A Concomitant Posterior Approach Improves Fusion Rates but not Overall Reoperation Rates in Multilevel Cervical Fusion for Spondylosis

Comparative Complications Associated With BMP Use In Patients Undergoing ACDF for Degenerative Spinal Conditions: Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic Review and Meta-Analysis.

OBJECTIVES

To compare complication incidence in patients with or without the use of recombinant human Bone Morphogenic Protein-2 (BMP2) undergoing anterior cervical discectomy and fusion (ACDF) for degenerative conditions.

METHODS

A systematic search of eight online databases was conducted using PRISMA guidelines. Inclusion criteria included English language studies with a minimum of 10 adult patients undergoing instrumented ACDF surgery for a degenerative spinal condition in which BMP2 was used in all patients or one of the treatment arms. Studies with patients undergoing circumferential fusions, with non-degenerative indications, or which did not report post-operative complication data were excluded. Patients with and without BMP2 were compared in terms of the incidence of dysphagia/dysphonia, anterior soft tissue complications (hematoma, seroma, infection, dysphagia/dysphonia), nonunion, medical complications, and new neurologic deficits.

RESULTS

Of 1832 preliminary search results, 27 manuscripts were included. Meta-analysis revealed the relative risk of dysphagia or dysphonia (RR = 1.39, CI 95% 1.18 - 1.64, P = <.001), anterior soft tissue complications (RR = 1.43, CI 95% 1.25-1.64, P = <.001), and medical complications (RR = 1.32, CI 95% 1.06-1.66, P = .013) were statistically significant in the BMP2 group while the relative risk of non-union (RR = .5, CI 95% .23 - 1.13, P = .09) trended lower in the BMP2 group. Neurological deficit (RR = 1.06, CI 95% .82-1.37, P = .66), and additional medical complications (RR = 1.53, CI 95% .98-2.38, P = .06) were not found to be statistically different between the groups.

CONCLUSIONS

This meta-analysis identified a high rate of arthrodesis when BMP2 was used in ACDF, but confirmed increased rates of dysphagia and anterior soft tissue complications. Surgeons may consider reserving BMP2 implementation for cases with a high risk of non-union, and should be aware of the risk of airway compromise.

Comparison of Perioperative Complications After Anterior-Posterior Versus Posterior-Anterior-Posterior Cervical Fusion: A Retrospective Review of 153 Consecutive Cases

BACKGROUND

Although published data support the utilization of circumferential fusion to treat select cervical spine pathologies, it is unclear whether the posterior-anterior-posterior (PAP) fusion has increased risks compared with the anterior-posterior fusion.

OBJECTIVE

To evaluate the differences in perioperative complications between the 2 circumferential cervical fusion approaches.

METHODS

One hundred fifty-three consecutive adult patients who underwent single-staged circumferential cervical fusion for degenerative pathologies from 2010 to 2021 were retrospectively reviewed. Patients were stratified into the anterior-posterior ( n = 116) and PAP ( n = 37) groups. The primary outcomes assessed were major complications, reoperation, and readmission.

RESULTS

Although the PAP group was older ( P = .024), predominantly female ( P = .024), with higher baseline neck disability index ( P = .026), cervical sagittal vertical axis ( P = .001), and previous cervical operation rate ( P < .00001), the major complication, reoperation, and readmission rates were not significantly different from the 360° group. Although the PAP group had higher urinary tract infection ( P = .043) and transfusion ( P = .007) rates, higher estimated blood loss ( P = .034), and longer operative times ( P < .00001), these differences were insignificant after the multivariable analysis. Overall, operative time was associated with older age (odds ratio [OR] 17.72, P = .042), atrial fibrillation (OR 158.30, P = .045), previous cervical operation (OR 5.05, P = .051), and lower baseline C1 - 7 lordosis (OR 0.93, P = .007). Higher estimated blood loss was associated with older age (OR 1.13, P = .005), male gender (OR 323.31, P = .047), and higher baseline cervical sagittal vertical axis (OR 9.65, P = .022).

CONCLUSION

Despite some differences in preoperative and intraoperative variables, this study suggests both circumferential approaches have comparable reoperation, readmission, and complication profiles, all of which are high.

Biomechanics of Circumferential Cervical Fixation Using Posterior Facet Cages: A Cadaveric Study

OBJECTIVE

Anterior cervical discectomy and fusion (ACDF) is a common procedure for the treatment of cervical disease. Circumferential procedures are options for multilevel pathology. Potential complications of multilevel anterior procedures are dysphagia and pseudarthrosis, whereas potential complications of posterior surgery include development of cervical kyphosis and postoperative chronic neck pain. The addition of posterior cervical cages (PCCs) to multilevel ACDF is a minimally invasive option to perform circumferential fusion. This study evaluated the biomechanical performance of 3-level circumferential fusion with PCCs as supplemental fixation to anteriorly placed allografts, with and without anterior plate fixation.

METHODS

Nondestructive flexibility tests (1.5 Nm) performed on 6 cervical C2-7 cadaveric specimens intact and after discectomy (C3-6) in 3 instrumented conditions: allograft with anterior plate (G+P), PCC with allograft and plate (PCC+G+P), and PCC with allograft alone (PCC+G). Range of motion (ROM) data were analyzed using 1-way repeated-measures analysis of variance.

RESULTS

All instrumented conditions resulted in significantly reduced ROM at the 3 instrumented levels (C3-6) compared to intact spinal segments in flexion, extension, lateral bending, and axial rotation (p < 0.001). No significant difference in ROM was found between G+P and PCC+G+P conditions or between G+P and PCC+G conditions, indicating similar stability between these conditions in all directions of motion.

CONCLUSION

All instrumented conditions resulted in considerable reduction in ROM. The added reduction in ROM through the addition of PCCs did not reach statistical significance. Circumferential fusion with anterior allograft, without plate and with PCCs, has comparable stability to ACDF with allograft and plate.

Comparison of anterior-only versus combined anterior and posterior fusion for unstable subaxial cervical injuries: a meta-analysis of biomechanical and clinical studies

OBJECTIVE

The purpose of the present study was to perform a meta-analysis comparing biomechanical and clinical outcomes between anterior-only and combined anterior and posterior fusions to determine which method of cervical fusion yielded better results for unstable cervical injuries.

METHODS

The MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Web of Science and SCOPUS electronic databases were searched for relevant articles published through 2000-2019 that compared the biomechanical and clinical outcomes of anterior-only and combined anterior and posterior fusion for unstable cervical fracture.

RESULTS

Eight biomechanical and four clinical studies were included in the analysis. There were significant biomechanical differences between the groups with respect to flexion-extension, axial rotation and lateral bending. Combined fusion provided better biomechanical stability for unstable cervical injuries than anterior-only fusion, regardless of the number of corpectomies or the presence of a posterior column injury. However, despite significant biomechanical differences, there were no significant differences in clinical outcomes, such as the degree of neurologic improvement and complications between the two groups.

CONCLUSION

Anterior-only and combined anterior and posterior fusions for unstable subaxial cervical injuries can both restore cervical stability. Although combined fusion might have some advantages in terms of stability biomechanically, there were no significant differences in clinical outcomes, such as the degree of neurologic improvement and perioperative complications. Therefore, rather than the routine use of combined fusion for unstable cervical injuries, the selective use of anterior-only or combined fusion according to the type of injury is recommended.

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

OBJECTIVES

Cervical corpectomy is an uncommon procedure and there are only limited data on the procedure's indications, surgical approaches, and complications. The diagnosis, indications, surgical planning, and complications of cervical corpectomy were therefore surveyed to clarify the treatment strategies used by spinal surgeons in central Europe, with special attention to preoperative planning and decision-making for additional dorsal approaches in multilevel cases.

MATERIALS AND METHODS

An online survey with 18 questions on the preoperative, intraoperative, and postoperative management of cervical corpectomies was conducted. The relevant specialist societies in Germany and Austria provided 1137 contacts for surgeons, and the responses were compared with recent literature reports.

RESULTS

In all, 302 surgeons (27 %) completed the survey, with wide variability in the treatment options offered. Most (51 %) perform fewer than five anterior cervical corpectomy and fusion (ACCF) procedures per year; 35 % do 5-20 per year. Anterior cervical discectomy and fusion (ACDF) was preferred by 41 % of the participants to laminoplasty/laminectomy (19 %/16 %) and ACCF (12 %). Most indications for ACCF involved degenerative (27 %), traumatic (17 %), and neoplastic (20 %) conditions. Intraoperative and postoperative complications were mainly associated with hardware failure. One-third of the surgeons tend to use an additional dorsal approach to increase the corpectomy construct's stability for either two-level or three-level corpectomies.

CONCLUSIONS

There is no current consensus in central Europe on the treatment of complex cervical disease and cervical corpectomy. The procedure is still rare, and the need for additional dorsal fixation is unclear. Further studies are needed in order to establish evidence-based standards for patient care.

Different Approaches for Treating Multilevel Cervical Spondylotic Myelopathy: A Retrospective Study of 153 Cases from a Single Spinal Center

OBJECTIVE

The optimal surgical treatment for multilevel cervical spondylotic myelopathy (MCSM) remains controversial. This study compared the outcomes of three surgical approaches for MSCM treatment, focusing on the efficacy and safety of a combined approach.

METHODS

This retrospective study included 153 consecutive MCSM patients (100 men, 53 women; mean age ± standard deviation, 55.7 ± 9.4 years) undergoing operations involving ≥3 intervertebral segments. The patients were divided into three groups according to surgical approach: anterior (n = 19), posterior (n = 76), and combined (n = 58). We assessed demographic variables, perioperative parameters, and clinical outcomes ≥12 months after surgery (20.5 ± 7.6 months), including Japanese Orthopaedic Association (JOA) score, improvement, recovery rate, and complications.

RESULTS

The anterior group had the most favorable preoperative conditions, including the highest preoperative JOA score (12.95 ± 1.86, p = 0.046). In contrast, the combined group had the highest occupancy ratio (48.0% ± 11.6%, p = 0.002). All groups showed significant neurological improvement at final follow-ups, with JOA recovery rates of 59.7%, 54.6%, and 68.9% in the anterior, posterior, and combined groups, respectively (p = 0.163). After multivariable adjustments, the groups did not have significantly different clinical outcomes (postoperative JOA score, p = 0.424; improvement, p = 0.424; recovery rate, p = 0.080). Further, subgroup analyses of patients with occupancy ratios ≥50% showed similar functional outcomes following the posterior and combined approaches. Overall complication rates did not differ significantly among the three approaches (p = 0.600). Occupancy ratios did not have a significant negative influence on postoperative recovery following the posterior approach.

CONCLUSIONS

If applied appropriately, all three approaches are effective for treating MCSM. All three approaches had equivalent neurological outcomes, even in subgroups with high occupancy ratios. Further investigations of surgical approaches to MCSM are needed, particularly prospective multicenter studies with long-term follow-up.

Utility of postoperative radiographs for cervical spine fusion: a comprehensive evaluation of operative technique, surgical indication, and duration since surgery

STUDY DESIGN

A retrospective study.

OBJECTIVE

To assess the utility of postoperative radiographs in patients across a spectrum of cervical fusion procedures, surgical indication, and time since surgery.

SUMMARY OF BACKGROUND DATA

Postoperative radiographs are routinely obtained after cervical spine fusion despite lack of evidence supporting such practice. Studies assessing postoperative radiographical utility in the cervical spine have been limited. To date, no study has comprehensively evaluated the utility of obtaining such radiographs across multiple cervical fusion procedures.

METHODS

A total of 972 clinic notes from 301 patients during a 10-year period at a single institution were retrospectively reviewed. Patients in this study underwent an anterior cervical discectomy and fusion, anterior corpectomy and fusion, a combined anterior cervical discectomy and fusion and anterior corpectomy and fusion (hybrid), posterior spine fusion, or 360° fusion. All postoperative clinic notes and radiographs were reviewed for abnormalities and changes in treatment course. It was determined whether an abnormal radiograph alone led to a change in treatment course among the various operative techniques, surgical indication, or time since surgery.

RESULTS

No statistical significant difference in radiograph utility between anterior cervical discectomy and fusion (0 changes in treatment course due to radiograph alone out of 332 clinic notes), anterior corpectomy and fusion (0 of 140), hybrid procedure (1 of 72), posterior spine fusion (5 of 357), and 360° fusion (0 of 71) was found. Surgical indication (trauma vs. degeneration) and duration from surgery yielded no statistical significant difference in radiograph utility. The overall sensitivity, specificity, and positive and negative predictive values of radiographs were 33.8%, 87.6%, 19.0%, and 93.9%, respectively.

CONCLUSION

Regardless of operative techniques performed, surgical indication, and time since surgery, routine postoperative radiographs provide low utility in guiding treatment course in asymptomatic patients. Although radiographs may provide important diagnostic utility in certain individual cases, the results of this study provide further evidence that radiographs should not be considered routine during postoperative visits, thus minimizing unnecessary radiation exposure and medical costs.

Biomechanical comparison of anterior cervical spine instrumentation techniques with and without supplemental posterior fusion after different corpectomy and discectomy combinations: Laboratory investigation

OBJECT

The objective of this study was to compare the stiffness and range of motion (ROM) of 4 cervical spine constructs and the intact condition. The 4 constructs consisted of 3-level anterior cervical discectomy with anterior plating, 1-level discectomy and 1-level corpectomy with anterior plating, 2-level corpectomy with anterior plating, and 2-level corpectomy with anterior plating and posterior fixation.

METHODS

Eight human cadaveric fresh-frozen cervical spines from C2-T2 were used. Three-dimensional motion analysis with an optical tracking device was used to determine motion following various reconstruction methods. The specimens were tested in the following conditions: 1) intact; 2) segmental construct with discectomies at C4-5, C5-6, and C6-7, with polyetheretherketone (PEEK) interbody cage and anterior plate; 3) segmental construct with discectomy at C6-7 and corpectomy of C-5, with PEEK interbody graft at the discectomy level and a titanium cage at the corpectomy level; 4) corpectomy at C-5 and C-6, with titanium cage and an anterior cervical plate; and 5) corpectomy at C-5 and C-6, with titanium cage and an anterior cervical plate, and posterior lateral mass screw-rod system from C-4 to C-7. All specimens underwent a pure moment application of 2 Nm with regards to flexion-extension, lateral bending, and axial rotation.

RESULTS

In all tested motions the statistical comparison was significant between the intact condition and the 2-level corpectomy with anterior plating and posterior fixation construct. All other statistical comparisons between the instrumented constructs were not statistically significant except between the 3-level discectomy with anterior plating and the 2-level corpectomy with anterior plating in axial rotation. There were no statistically significant differences between the 1-level discectomy and 1-level corpectomy with anterior plating and the 2-level corpectomy with anterior plating in any tested motion. There was also no statistical significance between the 3-level discectomy with anterior plating and the 2-level corpectomy with anterior plating and posterior fixation.

CONCLUSIONS

This study demonstrates that segmental plate fixation (3-level discectomy) affords the same stiffness and ROM as circumferential fusion in 2-level cervical spine corpectomy in the immediate postoperative setting. This obviates the need for staged circumferential procedures for multilevel cervical spondylotic myelopathy. Given that the posterior segmental instrumentation confers significant stability to a multilevel cervical corpectomy, the surgeon should strongly consider the placement of segmental posterior instrumentation to significantly improve the overall stability of the fusion construct after a 2-level cervical corpectomy.

Surgery for failed cervical spine reconstruction

STUDY DESIGN

Review article.

OBJECTIVE

To review the indications, operative strategy, and complications of revision cervical spine reconstruction.

SUMMARY OF BACKGROUND DATA

With many surgeons expanding their indications for cervical spine surgery, the number of patients being treated operatively has increased. Unfortunately, the number of patients requiring revision procedures is also increasing, but very little literature exists reviewing changes in the indications or operative planning for revision reconstruction.

METHODS

Narrative and review of the literature.

RESULTS

In addition to the well-accepted indications for primary cervical spine surgery (radiculopathy, myelopathy, instability, and tumor), we have used the following indications for revision surgery: pseudarthrosis, adjacent segment degeneration, inadequate decompression, iatrogenic instability, and deformity. Our surgical goal for pseudarthrosis is obviously to obtain a fusion, which can usually be performed with an approach not done previously. Our surgical goals for instability and deformity are more complex, with a focus on decompression of any neurologic compression, correction of deformity, and stability.

CONCLUSION

Revision cervical spine reconstruction is safe and effective if performed for the appropriate indications and with proper planning.

Does smoking influence fusion rates in posterior cervical arthrodesis with lateral mass instrumentation?

BACKGROUND

Smoking is associated with reduced fusion rates after anterior cervical decompression and arthrodesis procedures. Posterior cervical arthrodesis procedures are believed to have a higher fusion rate than anterior procedures.

QUESTIONS/PURPOSES

We asked whether smoking (1) would reduce the fusion rate in posterior cervical procedures; and (2) be associated with increased pain, decreased activity level, and a decreased rate of return of work as compared with nonsmokers.

METHODS

We retrospectively reviewed 158 patients who had a posterior cervical fusion with lateral mass instrumentation and iliac crest bone grafting between 2003 and 2008. Fusion rates and Odom Criteria grades were compared among smokers and nonsmokers. The minimum followup was 3 months (average, 14.5 months; range, 3-72 months).

RESULTS

Smokers and nonsmokers had similar fusion rates (100%). Although 80% of patients had Odom Criteria Grade I or II, smokers were five times more likely to have Grade III or IV with considerable limitation of physical activity. Age, gender, and diagnosis did not influence fusion rates or the Odom Criteria grade.

CONCLUSIONS

In contrast to the effect of smoking on anterior cervical fusion, we found smoking did not decrease posterior cervical fusion with lateral mass instrumentation and iliac crest bone grafting. Posterior cervical fusion with lateral mass instrumentation should be considered over anterior procedures in smokers if the abnormality can appropriately be addressed from a posterior approach.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The stabilizing potential of anterior, posterior and combined techniques for the reconstruction of a 2-level cervical corpectomy model: biomechanical study and first results of ATPS prototyping

Clinical studies reported frequent failure with anterior instrumented multilevel cervical corpectomies. Hence, posterior augmentation was recommended but necessitates a second approach. Thus, an author group evaluated the feasibility, pull-out characteristics, and accuracy of anterior transpedicular screw (ATPS) fixation. Although first success with clinical application of ATPS has already been reported, no data exist on biomechanical characteristics of an ATPS-plate system enabling transpedicular end-level fixation in advanced instabilities. Therefore, we evaluated biomechanical qualities of an ATPS prototype C4-C7 for reduction of range of motion (ROM) and primary stability in a non-destructive setup among five constructs: anterior plate, posterior all-lateral mass screw construct, posterior construct with lateral mass screws C5 + C6 and end-level fixation using pedicle screws unilaterally or bilaterally, and a 360° construct. 12 human spines C3-T1 were divided into two groups. Four constructs were tested in group 1 and three in group 2; the ATPS prototypes were tested in both groups. Specimens were subjected to flexibility test in a spine motion tester at intact state and after 2-level corpectomy C5-C6 with subsequent reconstruction using a distractable cage and one of the osteosynthesis mentioned above. ROM in flexion-extension, axial rotation, and lateral bending was reported as normalized values. All instrumentations but the anterior plate showed significant reduction of ROM for all directions compared to the intact state. The 360° construct outperformed all others in terms of reducing ROM. While there were no significant differences between the 360° and posterior constructs in flexion-extension and lateral bending, the 360° constructs were significantly more stable in axial rotation. Concerning primary stability of ATPS prototypes, there were no significant differences compared to posterior-only constructs in flexion-extension and axial rotation. The 360° construct showed significant differences to the ATPS prototypes in flexion-extension, while no significant differences existed in axial rotation. But in lateral bending, the ATPS prototype and the anterior plate performed significantly worse than the posterior constructs. ATPS was shown to confer increased primary stability compared to the anterior plate in flexion-extension and axial rotation with the latter yielding significance. We showed that primary stability after 2-level corpectomy reconstruction using ATPS prototypes compared favorably to posterior systems and superior to anterior plates. From the biomechanical point, the 360° instrumentation was shown the most efficient for reconstruction of 2-level corpectomies. Further studies will elucidate whether fatigue testing will enhance the benefit of transpedicular anchorage with posterior constructs and ATPS.