Surgical treatment of degenerative and traumatic spinal diseases with expandable screws in patients with osteoporosis: 2-year follow-up clinical study

Removal of a Floating and Migrated Plate Screw in a Patient with a Failed Anterior Cervical Discectomy and Fusion

BACKGROUND

Anterior cervical discectomy and fusion (ACDF) is a commonly performed procedure for degenerative cervical spine disease. Rare complications of ACDF surgery include hardware failure, in the form of screw loosening and migration, or rod breakage. We present a case in which we removed a migrated screw lodged in the esophagus from a patient with a failed anterior cervical fusion.

OBJECTIVE

To present a surgical technique and considerations to remove a migrated screw.

METHODS

The previous ACDF incision was reopened and exposure was gained under the guidance of a head and neck surgeon. Longus coli were mobilized off the spine bilaterally with electrocautery. After dissection, the screw was found lodged in the longitudinal muscle of the esophageal wall and excised with the use of a 15-blade. The integrity of the esophageal mucosa and submucosa was maintained and subsequently checked with rigid esophagoscopy. Fluoroscopy was used to confirm that all hardware was removed, with the exception of the anterior cages.

RESULTS

The dislodged screw, which was embedded in the esophagus, was successfully removed.

CONCLUSIONS

Failure of an ACDF carries a risk of screw migration, which may be asymptomatic even if the screw is lodged in the esophagus. Additional considerations are required with potential violations of the adjacent viscera.

Avicularin alleviates osteoporosis-induced implant loosening by attenuating macrophage M1 polarization via its inhibitory effect on the activation of NF-κB

Currently, the failure rate for internal fixation in patients with osteoporosis can be reduced by antiosteoporosis therapy alone. However, the administration of anti-osteoporotic drugs is not a complete solution. Therefore, it is necessary to investigate other causes of surgical failure, such as inflammation. In recent years, the inflammation caused by macrophage M1 polarization has garnered wide attention. The purpose of this research is to explore the inhibitory effect of avicularin (AL) on macrophage M1 polarization, by which it ameliorates inflammation, thus alleviating implant instability. We established an osteoporosis mouse model of implant loosening. The mouse tissues were taken out for morphological analysis, staining analysis and bone metabolic index analysis. In in vitro experiments, bone marrow derived macrophages (BMDM) and RAW264.7 cells were polarized to M1 macrophages using lipopolysaccharide (LPS), and analyzed by immunofluorescence (IF) staining, Western blot (WB) and flow cytometry. WB was also used to analyze the nuclear factor kappa-B (NF-κB) pathway. In addition, the expression levels of inflammatory cytokines were detected in cell supernatant using ELISA kits. Through observation of this experiments, we found that AL can inhibit M1 polarization of macrophages. Moreover, it can significantly inhibit the release of inflammatory factors to improve multiple mouse femur parameters. Furthermore, AL inhibited the phosphorylation of IKBα and P65 in the NF-κB pathway. The above data indicate that AL ameliorates inflammatory responses by inhibiting macrophage M1 polarization via its inhibitory effect on the NF-κB pathway, thus alleviating the instability of implants in mice with osteoporosis.

Study on the Optimal Surgical Scheme for Very Severe Osteoporotic Vertebral Compression Fractures

OBJECTIVE

Therapy of very severe osteoporotic compression fractures (VSOVCF) has been a growing challenge for spine surgeons. Opinions vary regarding the optimal surgical procedure for the treatment of VSOVCF and which internal fixation method is more effective is still under debate, and research on this topic is lacking. This retrospective study was conducted to compare the efficacy and safety of various pedicle screw fixation methods for treating VSOVCF.

METHODS

This single-center retrospective comparative study was conducted between January 2015 and September 2020. Two hundred and one patients were divided into six groups according to different surgical methods: 45 patients underwent long-segment fixation (Group 1); 39 underwent short-segment fixation (Group 2); 30 received long-segment fixation with cement-reinforced screws (Group 3); 32 received short-segment fixation with cement-reinforced screws (Group 4); 29 had long-segment fixation combined with kyphoplasty (PKP) (Group 5); and 26 cases had short-segment fixation combined with PKP (Group 6). The clinical records were reviewed and the visual analogue scale (VAS) score and the Oswestry Disability Index (ODI) score were used for clinical evaluation. The vertebral height (VH), fractured vertebral body height (FVBH), and Cobb's angle were objectively calculated and analyzed on lateral plain radiographs. Student's t-tests and one-way ANOVA among groups were conducted to analyze the continuous, and the chi-squared test was used to compare the dichotomous or categorical variables. The difference was considered statistically significant when the P-value was less than 0.05.

RESULTS

The six groups had similar distributions in age, gender, course of the disease, follow-up period, and injured level. In the postoperative assessment of the VAS score, the surgical intervention most likely to rank first in terms of pain relief was the short-segment fixation with cement-reinforced screws (Group 4). For the functional evaluation, the surgical intervention that is most likely to rank first in terms of ODI score was a short-segment fixation with cement-reinforced screws (Group 4), followed by long-segment fixation (Group 1). The long-segment fixation with cement-reinforced screws was the first-ranked surgical intervention for the maintenance of Cobb's angle and vertebral height, whereas the short-segment fixation performed the worst. The highest overall complication rate was in Group 6 with an incidence of 42.3% (11/26), followed by Group 2 with an incidence of 38.5% (15/39).

CONCLUSION

For the treatment of VSOVCF, the short-segment fixation with cement-reinforced screws is the most effective and optimal procedure, and should be used as the preferred surgical method if surgeons are proficient in using cemented screws; otherwise, directly and unquestionably use long-segment fixation to achieve satisfactory clinical results.

Clinical evaluation of the efficacy of a new bone cement-injectable cannulated pedicle screw in the treatment of spondylolysis-type lumbar spondylolisthesis with osteoporosis: a retrospective study

Purpose

To investigate the clinical efficacy and safety of a bone cement-injectable cannulated pedicle screw (CICPS) in the treatment of spondylolysis-type lumbar spondylolisthesis with osteoporosis.

Methods

A retrospective study was conducted on 37 patients (Dual-energy X-ray bone density detection showed different degrees of osteoporosis) with spondylolysis-type lumbar spondylolisthesis who underwent lumbar spondylolisthesis reduction and fusion using a new type of injectable bone cement screw from May 2011 to March 2015. Postoperative clinical efficacy was evaluated by the Visual Analogue Scale (VAS) scores and the Oswestry Disability Index (ODI). Imaging indexes were used to evaluate the stability of internal fixation of the devices 1, 3, 6, and 12 months after surgery and annually thereafter. The safety of the CICPS was assessed by the prevalence of intraoperative and postoperative complications.

Results

A total of 124 CICPS were implanted intraoperatively. Bone cement leakage occurred in 3 screws (2.42%), and no clinical discomfort was found in any patients. All 37 patients were followed up with an average follow-up time of 26.6 ± 13.4 months (12–58 months). In the evaluation of the clinical effects of the operation, the average postoperative VAS score of the patients decreased from 4.30 ± 1.58 before surgery to 0.30 ± 0.70 after surgery (P < 0.001), and the ODI decreased from 47.27% ± 16.97% before surgery to 3.36% ± 5.70% after surgery (P < 0.001). No screw was loose, broken or pulled out.

Conclusion

CICPS is safe and effective in the treatment of spondylolysis-type lumbar spondylolisthesis complicated by osteoporosis.

The study of distance changes between lumbar bi-cortical pedicle screws and anterior large vessels in patients with lumbar spondylolisthesis

OBJECTIVE

This paper was a anatomical radiographic study of distance between lumbar bi-cortical pedicle screws (BPSs) and anterior large vessels (ALVs) in patients with lumbar spondylolisthesis, and to provide clinical basis for evaluating the safety of bi-cortical pedicle screw implantation during lumbar spondylolisthesis.

METHODS

Complete Computed tomography (CT) data of 104 patients with grade I lumbar spondylolisthesis (L4 52 and L5 52) and 107 non-spondylolisthesis patients (control group) were collected in this study. The distances between lumbar 4,5(L4,5) and sacrum 1(S1) BPSs and ALVs (abdominal aorta, inferior vena cava, left and right common iliac artery, internal and external iliac artery) were respectively measured at different transverse screw angles (TSAs) (L4:5°,10°; L5:10°,15°; S1:0°,5°,10°) and analyzed by SPSS (v25.0). There were three types of distances from the anterior vertebral cortex (AVC) to the ALVs (D_AVC-ALV): D_AVC-ALV N, D_AVC-ALV ≥ 0.50 cm, and D_AVC-ALV < 0.50 cm; these different distances represented non-contact, distant and close ALV respectively.

RESULTS

We calculated the incidences of screw tip contacting large vessels at different TSAs and provided the appropriate angle of screw implantation. In non-spondylolisthesis group, in L4, the appropriate left TSA was 5°, and the incidence of the close ALV was 4.62%. In S1, the appropriate left TSA was 0° and the incidence of the close ALV was 22.4%, while the appropriate right TSA was 10° and the incidence of the close ALV was 17.8%. In L4 spondylolisthesis group, in L4, the appropriate left TSA was 5°, and the incidence of the close ALV was 3.8%. In L5 spondylolisthesis group, in S1, the appropriate left TSA was 0° and the incidence of the close ALV was 19.2%, while the appropriate right TSA was 10° and the incidence of the close ALV was 21.2%. The use of BPS was not appropriate on the right side of L4 or on the either side of L5 both in spondylolisthesis and control group. In patients with lumbar 4 spondylolisthesis, the incidences of screw tip contacting large vessels were less than the control group in both L4 and 5. In patients with lumbar 5 spondylolisthesis, the incidences of screw tip contacting large vessels were less than the control group in L5, while there were no significant difference in S1.

CONCLUSION

It is very important that considering the anatomical relationship between the AVC and the ALVs while planning BPSs. The use of BPS does not apply to every lumbar vertebra. In patients with lumbar spondylolisthesis and non-spondylolisthesis patients, the incidences of screw tip contacting large vessels are different.

Alternatives to Traditional Pedicle Screws for Posterior Fixation of the Degenerative Lumbar Spine

BACKGROUND

Traditional pedicle screws are currently the gold standard to achieve stable 3-column fixation of the degenerative lumbar spine. However, there are cases in which pedicle screw fixation may not be ideal. Due to their starting point lateral to the pars interarticularis, pedicle screws require a relatively wide dissection along with a medialized trajectory directed toward the centrally located neural elements and prevertebral vasculature. In addition, low bone mineral density remains a major risk factor for pedicle screw loosening, pullout, and pseudarthrosis. The purpose of this article is to review the indications, advantages, disadvantages, and complications associated with posterior fixation techniques of the degenerative lumbar spine beyond the traditional pedicle screws.

METHODS

Comprehensive literature searches of the PubMed, Scopus, and Web of Science databases were performed for 5 methods of posterior spinal fixation, including (1) cortical bone trajectory (CBT) screws, (2) transfacet screws, (3) translaminar screws, (4) spinous process plates, and (5) fusion mass screws and hooks. Articles that had been published between January 1, 1990, and January 1, 2020, were considered. Non-English-language articles and studies involving fixation of the cervical or thoracic spine were excluded from our review.

RESULTS

After reviewing over 1,700 articles pertaining to CBT and non-pedicular fixation techniques, a total of 284 articles met our inclusion criteria. CBT and transfacet screws require less-extensive exposure and paraspinal muscle dissection compared with traditional pedicle screws and may therefore reduce blood loss, postoperative pain, and length of hospital stay. In addition, several methods of non-pedicular fixation such as translaminar and fusion mass screws have trajectories that are directed away from or posterior to the spinal canal, potentially decreasing the risk of neurologic injury. CBT, transfacet, and fusion mass screws can also be used as salvage techniques when traditional pedicle screw constructs fail.

CONCLUSIONS

CBT and non-pedicular fixation may be preferred in certain lumbar degenerative cases, particularly among patients with osteoporosis. Limitations of non-pedicular techniques include their reliance on intact posterior elements and the lack of 3-column fixation of the spine. As a result, transfacet and translaminar screws are infrequently used as the primary method of fixation. CBT, transfacet, and translaminar screws are effective in augmenting interbody fixation and have been shown to significantly improve fusion rates and clinical outcomes compared with stand-alone anterior lumbar interbody fusion.

LEVEL OF EVIDENCE

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

Predictors and Correlative Factors for Low Back Pain after Long Fusion Arthrodesis in Patients with Adult Scoliosis

INTRODUCTION

Low back pain (LBP) still exists at the follow-up visit in some cases after long fusion arthrodesis for adult scoliosis. However, few available studies have elaborated the reasons and factors associated with this symptom. Therefore, the aim of the current study was to identify the correlative factors and predictors of postoperative LBP after long fusion arthrodesis and provide evidence to improve the surgical strategy.

METHODS

Seventy-nine patients with adult scoliosis who underwent long fusion arthrodesis were divided into a group with no or mild LBP (NLBP group) and one with moderate or severe LBP (MLBP group) according to the average Oswestry Dability Index (ODI) at the last follow-up visit. The Japanese Orthopaedic Association (JOA) score, ODI and complications were used to evaluate clinical outcomes. %Fat infltration area (%FIA), sagittal and coronal parameters were recorded to evaluate radiological outcomes. Multivariate logistic regression analysis was conducted to identify the predictors and correlative factors for postoperative LBP.

RESULTS

Thirty-three patients (41.77%) with ODI (30.06% ± 6.92%) higher than the average at the last follow-up were divided into the MLBP group, while the rest (58.23%) with last follow-up ODI (13.26% ± 5.31%) lower than the average were divided into the NLBP group. In multivariate logistic regression, the preoperative sagittal vertical axis (SVA) (P < 0.001), %FIA (P = 0.003) and osteoporosis (P = 0.016) were identified to be predictors and last follow-up SVA (P < 0.001), last follow-up lumbar lordosis (LL) (P = 0.031) and adjacent segment degeneration (ASD) (P = 0.043) were identified as correlative factors. The receiver-operating characteristic (ROC) curve showed satisfactory accuracy in preoperative SVA (P < 0.001) and %FIA (P < 0.001) to predict postoperative LBP.

CONCLUSION

Postoperative LBP after long fusion arthrodesis for adult scoliosis was common. Postoperative LBP was associated with increased SVA and decreased LL and ASD. Preoperative SVA > 3.54 cm, %FIA > 24.82% and osteoporosis showed good accuracy to predict the postoperative symptoms. Optimal surgical methods should be used for patients with these factors to decrease the incidence and degree of postoperative LBP.

Comparison of Percutaneous Kyphoplasty and Pedicle Screw Fixation for Treatment of Thoracolumbar Severe Osteoporotic Vertebral Compression Fracture with Kyphosis

BACKGROUND

Pedicle screw fixation (PSF) has been considered the preferred surgery for the treatment of severe osteoporotic vertebral compression fracture (sOVCF), and sOVCF was traditionally regarded as a relative contraindication to minimally invasive percutaneous kyphoplasty (PKP). Debate has continued regarding the selection of the best surgical method for sOVCF. In the present study, we compared the efficacy and safety between PKP and PSF.

METHODS

PKP was performed in 376 patients in group 1 and PSF in 121 patients in group 2. The visual analog scale (VAS), Oswestry disability index (ODI), local kyphotic angle, fractured vertebral body height, and complications were evaluated.

RESULTS

In the immediate postoperative analysis, the mean VAS score for group 1 was 2.4, significantly lower than the VAS score of 4.7 for group 2. The mean ODI score was 44.4% for group 1, lower than the ODI score of 57.1% for group 2. In addition, group 1 had had a significantly better ODI score at 1 year of follow-up. The local kyphotic angle and fractured vertebral body height had recovered better in group 2. In group 1, 113 patients had experienced cement leakage, and 29 patients had undergone PKP for adjacent new vertebral fractures. In group 2, 2 patients had developed wound infections, 4 had developed pneumonia, 2 had developed urinary tract infection, 3 had experienced asymptomatic screw loosening, and 7 had undergone PKP to treat new vertebral fractures and 1 had undergone removal of internal fixation because of back pain.

CONCLUSIONS

The results of the clinical and radiological evaluations showed that PKP is comparable to PSF for the treatment of sOVCF with kyphosis, with PKP having the advantages of minimal invasion, quick postoperative pain relief, and functional recovery.

Short-segment cement-augmented fixation in open separation surgery of metastatic epidural spinal cord compression: initial experience

OBJECTIVE

High-grade metastatic epidural spinal cord compression from radioresistant tumor histologies is often treated with separation surgery and adjuvant stereotactic body radiation therapy. Historically, long-segment fixation is performed during separation surgery with posterior transpedicular fixation of a minimum of 2 spinal levels superior and inferior to the decompression. Previous experience with minimal access surgery techniques and percutaneous stabilization have highlighted reduced morbidity as an advantage to the use of shorter fixation constructs. Cement augmentation of pedicle screws is an attractive option for enhanced stabilization while performing shorter fixation. Herein, the authors describe their initial experience of open separation surgery using short-segment cement-augmented pedicle screw fixation for spinal reconstruction.

METHODS

The authors performed a retrospective chart review of patients undergoing open (i.e., nonpercutaneous, minimal access surgery) separation surgery for high-grade epidural spinal cord compression using cement-augmented pedicle screws at single levels adjacent to the decompression level(s). Patient demographics, treatment data, operative complications, and short-term radiographic outcomes were evaluated.

RESULTS

Overall, 44 patients met inclusion criteria with radiographic follow-up at a mean of 8.5 months. Involved levels included 19 thoracic, 5 thoracolumbar, and 20 lumbar. Cement augmentation through fenestrated pedicle screws was performed in 30 patients, and a vertebroplasty-type approach was used in the remaining 14 patients to augment screw purchase. One (2%) patient required an operative revision for a hardware complication. Three (7%) nonoperative radiographic hardware complications occurred, including 1 pathologic fracture at the index level causing progressive kyphosis and 2 incidences of haloing around a single screw. There were 2 wound complications that were managed conservatively without operative intervention. No cement-related complications occurred.

CONCLUSIONS

Open posterolateral decompression utilizing short-segment cement-augmented pedicle screws is a viable alternative to long-segment instrumentation for reconstruction following separation surgery for metastatic spine tumors. Studies with longer follow-up are needed to determine the rates of delayed complications and the durability of these outcomes.

Predicting the Failure Risk of Internal Fixation Devices in Chinese Patients Undergoing Spinal Internal Fixation Surgery: Development and Assessment of a New Predictive Nomogram

The current study is aimed at developing and validating a nomogram of the risk of failure of internal fixation devices in Chinese patients undergoing spinal internal fixation. We collected data from a total of 1139 patients admitted for spinal internal fixation surgery at the First Affiliated Hospital of Guangxi Medical University from May 2012 to February 2019. Of these, 1050 patients were included in the spinal internal fixation group and 89 patients in the spinal internal fixation device failure group. Patients were divided into training and validation tests. The risk assessment of the failure of the spinal internal fixation device used 14 characteristics. In the training test, the feature selection of the failure model of the spinal internal fixation device was optimized using the least absolute shrinkage and selection operator (LASSO) regression model. Based on the characteristics selected in the LASSO regression model, multivariate logistic regression analysis was used for constructing the model. Identification, calibration, and clinical usefulness of predictive models were assessed using C-index, calibration curve, and decision curve analysis. A validation test was used to validate the constructed model. In the training test, the risk prediction nomogram included gender, age, presence or absence of scoliosis, and unilateral or bilateral fixation. The model demonstrated moderate predictive power with a C-index of 0.722 (95% confidence interval: 0.644-0.800) and the area under the curve (AUC) of 0.722. Decision curve analysis depicted that the failure risk nomogram was clinically useful when the probability threshold for internal fixation device failure was 3%. The C-index of the validation test was 0.761. This novel nomogram of failure risk for spinal instrumentation includes gender, age, presence or absence of scoliosis, and unilateral or bilateral fixation. It can be used for evaluating the risk of instrumentation failure in patients undergoing spinal instrumentation surgery.

Utility of Cement Augmentation via Percutaneous Fenestrated Pedicle Screws for Stabilization of Cancer-Related Spinal Instability

BACKGROUND

Cancer patients experience pathological fractures and the typical poor bone quality frequently complicates stabilization. Methods for overcoming screw failure include utilization of fenestrated screws that permit the injection of bone cement into the vertebral body to augment fixation.

OBJECTIVE

To evaluate the safety and efficacy of cement augmentation via fenestrated screws.

METHODS

A retrospective chart review of patients with neoplastic spinal instability who underwent percutaneous instrumented stabilization with cement augmentation using fenestrated pedicle screws. Patient demographic and treatment data and intraoperative and postoperative complications were evaluated by chart review and radiographic evaluation. Prospectively collected patient reported outcomes (PRO) were evaluated at short (2- <6 mo) and long term (6-12 mo).

RESULTS

Cement augmentation was performed in 216 fenestrated pedicle screws in 53 patients. Three patients required reoperation. One patient had an asymptomatic screw fracture at 6 mo postoperatively that did not require intervention. No cases of lucency around the pedicle screws, rod fractures, or cement extravasation into the spinal canal were observed. Eight cases of asymptomatic, radiographically-detected venous extravasation were found. Systemic complications included a pulmonary cement embolism, a lower extremity deep vein thrombosis, and a postoperative mortality secondary to pulmonary failure from widespread metastatic pulmonary infiltration. Significant improvement in PRO measures was found in short- and long-term analysis.

CONCLUSION

Cement augmentation of pedicle screws is an effective method to enhance the durability of spinal constructs in the cancer population. Risks include cement extravasation into draining blood vessels, but risk of clinically significant extravasation appears to be exceedingly low.

How to improve the safety of bicortical pedicle screw insertion in the thoracolumbar vertebrae: analysis base on three-dimensional CT reconstruction of patients in the prone position

BACKGROUND

Through the comparison of three-dimensional CT reconstruction between the supine position and the prone position, the relative position of thoracolumbar great vessels and vertebral body was studied, and the shortest safe distance between them was measured to improve the safety of bicortical pedicle screw insertion and reduce the risk of vascular injury.

METHODS

Forty adults were selected to participate the research. Three-dimensional reconstruction of thoracolumbar (T9-L3) CT was performed in the prone position and the supine position. The relative distance between the Aorta/Inferior Vena Cava (IVC) and vertebral body was obtained as AVD/VVD respectively. The relative angle of the Aorta/ IVC and the vertebral body was calculated as ∠AOY/∠VOY. Self-controlled experiments were carried out in the prone and the supine positions, and the data obtained were analyzed using SPSS 22.0 statistical software.

RESULTS

The AVD of the prone position and the supine position was the shortest at T12 (3.18 ± 0.68 mm), but the difference was not statistically significant. The aorta of the T9-L3 segment was shifted from the anterolateral to the anteromedial. The ∠AOY of the other groups differed significantly between the prone and supine positions in all vertebrae except T12 and L1 (P < 0.05), and the aorta in the prone position was more anteromedial than that of supine position. With regard to VVD/∠VOY, there was no significant difference between the prone and supine positions (P ≥ 0.05), and the minimum VVD of L3 segment is greater than 5.4 mm. The IVC has no obvious mobility and is fixed in the range of 20 ° ~ 30 ° near the midline.

CONCLUSION

When using bicortical anchoring of pedicle screws, it is safe to ensure that the protruding tips of the screw is less than 3 mm. Due to the mobility of the aorta in different postures and individual differences in anatomy, the prone position CT can help doctors to make better preoperative plans and decisions.

Computed tomography Hounsfield unit-based prediction of pedicle screw loosening after surgery for degenerative lumbar spine disease

OBJECTIVE

The authors investigated the relation between Hounsfield unit (HU) values measured on CT and the risk of pedicle screw loosening in patients who underwent lumbar pedicle screw fixation for degenerative lumbar spine disease.

METHODS

Patients who were treated with lumbar pedicle screw fixation between July 2011 and December 2015 at the authors' department were reviewed. Age, sex, BMI, smoking and diabetes histories, range of fixation, and fusion method were recorded as the basic patient information. The HU values for lumbar bone mineral density (BMD) for the L1, L2, L3, and L4 vertebra were measured on CT scans. Logistic regression analysis was used to identify the independent influencing factors of pedicle screw loosening.

RESULTS

A total of 503 patients were included in the final analysis. The pedicle screw loosening rate at the 12-month follow-up was 30.0% (151 of 503 patients). There were no significant differences in sex, BMI, or histories of smoking and diabetes between the patients with (loosening group) and those without (nonloosening group) screw loosening (p > 0.05). The mean HU value of L1-4 was lower in the loosening group than the nonloosening group (106.3 ± 33.9 vs 132.6 ± 42.9, p < 0.001). In logistic regression analysis, being male (OR 2.065; 95% CI 1.242-3.433), HU value (OR 0.977; 95% CI 0.970-0.985), length of fixation (OR 3.616; 95% CI 2.617-4.996), and fixation to S1 (OR 1.699; 95% CI 1.039-2.777) were the independent influencing factors for screw loosening.

CONCLUSIONS

HU value measured on CT was an independent predictor for pedicle screw loosening, and lower HU value was significantly correlated with higher risk of screw loosening.

Reduced cement volume does not affect screw stability in augmented pedicle screws

Purpose

Cement augmentation of pedicle screws is able to improve screw anchorage in osteoporotic vertebrae but is associated with a high complication rate. The goal of this study was to evaluate the impact of different cement volumes on pedicle screw fatigue strength.

Methods

Twenty-five human vertebral bodies (T12–L4) were collected from donors between 73 and 97 years of age. Bone density (BMD) was determined by quantitative computed tomography. Vertebral bodies were instrumented by conventional pedicle screws, and unilateral cement augmentation was performed. Thirteen vertebrae were augmented with a volume of 1 ml and twelve with a volume of 3 ml bone cement. A fatigue test was performed using a cranial–caudal sinusoidal, cyclic load (0.5 Hz) with increasing compression force (100 N + 0.1 N/cycles).

Results

The load to failure was 183.8 N for the non-augmented screws and was increased significantly to 268.1 N (p < 0.001) by cement augmentation. Augmentation with 1 ml bone cement increased the fatigue load by 41% while augmentation with 3 ml increased the failure load by 51% compared to the non-augmented screws, but there was no significant difference in fatigue loads between the specimens with screws augmented with 1 ml and screws augmented with 3 ml of bone cement (p = 0.504).

Conclusion

Cement augmentation significantly increases pedicle screw stability. The benefit of augmentation on screw anchorage was not significantly affected by reducing the applied volume of cement from 3 ml to 1 ml. Considering the high risk of cement leakage during augmentation, we recommend the usage of a reduced volume of 1 ml bone cement for each pedicle screw.

Graphic Abstract

These slides can be retrieved under Electronic Supplementary Material .

[Treatment of osteoporotic vertebral fracture combined with moderate to severe spinal kyphosis by transintervertebral release, bone impaction grafting, and posterior column compressed-closing]

OBJECTIVE

To explore the safety and preliminary effectiveness of transintervertebral release, bone impaction grafting, and posterior column compressed-closing in the treatment of osteoporotic vertebral fracture combined with moderate to severe spinal kyphosis.

METHODS

The clinical data of 21 elderly patients with osteoporotic vertebral fracture combined with moderate to severe spinal kyphosis were retrospectively analyzed between March 2016 and November 2017. There were 1 male and 20 females, aged 55-75 years, with an average of 64.8 years. The disease duration was 8-24 months, with an average of 13.1 months. The bone density T value ranged from -3.4 to -2.1, with an average of -2.3. Lesion segments: T 11 in 2 cases, T 12 in 6 cases, L 1 in 8 cases, L 2 in 1 case, T 11, 12 in 1 case, T 12, L 1 in 2 cases, and T 12, L 2 in 1 case. Preoperative neurological function was classified according to the American Spinal Injury Association (ASIA): 5 cases of grade D and 16 cases of grade E. All patients underwent transintervertebral release, bone impaction grafting, and posterior column compressed-closing. The effectiveness was evaluated by visual analogue scale (VAS) score and Oswestry dysfunction index (ODI) score before operation, at 3 months after operation, and at last follow-up. The neurological function was assessed by ASIA at last follow-up. Local kyphosis Cobb angle (LKCA), thoracic kyphosis (TK), lumbar lordosis (LL), and sagittal vertebral axis (SVA) were measured on the X-ray films of the full-length lateral spine of the patient before operation, at 1 week after operation, and at last follow-up.

RESULTS

No complication such as fracture of internal fixator or nerve injury occurred. LKCA, TK, and SVA were significantly improved at 1 week after operation and at last follow-up ( P<0.05). There was no significant difference between at 1 week after operation and at last follow-up ( P>0.05). There was no significant difference in LL before and after operation ( F=3.013, P=0.057). The VAS and ODI scores were significantly improved at 3 months after operation and at last follow-up, and further improved at last follow-up when compared with the scores at 3 months after operation, showing significant differences between time points ( P<0.05). Five patients with ASIA grade D neurological function recovered to grade E at 6 months after operation.

CONCLUSION

Transintervertebral release, bone impaction grafting, and posterior column compressed-closing for treating osteoporotic vertebral fracture combined with moderate to severe spinal kyphosis has definite effectiveness, strong orthopaedic ability, and minimal trauma, which can effectively restore the sagittal balance of the spine, alleviate pain, and improve the patients' quality of life.

The methods for inserting lumbar bicortical pedicle screws from the anatomical perspective of the prevertebral great vessels

BACKGROUND

At present, bicortical pedicle screws (BPSs) are not used clinically because they carry the potential risk of damaging the prevertebral great vessels (PGVs). The authors observed the anatomical relationship between the PGVs and simulated BPSs at different transverse screw angles (TSAs), exploring the insertion method of the BPS.

METHODS

Computed tomography angiography (CTA) images from 65 adults were collected. A total of 4-5 TSAs of the BPSs were simulated on the left and right sides of L1-L5 (L1-L3: 0°, 5°, 10°, 15°; L4-L5: 0°, 5°, 10°, 15°, 20°). There were three types of distances from the anterior vertebral cortex (AVC) to the PGVs (D_AVC-PGV); D_{AVC-PGV < 0.50 cm}, D_{AVC-PGV ≥ 0.50 cm}, and D_AVC-PGV↑; these distances represented close, distant, and noncontact PGV, respectively.

RESULTS

The ratio of every type of PGV was calculated, and the appropriate TSA of the BPS was recommended. In L1, the recommended left TSA of the BPS was 0°, and the ratio of the close PGV was 7.69%, while the recommended right TSA was 0°-10°, and the ratio of the close PGV was 1.54-4.62%. In L2, the recommended left TSA of the BPS was 0° and the ratio of the close PGV was 1.54%, while the recommended right TSA was 0°-15° and the ratio of the close PGV was 3.08-9.23%. In L3, the recommended left TSA was 0°-5°, and the ratio of the close PGV was 1.54-4.62%. In L4, the recommended left TSA was 0°, and the ratio of the close PGV was 4.62%. BPS use was not recommended on the right side of either L3 or L4 or on the either side of L5.

CONCLUSIONS

From the anatomical perspective of the PGVs, BPSs were not suitable for insertion into every lumbar vertebra. Furthermore, the recommended methods for inserting BPSs were different in L1-L4.

The prevalence of complications associated with lumbar and thoracic spinal deformity surgery in the elderly population: a meta-analysis

Background

The prevalence of spinal deformities increases with age, affecting between 30% and 68% of the elderly population (ages ≥65). The reported prevalence of complications associated with surgery for spinal deformities in this population ranges between 37% and 71%. Given the wide range of reported complication rates, the decision to perform surgery remains controversial.

Methods

A comprehensive search was conducted using PubMed, Embase, and Cochrane to identify studies reporting complications for spinal deformity surgery in the elderly population. Pooled prevalence estimates for individual complication types were calculated using the random-effects model.

Results

Of 5,586 articles, 14 met inclusion criteria. Fourteen complication types were reported, with at least 2 studies for each complication with the following pooled prevalence: reoperation (prevalence 19%; 95% CI, 9-36%; 107 patients); hardware failure (11%; 95% CI, 5-25%; 52 patients); infection (7%; 95% CI, 4-12%; 262 patients); pseudarthrosis (6%; 95% CI, 3-12%; 149 patients); radiculopathy (6%; 95% CI, 1-33%; 116 patients); cardiovascular event (5%; 95% CI, 1-32%; 121 patients); neurological deficit (5%; 95% CI, 2-15%; 248 patients); deep vein thrombosis (3%; 95% CI, 1-7%; 230 patients); pulmonary embolism (3%; 95% CI, 1-7%; 210 patients); pneumonia (3%; 95% CI, 1-11%; 210 patients); cerebrovascular or stroke event (2%; 95% CI, 0-9%; 85 patients); death (2%; 95% CI, 1-9%; 113 patients); myocardial infarction (2%; 95% CI, 1-6%; 210 patients); and postoperative hemorrhage (1%; 95% CI, 0-10%; 85 patients).

Conclusions

Most complication types following spinal deformity surgery in the elderly had prevalence point estimates of <6%, while all were at least ≤19%. Additional studies are needed to further explore composite prevalence estimates and prevalence associated with traditional surgical approaches as compared to minimally-invasive procedures in the elderly.

The prevalence of complications associated with lumbar and thoracic spinal deformity surgery in the elderly population: a meta-analysis

BACKGROUND

The prevalence of spinal deformities increases with age, affecting between 30% and 68% of the elderly population (ages ≥65). The reported prevalence of complications associated with surgery for spinal deformities in this population ranges between 37% and 71%. Given the wide range of reported complication rates, the decision to perform surgery remains controversial.

METHODS

A comprehensive search was conducted using PubMed, Embase, and Cochrane to identify studies reporting complications for spinal deformity surgery in the elderly population. Pooled prevalence estimates for individual complication types were calculated using the random-effects model.

RESULTS

Of 5,586 articles, 14 met inclusion criteria. Fourteen complication types were reported, with at least 2 studies for each complication with the following pooled prevalence: reoperation (prevalence 19%; 95% CI, 9-36%; 107 patients); hardware failure (11%; 95% CI, 5-25%; 52 patients); infection (7%; 95% CI, 4-12%; 262 patients); pseudarthrosis (6%; 95% CI, 3-12%; 149 patients); radiculopathy (6%; 95% CI, 1-33%; 116 patients); cardiovascular event (5%; 95% CI, 1-32%; 121 patients); neurological deficit (5%; 95% CI, 2-15%; 248 patients); deep vein thrombosis (3%; 95% CI, 1-7%; 230 patients); pulmonary embolism (3%; 95% CI, 1-7%; 210 patients); pneumonia (3%; 95% CI, 1-11%; 210 patients); cerebrovascular or stroke event (2%; 95% CI, 0-9%; 85 patients); death (2%; 95% CI, 1-9%; 113 patients); myocardial infarction (2%; 95% CI, 1-6%; 210 patients); and postoperative hemorrhage (1%; 95% CI, 0-10%; 85 patients).

CONCLUSIONS

Most complication types following spinal deformity surgery in the elderly had prevalence point estimates of <6%, while all were at least ≤19%. Additional studies are needed to further explore composite prevalence estimates and prevalence associated with traditional surgical approaches as compared to minimally-invasive procedures in the elderly.

Paravertebral injection of botulinum toxin-A reduces lumbar vertebral bone quality

Aging has been associated with decreases in muscle strength and bone quality. In older patients, paravertebral muscle atrophy tends to coincide with vertebral osteoporosis. The purpose of this study was to investigate the effects of a paravertebral injection of botulinum toxin-A (BTX) on paravertebral muscle atrophy and lumbar vertebral bone quality. Forty 16-week-old female SD rats were randomly divided into four groups: (1) a control group (CNT); (2) a resection of erector spinae muscles group (RESM); (3) a botulinum toxin-A group (BTX), treated with 5U BTX by local injection into the paravertebral muscles bilaterally; and (4) a positive control group (OVX), treated by bilateral ovariectomy. Rats were sacrificed at 12 weeks post-surgery, and the lumbar vertebrae (L3-L6) were collected. Micro-CT scans showed that rats in the three experimental groups-particularly the OVX rats-had fewer trabeculae and trabecular connections than rats in the CNT group. BMD was significantly lower in rats in the OVX, RESM, and BTX groups than in the CNT group (p < 0.01). Vertebral compression testing revealed significantly lower maximum load, energy absorption, maximum stress, and elastic modulus values in the three experimental groups compared with the CNT group (p < 0.01); these parameters were lowest in the OVX group (p < 0.05). Our results demonstrate that local BTX injection causes sufficient muscle atrophy and dysfunction to result in local lumbar vertebral bone loss and quality deterioration in a model of paravertebral muscle atrophy. Clinical Significance: The muscular tissues surrounding the lumbar vertebrae should be preserved during clinical surgery to avoid loss of bone quality and mass in the adjacent bone. Maintaining paravertebral muscle strength is an important consideration for patients with early osteoporosis. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2664-2670, 2018.

Application value of expansive pedicle screw in the lumbar short-segment fixation and fusion for osteoporosis patients

Clinical value of expansive pedicle screw in lumbar short-segment fixation and fusion for patients with osteoporosis was investigated. A total of 80 patients with lumbar compression fracture but without obvious nerve compression were selected and divided into the observation group (n=40) and the control group (n=40) using a random number table. The observation group used the expansive pedicle screw, and the control group received conventional pedicle screw fixation and bone graft fusion. In the observation group, the operation and hospitalization time after operation were shorter and the intraoperative bleeding amount was less than that in control group (p<0.05). At 1 week, 1, 3 and 6 months after operation, the observation group had better straight leg raising test (SLRT) scores, higher lower limb sensory scores but lower visual analogue scale (VAS) scores than control group (p<0.05). Besides, the proportions of postoperative infection, dural mater tear, nerve root injury and spinal cord injury during operation in the observation group were lower than those in the control group (p<0.05), and the bone graft fusion rates at 3 and 6 months after operation were obviously superior to those in control group (p<0.05). Moreover, after operation, the spinal stenosis rate in the observation group was lower than that in control group (p<0.05), the vertebral height ratio was larger than that in control group (p<0.05), and the Cobb's angle was smaller than that in the control group (p<0.05). In addition, there was a negative correlation between bone mineral density (BMD) and hospitalization time after operation in the observation group (p<0.05). In conclusion, the internal fixation with expansive pedicle screw for osteoporosis patients with lumbar compression fracture is characterized by short operation time, less intraoperative bleeding, few complications, quick recovery of postoperative neurological function and satisfactory surgical effect. However, reasonable intervention in osteoporosis is also necessary.

State of the Art Treatment of Spinal Metastatic Disease

Treatment paradigms for patients with spine metastases have evolved significantly over the past decade. Incorporating stereotactic radiosurgery into these paradigms has been particularly transformative, offering precise delivery of tumoricidal radiation doses with sparing of adjacent tissues. Evidence supports the safety and efficacy of radiosurgery as it currently offers durable local tumor control with low complication rates even for tumors previously considered radioresistant to conventional radiation. The role for surgical intervention remains consistent, but a trend has been observed toward less aggressive, often minimally invasive, techniques. Using modern technologies and improved instrumentation, surgical outcomes continue to improve with reduced morbidity. Additionally, targeted agents such as biologics and checkpoint inhibitors have revolutionized cancer care, improving both local control and patient survivals. These advances have brought forth a need for new prognostication tools and a more critical review of long-term outcomes. The complex nature of current treatment schemes necessitates a multidisciplinary approach including surgeons, medical oncologists, radiation oncologists, interventionalists, and pain specialists. This review recapitulates the current state-of-the-art, evidence-based data on the treatment of spinal metastases, integrating these data into a decision framework, NOMS, which integrates the 4 sentinel decision points in metastatic spine tumors: Neurologic, Oncologic, Mechanical stability, and Systemic disease and medical co-morbidities.

In vitro validation of a novel mechanical model for testing the anchorage capacity of pedicle screws using physiological load application

Biomechanical in vitro tests analysing screw loosening often include high standard deviations caused by high variabilities in bone mineral density and pedicle geometry, whereas standardized mechanical models made of PU foam often do not integrate anatomical or physiological boundary conditions. The purpose of this study was to develop a most realistic mechanical model for the standardized and reproducible testing of pedicle screws regarding the resistance against screw loosening and the holding force as well as to validate this model by in vitro experiments. The novel mechanical testing model represents all anatomical structures of a human vertebra and is consisting of PU foam to simulate cancellous bone, as well as a novel pedicle model made of short carbon fibre filled epoxy. Six monoaxial cannulated pedicle screws (Ø6.5 × 45mm) were tested using the mechanical testing model as well as human vertebra specimens by applying complex physiological cyclic loading (shear, tension, and bending; 5Hz testing frequency; sinusoidal pulsating forces) in a dynamic materials testing machine with stepwise increasing load after each 50.000 cycles (100.0N shear force + 20.0N per step, 51.0N tension force + 10.2N per step, 4.2Nm bending moment + 0.8Nm per step) until screw loosening was detected. The pedicle screw head was fixed on a firmly clamped rod while the load was applied in the vertebral body. For the in vitro experiments, six human lumbar vertebrae (L1-3, BMD 75.4 ± 4.0mg/cc HA, pedicle width 9.8 ± 0.6mm) were tested after implanting pedicle screws under X-ray control. Relative motions of pedicle screw, specimen fixture, and rod fixture were detected using an optical motion tracking system. Translational motions of the mechanical testing model experiments in the point of load introduction (0.9-2.2mm at 240N shear force) were reproducible within the variation range of the in vitro experiments (0.6-3.5mm at 240N shear force). Screw loosening occurred continuously in each case between 140N and 280N, while abrupt failures of the specimen were observed only in vitro. In the mechanical testing model, no translational motion was detected in the screw entry point, while in vitro, translational motions of up to 2.5mm in inferior direction were found, leading to a slight shift of the centre of rotation towards the screw tip. Translational motions of the screw tip of about 5mm in superior direction were observed both in vitro and in the mechanical testing model, while they were continuous in the mechanical testing model and rapidly increasing after screw loosening initiation in vitro. The overall pedicle screw loosening characteristics were qualitatively and quantitatively similar between the mechanical testing model and the human vertebral specimens as long as there was no translation of the screw at the screw entrance point. Therefore, the novel mechanical testing model represents a promising method for the standardized testing of pedicle screws regarding screw loosening for cases where the screw rotates around a point close to the screw entry point.