Subsidence after single-level anterior cervical fusion with a stand-alone cage

To investigate the risk factors for subsidence in patients treated with stand-alone anterior cervical discectomy and fusion (ACDF) using polyetheretherketone (PEEK) cages for single-level degenerative cervical disease. Seventy-seven consecutive patients who underwent single-level stand-alone ACDF with a PEEK cage between 2005 and 2012 were included. Subsidence was defined as a decrease in the interbody height of more than 3 mm on radiographs at the 1-year follow-up compared with that in the immediate post-operative image. Patients were divided into the subsidence and non-subsidence groups. The following factors were investigated in relation to the occurrence of subsidence: age, pre-operative overall cervical sagittal angle, segmental angle of the operated level, interbody height, cage height, cage devices and cage location (distance between anterior margin of the body endplate and that of the cage). The clinical outcomes were assessed with visual analog scale, modified Japanese Orthopedic Association score and neck disability index. Twenty-six out of the 77 (33.8%) patients had radiological signs of cage subsidence. Solid fusion was achieved in 25 out of the 26 patients (96.2%) in the subsidence group and in 47 out of the 51 patients (92.2%) in the non-subsidence group. More than 3 mm distance between anterior margin of the vertebral body and that of the cage was significantly associated with subsidence (p < 0.05). However, subsidence did not correlate with fusion rate or clinical outcomes. Cage location was the only significant risk factor. Therefore, cage location should be taken into consideration during stand-alone ACDF using PEEK cages.     

Comparison of Fusion with Cage Alone and Plate Instrumentation in Two-Level Cervical Degenerative Disease

Objective

This study assessed the efficacy of anterior cervical discectomy and fusion (ACDF) with cage alone compared with ACDF with plate instrumentation for radiologic and clinical outcomes in two-level cervical degenerative disease.

Methods

Patients with cervical degenerative disc disease from September 2004 to December 2009 were assessed retrospectively. A total of 42 patients received all ACDF at two-level cervical lesion. Twenty-two patients who underwent ACDF with cage alone were compared with 20 patients who underwent ACDF with plate fixation in consideration of radiologic and clinical outcomes. Clinical outcomes were assessed using Robinson''s criteria and posterior neck pain, arm pain described by a 10 point-visual analog scale. Fusion rate, subsidence, kyphotic angle, instrument failure and the degenerative changes in adjacent segments were examined during each follow-up examination.

Results

VAS was checked during each follow-up and Robinson''s criteria were compared in both groups. Both groups showed no significant difference. Fusion rates were 90.9% (20/22) in ACDF with the cage alone group, 95% (19/20) in ACDF with the plate fixation group (p = 0.966). Subsidence rates of ACDF with cage alone were 31.81% (7/22) and ACDF with plate fixation were 30% (6/20) (p = 0.928). Local and regional kyphotic angle difference showed no significant difference. At the final follow-up, adjacent level disease developed in 4.54% (1/22) of ACDF with cage alone and 10% (2/20) of ACDF with plate fixation (p = 0.654).

Conclusion

In two-level ACDF, ACDF with cage alone would be comparable with ACDF with plate fixation with regard to clinical outcome and radiologic result with no significant difference. We suggest that the routine use of plate and screw in 2-level surgery may not be beneficial.     

The Effect of Hounsfield Unit Value with Conventional Computed Tomography and Intraoperative Distraction on Postoperative Intervertebral Height Reduction in Patients Following Stand-Alone Anterior Cervical Discectomy and Fusion

ObjectiveThe most common complication of anterior cervical discectomy and fusion (ACDF) is cage subsidence and maintenance of disc height affects postoperative clinical outcomes. We considered cage subsidence as an inappropriate indicator for evaluating preservation of disc height. Thus, this study aimed to consider patients with complications such as reduced total disc height compared to that before surgery and evaluate the relevance of several factors before ACDF. MethodsWe retrospectively reviewed the medical records of 40 patients who underwent stand-alone single-level ACDF using a polyetheretherketone (PEEK) cage at our institution between January 2012 and December 2018. Our study population comprised 19 male and 21 female patients aged 24–70 years. The minimum follow-up period was 1 year. Twenty-seven patients had preoperative bone mineral density (BMD) data on dual-energy X-ray absorptiometry. Clinical parameters included sex, age, body mass index, smoking history, and prior medical history. Radiologic parameters included the C2-7 cobb angle, segmental angle, sagittal vertical axis, disc height, and total intervertebral height (TIH) at the preoperative and postoperative periods. Cage decrement was defined as the reduction in TIH at the 6-month follow-up compared to preoperative TIH. To evaluate the bone quality, Hounsfield unit (HU) value was calculated in the axial and sagittal images of conventional computed tomography. ResultsLumbar BMD values and cervical HU values were significantly correlated (r=0.733, p<0.001). We divided the patients into two groups based on cage decrement, and 47.5% of the total patients were regarded as cage decrement. There were statistically significant differences in the parameters of measuring the HU value of the vertebra and intraoperative distraction between the two groups. Using these identified factors, we performed a receiver operating characteristic (ROC) curve analysis. Based on the ROC curve, the cut-off point was 530 at the HU value of the upper cortical and cancellous vertebrae (p=0.014; area under the curve [AUC], 0.727; sensitivity, 94.7%; specificity, 42.9%) and 22.41 at intraoperative distraction (p=0.017; AUC, 0.722; sensitivity, 85.7%; specificity, 57.9%). Using this value, we converted these parameters into a bifurcated variable and assessed the multinomial regression analysis to evaluate the risk factors for cage decrement in ACDF. Intraoperative distraction and HU value of the upper vertebral body were independent factors of postoperative subsidence. ConclusionInsufficient intraoperative distraction and low HU value showed a strong relationship with postoperative intervertebral height reduction following single stand-alone PEEK cage ACDF.     

Outcomes of contemporary use of rectangular titanium stand-alone cages in anterior cervical discectomy and fusion: Cage subsidence and cervical alignment

Cervical intervertebral disc replacement using a rectangular titanium stand-alone cage has become a standard procedure for anterior cervical discectomy and fusion (ACDF). We examined outcomes resulting from the contemporary use of rectangular titanium stand-alone cages for ACDF, particularly focusing on cage subsidence and subsequent kyphotic malalignment. Patient data were collected prospectively, and a total of 47 consecutive patients who underwent periodic follow-up of at least 1 year’s duration after ACDF were studied retrospectively. Sixty-three rectangular titanium cages were implanted during 31 1-level and 16 2-level procedures. None of the patients developed surgery-related complications (including cage displacement or extrusion). Mean Neurosurgical Cervical Spine Scale scores were significantly improved at 1 year after surgery. Twelve of the 63 inserted cages (19.0%) were found to have cage subsidence, occurring in 11 of 47 patients (23.4%). There was no significant difference in functional recovery between patients with and without cage subsidence. Logistic regression analysis indicated that fusion level, cage size and cage position were significantly related to cage subsidence. The distraction ratio among patients with cage subsidence was significantly higher than that among patients without cage subsidence. Cage subsidence resulted in early deterioration of local angle and total alignment of the cervical spine. Although a longer follow-up is warranted, a good surgical outcome with negligible complications appears to justify the use of rectangular titanium stand-alone cages in 1- and 2-level ACDF. Excessive distraction at the fusion level should be avoided, and cage position should be adjusted to the anterior vertical line.     

Safety of anterior cervical discectomy and fusion using titanium-coated polyetheretherketone stand-alone cages: Multicenter prospective study of incidence of cage subsidence

This multicenter prospective study investigated cage subsidence in anterior cervical discectomy and fusion (ACDF) using titanium-coated polyetheretherketone (PEEK) stand-alone cages. This study recruited patients who underwent 1- or 2-level ACDF using titanium-coated PEEK stand-alone cages for cervical disc disease. Patients with acute trauma or past cervical spine operations were excluded. Sixty-two cages in 42 patients were eligible for analysis. Minimum follow-up was 6 months after ACDF. Significant cage subsidence was recognized in 11 of 62 cages (17.7%). Cage subsidence was predominantly moderate (14.5%), with severe subsidence found in only 2 cages (3.2%). The slowest occurrence of cage subsidence was 6 months after surgery, in 4 of 11 cages. Frequency of cage subsidence did not differ significantly between patients <65 and ≥65 years old. Patients with and without cage subsidence both demonstrated significant improvement of neurological function. Cage subsidence resulted in aggravation of local angle, but finally did not affect C2-7 angle or cervical tilt angle. Severe cage subsidence was found in only 3.2% of patients within 6 months after ACDF. Cage subsidence aggravated local angle, but finally did not affect C2-7 angle or cervical tilt angle. One- or 2-level ACDF using titanium-coated PEEK stand-alone cages appears safe and justified, even in elderly patients.     

Clinical and Radiological Comparison of Femur and Fibular Allografts for the Treatment of Cervical Degenerative Disc Diseases

Objective

This consecutive retrospective study was designed to analyze and to compare the efficacy and outcomes of anterior cervical discectomy and fusion (ACDF) using a fibular and femur allograft with anterior cervical plating.

Methods

A total of 88 consecutive patients suffering from cervical degenerative disc disease (DDD) who were treated with ACDF from September 2007 to August 2010 were enrolled in this study. Thirty-seven patients (58 segments) underwent anterior interbody fusion with a femur allograft, and 51 patients (64 segments) were treated with a fibular allograft. The mean follow-up period was 16.0 (range, 12-25) months in the femur group and 19.5 (range, 14-39) months in the fibular group. Cage fracture and breakage, subsidence rate, fusion rate, segmental angle and height and disc height were assessed by using radiography. Clinical outcomes were assessed using a visual analog scale and neck disability index.

Results

At 12 months postoperatively, cage fracture and breakage had occurred in 3.4% (2/58) and 7.4% (4/58) of the patients in the femur group, respectively, and 21.9% (14/64) and 31.3% (20/64) of the patients in the fibular group, respectively (p<0.05). Subsidence was noted in 43.1% (25/58) of the femur group and in 50.5% (32/64) of the fibular group. No difference in improvements in the clinical outcome between the two groups was observed.

Conclusion

The femur allograft showed good results in subsidence and radiologic parameters, and sustained the original cage shape more effectively than the fibular allograft. The present study suggests that the femur allograft may be a good choice as a fusion substitute for the treatment of cervical DDD.     

Comparative Analysis of Cervical Arthroplasty Using Mobi-C? and Anterior Cervical Discectomy and Fusion Using the Solis? -Cage

Objective

Although anterior cervical discectomy and fusion (ACDF) is the standard treatment for degenerative cervical disc disease, concerns regarding adjacent level degeneration and loss of motion have suggested that arthroplasty may be a better alternative. We have compared clinical and radiological results in patients with cervical disc herniations treated with arthroplasty and ACDF.

Methods

We evaluated 53 patients treated for cervical disc herniations with radiculopathy, 21 of whom underwent arthroplasty and 32 of whom underwent ACDF. Clinical results included the Visual Analogue Scale (VAS) score for upper extremity radiculopathy, neck disability index (NDI), duration of hospital stay and convalescence time. All patients were assessed radiologically by measuring cervical lordosis, segmental lordosis and segmental range-of-movement (ROM) of operated and adjacent disc levels.

Results

Mean hospital stay (5.62 vs. 6.26 days, p<0.05) and interval between surgery and return to work (1.10 vs. 2.92 weeks, p<0.05) were significantly shorter in the arthroplasty than in the fusion group. Mean NDI and extremity VAS score improved after 12 months in both groups. Although it was not significant, segmental ROM of adjacent levels was higher in the fusion group than in the arthroplasty group. And, segmental motion of operated levels in arthroplasty group maintained more than preoperative value at last follow up.

Conclusion

Although clinical results were similar in the two groups, postoperative recovery was significantly shorter in the arthroplasty group. Although it was not significant, ROM of adjacent segments was less in the arthroplasty group. Motion of operated levels in arthroplasty group was preserved at last follow up.     

Is it necessary to place screws in the intervening vertebrae in two-level anterior cervical discectomy with fusion and plating?

ObjectiveThe clinical outcomes, radiological parameters, complication rate and the cost of implants in two-level ACDF with and without screws in the intervening segment were compared.MethodsA retrospective study of 68 patients who underwent 2-level ACDF from January 2014 to June 2016 was performed. The patients were divided into two groups: ACDF with screws in the intervening vertebra and those without screws in the intervening vertebra. Perioperative factors, clinical outcomes, postoperative complications, radiological parameters, and cost of the implants were evaluated in both groups.ResultsNo statistical differences in clinical outcomes, operative blood loss, hospital stay, restoration of cervical lordosis or segment height, postoperative complications, and fusion rate were found between the ACDF (middle vertebra with screw) and ACDF (middle vertebra without screw) groups (P > 0.05). But the operative time of added screw placement and cost of implants in the ACDF (middle vertebra without screw) group were significantly less than the ACDF (middle vertebra with screw) group (P < 0.05).ConclusionTwo kinds of screw placement with ACDF were found to be similar in terms of clinical outcomes. However, ACDF (middle vertebra without screw) was found to be superior to ACDF (middle vertebra with screw) in terms of the screw placement time and cost of implants.     

Effect of posterior subsidence on cervical alignment after anterior cervical corpectomy and reconstruction using titanium mesh cages in degenerative cervical disease

Subsidence after anterior cervical reconstruction using a titanium mesh cage (TMC) has been a matter of debate. The authors investigated and analyzed subsidence and its effect on clinical and radiologic parameters after cervical reconstruction using a TMC for degenerative cervical disease. Thirty consecutive patients with degenerative cervical spine disorders underwent anterior cervical corpectomy followed by reconstruction with TMC. Twenty-four patients underwent a single-level corpectomy, and six patients underwent a two-level corpectomy. Clinical outcomes were assessed using a Visual Analogue Scale (VAS), the Japanese Orthopedic Association (JOA) score and the Neck Disability Index (NDI). Fusion status, anterior and posterior subsidence of the TMC, segmental angle (SA) and cervical sagittal angle (CSA) were assessed by lateral and flexion-extension radiographs of the neck. The mean follow-up period was 27.6 months (range, 24 to 49 months). The VAS, NDI and JOA scores were all significantly improved at the last follow-up. No instances of radiolucency or motion-related pseudoarthrosis were detected on radiographic analysis, yielding a fusion rate of 100%. Subsidence occurred in 28 of 30 patients (93.3%). The average anterior subsidence of the cage was 1.4 ± 0.9 mm, and the average posterior subsidence was 2.9 ± 1.2 mm. The SA and CSA at the final follow-up were significantly increased toward a lordotic angle. Anterior cervical reconstruction using TMC and plating in patients with cervical degenerative disease provides good clinical and radiologic outcomes. Cage subsidence occurred frequently, especially at the posterior part of the cage. Despite the prominent posterior subsidence of the TMC, SA and CSA were improved on final follow-up radiographs, suggesting that posterior subsidence may contribute to cervical lordosis.     

Surgical Outcome of Cervical Arthroplasty Using Bryan?

Objective

Recently, motion preservation has come to the forefront of emerging technologies in spine surgery. This is the important background information of the emergence of cervical arthroplasty as an alternative to arthrodesis that offers the promise of restoring normal spinal movement and reduces a kinematic strain on adjacent segments. The study was designed to evaluate early surgical outcome and radiological effects of Bryan® cervical disc prosthesis.

Methods

The authors retrospectively reviewed radiographic and clinical outcomes in 52 patients who received the Bryan® Cervical Disc prosthesis, for whom follow-up data were available. Static and dynamic radiographs were measured by computer to determine the angles formed by the endplates of the natural disc preoperatively, those formed by the shells of the implanted prosthesis, the angle of functional spine unit (FSU), and the C2-7 Cobb angle. The range of motion (ROM) was also determined radiographically, whereas clinical outcomes were assessed using Odom''s criteria, visual analogue pain scale (VAS) and neck disability index (NDI).

Results

A total of 71 Bryan® disc were placed in 52 patients. A single-level procedure was performed in 36 patients, a two-level procedure in 13 patients, and a three-level procedure in 3. Radiographic and clinical assessments were made preoperatively. Mean follow-up duration was 29.2 months, ranging from 6 to 36 months. All of the patients were satisfied with the surgical results by Odom''s criteria, and showed significant improvement by VAS and NDI score (p < 0.05). The postoperative ROM of the implanted level was preserved without significant difference from preoperative ROM of the operated level (p < 0.05). 97% of patients with a preoperative lordotic sagittal orientation of the FSU were able to maintain lordosis. The overall sagittal alignment of the cervical spine was preserved in 88.5% of cases at the final follow up. Interestingly, preoperatively kyphotic FSU resulted in lordotic FSU in 70% of patients during the late follow up, and preoperatively kyphotic overall cervical alignment resulted in lordosis in 66.6% of the patients postoperatively.

Conclusion

Arthroplasty using the Bryan® disc seemed to be safe and provided encouraging clinical and radiologic outcome in our study. Although the early results are promising, this is a relatively new approach, therefore long-term follow up studies are required to prove its efficacy and its ability to prevent adjacent segment disease.     

Clinical and radiologic comparison of dynamic cervical implant arthroplasty versus anterior cervical discectomy and fusion for the treatment of cervical degenerative disc disease

This study compared the clinical and radiological outcomes of dynamic cervical implant (DCI; Scient’x, Villers-Bretonneux, France) arthroplasty versus anterior cervical discectomy and fusion (ACDF) for the treatment of cervical degenerative disc disease. This prospective cohort study enrolled patients with single-level cervical degenerative disc disease who underwent DCI arthroplasty or ACDF between September 2009 and June 2011. Patients were followed up for more than 2 years. Clinical evaluation included the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36), Neck Disability Index (NDI), Japan Orthopedic Association (JOA) score, and visual analog scale (VAS) scores for neck and arm pain. Radiological assessments included segmental range of motion (ROM), overall ROM (C2–C7), disc height (DHI), and changes in adjacent disc spaces. The VAS, SF-36, JOA, and NDI scores improved significantly after surgery in both the DCI and ACDF groups. The VAS, JOA, and SF-36 scores were not significantly different between the DCI and ACDF groups at the final follow-up. The segmental ROM at the treated level and overall ROM increased significantly after surgery in the DCI group, but the ROM in the adjacent cephalad and caudal segments did not change significantly. The mean DHI at the treated level was significantly restored after surgery in both groups. Five patients (12.8%) in the DCI group showed new signs of adjacent segment degeneration. These results indicate that DCI is an effective, reliable, and safe procedure for the treatment of cervical degenerative disc disease. However, there is no definitive evidence that DCI arthroplasty has better intermediate-term results than ACDF.     

The Impact of Menopause on Bone Fusion after the Single-Level Anterior Cervical Discectomy and Fusion

Objective

To evaluate the successful fusion rate in postmenopausal women with single-level anterior cervical discectomy and successful fusion (ACDF) and identify the significant factors related to bone successful fusion in pre- and postmenopausal women.

Methods

From July 2004 to December 2010, 108 consecutive patients who underwent single-level ACDF were prospectively selected as candidates. Among these, the charts and radiological data of 39 women were reviewed retrospectively. These 39 women were divided into two groups : a premenopausal group (n=11) and a postmenopausal group (n=28). To evaluate the significant factors affecting the successful fusion rate, the following were analyzed : the presence of successful fusion, successful fusion type, age, operated level, bone mineral density, graft materials, stand-alone cage or plating with autologous iliac bone, subsidence, adjacent segment degeneration, smoking, diabetes mellitus, and renal disease.

Results

The successful fusion rates of the pre- and postmenopausal groups were 90.9% and 89.2%, respectively. There was no significant difference in the successful fusion rate or successful fusion type between the two groups. In the postmenopausal group, three patients (10.8%) had successful fusion failure. In the postmenopausal group, age and subsidence significantly affected the successful fusion rate (p=0.016 and 0.011, respectively), and the incidence of subsidence in patients with a cage was higher than that in patients with a plate (p=0.030).

Conclusion

Menopausal status did not significantly affect bone successful fusion in patients with single-level ACDF. However, in older women with single-level ACDF, the combination of use of a cage and subsidence may unfavorably affect successful fusion.     

Is Stent-Assisted Coil Embolization for the Treatment of Ruptured Blood Blister-Like Aneurysms of the Supraclinoid Internal Carotid Artery Effective? : An Analysis of Single Institutional Experience with Pooled Data

ObjectiveGiven the high risk of rebleeding and recurrence of blood blister-like aneurysms (BBAs), we treated ruptured BBAs of the internal carotid artery (ICA) with stent-assisted coil embolization (SAC). This study aimed to evaluate the efficacy and safety of SACs. MethodsWe retrospectively reviewed clinical and radiological data from eight patients with ruptured BBAs of the supraclinoid ICA. The modified Rankin Scale (mRS) was used to assess clinical outcomes, while radiological outcomes were evaluated on angiographs. For a pooled analysis, data from literature reporting the outcomes of ruptured BBAs treated with SAC were collected and analyzed in conjunction with our data. ResultsIn our cohort, the mean Raymond classification score was 1.57±0.53 immediately after initial endovascular treatment. There were no perioperative complications or rebleeding events during the follow-up period. The mean mRS score at patient discharge was 1.00±0.81 and improved to 0.28±0.48 by the last follow-up day. The recurrence rate was 25% with an asymptomatic presentation and successful treatment with multiple stent insertion. Pooled analysis of 76 cases of SAC revealed a complete occlusion rate immediately after treatment of 54.8%, rebleeding rate 7.94%, and recurrence rate 24.2%. Good clinical outcomes with mRS score 0–2 were observed in 89.9% by the last clinical follow-up. Total mortality rate was 7.7%. ConclusionThis treatment appears to not only minimize the hemodynamic burden on the fragile dome specific to this type of aneurysm, but also provides an opportunity for safe and effective treatment in recurrent cases.     

Comparison between Anterior Cervical Decompression with Fusion and Posterior Cervical Fusion with Wide Facetectomy for Treatment of Severe Bony Foraminal Stenosis

ObjectiveTo compare the anterior cervical discectomy and fusion (ACDF) and posterior cervical fusion (PCF) with wide facetectomy in the treatment of parallel-shaped bony foraminal stenosis (FS). MethodsThirty-six patients underwent surgery due to one-or-two levels of parallel-shaped cervical FS. ACDF was performed in 16 patients, and PCF using CPS was performed in 20 patients. All patients were followed up at 1, 3, 6, and 12 months postoperatively. Standardized outcome measures such as Numeric rating scale (NRS) score for arm/neck pain and Neck disability index (NDI) were evaluated. Cervical radiographs were used to compare the C2–7 Cobb’s angle, segmental angle, and fusion rates. ResultsThere was an improvement in NRS scores after both approaches for radicular arm pain (mean change -6.78 vs. -8.14, p=0.012), neck pain (mean change -1.67 vs. -4.36, p=0.038), and NDI score (-19.69 vs. -18.15, p=0.794). The segmental angle improvement was greater in the ACDF group than in the posterior group (9.4°±2.7° vs. 3.3°±5.1°, p=0.004). However, there was no significant difference in C2–7 Cobb angle between groups (16.2°±7.9° vs. 14.8°±8.5°, p=0.142). As a complication, dysphagia was observed in one case of the ACDF group. ConclusionIn the treatment of parallel-shaped bony FS up to two surgical levels, segmental angle improvement was more favorable in patients who underwent ACDF. However, PCF with wide facetectomy using CPS should be considered as an alternative treatment option in cases where the anterior approach is burdensome.     

The Relationship between Increased Intervertebral Disc Height and Development of Postoperative Axial Neck Pain after Anterior Cervical Fusion

Objective

To evaluate the relationship between postoperative increase in intervertebral disc space height (IVH) and posterior axial neck in cases of degenerative cervical disease treated with anterior cervical discectomy and fusion (ACDF).

Methods

A total of 155 patients who underwent ACDF with more than 1 year follow up were included. Radiologically, IVH and interfacet distance (IFD) of the operated segment were measured preoperatively and postoperatively. We clinically evaluated neck and arm pains according to visual analogue scale (VAS) scores and assessed neck disability index (NDI) scores preoperatively, postoperatively, at 3 months, 6 months, and 1 year postoperatively. The relationship between radiological parameters, and clinical scores were analyzed using a regression analysis.

Results

The mean increase in IVH was 2.62 mm, and the mean increase in IFD was 0.67 mm. The VAS scores for neck pain preoperatively, postoperatively, and at 3 months, 6 months, 1 year postoperatively were 4.46, 2.11, 2.07, 1.95, and 1.29; those for arm pain were 5.89, 3.24, 3.20, 3.03, and 2.18. The NDI scores were improved from 18.52 to 7.47. No significant relationship was observed between the radiological evaluation results regarding the increase in intervertebral height or interfacet distance and clinical changes in VAS or NDI scores.

Conclusion

The increase in intervertebral space or interfacet distance by the insertion of a large graft material while performing ACDF for the treatment of degenerative cervical disease was not related with the change in VAS scores for neck and arm pains and NDI scores postoperatively and during the follow-up period.     

Radiologic Assessment of Subsidence in Stand-Alone Cervical Polyetheretherketone (PEEK) Cage

Objective

Aim of study was to find a proper method for assessing subsidence using a radiologic measurement following anterior cervical discectomy and fusion (ACDF) with stand-alone polyetheretherketone (PEEK), Solis™ cage.

Methods

Forty-two patients who underwent ACDF with Solis™ cage were selected. With a minimum follow-up of 6 months, the retrospective investigation was conducted for 37 levels in 32 patients. Mean follow-up period was 18.9 months. Total intervertebral height (TIH) of two fused vertebral bodies was measured on digital radiographs with built-in software. Degree of subsidence (ΔTIH) was reflected by the difference between the immediate postoperative and follow-up TIH. Change of postoperative disc space height (CT-MRΔTIH) was reflected by the difference between TIH of the preoperative mid-sagittal 2D CT and that of the preoperative mid-sagittal T1-weighted MRI.

Results

Compared to preoperative findings, postoperative disc height was increased in all cases and subsidence was observed only in 3 cases. For comparison of subsidence and non-subsidence group, TIH and CT-MRΔTIH of each group were analyzed. There was no statistically significant difference in TIH and CT-MRΔTIH between each group at 4 and 8 weeks, but a difference was observed at the last follow-up TIH (p=0.0497).

Conclusion

ACDF with Solis™ cage was associated with relatively good radiologic long-term results. Fusion was achieved in 94.5% and subsidence occurred in 8.1% by the radiologic assessment. Statistical analysis reveals that the subsidence seen later than 8 weeks after surgery and the development of subsidence does not correlate statistically with the change of the postoperative disc space height.     

Comparison of allograft and polyetheretherketone (PEEK) cage subsidence rates in anterior cervical discectomy and fusion (ACDF)

Structural allografts and PEEK cages are commonly used interbody fusion devices in ACDF. The subsidence rates of these two spacers have not yet been directly compared. The primary aim of this study was to compare the subsidence rate of allograft and PEEK cage in ACDF. The secondary aim was to determine if the presence of subsidence affects the clinical outcome. We reviewed 67 cases (117 levels) of ACDF with either structural allograft or PEEK cages. There were 85 levels (48 cases) with PEEK and 32 levels (19 cases) with allograft spacers. Anterior and posterior disc heights at each operative level were measured at immediate and 6 months post-op. Subsidence was defined as a decrease in anterior or posterior disc heights >2 mm. NDI of the subsidence (SG) and non-subsidence group (NSG) were recorded. Chi-square test was used to analyze subsidence rates. T-test was used to analyze clinical outcomes (α = 0.05). There was no statistically significant difference between subsidence rates of the PEEK (29%; 25/85) and allograft group (28%; 9/32) (p = 0.69). Overall mean subsidence was 2.3 ± 1.7 mm anteriorly and 2.6 ± 1.2 mm posteriorly. Mean NDI improvement was 11.7 (from 47.1 to 35.4; average follow-up: 12 mos) for the SG and 14.0 (from 45.8 to 31.8; average follow-up: 13 mos) for the NSG (p = 0.74). Subsidence rate does not seem to be affected by the use of either PEEK or allograft as spacers in ACDF. Furthermore, subsidence alone does not seem to be predictive of clinical outcomes of ACDF.     

Is instrumented lateral lumbar interbody fusion superior to stand-alone lateral lumbar interbody fusion for the treatment of lumbar degenerative disease? A meta-analysis

The purpose of this meta-analysis was to compare the fusion rate and outcomes directly between patients who underwent stand-alone lateral lumbar interbody fusion (LLIF) and LLIF with supplemental posterior instrumentation. A comprehensive literature search was performed for relevant studies using PubMed, EMBASE, Web of Science, and Cochrane Library. The stand-alone and instrumented LLIF were compared by the fusion rate, the radiographic parameters, the cage subsidence rate, the clinical outcomes, the complication rate, and the reoperation rate. A total of 13 studies comprising 1090 patients with lumbar degenerative disease (LDD) were included. There was no significant statistical difference in the complication rate, and there was no significant clinical difference in the improvement of clinical outcomes at the last follow-up between patients who underwent stand-alone and instrumented LLIF. Nevertheless, lower fusion rate (RR, 0.92; 95% CI 0.87 to 0.98, P = 0.006), inferior restoration of disk height (WMD, −0.68; 95% CI −1.04 to −0.32, P < 0.001) and segmental lordosis (WMD, −1.28; 95% CI −2.30 to −0.27, P = 0.013), higher cage subsidence rate (RR, 1.68; 95% CI 1.36 to 2.07, P < 0.001), and higher reoperation rate (RR, 2.12; 95% CI 1.02 to 4.43, P = 0.045) were observed in the stand-alone group. Both stand-alone and instrumented LLIF were effective in improving the clinical outcomes of patients with LDD. However, the stand-alone LLIF was associated with lower fusion rate, inferior maintenance of indirect decompression, and higher reoperation rate due to high-grade cage subsidence. For patients with risk factors of high-grade cage subsidence, the LLIF with posterior instrumentation may be the better choice.     

Anterior Cervical Discectomy and Fusion Using a Stand-Alone Polyetheretherketone Cage Packed with Local Autobone : Assessment of Bone Fusion and Subsidence

Objective

It remains debatable whether cervical spine fusion cages should be filled with any kind of bone or bone substitute. Cortical and subcortical bone from the anterior and posterior osteophytes of the segment could be used to fill the cage. The purposes of the present study are to evaluate the clinical outcomes and radiological outcomes including bone fusion and subsidence that occurred after anterior cervical discectomy and fusion using a stand-alone cage packed with local autobone graft.

Methods

Thirty-one patients who underwent anterior cervical fusion using a stand-alone polyetheretherketone (PEEK) cage packed with local autobone graft from July 2009 to december 2011 were enrolled in this study. Bone fusion was assessed by cervical plain radiographs and computed tomographic scan. Nonunion was evaluated according to the absence of bony bridge on computed tomographic scan. Subsidence was defined as a ≥2 mm decrease of the interbody height at the final follow-up compared to that measured at the immediate postoperative period.

Results

Subsidence was observed in 7 patients (22.6%). Of 7 patients with subsidence greater 2 mm, nonunion was developed in 3. Three patients with subsidence greater 2 mm were related with endplate damage during intraoperative endplate preparation. Solid bone fusion was achieved in 28 out of 31 patients (90.3%).

Conclusion

With proper patient selection and careful endplate preparation, anterior cervical discectomy and fusion (ACDF) using a stand-alone PEEK cage packed with local autobone graft could be a good alternative to the standard ACDF techniques with plating.     

Use of an empty, Plasmapore-covered titanium cage for interbody fusion after anterior cervical microdiscectomy.

The use of cages of different material and shapes for cervical discectomy with fusion (ACDF) has increased during the last few years. The use of additional osteogenic material is controversial. We prospectively evaluated an empty, Plasmapore-covered titanium cage (PCTC) in 45 patients undergoing 58 ACDFs. Patients were evaluated using standard clinical and radiological criteria. Good to excellent outcome was achieved in 93%, 78% and 75% after 3, 12 and 48 months, respectively. Sixty-five percent of patients could resume their prior work after 48 months. Disc space height and lordosis could be preserved in all cases. Two percent of the treated levels showed subsidence and 2% increased segmental motion. There were no procedure-related complications. Implantation of an empty PCTC after microsurgical anterior cervical discectomy is a safe procedure with good results and low incidence of complications. Disc height and lordosis can be preserved with low incidence of subsidence and good fusion rates.