Adjacent Segment Pathology after Anterior Cervical Fusion

Biomechanical analysis of the door-shaped titanium plate in single-level anterior cervical discectomy and fusion

BACKGROUND

Analyse and discuss the immediate stability of the cervical spine after anterior cervical discectomy and fusion using a door-shaped titanium plate and compare it with the traditional titanium plate, to provide biomechanical evidence for the rationality and effectiveness of the door-shaped titanium plate in clinical applications.

METHODS

Ten adult goat C4/5 vertebral bodies were obtained, and models were prepared using denture base resin. Biomechanical experiments were performed on the specimens before internal fixation. MTS was used to conduct non-destructive biomechanical loading tests in six directions, including flexion, extension, left-right bending, and left-right torsion, recording the range of motion (ROM) and neutral zone (NZ) of each specimen. The specimens were then randomly divided into two groups: the study group was fixed with a door-shaped titanium plate, and the control group was fixed with a traditional titanium plate. ROM and NZ in each direction were measured again. After measurements, both groups were subjected to 0.5 Hz torsion loading with a torque of 2 N m for a total of 3000 cycles, followed by measuring ROM and NZ in six directions once more.

RESULTS

Compared to before fixation, ROM and NZ in both groups significantly decreased in all six directions after fixation, with statistical significance (P < 0.05); after fixation, the study group showed slightly lower values for various mechanical reference parameters compared to the control group, with no statistical significance (P > 0.05); after 3000 torsional loads, both internal fixation groups showed increased ROM and NZ compared to after fixation but to a lower extent, and no screw or titanium plate loosening was observed. Compared to before fixation, the differences were still statistically significant (P < 0.05), with the study group having slightly lower ROM and NZ values in all directions compared to the control group, with no statistical significance (P > 0.05).

CONCLUSION

The door-shaped titanium plate exhibits mechanical properties similar to the traditional titanium plate in all directions, and its smaller size and simpler surgical operation can be used for anterior cervical endoscopic surgery, reducing surgical trauma. It is clinically feasible and deserves further research and promotion.

The impact of over-distraction on adjacent segment pathology and cage subsidence in anterior cervical discectomy and fusion

Over-distraction has been shown to be a risk factor for cage subsidence and postoperative neck pain after anterior cervical discectomy and fusion (ACDF). Biomechanical studies have demonstrated increased adjacent segment intradiscal pressure after ACDF. The purpose of this study is to determine if over-distraction of the index disc has an effect on adjacent segment pathology. A consecutive series of 145 patients who received primary ACDF for cervical degenerative pathologies from January 2010 to December 2017 were retrospectively reviewed. The patients were divided into: (1) Over-distraction group (postoperative-preoperative index disc height ≥ 2 mm), and (2) No-distraction group (postoperative-preoperative index disc height < 2 mm). Outcome measures included radiographic parameters, Japanese Orthopaedic Association (JOA) score, and incidences of cage subsidence, radiological and clinical adjacent segment pathologies (RASP and CASP) were compared between the two groups preoperatively, postoperatively, and at the final follow-up. The two groups were comparable with respect to age, follow-up length, JOA score, incidence of CASP, and radiographic parameters. The Over-distraction group (83 patients; 115 levels) had smaller preoperative index disc height (4.5 vs. 5.2 mm, p < 0.001), but taller postoperative index disc height (7.7 vs. 6.6 mm, p < 0.001) than No-distraction group (62 patients; 90 levels) Furthermore, significantly higher incidences of cage subsidence (47% vs. 31%, p = 0.04) and RASP (any progression: 48% vs. 15%, p < 0.001; progress ≥ 2 grades: 25% vs. 7%, p = 0.001) were observed in the Over-distraction group. The multivariate analysis indicated that over-distraction and multilevel fusion were independent risk factors for RASP. There were no clinical outcome differences between the Over-distraction group and the No-distraction group in ACDF. Over-distraction of the index level of ≥ 2 mm should be avoided because it significantly increases the incidences of RASP and cage subsidence.

Brown Sequard syndrome in a patient with Klippel-Feil syndrome following minor trauma: a case report and literature review

BACKGROUND

There are some cases of Klippel-Feil syndrome with spinal cord injury in clinical work. However, there is no literature report on Brown-Sequard syndrome after trauma. We report a case of Brown-Sequard syndrome following minor trauma in a patient with KFS type III. Her Brown-Sequard syndrome is caused by Klippel-Feil syndrome.

CASE PRESENTATION

We found a 38-year-old female patient with KFS in our clinical work. She was unconscious on the spot following a minor traumatic episode. After treatment, her whole body was numb and limb activity was limited. Half an hour later, she felt numb and weak in the right limb and weak in the left limb. She had no previous hypertension, diabetes, or coronary heart disease. After one-month treatment of medication, hyperbaric oxygen, rehabilitation, and acupuncture in our hospital, her muscle strength partially recovered, but the treatment effect was still not satisfactory. Then, she underwent surgical treatment and postoperative comprehensive treatment, and rehabilitation training. She was able to take care of herself with assistance, and her condition improved from grade B to grade D according to the ASIA (ASIA Impairment Scale) classification.

CONCLUSION

KFS, also known as short neck deformity, is a kind of congenital deformity characterized by impaired formation and faulty segmentation of the cervical spine, often associated with abnormalities of other organs. The cervical deformity in patients with KFS can alter the overall mechanical activity of the spine, as well as the compensatory properties of the spine for decelerating and rotatory forces, thus increasing the chance of spinal cord injury (SCI) following trauma. Many mechanisms can make patients more susceptible to injury. Increased range of motion of the segment adjacent to the fused vertebral body may lead to slippage of the adjacent vertebral body and altered disc stress, as well as cervical instability. SCI can result in complete or incomplete impairment of motor, sensory and autonomic nervous functions below the level of lesion. This woman presented with symptoms of BSS, a rare neurological disorder with incomplete SCI. Judging from the woman's symptoms, we concluded that previously she had KFS, which resulted in SCI without fracture and dislocation following minor trauma, with partial BSS. After the comprehensive treatment of surgery, hyperbaric oxygen, rehabilitation therapy, and neurotrophic drugs, two years later, we found her symptoms significantly improved, with ASIA Impairment Scale from grade B to grade D, and her ability to perform activities of daily living with aids.

Adjacent Segment Disease After Spinal Fusion

» Adjacent segment disease is characterized by a degenerative process adjacent to a previously fused spine segment, with new onset of clinical symptoms such as radiculopathy, myelopathy, or instability.» Etiology is related to the natural history of the disease process, increased biomechanical stress at adjacent segments, clinical factors specific to the individual patient, intraoperative factors, and malalignment.» Treatment is usually nonoperative, but surgical intervention can be indicated. Decompression and fusion remain the mainstay of operative treatment, and isolated decompression should be considered in specific cases.» Further randomized controlled trials are needed to establish how the treatment should progress, particularly with the development of minimally invasive and endoscopic surgery.

Risk Factors for Adjacent Segment Disease Following Anterior Cervical Discectomy and Fusion with Plate Fixation: A Systematic Review and Meta-Analysis

BACKGROUND

Adjacent segment disease (ASD) following anterior cervical discectomy and fusion with plating (ACDF-P) may yield a poor prognosis or reoperation. This review aimed to summarize risk factors for radiographic ASD (RASD) and clinical ASD (CASD) after ACDF-P.

METHODS

Six electronic databases were searched from inception to October 30, 2021. Four reviewers independently screened titles, abstracts, and full-text articles to identify relevant studies. Methodological quality of the included studies was evaluated. Meta-analyses for risk factors were conducted, if possible.

RESULTS

Sixteen cohort and 3 case-control studies (3,563 participants) were included. These studies showed low (n = 2), moderate (n = 9), and high (n = 8) risk of bias. One risk factor for RASD was pooled for 2 meta-analyses based on the follow-up period. Four different risk factors for CASD at ≥4 years were pooled for meta-analyses. Limited evidence showed that multi-level fusion, greater asymmetry in total or functional cross-sectional area of the cervical paraspinal muscle, and preoperative degeneration in a greater number of segments were associated with a higher RASD incidence <4 years after ACDF-P. In contrast, no significant risk factors were identified for CASD <4 years after ACDF-P. At ≥4 years after ACDF-P, limited evidence supported that both cephalad and caudal plate-to-disc distances of <5 mm were associated with a higher RASD incidence, and very limited evidence supported that developmental canal stenosis, preoperative RASD, unfused C5-C6 or C6-C7 adjacent segments, use of autogenous bone graft, and spondylosis-related ACDF-P were associated with a higher CASD incidence.

CONCLUSIONS

Although several risk factors for RASD and CASD development after ACDF-P were identified, the supporting evidence was very limited to limited. Future prospective studies should extend the existing knowledge by more robustly identifying risk factors for RASD and CASD after ACDF-P to inform clinical practice.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

In Vitro Biomechanics of Human Cadaveric Cervical Spines With Mature Fusion

BACKGROUND

This study sought to compare index and adjacent-level biomechanics of cadaveric specimens with mature fusion versus normal spines in intact and acutely fused conditions.

METHODS

Eight human cadaveric cervical spines with mature fusion across 1 to 3 levels were studied. Intervertebral angular range of motion (ROM) was determined at fused and adjacent levels during pure moments inducing flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Mature fusion data were compared to data from normal spine specimens tested intact and then with a 1-level anterior plate/graft (fresh fixation). Bone qualities were compared using dual-energy x-ray absorptiometry.

RESULTS

Mean bone mineral density was significantly greater in mature fusion spines (0.632 ± 0.239 g/cm²) than in normal spines (0.489 ± 0.195 g/cm²) (P < .001). Mean ROM for levels with mature fusion was 42% (FE), 42% (LB), and 29% (AR) of the mean same-level ROM in freshly fixated specimens (P ≤ .045). The mean adjacent-level ROM in spines with mature fusion was less than in normal spines (matched levels) in all directions, with the greatest difference 1 level below fusion (FE: -38%, P < .001; LB: -42%, P < .001; AR: -49%, P = .001), followed by 1 level above fusion (FE: -23%, P = .04; LB: -22%, P = .07; AR: -28%, P = .02) and 2 levels above fusion (FE: -20%, P = .08; LB: -18%, P = .11; AR: -31%, P = .009). Mature fusion reduced the magnitude of coupled LB during AR at C6-7 and C7-T1 (P ≤ .03).

CONCLUSION

Cervical spine segments with mature fusion have higher bone mass, are less flexible than freshly fixed spines, and have reduced mobility at adjacent levels.

Differences in the Prevalence of Clinical Adjacent Segment Pathology among Continents after Anterior Cervical Fusion: Meta-Analysis of Randomized Controlled Trials

Development of adjacent segment pathology leading to secondary operation is a matter of concern after anterior cervical discectomy and fusion (ACDF). Some studies have reported anatomic difference between races, but no epidemiological data on prevalence of clinical adjacent segment pathology (cASP) among races or continents has been published. The purpose of this study was to compare the prevalence of cASP that underwent surgery after monosegmental ACDF among continents by meta-analysis. MEDLINE, EMBASE, and Cochrane Library with manual searching in key journals, reference lists, and the National Technical Information Service were searched from inception to December 2018. Twenty studies with a total of 2009 patients were included in the meta-analysis. We extracted the publication details, sample size, and prevalence of cASP that underwent surgery. A total of 15 papers from North America, three from Europe, and two from Asia met the inclusion criteria. A total number of 2009 patients underwent monosegmental ACDF, and 113 patients (5.62%) among them had cASP that underwent surgery. The rate of cASP that underwent surgery was 4.99% in the North America, 3.65% in the Europe, 6.34% in the Asia, and there were no statistically significant differences (p = 0.63). The current study using the method of meta-analysis revealed that there were no significant differences in the rate of cASP that underwent surgery after ACDF among the continents.

The aiming device for cervical distractor pin insertion: a proof-of-concept, feasibility study

Background

Restoration of cervical lordosis after anterior discectomy and fusion is a desirable goal. Proper insertion of the vertebral distraction or Caspar pin can assist lordotic restoration by either putting the tips divergently or parallel to the index vertebral endplates. With inexperienced surgeons, the traditional free-hand technique for Caspar pin insertion may require multiple insertion attempts that may compromise the vertebral body and increase radiation exposure during pin localization. Our purpose is to perform a proof-of-concept, feasibility study to evaluate the effectiveness of a pin insertion aiming device for vertebral distraction pin insertion.

Methods

A Smith-Robinson approach and anterior cervical discectomy were performed from C3 to C7 in 10 human cadaveric specimens. Caspar pins were inserted using a novel pin insertion aiming device at C3-4, C4-5, C5-6, and C6-7. The angles between the cervical endplate slope and Caspar pin alignment were measured with lateral cervical imaging.

Results

The average Superior Endplate-to-Caspar Pin angle (SE-CP) and the average Inferior Endplate-to-Caspar Pin angle (IE-CP) were 6.2 ± 2.0° and 6.3 ± 2.2° respectively. For the proximal pins, the SE-CP and the IE-CP were 4.0 ± 1.1°and 5.2 ± 2.4° respectively. For the distal pins, the SE-CP and the IE-CP were 7.7 ± 1.4° and 6.2 ± 2.0° respectively. No cervical endplate violations occurred.

Conclusion

The novel Caspar pin insertion aiming device can control the pin entry points and pin direction with the average SE-CP and average IE-CP of 6.2 ± 2.0° and 6.3 ± 2.2°, respectively. The study shows that the average different angles between the Caspar pin and cervical endplate are less than 7°.

Short Plate with Screw Angle over 20 Degrees Improves the Radiologic Outcome in ACDF: Clinical Study

BACKGROUND

Anterior cervical discectomy and fusion surgery is a common procedure for degenerative cervical spine. This describes allospacer and implant-related outcomes, comparing medium plate-low screw angle and short plate-high screw angle techniques.

METHODS

From January 2016 to June 2019, 79 patients who underwent ACDF were prospectively enrolled. Patients were divided, depending on the plate-screw system used: medium plate-low screw angle (12.3 ± 2.5 to 13.2 ± 3.2 degrees), and short plate-high screw angle (22.8 ± 5.3 to 23.3 ± 4.7 degrees). Subsidence, ALOD, and sagittal cervical balance were analyzed using lateral cervical X-rays. NDI and VAS scores were also evaluated.

RESULTS

Age for medium plate-low-angled screw group is 58.0 ± 11.3 years, and 55.3 ± 12.0 in the short plate-high-angled screw group (p-value = 0.313). Groups were comparable in mean NDI (p-value = 0.347), VAS (p-value = 0.156), C2-C7 SVA, (p-value = 0.981), and lordosis angle (p-value = 0.836) at 1-year post-surgery. Subsidence was higher in the medium plate-low-angled screw than in the short plate-high-angled screw (25% and 8.5%, respectively, p-value = 0.045). ALOD is also more common in the medium plate group (p-value = 0.045).

CONCLUSION

Use of a short plate and insertion of high-angled screws (more than 20 degrees) has less chance of subsidence and occurrence of ALOD than the traditional technique of using medium plate and low angle.

A biomechanical analysis of four anterior cervical techniques to treating multilevel cervical spondylotic myelopathy: a finite element study

BACKGROUND

The decision to treat multilevel cervical spondylotic myelopathy (MCSM) remains controversial. The purpose of this study is to compare the biomechanical characteristics of the intervertebral discs at the adjacent segments and internal fixation, and to provide scientific experimental evidence for surgical treatment of MCSM.

METHODS

An intact C2-C7 cervical spine model was developed and validated. Four additional models were developed from the fusion model, including multilevel anterior cervical discectomy and fusion (mACDF), anterior cervical corpectomy and fusion (ACCF), hybrid decompression and fusion (HDF), and mACDF with cage alone (mACDF-CA). Biomechanical characteristics on the plate and the disc of adjacent levels (C2/3, C6/7) were comparatively analyzed.

RESULTS

Of the four models, stress on the upper (C2/3) adjacent intervertebral disc was the lowest in the mACDF-CA group and highest in the ACCF group. Stress on the intervertebral discs at adjacent segments was higher for the upper C2/3 than the lower C6/7 intervertebral disc. In all models, the mACDF-CA group had the lowest stress on the intervertebral disc, while the ACCF group had the highest stress. In the three surgical models with titanium plate fixation (mACDF, ACCF, and HDF), the ACCF group had the highest stress at the titanium plate-screw interface, while the mACDF group had the lowest stress.

CONCLUSION

Among the four anterior cervical reconstructive techniques for MCSM, mACDF-CA makes little effect on the adjacent disc stress, which might reduce the incidence of adjacent segment degeneration (ASD) after fusion. However, the accompanying risk of the increased incidence of cage subsidence should never be neglected.

Comparative evaluation of posterior percutaneous endoscopy cervical discectomy using a 3.7 mm endoscope and a 6.9 mm endoscope for cervical disc herniation: a retrospective comparative cohort study

Background

Posterior percutaneous endoscopy cervical discectomy (p-PECD) is an effective strategy for the treatment of cervical diseases, with a working cannula ranging from 3.7 mm to 6.9 mm in diameter. However, to date, no studies have been performed to compare the clinical outcomes of the use of endoscopes with different diameters in cervical disc herniation (CDH) patients. The purpose of this study was to compare the clinical outcomes of patients with unilateral CDH treated with p-PECD using a 3.7 mm endoscope and a 6.9 mm endoscope.

Methods

From January 2016 to June 2018, a total of 28 consecutive patients with single-level CDH who received p-PECD using either the 3.7 mm or the 6.9 mm endoscope were enrolled. The clinical results, including the surgical duration, hospitalization, visual analog scale (VAS) score and modified MacNab criteria, were evaluated. Cervical fluoroscopy, CT, and MRI were also performed during follow-up.

Results

Tthere was a significant difference in regard to the average identification time of the “V” point (18.608 ± 3.7607 min vs. 11.256 ± 2.7161 min, p < 0.001) and the mean removal time of the overlying tissue (16.650 ± 4.1730 min vs. 12.712 ± 3.3079 min, p < 0.05) for the use of the 3.7 mm endoscope and the 6.9 mm endoscope, respectively. The postoperative VAS and MacNab scores of the two endoscopes were significantly improved compared with those the preoperative scores (p < 0.05).

Conclusion

The application of both the 3.7 mm endoscope and 6.9 mm endoscope represent an effective method for the treatment of CDH in selected patients, and no significant difference can be observed in the clinical outcomes of the endoscopes. The 6.9 mm endoscope shows superiority to the 3.7 mm endoscope in terms of the efficiency of “V” point identification, the removal of overlying soft tissue and the prevention of spinal cord injury. However, the 6.9 mm endoscope may be inferior to the 3.7 mm endoscope in regards to anterior foraminal decompression due to its large diameter; this result needs to be further evaluated with the support of a large number of randomized controlled trials.

Keyhole Foraminotomy via a Percutaneous Posterior Full-endoscopic Approach for Cervical Radiculopathy: An Advanced Procedure and Clinical Study

Endoscopic cervical foraminotomy is increasingly used for cervical spondylotic radiculopathy (CSR), but there is great concern about radiation exposure because of the heavy dependence of this surgical method on fluoroscopy. The objective of this study was to introduce in detail an advanced surgical technique of keyhole foraminotomy via a percutaneous posterior full-endoscopic approach as a treatment for CSR and investigate its clinical outcomes. We retrospectively reviewed 33 consecutive patients with CSR who underwent keyhole foraminotomy via a percutaneous posterior full-endoscopic approach from October 2015 to April 2017. The patients' general characteristics, including operative time, blood loss, hospital stay, complications, and recurrence, were obtained. Clinical outcomes were evaluated using the visual analogue scale (VAS) for radicular pain, the neck disability index (NDI) for functional assessment, and the modified MacNab criteria for patient satisfaction. All operations were successfully performed (mean operation time, 62 min), with no measurable blood loss or severe related complications. The mean follow-up was 25 months. The VAS and NDI scores were significantly improved as compared with those in the preoperative period (preoperative vs. final follow-up: 7.6±1.6 vs. 3.83±7.34 for VAS, P<0.01; 69.5%±10.5% vs. 17.54%±13.40% for NDI, P<0.01). Of the 33 patients, 32 (97.0%) had good-to-excellent global outcomes and all patients obtained symptomatic improvement. In conclusion, keyhole foraminotomy via a percutaneous posterior full-endoscopic approach is an efficient, safe, and feasible procedure for the treatment of CSR. Its simplified single-step blunt incision for localization appears to decrease radiation exposure risks.

Adjacent Level Ossification Development Following Anterior Cervical Fusion: How Does it Affect the Next Level Disc?

STUDY DESIGN

Retrospective matched cohort analysis.

OBJECTIVE

The aim of this study was to investigate the impact of adjacent level ossification development (ALOD) on the affected as well as the next-level discs with regards to range of motion (ROM) and degenerative changes.

SUMMARY OF BACKGROUND DATA

Although ALOD is not a rare condition in patients who undergo anterior cervical fusion procedures, there has been little discussion to date about its clinical implications.

METHODS

Patients who underwent anterior cervical instrumented fusion with a minimum 2-year follow-up were reviewed. Twelve patients with each respective ossification grade (totally 48 patients) were matched based on age, sex, and number of fusion levels. On the preoperative and final follow-up x-rays, disc height, osteophytes, ROM, and maximal listhesis were assessed at the segments which were one- (the adjacent segment) and two-level cranial (the next segment) to the uppermost fused disc. Then, the patients were divided into two groups according to ALOD degree: group 1 (grade 0-1, N = 24) versus group 2 (grade 2-3, N = 24). The changes of all variables were compared between the two groups.

RESULTS

The mean ROM of the adjacent segment increased by 3.6 degree in group 1 and conversely decreased by 2.8 degree in group 2 (P = 0.002). The mean ROM increase of the next segment was significantly greater in group 2 than in group 1 (4.5 vs. 1.2 degree, P = 0.016). The osteophyte growth and the progression of listhesis at the next segment were significantly greater in group 2 (P < 0.05). Disc height of the next segment significantly decreased in group 2, but did not change in group 1.

CONCLUSION

Severe ALOD (grade 2-3) following anterior cervical fusion significantly reduced ROM at the affected segment and conversely increased motion at the next segment. This increased motion probably accelerated the degeneration of the next-level disc.

LEVEL OF EVIDENCE

3.

Percutaneous posterior full-endoscopic cervical foraminotomy and discectomy: a finite element analysis and radiological assessment

Percutaneous posterior full-endoscopic cervical foraminotomy and discectomy (PECFD) is recognized as a safe, effective, and minimally invasive treatment for cervical spondylotic radiculopathy (CSR). However, the potential mechanisms of the degenerative changes and postoperative recurrence after PECFD are unclear. In this study, a finite element (FE) analysis and radiological assessment were performed to evaluate the biomechanical effects after PECFD. The FE model indicated that the ROM and IDP of C5-C6 increased significantly after PECFD in the extension loading. The radiological evaluation revealed that the extension ROM of C2-C7 and the operative level increased significantly at the one-year follow-up compared with that obtained preoperatively. Combining the FE results and radiological changes, we conclude that the increase in the ROM and IDP at the operative level in the extension loading is the potential cause of the degenerative changes and recurrences after PECFD surgery.

Adjacent-level biomechanics after single-level anterior cervical interbody fusion with anchored zero-profile spacer versus cage-plate construct: a finite element study

BACKGROUND

The development of adjacent segment degeneration (ASD) following ACDF is well established. There is no analytical study related to effects of plate profile on the biomechanics of the adjacent-level after ACDF. This study aimed to test the effects of plate profile on the adjacent-level biomechanics after single-level anterior cervical discectomy and fusion (ACDF).

METHODS

A three-dimensional finite element model (FEM) of an intact C2-T1 segment was built and validated. From this intact model, two instrumentation models were constructed with the anchored zero-profile spacer or the standard plate-interbody spacer after a C5-C6 corpectomy and fusion. Motion patterns, the stresses in the disc, the endplate, and the facet joint at the levels cephalad and caudal to the fusion were assessed.

RESULTS

Compared with the normal condition, the biomechanical responses in the adjacent levels were increased after fusion. Relative to the intact model, the average increase of range of motion (ROM) and stresses in the endplate, the disc, and the facet of the zero-profile spacer fusion model were slightly lower than that of the standard plate-interbody spacer fusion model. The kinematics ROM and stress variations above fusion segment were larger than that below. The biomechanical features of the adjacent segment after fusion were most affected during extension.

CONCLUSIONS

The FE analysis indicated that plate profile may have an impact on the biomechanics of the adjacent-level after a single-level ACDF. The impact may be long-term and cumulative. The current findings may help explain the decreasing incidence of ASD complications in the patients using zero-profile spacer compared with the patients using cage and plate construct.

A Biomechanical Evaluation of a Next-Generation Integrated and Modular ACDF Device Possessing Full-Plate, Half-Plate, and No-Profile Fixation Iterations

STUDY DESIGN

In vitro biomechanical study.

OBJECTIVES

The objective of this in vitro biomechanical range-of-motion (ROM) study was to evaluate spinal segmental stability following fixation with a novel anterior cervical discectomy and fusion (ACDF) device ("novel device") that possesses integrated and modular no-profile, half-plate, and full-plate fixation capabilities.

METHODS

Human cadaveric (n = 18, C3-T1) specimens were divided into 3 groups (n = 6/group). Each group would receive one novel device iteration. Specimen terminal ends were potted. Each specimen was first tested in an intact state, followed by anterior discectomy (C5/C6) and iterative instrumentation. Testing order: (1) novel device (group 1, no-profile; group 2, half-plate; group 3, full-plate); (2) novel device (all groups) with lateral mass screws (LMS); (3) traditional ACDF plate + cage; (4) traditional ACDF plate + cage + LMS. A 2 N·m moment was applied in flexion/extension (FE), lateral bending (LB), and axial rotation (AR) via a kinematic testing machine. Segmental ROM was tracked and normalized to intact conditions. Comparative statistical analyses were performed.

RESULTS

Key findings: (1) the novel half- and full-plate constructs provided comparable reduction in FE and LB ROM to that of traditional plated ACDF (P ≥ .05); (2) the novel full-plate construct significantly exceeded all other anterior-only constructs (P ≤ .05) in AR ROM reduction; and (3) the novel half-plate construct significantly exceeded the no-profile construct in FE (P < .05).

CONCLUSIONS

The novel ACDF device may be a versatile alternative to traditional no-profile and independent plating techniques, as it provides comparable ROM reduction in all principle motion directions, across all device iterations.

Clinical Outcomes of Treating Cervical Adjacent Segment Disease by Anterior Cervical Discectomy and Fusion Versus Total Disc Replacement: A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVE

To compare clinical outcomes of all available adjacent segment disease (ASD) cohorts being treated by either anterior cervical discectomy and fusion (ACDF) or total disc replacement (TDR).

METHODS

We followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines for systematic reviews. Searches of electronic databases from inception to August 2017 identified 349 articles for screening. Data was extracted and analyzed using meta-analysis of proportions.

RESULTS

The search identified 1 double-armed study and 8 single-armed studies from which data of 5 TDR and 5 ACDF cohorts treating ASD were extracted. Between the 2 pooled TDR (n = 103) and ACDF (n = 258) groups, baseline characteristics were predominantly similar. Compared with ACDF, TDR demonstrated superior operation duration (107 vs 188 minutes, P = .011) and range of motion of C2-C7 at final follow-up at least 1 year after surgery (40.2° vs 35.1°, P = .001). Other surgical and performance parameters including estimated blood loss, complications, and Japanese Orthopedic Association score, Neck Disability Index, Visual Analog Scale neck, and Visual Analog Scale upper limb measures were comparable between cohorts.

CONCLUSION

TDR confers similar surgical and postoperative outcomes to the treatment of ASD as ACDF. Both procedures lead to improvement in all performance outcomes. Larger, prospective, randomized studies will validate the findings of this meta-analysis. Longer term studies are required to ascertain the recurrence rates of ASD following either surgical treatment of primary ASD.

Ninety-Day Bundled Payment Reimbursement for Patients Undergoing Anterior and Posterior Procedures for Degenerative Cervical Radiculopathy

BACKGROUND

Anterior cervical discectomy with fusion (ACDF) or posterior cervical foraminotomy (PCF) are the mainstay surgical treatment options for patients with degenerative cervical radiculopathy (DCR).

OBJECTIVE

To compare 90-d bundled payments between ACDF and PCF for DCR in a cohort study.

METHODS

Data were extracted from MarketScan database (2000-2016) using ICD-9, ICD-10, and CPT-4 codes. The bundle payments were calculated as the payments accumulated from the index hospitalization admission to 90 d postsurgery. We also analyzed the index hospitalization (physician, hospital, and total) and the postdischarge payments (hospital readmission, outpatient services, medications, and total). Surgical groups were matched based on baseline characteristics (age, sex, insurance type, and Elixhauser score).

RESULTS

A total of 100 041 patients met the inclusion criteria. 94.9% of patients (n = 95 031). Patients underwent ACDF with 5.1% (n = 5 010) treated via PCF. Overall, median 90-d costs were significantly higher for ACDF than for PCF ($31567 vs $18412; P < .0001). The median total index hospitalization ($27841 vs $15043), physician ($4572 vs $1920), and hospital payments ($14540 vs $7404) were higher for ACDF compared to PCF for both single- and multiple-level cohorts (P < .0001). There was no difference in overall 90-d postdischarge payments. Factors associated with higher 90-d payments for both cohorts included age and comorbidity scores.

CONCLUSION

ACDF is associated with greater bundle payments in patients diagnosed with DCR. No difference was noted for the total postdischarge payments. PCF may be a cost-effective surgical option in appropriately selected patients with unilateral, paracentral, and foraminal soft herniated discs.

Posterior percutaneous full-endoscopic cervical laminectomy and decompression for cervical stenosis with myelopathy: a technical note

PURPOSE

Cervical stenosis with myelopathy caused by ossification of the ligamentum flavum is relatively rare, and surgical treatment is the preferred option. Previous surgical procedures usually require assisted internal fixation, while some problems may occur, such as large trauma, intraoperative bleeding, wound infection and internal fixation failure. The aim of this paper is to introduce a new minimally invasive surgical procedure for the treatment of upper cervical spinal stenosis complicated with myelopathy.

METHODS AND RESULTS

A 56-year-old male patient with cervical myelopathy (C2-3) caused by calcification of the ligamentum flavum underwent posterior percutaneous full-endoscopic cervical laminectomy and decompression (PECLD) and achieved a good clinical efficacy. A surgical incision just 1 cm in size was made, and there was little bleeding during the operation. The patient was hospitalized for 2 days and returned to work after 4 weeks. The patient's postoperative recovery of neurological function was significantly improved, the pain was obviously reduced, and the quality of life was remarkably improved. No intra- or postoperative surgical complications were encountered.

CONCLUSIONS

PECLD is an effective method for treating cervical stenosis associated with myelopathy due to ossification of the ligamentum flavum. It has the advantages of smaller trauma, less bleeding, shorter postoperative hospital stays and faster recovery. Taken together, this minimally technique can be considered as a good alternative to traditional open surgery.

[Comparison of the long-term outcomes of total arthroplasty and anterior spinal fusion in the treatment of cervical degenerative disc disease: a metaanalysis]

AIM

The study aim was to perform a meta-analysis based on the results of randomized clinical trials comparing long-term outcomes of total intervertebral disc arthroplasty (TA) and anterior cervical spinal fusion (ACSF) in the surgical treatment of cervical degenerative disc disease.

MATERIAL AND METHODS

We searched Pubmed, EMBASE, ELibrary, and Cochrane Library databases for randomized clinical trials reported between 2008 and August 2018. The relative risk and 95% confidence interval were calculated for dichotomous variables; for continuous variables, we used the standardized mean difference and their 95% CI with application of a random effects model.

RESULTS

The metaanalysis involved 9 randomized controlled clinical trials including the long-term outcomes of surgical treatment in 2,439 patients. A pooled analysis of the data showed that regression of neurological symptoms (p<0.00001), improvement in the quality of life of patients (Neck Disability Index), and lower pain severity (visual analogue scale for upper extremities) were significantly more often observed (p=0.02) in the group of TA patients. In addition, the TA technique was characterized by a statistically significantly lower rate of re-surgery (p<0.0005) and degeneration of the superjacent segment (p<0.0001), with the rate of adverse events being slightly increased (p=0.04).

CONCLUSION

Compared to anterior cervical spinal fusion, TA of cervical intervertebral discs is characterized by significantly better clinical efficacy in patients with cervical degenerative disc disease in the long-term postoperative follow-up.

The Seven-Year Cost-Effectiveness of Anterior Cervical Discectomy and Fusion Versus Cervical Disc Arthroplasty: A Markov Analysis

STUDY DESIGN

Markov model analysis.

OBJECTIVE

The aim of this study was to determine the 7-year cost-effectiveness of single-level anterior cervical discectomy and fusion (ACDF) versus cervical disc replacement (CDR) for the treatment of cervical disc degeneration.

SUMMARY OF BACKGROUND DATA

Both ACDF and CDR are acceptable surgical options for the treatment of symptomatic cervical disc degeneration. Past studies have demonstrated at least equal effectiveness of CDR when compared with ACDF in large randomized Investigational Device Exemption (IDE) studies. Short-term cost-effectiveness analyses at 5 years have suggested that CDR may be the preferred treatment option. However, adjacent segment disease and other postoperative complications may occur after 5 years following surgery.

METHODS

A Markov model analysis was used to evaluate data from the LDR Mobi-C IDE study, incorporating five Markov transition states and seven cycles with each cycle set to a length of 1 year. Transition state probabilities were determined from complication rates, as well as index and adjacent segment reoperation rates from the IDE study. Raw SF-12 data were converted to health state utility values using the SF-6D algorithm for 174 CDR patients and 79 ACDF patients.

RESULTS

Assuming an ideal operative candidate who is 40-years-old and failed appropriate conservative care, the 7-year cost was $103,924 for ACDF and $105,637 for CDR. CDR resulted in the generation of 5.33 quality-adjusted life-years (QALYs), while ACDF generated 5.16 QALYs. Both ACDF and CDR were cost-effective, but the incremental cost-effectiveness ratio (ICER) was $10,076/QALY in favor of CDR, which was less than the willingness-to-pay (WTP) threshold of $50,000/QALY.

CONCLUSION

ACDF and CDR are both cost-effective strategies for the treatment of cervical disc degeneration. However, CDR is the more cost-effective procedure at 7 years following surgery. Further long-term studies are needed to validate the findings of this model.

LEVEL OF EVIDENCE

1.

Posterior Percutaneous Endoscopic Cervical Diskectomy: A Single-Center Experience of 252 Cases

BACKGROUND

Posterior percutaneous endoscopic cervical foraminotomy and diskectomy has remarkably evolved with successful results. Although percutaneous endoscopic cervical diskectomy (PECD) has gained popularity, the risk of surgical failure may be a major obstacle to performing PECD. We analyzed unsuccessful cases requiring reoperation. The objective of this article was to find common causes of surgical failure and elucidate the limitations of the conventional PECD technique.

METHODS

Surgery-related complications were reviewed from the initial 252 cases of a single surgeon. The patients had cervical disk herniation or radiculopathy and underwent percutaneous endoscopic surgical management. We investigated clinical outcomes and complications. A retrospective review was performed on all patients who had undergone PECD between April 2013 and April 2016. Unsuccessful PECD was defined as a case requiring reoperation within 6 weeks after primary surgery. Chart review was done, and pre-, intra-, and postoperative radiographic reviews were performed. All unsuccessful PECD cases were classified according to the type of herniated disc, location of herniation, extruded disk migration, working channel position, and intra- and postoperative findings.

RESULTS

The mean operative time was 89.4 minutes (range, 60-180 minutes). The mean intraoperative blood loss was 20.3 mL (range, 10-800 mL). Cerebrospinal fluid leakage occurred in 1 patient and healed well. The follow-up period ranged from 24 to 60 months. The mean score on the visual analog scale improved from 8.67 ± 1.30 preoperatively to 7.83 ± 1.40 at 1 month postoperatively to 1.67 ± 1.30 at the final follow-up (P < 0.05), with a recovery rate of 67.9% ± 21.2%.

CONCLUSIONS

Surgeons should be aware of the specific complications for the PECD approach.

The change of adjacent segment after cervical disc arthroplasty compared with anterior cervical discectomy and fusion: a meta-analysis of randomized controlled trials

BACKGROUND CONTEXT

Many meta-analyses have been performed to study the efficacy of cervical disc arthroplasty (CDA) compared with anterior cervical discectomy and fusion (ACDF); however, there are few data referring to adjacent segment within these meta-analyses, or investigators are unable to arrive at the same conclusion in the few meta-analyses about adjacent segment. With the increased concerns surrounding adjacent segment degeneration (ASDeg) and adjacent segment disease (ASDis) after anterior cervical surgery, it is necessary to perform a comprehensive meta-analysis to analyze adjacent segment parameters.

PURPOSE

To perform a comprehensive meta-analysis to elaborate adjacent segment motion, degeneration, disease, and reoperation of CDA compared with ACDF.

STUDY DESIGN

Meta-analysis of randomized controlled trials (RCTs).

METHODS

PubMed, Embase, and Cochrane Library were searched for RCTs comparing CDA and ACDF before May 2016. The analysis parameters included follow-up time, operative segments, adjacent segment motion, ASDeg, ASDis, and adjacent segment reoperation. The risk of bias scale was used to assess the papers. Subgroup analysis and sensitivity analysis were used to analyze the reason for high heterogeneity.

RESULTS

Twenty-nine RCTs fulfilled the inclusion criteria. Compared with ACDF, the rate of adjacent segment reoperation in the CDA group was significantly lower (p<.01), and the advantage of that group in reducing adjacent segment reoperation increases with increasing follow-up time by subgroup analysis. There was no statistically significant difference in ASDeg between CDA and ACDF within the 24-month follow-up period; however, the rate of ASDeg in CDA was significantly lower than that of ACDF with the increase in follow-up time (p<.01). There was no statistically significant difference in ASDis between CDA and ACDF (p>.05). Cervical disc arthroplasty provided a lower adjacent segment range of motion (ROM) than did ACDF, but the difference was not statistically significant.

CONCLUSIONS

Compared with ACDF, the advantages of CDA were lower ASDeg and adjacent segment reoperation. However, there was no statistically significant difference in ASDis and adjacent segment ROM.

Minimally invasive procedure reduces adjacent segment degeneration and disease: New benefit-based global meta-analysis

Objective

Adjacent segment pathology (ASP) is a common complication presenting in patients with axial pain and dysfunction, requiring treatment or follow-up surgery. However, whether minimally invasive surgery (MIS), including MIS transforaminal / posterior lumbar interbody fusion (MIS-TLIF/PLIF) decreases the incidence rate of ASP remains unknown. The aim of this meta-analysis was to compare the incidence rate of ASP in patients undergoing MIS versus open procedures.

Methods

This systematic review was undertaken by following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement. We searched electronic databases, including PubMed, EMBASE, SinoMed, and the Cochrane Library, without language restrictions, to identify clinical trials comparing MIS to open procedures. The results retrieved were last updated on June 15, 2016.

Results

Overall, 9 trials comprising 770 patients were included in the study; the quality of the studies included 4 moderate and 5 low-quality studies. The pooled data analysis demonstrated low heterogeneity between the trials and a significantly lower ASP incidence rate in patients who underwent MIS procedure, compared with those who underwent open procedure (p = 0.0001). Single-level lumbar interbody fusion was performed in 6 trials of 408 patients and we found a lower ASP incidence rate in MIS group, compared with those who underwent open surgery (p = 0.002). Moreover, the pooled data analysis showed a significant reduction in the incidence rate of adjacent segment disease (ASDis) (p = 0.0003) and adjacent segment degeneration (ASDeg) (p = 0.0002) for both procedures, favoring MIS procedure. Subgroup analyses showed no difference in follow-up durations between the procedures (p = 0.93).

Conclusion

Therefore, we conclude that MIS-TLIF/PLIF can reduce the incidence rate of ASDis and ASDeg, compared with open surgery. Although the subgroup analysis did not indicate a difference in follow-up duration between the two procedures, larger-scale, well-designed clinical trials with extensive follow-up are needed to confirm and update the findings of this analysis.

Acute airway obstruction due to postoperative retropharyngeal hematoma after anterior cervical fusion: a retrospective analysis

Background

Acute airway obstruction (AAO) after anterior cervical fusion (ACF) can be caused by postoperative retropharyngeal hematoma, which requires urgent recognition and treatment. However, the causes, evaluation, and appropriate treatment of this complication are not clearly defined. The purpose of this retrospective review of a prospective database was to investigate etiologic factors related to the development of AAO due to postoperative hematoma after ACF and formulate appropriate prevention and treatment guidelines.

Methods

Cervical spinal cases treated at our academic institutions from 1998 to 2013 were evaluated. Demographic data, including factors related to hemorrhagic tendency, and operative data were analyzed. Patients who developed a hematoma were compared with those who did not to identify risk factors. Cases complicated by hematoma were reviewed, and times until development of hematoma and surgical evacuation were determined. Degrees of airway compromise and patient behavior were classified and evaluated. Treatment was selected according to the patient’s status.

Results

Among 785 ACF procedures performed, there were nine cases (1.15%) of AAO. None of these nine patients had preoperative risk factors. In six patients (67%), the hematoma occurred within 24 h, whereas three patients (33%) presented with hematoma at a median of 72 h postoperatively. Four of the nine patients with AAO underwent evacuation of the hematoma. Two patients with inspiratory stridor, anterior neck swelling, and facial edema progressed to respiratory distress and their hematomas were removed by surgery, during which, sustained superficial venous bleeding was confirmed. Intubation was attempted several times in one patient with cyanosis, but is unsuccessful; cricothyroidotomy was performed in this patient and pumping in the small muscular arterial branches was confirmed in the operating room. All of the patients recovered without any complications.

Conclusions

With rapid recognition and appropriate treatment, there were no long-term complications caused by postoperative hematoma. There were no specific preoperative risk factors for hematoma. Systematic evaluation and appropriate management can be helpful for preventing serious complications after development of a postoperative hematoma.