To Plate or Not to Plate after a Single- or Two-Level Anterior Cervical Discectomy: Fusion with Cage-Plate Construct or Stand-Alone Cage

Double-Plate Technique for Long-Construct Anterior Cervical Discectomy and Fusion

The standard technique for multilevel anterior cervical discectomy and fusion (ACDF) uses a single plate to span multiple vertebral levels. However, the usage of single long plates is linked to potential hardware failure and screw pullout from stress overload. A single long plate is also more likely to fail at the caudal levels. Furthermore, centering a long plate spanning multiple levels requires simultaneous exposure to anatomy that may require more traction, technical expertise, and a potential increase in operative time. The use of a double-plate technique may be less technically demanding and, at the same time, allow for future revision to be confined to a shorter segment rather than requiring the removal of the entire single plate. In this study, we describe a surgical technique that involves using two plates during three or more levels of ACDF, discussing its advantages and limitations.

Anterior Plate-Screws and Lower Postoperative T1 Slope Affect Cervical Allospacer Failures in Multi-Level ACDF Surgery: Anterior Versus Posterior Fixation

STUDY DESIGN

Prospective observational study.

OBJECTIVE

In ACDF, graft failure and subsidence are common complications of surgery. Depending on the cervical fixation, different biomechanical characteristics are applied on the grafts. This aims to describe the incidence of cervical spacer failure in patients with cervical degenerative condition according to the cervical fixation method and sagittal balance.

METHOD

From November 2011 to December 2015, 262 patients who underwent cervical spine surgery were enrolled prospectively. Patients were divided into 3 groups based on fixation method: anterior plate/screw (APS), posterior lateral mass screw (LMS), pedicle screw (PPS) groups. Serial X-rays and CT scans were utilized to evaluate radiologic outcomes.

RESULTS

Mean patient ages were 56.1 years in the APS group, 61.5 years in the LMS group, and 57.6 years in the PPS group (P = 0.002). Allospacer failure was most common in the APS group, compared to the LMS and PPS groups (chi-square, P = 0.038). Longer fusion level was associated with greater allospacer failure (Baseline 2 level surgery; Odds ratio (OR) 3.4 in 3 level, 15.2 in 4 level, P = 0.036,0.013). Higher T1 slope was correlated with less allospacer failure (OR 0.875, P = 0.001). ORs of allospacer failure in the LMS and PPS groups were 0.04 and 0.02, respectively, (P = 0.01, 0.01), compared with the APS group.

CONCLUSION

This study was able to show that allospacer failure in multi-level ACDF surgery is more common with a longer fusion length, less postoperative T1 slope, and an anterior plate-screws technique. Pedicle screws provided the best biomechanical stability among the 3 constructs.

Effects of Anterior Plating on Achieving Clinically Meaningful Improvement Following Single-Level Anterior Cervical Discectomy and Fusion

Objective

The clinical utility of anterior cervical plating for anterior cervical discectomy and fusion (ACDF) procedures remains controversial. This study aims to compare the impact of cervical plating on achievement of minimum clinically important difference (MCID) up to 2 years following ACDF.

Methods

Patients undergoing primary, single-level ACDF procedures were grouped based on whether their procedure included application of an anterior cervical plate. Demographics, preoperative spinal diagnoses, operative characteristics, and patient-reported outcome measures (PROMs) were compared between plating groups. Achievement of an MCID was assessed using the following previously established thresholds: 12-item Short Form health survey physical component summary (SF-12 PCS) 8.1, visual analogue scale (VAS) neck 2.6, VAS arm 4.1, Neck Disability Index (NDI) 8.5. Rates of MCID achievement were compared between groups.

Results

The cohort included 192 patients of whom 102 received plating and 90 received no plating. Plating status was significantly associated with Charlson Comorbidity Index and insurance status. Operative duration and estimated blood loss were significantly greater for the plating group. Both groups demonstrated significant improvements at the majority of postoperative timepoints. Significant intergroup differences in PROM improvement were demonstrated for VAS neck and NDI at 6 weeks. Rates of MCID achievement differed significantly between groups for NDI at 6 weeks, and 12 weeks, and SF-12 PCS overall.

Conclusion

Patients improved significantly in terms of pain, disability and physical function, regardless of plating status, and with the exception of early neck pain and disability, these improvements were similar between groups. Patients that underwent plating as part of their ACDF procedure achieved an MCID for physical function at lower rates overall.

Subjective and Objective Quality-of-Life Assessment of Outcome Measures in Cervical Spine Surgery for Degenerative Changes

Cervical spine diskectomy is a commonly used procedure in degenerative disease of cervical spine surgery. However, it is difficult to assess the quality of life after this widely applied and variously modified procedure. This literature review presents cervical diskectomy results, according to various scales and measures in multidirectional surgical strategies. Using relevant databases, we tried to find the best treatment options for degenerative disk disease and the best method of quality-of-life assessment, searching for modalities that may influence the outcome.

Adjacent-Level Ossification Development in Single-Level Standalone Anterior Cervical Discectomy and Fusion Versus Anterior Cervical Discectomy and Fusion With Plate

STUDY DESIGN

Retrospective case control study.

OBJECTIVES

Adjacent-level ossification development (ALOD) is a distinct form of adjacent segmental degeneration that has been recognized to occur after anterior cervical discectomy and fusion (ACDF). It is unclear whether ACDF with plate versus standalone has an effect on rates of ALOD. This retrospective case-control study aims to assess the rate of ALOD in a large series of patients undergoing ACDF with and without plate and factors causing ALOD.

METHODS

Data was collected for patients undergoing ACDF from January 2009 to July 2016. Data collected was from multiple centers and included demographic data, surgical data, radiological imaging at time of surgery, and serial follow-up imaging. The radiology for ALOD was independently reviewed. Cohorts were divided into ACDF with plate (Group P = plate) and ACDF without plate (Groups S = standalone) and outcomes were compared.

RESULTS

There were 260 patients with 138 (53%) in Group P and 122 (47%) in Group S. ALOD was observed in 15.3% of patients overall, 29% in group P and 2.8% in group S (P < .001). Following multivariate adjustment, statistically significant association was found between use of plate and ALOD (odds ratio = 12.8, 95% confidence interval = 3.52-45.45, P < .001). Plate-to-disc distance <5 mm was significantly associated with ALOD (odds ratio = 13.5, 95% confidence interval = 3.83-47.62, P < .001).

CONCLUSION

The use of anterior plate with ACDF was associated with ALOD. Plate-to-disc distance <5 mm was significantly associated with ALOD even after adjustment for confounding factors. We conclude utilization of standalone cages or cages with plate with more than 5 mm distance from adjacent disc to minimize ALOD.

Biomechanical Analysis of Allograft Spacer Failure as a Function of Cortical-Cancellous Ratio in Anterior Cervical Discectomy/Fusion: Allograft Spacer Alone Model

The design and ratio of the cortico-cancellous composition of allograft spacers are associated with graft-related problems, including subsidence and allograft spacer failure. Methods: The study analyzed stress distribution and risk of subsidence according to three types (cortical only, cortical cancellous, cortical lateral walls with a cancellous center bone) and three lengths (11, 12, 14 mm) of allograft spacers under the condition of hybrid motion control, including flexion, extension, axial rotation, and lateral bending,. A detailed finite element model of a previously validated, three-dimensional, intact C3–7 segment, with C5–6 segmental fusion using allograft spacers without fixation, was used in the present study. Findings: Among the three types of cervical allograft spacers evaluated, cortical lateral walls with a cancellous center bone exhibited the highest stress on the cortical bone of spacers, as well as the endplate around the posterior margin of the spacers. The likelihood of allograft spacer failure was highest for 14 mm spacers composed of cortical lateral walls with a cancellous center bone upon flexion (PVMS, 270.0 MPa; 250.2%) and extension (PVMS: 371.40 MPa, 344.2%). The likelihood of allograft spacer subsidence was also highest for the same spacers upon flexion (PVMS, 4.58 MPa; 28.1%) and extension (PVMS: 12.71 MPa, 78.0%). Conclusion: Cervical spacers with a smaller cortical component and of longer length can be risk factors for allograft spacer failure and subsidence, especially in flexion and extension. However, further study of additional fixation methods, such as anterior plates/screws and posterior screws, in an actual clinical setting is necessary.

Biomechanical comparison of the angle of inserted screws and the length of anterior cervical plate systems with allograft spacers

BACKGROUND

Comparative studies of the biomechanical effects of plates of varying lengths and different screw insertion angles on allograft spacers are lacking.

METHODS

Finite element model analysis of a previously validated, three-dimensional, intact cervical spinal segment model of C3-6 was conducted in the present study. On the C5-6 segment, anterior discectomy and fusion were performed using allograft spacers and different combinations of anterior plates and screws. The biomechanical characteristics of combinations of short, medium, and maximal length plates with screw insertion angles of 0°, 8°, 16°, and 32° were analyzed.

FINDINGS

In flexion and extension, the risk of allograft spacer subsidence decreased as screw angles increased. Short plates with a screw insertion angle of 32° posed the lowest subsidence risk, similar to medium length plates with a screw insertion angle of 16°, in all motion conditions. The risk of bone yielding increased as plate length increased, but decreased as the screw insertion angle increased.

INTERPRETATION

Short plates with a large screw insertion angle (32°) showed the highest mechanical stability and load sharing of allograft spacers and the lowest risk of screw loosening. Accordingly, we recommend the use of a short plate and large screw insertion angle for anterior cervical discectomy and fusion.

Biomechanical comparison of cervical discectomy/fusion model using allograft spacers between anterior and posterior fixation methods (lateral mass and pedicle screw)

BACKGROUND

The purpose of this study is to investigate effects of different fixation methods on the physical stress on allospacers, endplate-vertebral body, and implants using finite element model analyses.

METHODS

Stress distribution and subsidence risk according to the fixation methods under the condition of hybrid motion control were analyzed. The detailed finite element model of a previously validated, three-dimensional, intact cervical spinal segment model, with C5-C6 segmental fusion using allospacer, was used to evaluate the biomechanical characteristics of different fixation combinations, such as anterior plate/screws, lateral mass screw, and posterior pedicle screw.

FINDINGS

The load sharing on allospacers increased in extension in order of posterior pedicle screws (21.4%), lateral mass screws (31.5%), and anterior plate/screws (56.6%). lateral mass screw demonstrated the highest load sharing (68.1%) on the allospacer in flexion. The Peak von Mises stress of the allospacer was the lowest in flexion and axial rotation but the highest in extension with anterior plate/screws. Allospacer subsidence risk was the lowest in extension, lateral bending, and axial rotation with posterior pedicle screws but the lowest in flexion with anterior plate/screws. The bone-screw loosening risk was the lowest in all modes with posterior pedicle screws but the highest with anterior plate/screws.

INTERPRETATION

Posterior pedicle screws demonstrated the best mechanical stability of allospacer failure-subsidence and the lowest risk of screw loosening. Different motion restrictions depending on the fixation method should be considered for implant and allospacer safety.

Comparison of stand-alone cage and cage-with-plate for monosegmental cervical fusion and impact of virtual reality in evaluating surgical results

OBJECTIVES

After ventral decompression of monosegmental cervical spondylotic stenosis, a stand-alone cage (SC) or cage-with-plate (CP) can be inserted for fusion. Postoperative radiological evaluation can be achieved using different imaging modalities. We retrospectively compared complications, as well as clinical and radiological outcomes for both fusion techniques, and analyzed the possible role of virtual reality (VR) in evaluating the postoperative results.

PATIENTS AND METHODS

One hundred seventeen patients were included (SC/CP: 54/63). Complications, as well as clinical and radiological outcomes of both fusion techniques were compared. Computed tomography (CT) scans were visualized via VR to measure the smallest cross-sectional area of the intervertebral neuroforamen in the lateral resection region, and to assess the degree of the intersegmental ossification.

RESULTS

There were no significant differences between the two fusion techniques regarding perioperative complication rates, fusion rates, or pain parameter (visual analogue scale (VAS) of arm pain, neck disability index). However, advantages regarding subsidence, kyphosis, and VAS of neck pain were found when using the CP versus SC. Using the VR technique, there was no significant difference between the two fusion techniques in the mean size of the cross-sectional area at the end of follow-up.

CONCLUSION

Due to the long-term advantages of CP fusion, we prefer a monosegmental cervical spinal fusion using CP. Reconstruction of postsurgical two-dimensional CT images into three-dimensional images, and the spatial and anatomical presentation in VR models, improved the evaluation of these postoperative results.

[Observation of stand-alone MC+polyether-ether-ketone (PEEK) Cage in anterior cervical double-level fusion for more than 2 years follow-up]

OBJECTIVE

To investigate the effectiveness of stand-alone MC+polyether-ether-ketone (PEEK) Cage (single blade type) in anterior cervical double-level fusion for more than 2 years follow-up.

METHODS

A clinical data of 30 patients who were treated with anterior cervical fusion surgery with stand-alone MC+PEEK Cage (single blade type) between January 2013 and December 2016 and followed up for more than 2 years, was retrospectively analyzed. There were 16 males and 14 females, aged from 34 to 72 years with an average of 52.2 years. There were 16 cases of cervical spondylotic myelopathy, 8 cases of cervical spondylotic myelopathy, and 6 cases of traumatic cervical disc herniation. The continuous double segments were C 4, 5, C 5, 6 in 12 cases and C 5, 6, C 6, 7 in 18 cases; and the disease duration ranged from3 days to 24 months (mean, 12 months). Postoperative neck hematoma and wound healing were observed; dysphagia was assessed by Bazaz system; and bone fusion was assessed by Suk method. Before operation, at 1 week after operation, and at last follow-up, the Japanese Orthopaedic Association (JOA) score was used to evaluate the neurological recovery; the cervical X-ray film was performed to record the cervical curvature (C 2-C 7 Cobb angle), the height of the intervertebral space of the fusion segment, and to judge the occurrence of the fusion Cage subsidence.

RESULTS

No complication such as neck hematoma, incision infection, or esophageal fistula was found, primary healing of incisions was obtained in all cases. All patients were followed up 24-72 months (mean, 46 months). Neurological symptoms such as limb numbness and pain gradually disappeared after operation; during the follow-up period, the cervical curvature could be effectively maintained; dysphagia and internal fixation related complications such as displacement of Cages were not found. All patients obtained bony fusion from 3 to 8 months with an average time of 4.3 months. Compared with preoperative ones, the JOA score, intervertebral space height, and Cobb angle of cervical spine were significantly improved at 1 week after operation and at last follow-up ( P<0.05), but there was no significant difference between 1 week after operation and last follow-up ( P>0.05).

CONCLUSION

The application of stand-alone MC+PEEK Cage (single card type) in anterior cervical fusion can provide early cervical stability, effectively maintain the physiological curvature of cervical spine and the height of fusion intervertebral space.

Comparison of the outcomes of cage-stand-alone with cage-with-plate fixation in one level and two levels for treating cervical disk diseases

Introduction:

Anterior cervical discectomy and fusion (ACDF) surgery is an accepted method for many spinal cord abnormalities. The purpose of this study was to evaluate the outcomes of treating patients with spinal cord lesions at one level or two levels through ACDF with cage-stand-alone (ACDF-CA) and ACDF with cage-with-plate fixation (ACDF-CP) surgery and comparing these results with each other.

Methods:

In this prospective, cross-sectional, descriptive study, eighty patients undergoing ACDF surgery were enrolled according to the inclusion and exclusion criteria. Demographic data, before and after surgery findings, and clinical symptoms were investigated. Data were collected by means of visual analog scale (VAS) and Neck Disability Index (NDI) questionnaires. The adverse effects and surgical outcomes were evaluated based on Odom's criteria and patients’ satisfaction. The collected data of the groups were then compared and assessed.

Results:

There was no significant difference between the groups in regards of gender, age, duration of surgery to visit, surgical level, preoperative and postoperative VAS and cervical range of motion, preoperative NDI, results based on Odom's criteria, and satisfaction of patients (P > 0.05). The VAS, NDI, and range of motion scores were significantly reduced in the four groups after the operation compared to the preoperative stage. Postoperative NDI scores in the ACDF-CA group at one level were significantly lower than other groups (P < 0.05).

Conclusion:

Both of the methods revealed acceptable outcomes in comparison to the preoperative stage, and despite some minor differences, there are generally no significant differences in outcomes and complications.