Relationship between facet joint distraction during anterior cervical discectomy and fusion for trauma and functional outcome

A Novel Intraoperative Posture-Adjustment Apparatus for Correction of Cervical Lordosis in Anterior Cervical Surgery

OBJECTIVE

Cervical alignment is a crucial factor related to the success of anterior cervical surgical procedures. In patients with severe spinal cord compression, a traditional neck pillow (TNP) may not adequately correct cervical position during surgery. Therefore, the aim of this study was to introduce this innovative intraoperative posture-adjustment apparatus (IPAA), and explored its clinical and radiological results in cervical angle correction against TNP in patients who had undergone anterior cervical surgery.

METHODS

The clinical and radiological data of 86 patients who underwent anterior cervical surgery with a minimum follow-up period of 1 year were retrospectively reviewed. Of these, 58 patients underwent IPAA, whereas 28 underwent TNP. Radiological parameters such as the degree of C2-C7 lordosis (CL), functional spinal unit angle (FSUA), C7 slope (C7S), fusion rate, and adjacent segment disease (ASD) were recorded and compared between the groups. Clinical outcomes including the Japanese Orthopaedic Association (JOA), neck disability index (NDI), visual analogue scale (VAS) for neck and arm were recorded. Complications such as kyphosis, dysphagia, Braden Scale score, revision surgery, hematoma, cerebrospinal fluid leakage, wound infection, and deep venous thrombosis were also recorded. The independent t-test or Mann-Whitney U test was used to compare continuous data, and categorical variables were assessed using the Pearson's chi-square test or Fisher's exact test.

RESULTS

Compared with the pre-operative data, the post-operative CL, FSUA, and C7S were significantly increased in both groups. CL, FSUA, and C7S in the IPAA group (14.44 ± 4.94°, 7.36 ± 2.91°, 16.54 ± 4.63°) were significantly higher than those in the TNP group (7.17 ± 8.19°, 4.99 ± 5.36°, 14.19 ± 4.48°; P < 0.05). Although there were no significant differences between the groups in terms of VAS arm and JOA scores, the post-operative and final follow-up NDI and VAS neck scores in the IPAA group were significantly lower than those in the TNP group (p < 0.05). At the last follow-up, the TNP group had significantly more kyphotic patients than the IPAA group (2 vs. 0, p = 0,041). There was no significant difference between the groups in terms of fusion rate, ASD, or complications such as dysphagia, Braden's Scale score, revision surgery, hematoma, cerebrospinal fluid leakage, wound infection, or deep venous thrombosis.

CONCLUSION

IPAA was shown to be more effective than TNP in adjusting cervical alignment (CL, FSUA, and C7S). These findings suggest that IPAA could be used as an alternative way to TNP in neck setting and cervical alignment adjustment and IPAA could potentially improve clinical outcomes after anterior cervical surgery.

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.

The influence of over-distraction on biomechanical response of cervical spine post anterior interbody fusion: a comprehensive finite element study

Introduction: Anterior cervical discectomy and fusion (ACDF) has been considered as the gold standard surgical treatment for cervical degenerative pathologies. Some surgeons tend to use larger-sized interbody cages during ACDF to restore the index intervertebral disc height, hence, this study evaluated the effect of larger-sized interbody cages on the cervical spine with ACDF under both static and cyclic loading. Method: Twenty pre-operative personalized poro-hyperelastic finite element (FE) models were developed. ACDF post-operative models were then constructed and four clinical scenarios (i.e., 1) No-distraction; 2) 1 mm distraction; 3) 2 mm distraction; and 4) 3 mm distraction) were predicted for each patient. The biomechanical responses at adjacent spinal levels were studied subject to static and cyclic loading. Non-parametric Friedman statistical comparative tests were performed and the p values less than 0.05 were reflected as significant. Results: The calculated intersegmental range of motion (ROM) and intradiscal pressure (IDP) from 20 pre-operative FE models were within the overall ranges compared to the available data from literature. Under static loading, greater ROM, IDP, facet joint force (FJF) values were detected post ACDF, as compared with pre-op. Over-distraction induced significantly higher IDP and FJF in both upper and lower adjacent levels in extension. Higher annulus fibrosus stress and strain values, and increased disc height and fluid loss at the adjacent levels were observed in ACDF group which significantly increased for over-distraction groups. Discussion: it was concluded that using larger-sized interbody cages (the height of ≥2 mm of the index disc height) can result in remarkable variations in biomechanical responses of adjacent levels, which may indicate as risk factor for adjacent segment disease. The results of this comprehensive FE investigation using personalized modeling technique highlight the importance of selecting the appropriate height of interbody cage in ACDF surgery.

Does Facet Distraction Affect Patient Outcomes After ACDF?

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim of this study is to determine if there is a correlation between the amount of facet distraction and postoperative patient-reported outcomes after ACDF.

METHODS

A retrospective cohort analysis of patients undergoing 1 to 3 level ACDF for degenerative pathologies at a single academic center was performed. Each patient received upright, lateral cervical spine x-rays at the immediate postoperative time point from which interfacet distance (facet distraction) was measured. Patient-reported outcome measures including NDI, PCS-12, MCS-12, VAS Neck, and VAS Arm pain scores were obtained preoperatively and at short-term (<3 months) and long-term (>1 year) follow-up. Receiver operating curves were generated to evaluate the possibility of a critical interfacet distraction distance. Univariate and multivariate analysis were performed to compare outcomes between groups based on the degree of facet distraction.

RESULTS

A total of 229 patients met the inclusion criteria. Receiver operating curves failed to yield a critical interfacet distraction distance associated with worse post-operative outcomes. Patients were instead grouped based on facet distraction distance below and above the third quartile (0.8mm-2.0 mm, 2.0mm-3.7 mm), with 173 and 56 patients in each respective group. Univariate analysis did not detect any statistically significant differences in outcome measures, recovery ratio, or % MCID achievement at short- and long-term follow-up between groups. Multivariate analysis also failed to demonstrate any significant differences between the facet distraction groups.

CONCLUSION

Increased interfacet distance did not correlate with increased neck pain or disability after an ACDF.

Facet Distraction and Dysphagia: A Prospective Evaluation of This Common Postoperative Issue Following Anterior Cervical Spine Surgery

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

Our primary study was to investigate whether the degree of postoperative facet and disk space distraction following anterior cervical discectomy and fusion (ACDF) affects the rate of postoperative dysphagia.

SUMMARY OF BACKGROUND DATA

Although ACDF is safe and well tolerated, postoperative dysphagia remains a common complication. Intervertebral disk space distraction is necessary in ACDF to visualize the operative field, prepare the endplates for fusion, and facilitate graft insertion. However, the degree of distraction tolerated, before onset of dysphagia, is not well characterized ACDF.

MATERIALS AND METHODS

A prospective cohort study was conducted of 70 patients who underwent ACDF between June 2018 and January 2019. Two independent reviewers measured all preoperative and postoperative radiographs measured for interfacet distraction distance and intervertebral distraction distance, with intrareviewer reproducibility measurements after one month. For multilevel surgery, the level with the greatest distraction was measured. Primary outcomes were numerical dysphagia (0-10), Eating Assessment Tool 10, and Dysphagia Symptom Questionnaire score collected at initial visit and two, six, 12, and 24 weeks postoperatively.

RESULTS

A total of 70 patients were prospectively enrolled, 59 of whom had adequate radiographs. An average of 1.71 (SD: 0.70) levels were included in the ACDF construct. Preoperatively, 13.4% of patients reported symptoms of dysphagia, which subsequently increased in the postoperative period at through 12 weeks postoperatively, before returning to baseline at 24 weeks. Intrareviewer and interreviewer reliability analysis demonstrated strong agreement. There was no relationship between interfacet distraction distance/intervertebral distraction distance and dysphagia prevalence, numerical rating, Eating Assessment Tool 10, or Dysphagia Symptom Questionnaire.

CONCLUSIONS

Patients who had an ACDF have an increased risk of dysphagia in the short term, however, this resolved without intervention by six months. Our data suggests increased facet and intervertebral disk distraction does not influence postoperative dysphagia rates.

LEVEL OF EVIDENCE

3.

Establishing a relationship using CT between Facet Distraction and clinical outcomes after ACDF

BACKGROUND CONTEXT

Anterior cervical discectomy and fusion (ACDF), the gold standard treatment for radiculopathy and myelopathy, has the potential risk of inducing facet-mediated pain through over-distraction. However, the relationship between the clinical outcomes and facet distraction after ACDF remains unclear.

PURPOSE

To measure facet distraction using computed tomography (CT) and compare the results with the clinical outcomes after ACDF.

STUDY DESIGN

Retrospective cohort study.

PATIENT SAMPLE

A consecutive series of patients (n = 144) who underwent a single-level ACDF were included.

OUTCOME MEASURES

Interfacet distance on preoperative and postoperative lateral cervical radiographs and CT. Visual analog scale for neck pain (VASn), and arm pain (VASa), neck disability index (NDI), the Short Form 36-item health survey (SF-36) were used for clinical outcomes.

METHODS

Each patient underwent plain radiography of the lateral cervical spine preoperatively, immediately and two years postsurgery. CT was performed preoperatively, and at 3 days and 1-year postsurgery. The inter-facet distance was measured at each time point, and changes in values from the preoperative distance were noted and used for study. Patient-reported outcome measures were obtained preoperatively and at 2-year follow-up. Receiver operating characteristic (ROC) curves were generated to derive the critical facet distraction point.

RESULTS

The 3 weeks postoperative VASn score was the most severe and showed a tendency to decrease during the follow-up period. There was a significant positive correlation between the change value of facet distraction measured using CT and 3 weeks postoperative VASn score. ROC curve analysis showed that the cut-off value of Δ facet distraction was 1.8 mm. The over-distraction group (Δ facet distraction ≥1.8 mm, n = 75) showed significantly worse clinical outcomes than the control group (Δ facet distraction <1.8 mm, n = 69), including neck and arm pain VAS scores at all time points until the final 2-year follow-up.

CONCLUSION

The change value of facet distraction measured using CT rather than plain radiography correlated better with neck pain, and over-distraction contributed to adverse long-term outcomes, including neck and arm pain after ACDF. Additionally, an over-distraction of ≥1.8 mm may cause radiculopathy of adjacent segments along with facet-mediated axial pain; therefore, cage height should be carefully determined to avoid over-distraction during ACDF.

Effect of facet joint distraction on the functional and radiological outcomes after anterior cervical disc replacement

OBJECTIVE

The purpose of this study is to explore: 1) whether the extent of facet joint distraction affects functional outcomes following single-level anterior cervical disc replacement (ACDR) for cervical spondylotic radiculopathy and 2) whether the extent of facet joint distraction correlates with the cervical sagittal parameters.

METHODS

We performed a retrospective analysis on 70 patients who had undergone a single-level ACDR to treat cervical spondylotic radiculopathy between January 2014 and December 2018. Pre- and post-operative lateral cervical spine X-ray radiographs were collected to determine radiographic parameters, including C0-C2 angle, C2-C7 angle, C7 Slope (C7S), T1 Slope (T1S), C2-C7 sagittal vertical axis (SVA), C2-C7 range of motion (ROM), Segmental ROM, disc height (DH) and inter-facet distance (ID). And the extend of facet joint distraction was evaluated by the two indexes: degree of intervertebral distraction (DID) defined and degree of facet joint distraction (DFJD). The visual analog scale (VAS_neck) and the Neck Disability Index scores (NDI) were adopted to demonstrate functional outcomes. Patients with the functional outcome improvement below the average were set as the positive group in the receiver operating characteristic (ROC) curve analysis, to find an optimal cut-off value of extent of facet joint distraction.

RESULTS

VAS_neck and NDI scores improved significantly from pre- to post-operation among the entire cohort, and DFJD had a statistically significant negative correlation with ΔVAS_neck (p < 0.001) and ΔNDI (p < 0.001). According to ROC curve analysis, the cut-off value of DFJD for differing the appropriate and excessive distraction groups was set at 29.16% (sensitivity = 70.73%, specificity = 67.86%). Between these two groups, the ΔT1S, ΔROM, ΔVAS_neck, and ΔNDI were significantly different (p < 0.05).

CONCLUSION

Single-segment ACDR may improve the functional outcome of patients with cervical spondylotic radiculopathy. However, those whose DFJD was greater than 29.16% had worse VAS_neck and NDI scores, as well as a lower ΔT1S and a lower ΔROM.

Analysis of Functional Outcomes and Risk Factors for Facet Joint Distraction During Anterior Cervical Discectomy and Fusion for Cervical Spondylotic Myelopathy

OBJECTIVE

This study aimed to clarify functional outcomes of facet joint distraction (FJD) and identify specific risk factors for excessive FJD during single-level anterior cervical discectomy and fusion (ACDF) for cervical spondylotic myelopathy (CSM).

METHODS

This study retrospectively analyzed 100 patients who underwent single-level ACDF for CSM from January 2016 to May 2020. Anteroposterior and lateral radiographs were obtained before surgery and 12 months after surgery. Radiographic parameters including anterior intervertebral height (AIH), posterior intervertebral height, facet joint gap, cage posterior depth (CPD), upper vertebral length, cervical segmental Cobb angle (CSCA), C2-C7 Cobb angle, and C2-C7 sagittal vertical axis were analyzed. Functional outcomes were evaluated using the modified Japanese Orthopedic Association Score, visual analog scale (VAS), and Neck Disability Index (NDI).

RESULTS

Comparison between the appropriate FJD and excessive FJD groups showed statistically significant differences in the NDI, VAS, CPD, and ΔAIH (P < 0.05). Multivariate logistic regression analysis showed that independent factors associated with excessive FJD were as follows: a ΔAIH > 2.28 mm (odds ratio [OR] = 6.792, 95% confidence interval [CI] = 1.885-24.470, P = 0.003), CPD > 12.45 mm (OR = 5.876, 95% CI = 1.828-18.895, P = 0.003), and post-CSCA < 0° (OR = 6.251, 95% CI = 1.275-30.633, P = 0.024). Furthermore, receiver operating characteristic curve analysis for the multilevel logistic regression model produced an area under the curve of 0.783 (P < 0.001).

CONCLUSION

Patients with an FJD of >0.905 mm had worse NDI and VAS pain scores, but not a poorer modified Japanese Orthopedic Association Score recovery rate. Our findings suggested that a ΔAIH > 2.28 mm, CPD > 12.45 mm, and post-CSCA < 0° were independent risk factors for excessive FJD after single-level ACDF for CSM.

Intervertebral-spreader-assisted anterior cervical discectomy and fusion prevents postoperative axial pain by alleviating facet joint pressure

Objective

To evaluate the relationship of postoperative cervical axial pain with different vertebral distraction methods used during ACDF procedures in cervical spondylosis patients.

Methods

Ninety-four single-level cervical spondylotic myelopathy patients with significantly loss of intervertebral disc height who underwent ACDF surgery in our institute between January 2018 and January 2020 were enrolled. Cervical spine lateral radiographs were taken preoperatively, 3 days, 1-month, 2-month and 6-month after the surgery. The intervertebral disc height (IDH), interfacet distance (IFD), JOA (Japanese Orthopaedic Association) score, NDI (Neck Disability Index) score, nVAS (Neck Visual Analogue Scale) score and aVAS (Arm Visual Analogue Scale) score were measured. The correlation of clinical parameters and intervertebral disc height was evaluated. Then the correlation of clinical outcomes and different distraction method was evaluated. The patients were randomly divided into two groups, one uses Casper pin distractor system alone for distraction (Caspar alone group) and the other uses spreader assisted distraction method (Casper + spreader group). In biomechanical study, four cervical spine cadavers were selected for facet pressure measurements under different vertebral distraction methods, and the facet joint pressure was measured using force sensors.

Results

Satisfactory cervical fusion and neurological recovery were achieved in all patients. No significant correlation of IDH, IFD, JOA, NDI or aVAS with nVAS score was found. No significant difference between the change in disc height and clinical outcomes was found. However, by comparing the clinical parameters of patients in different vertebral distraction groups, we found significant changes in the early nVAS and NDI scores (P = 0.11, P = 0.48) of the Casper + spreader group (3 days postoperation), and was associated with a better nVAS score at 2 months postoperation (P < 0.05). The biomechanical study in cervical cadavers also showed significantly and continuously decreased facet joint pressure in the spreader assisted vertebral distraction group (P < 0.01).

Conclusions

Spreader-assisted vertebral distraction method effectively alleviates postoperative neck pain in degenerative cervical spondylosis patients treated with ACDF. The mechanism may be related to the transient relief of facet joint pressure during the vertebral distraction procedure in ACDF.

Impact of Interspace Distraction on Fusion and Clinical Outcomes in Anterior Cervical Discectomy and Fusion: A Longitudinal Cohort Study

Study Design

Longitudinal cohort study.

Purpose

To determine the effect of change in interspace height on fusion and postoperative neck pain.

Overview of Literature

The optimal height of a cervical interbody device (cage) in anterior cervical discectomy and fusion (ACDF) is not well defined. In addition, the effect of interspace distraction on fusion and postoperative neck pain remains unclear.

Methods

We retrospectively reviewed the charts of consecutive patients who underwent one- or two-level ACDF using polyetheretherketone cages by multiple surgeons from January 2015 to June 2016. We excluded patients younger than 18 years old, patients who had prior surgery at the same level (s), those with two-stage procedures, and those with less than 3 months of follow-up. Fusion was determined using the “Song” criteria. Ordinal regression was used to determine predictors of fusion. Patient-reported outcomes (PRO) were analyzed.

Results

We identified 323 consecutive patients. Twenty-two patients met the exclusion criteria. A total of 435 operative levels were included in the 301 remaining patients. Interspace fusion did not significantly vary by increasing interspace height with fusion rates between 76.2% and 82.8% at a mean follow-up of 17.9±12.6 months. The effect of an increase in interspace height and neck pain PRO was available for 163 patients who underwent one-level ACDF at a mean follow-up period of 16.2±13.1 months. We found no significant difference in fusion rate or neck pain score with increasing interspace height from 1 to 8 mm. Ordinal regression demonstrated no significant predictors of fusion.

Conclusions

Interspace distraction from 1 to 8 mm did not result in significantly different pseudarthrosis rates or postoperative neck pain.

Comparison of anterior and posterior approaches for treatment of traumatic cervical dislocation combined with spinal cord injury: Minimum 10-year follow-up

Anterior reduction and interbody fusion fixation has not been compared directly with posterior reduction and short-segmental pedicle screw fixation for lower cervical dislocation, and so consensus is lacking as to which is the optimal method. The purpose of this paper is to compare long-term outcomes of the anterior versus posterior approach for traumatic cervical dislocation with spinal cord injury. One hundred and fifty-nine patients could be followed for more than 10 years (follow-up rate 84.1%). Ninety-two patients underwent anterior reduction and interbody fusion and fixation, and 67 patients underwent posterior reduction and short-segmental pedicle screw fixation. Japanese Orthopaedic Association (JOA) scores, the Neck Disability Index (NDI), the American Spinal Injury Association grading (ASIA), Odom's criteria, cervical kyphosis, operative parameters, and surgical or post-operative complications were evaluated. Patients were followed for 10 to 17 years. There was no significant difference in main JOA scores, NDI scores or ASIA scores between the two groups at follow-up. The posterior approach was associated with greater loss of alignment by two years (P = 0.012) and at final follow-up (P < 0.001). The posterior approach group had more blood loss (P < 0.001), longer operation times (P < 0.001), longer hospital stays (P < 0.001) and fewer complications than the anterior approach group. The anterior approach is better than the posterior approach for preserving cervical lordosis, which is associated with a better long-term effect.

3D printed anatomical (bio)models in spine surgery: clinical benefits and value to health care providers

The applications of three-dimensional printing (3DP) for clinical purposes have grown rapidly over the past decade. Recent advances include the fabrication of patient specific instrumentation, such as drill and cutting guides, patient specific/custom long term implants and 3DP of cellular scaffolds. Spine surgery in particular has seen enthusiastic early adoption of these applications. 3DP as a manufacturing method can be used to mass produce objects of the same design, but can also be used as a cost-effective method for manufacturing unique one-off objects, such as patient specific models and devices. Perhaps the first, and currently most widespread, application of 3DP for producing patient specific devices is the production of patient specific anatomical models, often termed biomodels. The present manuscript focuses on the current state of the art in anatomical (bio)models as used in spinal clinical practice. The biomodels shown and discussed include: translucent and coloured models to aid in identification of extent and margins of pathologies such as bone tumours; dynamic models for implant trial implantation and pre-operative sizing; models that can be disassembled to simulate surgical resection of diseased tissue and subsequent reconstruction. Biomodels can reduce risk to the patient by decreasing surgery time, reducing the probability of the surgical team encountering unexpected anatomy or relative positioning of structures and/or devices, and better pre-operative planning of the surgical workflow including ordered preparation of the necessary instrumentation for multi-step and revision procedures. Conversely, risks can be increased if biomodels are not accurate representations of the anatomy, which can occur if MRI/CT scan data is simply converted into 3DP format without interpretation of what the scan represents in terms of patient anatomy. A review and analysis of the cost-benefits of biomodels shows that biomodels can potentially reduce cost to health care providers if operating room time is reduced by 14 minutes or more.