Cervical corpectomies: results of a survey and review of the literature on diagnosis, indications, and surgical technique

In vivo study of a novel 3D-printed motion-preservation artificial cervical corpectomy construct: short-term imaging and biocompatibility evaluations in a goat model

BACKGROUND

Nonfusion technologies, such as motion-preservation devices, have begun a new era of treatment options in spine surgery. Motion-preservation approaches mainly include total disc replacement for anterior cervical discectomy and fusion. However, for multisegment fusion, such as anterior cervical corpectomy and fusion, the options are more limited. Therefore, we designed a novel 3D-printed motion-preservation artificial cervical corpectomy construct (ACCC) for multisegment fusion. The aim of this study was to explore the feasibility of ACCC in a goat model.

METHODS

Goats were treated with anterior C3 corpectomy and ACCC implantation and randomly divided into two groups evaluated at 3 or 6 months. Radiography, 3D CT reconstruction and MRI evaluations were performed. Biocompatibility was evaluated using micro-CT and histology.

RESULTS

Postoperatively, all goats were in good condition, with free neck movement. Implant positioning was optimal. The relationship between facet joints was stable. The range of motion of the C2-C4 segments during flexion-extension at 3 and 6 months postoperatively was 7.8° and 7.3°, respectively. The implants were wrapped by new bone tissue, which had grown into the porous structure. Cartilage tissue, ossification centres, new blood vessels, and bone mineralization were observed at the porous metal vertebrae-bone interface and in the metal pores.

CONCLUSIONS

The ACCC provided stabilization while preserving the motion of the functional spinal unit and promoting bone regeneration and vascularization. In this study, the ACCC was used for anterior cervical corpectomy and fusion (ACCF) in a goat model. We hope that this study will propel further research of motion-preservation devices.

Cervical Anatomical Landmarks Indicate the Amount of Vertebra Resection during ACAF Surgery: A Semi-Quantitative Anatomical Parameter Study on Imaging Data

OBJECTIVE

With the innovation and development of cervical spine surgical procedures, there is currently a lack of new and reliable data on cervical anatomical landmarks. The purpose of this study is to measure the CT data of the cervical vertebrae of healthy volunteers, so as to make up for the missing part of the measured value of cervical vertebra bone markers, and provide data support for the safety and accuracy of anterior controllable antedisplacement and fusion (ACAF) surgery.

METHODS

From January 2019 to January 2020, the cervical computed tomography (CT) scan image data of volunteers in Changhai Hospital and Zhabei Hospital were randomly selected. The radiological parameters included three parameters were measured in the upper lamina plane. a: the distance from the anterior edge of the vertebral body to the anterior edge of the bilateral uncinate joint; c1: the sagittal diameter of the vertebral body; and d: the distance between the anterior edge of the uncinate joint. Three parameters were measured in the pedicle plane. b: the vertical distance from the anterior edge of the vertebral body to the junction line between the two lateral processes; c2: the sagittal diameter of the vertebral body; e: the transverse diameter of the vertebral body; and f: the sagittal diameter of the vertebral canal. The correlation ratios were calculated: a/c1, b/c2, a/f, b/f, d/e. The data between the two groups were compared by independent sample t-test.

RESULTS

Finally, 51 patients were included in this study, 18 males and 33 females, with an average age of 47.9 years (21-72 years). The maximum values of seven parameters measured were all at C7. The minimum b value was at C5, and the minimum f value was at C4. The minimum values of the other five parameters were all at C3, and there was an increasing relationship from C3 to C7 (P < 0.05). There was significant difference between male and female with regard to c1, c2, e and d values (P < 0.05). No significant differences were observed between men and women regard to the ratio of related parameters (a/c1, b/c2, a/f, b/f, d/e).

CONCLUSIONS

Anatomical consideration of this area is useful to estimate amount of vertebral body resection when performing the bony cut made in ACAF surgery; however, pre-operative examinations with appropriate radiographic analysis are also recommended.

Anterior Cervical Corpectomy and Fusion for Degenerative and Traumatic Spine Disorders, Single-Center Experience of a Case Series of 119 Patients

BACKGROUND

Anterior cervical corpectomy and fusion (ACCF) is a treatment option for several cervical pathologies. Various graft materials such as autografts, titanium mesh cages (TMC), or poly-ether-ether-ketone (PEEK) cages are used. Additional posterior fixation (PF) to provide extra support and improve stability is sometimes performed initially, or later as supplementary treatment.

OBJECTIVE

To describe our retrospective study of 119 consecutive cases of ACCF with synthetic grafts, in 3 cohorts of cervical spondylotic myelopathy (CSM), infectious and neoplastic processes, and trauma, with special focus on need for supplementary PF.

METHODS

A total of 135 adult patients treated with ACCF between January 2005 and January 2018 were identified. Patients lost to follow-up were excluded, and 119 remaining patients were included for retrospective clinical and radiological assessment.

RESULTS

Synthetic grafts were used in 116 (97%) cases. Only 9 (8%) ACCF cases required later supplementary PF, where 7 (78%) cases were multilevel. There was a statistically significant difference in revision rate with PF for single-level compared to multilevel ACCFs (P = .001). Revision rates with PF were 2%, 29%, and 7% in CSM, infectious and neoplastic processes, and trauma cohorts, respectively.

CONCLUSION

The results indicate that ACCF is a safe and effective treatment for degenerative and traumatic cervical spine disorders, with low complication and revision rates. Single-level ACCF can be performed without additional PF. Multilevel ACCF (n > 2) and pathologies affecting bone quality seem to be risk factors for material subsidence and instability. In these cases, additional PF should be considered.

The Effect of Rod Pattern, Outrigger, and Multiple Screw-Rod Constructs for Surgical Stabilization of the 3-Column Destabilized Cervical Spine - A Biomechanical Analysis and Introduction of a Novel Technique

Objective

Anterior-only reconstructions for cervical multilevel corpectomies are prone to fail under continuous mechanical loading. This study sought to define the mechanical characteristics of different constructs in reducing a range of motion (ROM) of the 3-column destabilized cervical spine, including posterior cobalt-chromium (CoCr)-rods, outrigger-rods (OGR), and a novel triple rod construct using lamina screws (6S3R). The clinical implications of biomechanical findings are discussed in depth from the perspective of the challenges surgeons face cervical deformity correction.

Methods

Three-column deficient cervical spinal models were produced based on reconstructed computed tomography scans. The corpectomy defect between C3 and C7 end-level vertebrae was restored with anterior titanium (Ti) mesh-cage. The ROM was evaluated in a customized 6-degree of freedom spine tester. Tests were performed with different rod materials (Ti vs. CoCr), varying diameter rods (3.5 mm vs. 4.0 mm), with and without anterior plating, and using different construct patterns: bilateral rod fixation (standard-group), OGR-group, and 6S3R-Group. Construct stability was expressed in changes and differences of ROM (°).

Results

The largest reduction of ROM was noticed in the 6S3R-group compared to the standard- and the OGR-group. All differences observed were emphasized with an increasing number of corpectomy levels and if anterior plating was not added. For all simulated 1-, 2-, and 3-level corpectomy constructs, the OGR-group revealed decreased ROM for all motion directions compared to the standard-group. An increase of construct stiffness was also recorded for increased rod diameter (4.0 mm) and stiffer rod material (CoCr), though these effects lacked behind the more advanced construct pattern.

Conclusion

A novel reconstructive technique, the 6S3R-construct, was shown to outperform all other constructs and might resemble a new standard of reference for advanced posterior fixation.

Degenerative Cervical Myelopathy: A 7-Letter Coding System That Supports Decision-Making for the Surgical Approach

Objective

To validate with a prospective study a decision-supporting coding system for the surgical approach for multilevel degenerative cervical myelopathy.

Methods

Ten cases were presented on an internet platform, including clinical and imaging data. A single-approach (G1), a choice between 2 (G2), or 3 approaches (G3) were options. Senior and junior spine surgeons analyzed 7 parameters: location and extension of the compression of the spinal cord, C-spine alignment and instability, general morbidity and bone diseases, and K-line and multilevel corpectomy. For each parameter, an anterior, posterior, or combined approach was suggested. The most frequent letter or the last letter (if C) of the resulting 7-letter code (7LC) suggested the surgical approach. Each surgeon performed 2 reads per case within 8 weeks.

Results

G1: Interrater reliability between junior surgeons improved from the first read (κ = 0.40) to the second (κ = 0.76, p < 0.001) but did not change between senior surgeons (κ = 0.85). The intrarater reliability was similar for junior (κ = 0.78) and senior (κ = 0.71) surgeons. G2: Junior/senior surgeons agreed completely (58%/62%), partially (24%/23%), or did not agree (18%/15%) with the 7LC choice. G3: junior/senior surgeons agreed completely (50%/50%) or partially (50%/50%) with the 7LC choice.

Conclusion

The 7LC showed good overall reliability. Junior surgeons went through a learning curve and converged to senior surgeons in the second read. The 7LC helps less experienced surgeons to analyze, in a structured manner, the relevant clinical and imaging parameters influencing the choice of the surgical approach, rather than simply pointing out the only correct one.

Biomechanical Comparison of Integrated Fixation Cage Versus Anterior Cervical Plate and Cage in Anterior Cervical Corpectomy and Fusion (ACCF): A Finite Element Analysis

Background

Anterior cervical plate and cage fixation system (ACPC) used in anterior cervical corpectomy and fusion (ACCF) is reported to incur excess complications. This study aimed to introduce integrated fixation cage (IFC) into ACCF to eliminate the anterior cervical plate (ACP)-related complications.

Material/Methods

One validated intact and 3 ACCF-simulated C3–C7 cervical spine models were developed. In ACCF models, C5 was corpectomied and fixed by IFC or ACPC. For each model, 1.0 Nm moments of flexion, extension, lateral bending, and torsion were imposed on the C3 vertebra. The range of motion (ROM) of each segment and the stress distribution on screw-vertebra interface, bone graft, and cage-endplate were recorded and analyzed.

Results

ROMs of C3–C7 were not different in any motion condition between IFC and ACPC models. The maximal von Mises stress on screw-vertebra interface of the IFC model was lower than that of the ACPC models in flexion, extension, and lateral bending, but higher in rotation. The maximal von Mises stress on bone graft of the IFC model was higher compared with the ACPC models, except in flexion. The IFC model showed a higher maximal von Mises stress on cage-endplate interface in all motion planes.

Conclusions

Based on finite element analysis, IFC provided identical C3–C7 construct stability as ACPC. Compared with ACPC, IFC showed better biomechanical performance on screw-vertebra interface and bone graft, but worse biomechanical performance on cage-endplate interface.

The application of a new type of titanium mesh cage in hybrid anterior decompression and fusion technique for the treatment of continuously three-level cervical spondylotic myelopathy

PURPOSE

To evaluate the efficacy and safety of a new type of titanium mesh cage (NTMC) in hybrid anterior decompression and fusion method (HDF) in treating continuously three-level cervical spondylotic myelopathy (TCSM).

METHODS

Ninety-four cases who had TCSM and accepted the HDF from Jan 2007 to Jan 2010 were included. Clinical and radiological outcomes were compared between cases who had the NTMC (Group A, n = 45) and traditional titanium mesh cage (TTMC, Group B, n = 49) after corpectomies. Each case accepted one polyetheretherketone cage (PEEK) after discectomy.

RESULTS

Mean follow-up were 74.4 and 77.3 months in Group A and B, respectively (p > 0.05). Differences in cervical lordosis (CL), segmental lordosis (SL), anterior segmental height (ASH) and posterior segmental height (PSH) between two groups were not significant preoperatively, 3-days postoperatively or at final visit. However, losses of the CL, SL, ASH and PSH were all significantly larger in Group B at the final visit, so did incidences of segmental subsidence and severe subsidence. Difference in preoperative Japanese Orthopedic Association (JOA), visual analog scale (VAS), neck disability index (NDI) or SF-36 between two groups was not significant. At the final visit, fusion rate, JOA, and SF-36 were all comparable between two groups, but the VAS and NDI were both significantly greater in Group B.

CONCLUSIONS

For cases with TCSM, HDF with the NTMC and TTMC can provide comparable radiological and clinical improvements. But application of the NTMC in HDF is of advantages in decreasing the subsidence incidence, losses of lordosis correction, VAS and NDI.