusion, to prevent failure. To avoid secondary posterior surgery, particularly in the elderly population, while increasing primary construct rigidity of anterior-only reconstructions, the authors introduced the concept of anterior transpedicular screw (ATPS) fixation and plating. We demonstrated its morphological feasibility, its superior biomechanical pull-out characteristics compared with vertebral body screws and the accuracy of inserting ATPS using a manual fluoroscopically assisted technique. Although accuracy was high, showing non-critical breaches in the axial and sagittal plane in 78 and 96%, further research was indicated refining technique and increasing accuracy. In light of first clinical case series, the authors analyzed the impact of using an electronic conductivity device (ECD, PediGuard) on the accuracy of ATPS insertion. As there exist only experiences in thoracolumbar surgery the versatility of the ECD was also assessed for posterior cervical pedicle screw fixation (pCPS). 30 ATPS and 30 pCPS were inserted alternately into the C3-T1 vertebra of five fresh-frozen specimen. Fluoroscopic assistance was only used for the entry point selection, pedicle tract preparation was done using the ECD. Preoperative CT scans were assessed for sclerosis at the pedicle entrance or core, and vertebrae with dense pedicles were excluded. Pre- and postoperative reconstructed CT scans were analyzed for pedicle screw positions according to a previously established grading system. Statistical analysis revealed an astonishingly high accuracy for the ATPS group with no critical screw position (0%) in axial or sagittal plane. In the pCPS group, 88.9% of screws inserted showed non-critical screw position, while 11.1% showed critical pedicle perforations. The usage of an ECD for posterior and anterior pedicle screw tract preparation with the exclusion of dense cortical pedicles was shown to be a successful and clinically sound concept with high-accuracy rates for ATPS and pCPS. In concert with fluoroscopic guidance and pedicle axis views, application of an ECD and exclusion of dense cortical pedicles might increase comfort and safety with the clinical use of pCPS. In addition, we presented a reasonable laboratory setting for the clinical introduction of an ATPS-plate system.

Anterior corpectomy and fusion for severe ossification of posterior longitudinal ligament in the cervical spine

Between May 2002 and October 2006, 19 patients (17 men and 2 women; average age 57.2; range 47-71 years) received anterior corpectomy and fusion for severe ossification of the posterior longitudinal ligament (OPLL) in our department. Preoperative radiological evaluation showed the narrowing by the OPLL exceeded 50% in all cases, and OPLL extended from one to three vertebrae. We followed-up all patients for 12-36 months (mean 18 months). The Japanese Orthopaedic Association (JOA) score before surgery was 9.3 +/- 1.8 (range 5-12) which significantly increased to 14.2 +/- 1.3 (range 11-16) points at the last follow-up (P < 0.01). The improvement rate (IR) of neurological function ranged from 22.2-87.5%, with a mean of 63.2% +/- 15.2%. The operation also provided a significant increase in the cervical lordosis and the cord flatting rate (P < 0.01). No severe neurological complication developed. We therefore concluded that anterior decompression and fusion was effective and safe in the treatment of the selected patients, although OPLL exceeded 50% diameter of the spinal canal.

Comparison of multisegment anterior cervical fixation using bone strut graft versus a titanium rod and buttress prosthesis: analysis of outcome with long-term follow-up and interview by independent physician

STUDY DESIGN

A retrospective study of 73 consecutive patients who underwent cervical corpectomy and anterior strut fixation over 3 or more disc levels between July 1989 and May 1999.

OBJECTIVE

To compare the efficacy of cervical spine fixation by autologous strut graft from iliac crest or fibula versus a titanium prosthesis without bone graft.

SUMMARY OF BACKGROUND DATA

Strut grafting after multilevel anterior cervical corpectomy remains a challenging procedure, with published dislocation rates from 0% to 71%, and nonunion from 0% to 54%. This paper describes a quicker and easier alternative to the use of a bone strut, imparting a very high degree of immediate spinal stability, and osseous integration equivalent to bone fusion.

METHODS

Thirty-eight bone-graft operations and 38 titanium prosthesis operations were performed on 73 patients between July 24, 1989 and May 20, 1999. Average follow-up was 53.2 months (range 19.8-134).

RESULTS

The group of patients who received the prosthesis was significantly older than the bone-grafted group and required significantly more segments excised, but operation times were significantly shorter than for the bone strut operation. The titanium prosthesis had a lower incidence of dislodgement in the early postoperative period (1/38 vs. 4/38 for bone struts) but a higher rate of late reoperation (4/38 vs. 1/38 for bone struts). The SF-36 scores in the domain of Physical Function (only) were significantly higher in the bone-grafted group (P = 0.016, Mann Whitney), consistent with the difference in mean ages of the 2 groups. The groups were indistinguishable by Odom criteria, patient verdict, pain scores, analgesic intake, length of hospital stay, radiologic fusion rate, and residual symptoms.

CONCLUSION

A titanium rod and buttress prosthesis may be a faster and easier alternative to conventional iliac crest/fibula autograft after multisegmental cervical vertebral corpectomy.

Complications and Long-Term Follow-Up Results in Titanium Mesh Cage Reconstruction After Cervical Corpectomy

OBJECTIVE

The incidence of the complications and long-term outcome with a minimum 2-year follow-up of anterior cervical reconstruction using titanium mesh cage is evaluated. Relevant literature was also reviewed to discuss the potential risk factors of the complications of this procedure.

METHODS

From 1999 to 2003, 26 patients with cervical spine disorders, (12 patients with OPLL, 7 with cervical spondylosis, 3 with vertebral tumors, 2 with osteomyelitis, and 2 with traumatic lesions) were operated on by this procedure. The series included 14 males and 12 females with a mean age of 60.9 years. Corpectomy was performed on 1 (14 cases), 2 (12 cases). Autologous bone fragments were taken from the excised vertebra.

RESULTS

The average improvement rate as scored on the neurosurgical cervical spine scale was 67.4%. The average follow-up period was 54.3 months (range, 24 to 72 months) in 21 who were followed up, and bone union was observed in all cases (22/22 cases) that could be followed up for more than 6 months postoperatively. The average time required for fusion was 6.7 months. Postoperative complications included dyspnea (1 case) and cerebrospinal fluid leakage (2 cases), which was treated by lumbar drainage, without any additional repair operation. No hardware-related complications or adjacent segment degenerative changes were encountered during the follow-up periods.

CONCLUSIONS

This reconstruction technique yielded good clinical results and helped to avoid complications associated with harvesting bone from the iliac crest donor site. However, risk factors related to the method should be carefully considered.

Titanium Cage-assisted Polymethylmethacrylate Reconstruction for Cervical Spinal Metastasis: Technical Note

OBJECTIVE:

Reconstruction and stabilization of the cervical spine after vertebrectomy is an important goal in the surgical management of spinal metastasis. The authors describe their reconstruction technique using a titanium cage-Silastic tube construct injected with polymethylmethacrylate (PMMA) augmented by an anterior cervical plate. The surgical results using this technique are reviewed.

METHODS:

Six patients ranging from 43 to 70 years of age underwent resection of metastatic tumor in the cervical spine followed by cage-assisted PMMA reconstruction of the anterior spinal column. The following reconstruction technique was performed. A Silastic tube is incised longitudinally and placed circumferentially around a titanium cage with the opening facing anteriorly. The cage-Silastic tube construct is carefully tapped into the corpectomy defect and filled with PMMA. The final construct is then augmented with anterior cervical plate fixation.

RESULTS:

Two patients required additional posterior stabilization with lateral mass screws and rods. All patients achieved immediate stabilization, restoration of vertebral body height and normal lordosis, and preservation of the ability to walk independently. Five patients experienced significant palliation of biomechanical neck pain. There were no complications of neurological worsening, postoperative hematoma, wound infection, subsidence, graft dislodgement, or construct failure during a follow-up period of 1 to 19 months (mean, 6.8 mo).

CONCLUSION:

Titanium cage-assisted PMMA reconstruction augmented with an anterior cervical plate is an effective means of reconstruction after tumor resection in patients with cervical spinal metastasis. The Silastic tube holds the PMMA within the cage and protects the spinal cord from potential thermal injury.

[Vertebral body replacement in spine surgery]

Autografts and allogeneous bone grafts as well as cages are used for the reconstruction of the anterior column after corpectomy. Recently, expandable cages for vertebral body replacement have been developed. Based on our own experience, the purpose of this study was to summarize the available biomechanical and clinical data of expandable corpectomy cages and to compare it with established fixation techniques. If used correctly, expandable cages offer several surgical advantages in comparison to non-expandable cages. However there were no significant differences between the biomechanical properties of expandable and non-expandable cages. Additionally, design variations of expandable corpectomy cages did not show any significant impact on the biomechanical stability. Currently available mid-term clinical and radiological data on the treatment of fractures, metastasis and infection of the cervical, thoracic and lumbar spine demonstrated no significant difference between expandable and non-expandable cages. However, the increased stress-shielding effect of expandable cages compared to non-expandable cages might result in a deterioration of the long-term clinical outcome.