Surgical treatment of osteoporotic thoraco-lumbar compressive fractures: the use of pedicle screw with augmentation PMMA

Performance evolution of the Nano Boron nitride enhanced bone cement composites

Bone cement is a research hotspot and has been partially applied in the field of bone repair thanks to the good mechanical, physical and antibacterial properties. However, the easy wear and high temperature during curing characteristics would cause surrounding tissue necrosis, which seriously limits the wider application to some extent. In this work, the hexagonal boron nitride (h-BN) nano flakes were optimized to enhance the bone cement matrix (PMMA) via mechanical doping. The doping of h-BN into PMMA results in an improved mechanical (bending stress increased by 26%), thermal-conductivity (increased by 175% with the loading of 20 wt%), wear-resistance properties, in addition, the h-BN has no significant impact on cell activity. What's more, the co-modification of PMMA with h-BN and Vancomycin (Va) endows the bone cement composites with more persistent drug release characteristics. This comprehensive performance evolution evaluation provides a reference for the innovative application of modified bone cement.

[Current surgical treatment concepts for traumatic fractures of the thoracic and lumbar spine with osteoporotic bone substance]

Osteoporosis-related vertebral fractures are among the most frequent fracture entities in geriatric patients. They are associated with far-reaching individual and socioeconomic consequences. Adequate diagnostics and treatment are therefore essential. The osteoporotic fracture (OF) score is a central element in determining the right treatment. Although the majority of fractures can be healed with conservative treatment, a change of treatment should be considered in good time in cases of failure. Isolated cement augmentation procedures are particularly suitable for reducing pain in primarily stable osteoporotic vertebral fractures with a preserved framework structure (OF types 1-3) and a largely intact posterior edge. Dorsal cement-augmented stabilization with cementing of the fractured vertebral body leads to good results in unstable OF types 3 and 4 fractures. Dorsoventral procedures with cement-augmented internal fixator from the dorsal side and vertebral body replacement from the ventral side play a more subordinate role. Purely ventral procedures should be avoided in this patient group.

Vertebral Augmentation plus Pedicle Screw Fixation versus Vertebral Augmentation Alone in the Treatment of Osteoporotic Thoracolumbar Fractures: A Meta-Analysis

BACKGROUND

This meta-analysis was conducted to compare the efficacy and safety of vertebral augmentation (VA) plus pedicle screw fixation (PSF) with VA for treating osteoporotic thoracolumbar fractures (OTLFs).

METHODS

A comprehensive search was conducted in PubMed, Embase, Cochrane Library, and CNKI (China National Knowledge Infrastructure) to identify studies comparing PSF + VA with VA for treating OTLF. The primary outcomes were operation time, blood loss, length of stay, visual analog scale (VAS) score, Oswestry Disability Index (ODI), Cobb angle, anterior vertebral height (AVH), bone cement leakage, secondary fracture, and other adverse events. Standardized mean deviation (SMD) and risk ratio with 95% confidence interval (CI) were calculated.

RESULTS

Fourteen studies met the entire inclusion criteria for our meta-analysis. The PSF + VA group was associated with significantly more operation time (SMD, 4.41; 95% CI, 3.32-5.51), blood loss (SMD, 6.72; 95% CI, 4.50-8.95), and length of stay (SMD, 2.05; 95% CI, 1.02-3.07). There was no significant VAS score or ODI difference at early follow-up. No significant difference was found in AVH between the 2 groups before 2 years. The remaining outcomes (VAS at 6 months and 2 years; ODI at 6 months and 1 year; Cobb angle at all follow-up periods; AVH at 2 years; bone cement leakage and secondary fracture) favored the PSF + VA group.

CONCLUSIONS

PSF + VA was superior to VA for the VAS score, ODI, Cobb angle, AVH, and complications, especially in the long-term follow-up. However, more operation time, blood loss, and length of stay were the disadvantages for PSF + VA.

Value of different preoperative bone evaluation methods in predicting intraoperative screw insertion torque: a prospective clinical comparative trial

BACKGROUND CONTEXT

Establishing good screw-bone structural stability is conducive to reducing the risk of postoperative screw loosening. Screw insertion torque is an objective index for evaluating screw-bone structural stability. Therefore, accurate prediction of screw insertion torque can improve the preoperative evaluation of patients, optimize the surgical plan, and improve the surgical effect. At present, the correlation between different bone assessment methods and screw insertion torque is unclear.

PURPOSE

The aim of this study was to evaluate the correlation between different bone assessment methods and screw insertion torque and to optimize the predictive performance of screw insertion torque through mathematical modeling combined with different radiology methods.

DESIGN

Prospective cross-sectional study.

PATIENT SAMPLES

Seventy-seven patients with preoperatively available DXA, CT and MRI data who underwent spinal fixation surgeries between October 2022 and September 2023 and 357 sets of screw data were included in this analysis.

OUTCOME MEASURES

Spinal, vertebrae-specific and screw trajectory's BMD were measured preoperatively by different imaging modalities. Intraoperative screw insertion torque was measured using an electronic torque wrench.

METHODS

Pearson linear correlation, scatter plots and univariate linear regression were used to evaluate the correlation between different bone evaluation methods and screw insertion torque. Different bone evaluation methods were fitted into the prediction model of screw torque and the related equations were obtained.

RESULTS

Screw insertion torque had the strongest positive correlation with the volumetric bone mineral density (vBMD) of the screw trajectory (Pedicle screw insertion torque (PSIT): R = 0.618, p<.001; Terminal screw insertion torque (TSIT): R = 0.735, p<.001). A weak negative correlation was found between the screw insertion torque and level specific vertebral bone quality (VBQ) (PSIT: R = -0.178, p=.001; TSIT: R = -0.147, p=.006). We also found that the PSIT was strongly correlated with the TSIT (R = 0.812, p<.001).

CONCLUSIONS

Compared to other bone quality assessment methods, screw trajectory vBMD may be better predict the magnitude of screw insertion torque. In addition, we further optimized preoperative assessments by constructing a mathematical model to better predict screw insertion torque. In conclusion, clinicians should select appropriate preoperative bone quality assessment methods, identify potential low-torque patients, optimize surgical plans, and ultimately improve screw insertion accuracy and reduce postoperative screw loosening rate.

The Significance of Combined OSTA, HU Value and VBQ Score in Osteoporosis Screening Before Spinal Surgery

OBJECTIVE

This study aimed to assess the utility of a combined assessment using the Osteoporosis Self-Assessment Tool for Asians (OSTA), Hounsfield unit (HU) value, and vertebral bone quality (VBQ) score for preoperative osteoporosis (OP) screening in patients scheduled for spinal surgery.

METHODS

This study encompassed 288 participants, including 128 males and 160 females. Patients were stratified into 2 groups: the OP group (T-score ≤ -2.5) and the non-OP group (T-score > -2.5), determined by dual-energy X-ray absorptiometry (DEXA). Binary logistic regression was used to construct a combined diagnostic model, and the receiver operating characteristic (ROC) curve evaluated the sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of these metrics individually or in combination to screen for OP.

RESULTS

Osteoporosis patients exhibited significantly lower OSTA and HU values in comparison to non-OP patients, while their VBQ scores were significantly higher (P < 0.001). The ROC curve analysis results indicated that within the male group, the combined diagnosis had a sensitivity of 93.8%, specificity of 82.3%, accuracy of 85.2%, PPV of 63.8%, and NPV of 97.5%. In the female group, the combined diagnosis had a sensitivity of 93.9%, specificity of 87.4%, accuracy of 90.0%, PPV of 83.6%, and NPV of 95.4%.

CONCLUSIONS

The combined use of OSTA, HU values, and VBQ scores in preoperative OP screening for spinal surgery demonstrates significantly higher accuracy and superior screening value compared to individual assessments. These results establish a robust scientific foundation for conducting preoperative OP screening in patients undergoing spinal surgery.

MRI-based Vertebral Bone Quality Score for Osteoporosis Screening Based on Different Osteoporotic Diagnostic Criteria Using DXA and QCT

In this study, we aim to evaluate the correlation between T score measured by dual X-ray absorptiometry (DXA), volumetric bone mineral density (vBMD) derived from quantitative computed tomography (QCT) and MRI-based vertebral bone quality (VBQ), explore the diagnostic performance of VBQ in osteoporosis and determine the recognition value of VBQ in osteoporotic fracture in a relatively large cohort of elderly patients scheduled to undergo spinal surgery. A total of 260 patients were enrolled in the study. DXA and QCT were used to evaluate osteoporotic status. We calculated the lumbar VBQ score, analyzed the correlation between T score, vBMD and VBQ, and explored whether VBQ was an influential factor of bone quality and fracture by binary logistic regression as well as the diagnostic performance of VBQ in osteoporosis and fracture by ROC curve. VBQ was negatively correlated with vBMD and T score. (r = - 0.487 vs. r = - 0.220). The VBQ score was a risk factor for osteoporosis under the QCT diagnostic criteria (OR = 2.245, 95% CI 1.456-3.460) and osteoporotic fractures (OR = 1.496, 95% CI 1.097-2.040). It exhibited superior discriminant performance for osteoporosis diagnosed by QCT, with a cutoff value of 3.70 and an AUC of 0.7354. Its cutoff value for osteoporotic fractures was 3.72, and its AUC was 0.6717. In a cohort of elderly patients scheduled to undergo spinal surgery, the VBQ score was more strongly associated with vBMD than the T score and could identify patients with osteoporosis and corresponding vertebral compression fracture (VCF).

Cement-augmented pedicle screw for thoracolumbar degenerative diseases with osteoporosis: a systematic review and meta-analysis

BACKGROUND

Cement-augmentation pedicle screws have been widely used in spinal internal fixation surgery combined with osteoporosis in recent years, which can significantly improve the fixation strength, but compared with conventional methods, whether it has more advantages is still inconclusive of evidencebased medicine. To systematically evaluate the efficacy and safety of cement-augmented pedicle screw in the treatment of thoracolumbar degenerative diseases with osteoporosis.

METHODS

We searched PubMed, Embase, and Cochrane Library for studies published from the establishment of the database up until June 2023. We included studies that concerning the cement-augmented pedicle screw and the traditional pedicle screw placement for thoracolumbar degenerative diseases with osteoporosis. We excluded repeated publication, researches without full text, incomplete information or inability to conduct data extraction and animal experiments, case report, reviews and systematic reviews. STATA 15.1 software was used to analyze the data.

RESULTS

A total of 12 studies were included in this meta-analysis. The sample size of patients were totally 881, of which, 492 patients in cement-augmented screw group and 389 patients in conventional screw group. Meta-analysis results showed that Japanese Orthopaedic Association (JOA) score (WMD = 1.69, 95% CI 1.15 to 2.22), intervertebral space height (WMD = 1.66, 95% CI 1.03 to 2.29) and post-operation fusion rate (OR = 2.80, 95% CI 1.49 to 5.25) were higher in the cement-augmented screw group than those in the conventional screw group. Operation time was longer in the cement-augmented screw group than that in the conventional screw group (WMD = 15.47, 95% CI 1.25 to 29.70). Screw loosening rate was lower in the cement-augmented screw group than those in the conventional screw group (OR = 0.13, 95% CI 0.07 to 0.22). However, hospitalization time, intraoperative blood loss and Visual analog scale (VAS) score were not significantly different between the two groups (P > 0.05).

CONCLUSION

Compared with conventional pedicle screw placement, cement-augmented pedicle screw is more effective in the treatment of osteoporotic thoracolumbar degenerative disease by improving fusion rate and interbody height, reducing the incidence of screw loosening, and elevating long-term efficacy.

Assessment of bone density using the 1.5 T or 3.0 T MRI-based vertebral bone quality score in older patients undergoing spine surgery: Does field strength matter?

BACKGROUND CONTEXT

Recently published studies have revealed a correlation between MRI-based vertebral bone quality (VBQ) score and bone mineral density (BMD) measured using dual X-ray absorptiometry (DXA) or quantitative computed tomography (QCT). However, no studies have determined if differences in field strength (1.5 vs. 3.0 T) could affect the comparability of the VBQ score among different individuals.

PURPOSE

To compare the VBQ score obtained from 1.5 T and 3.0 T MRI (VBQ_1.5T versus VBQ_3.0T) in patients undergoing spine surgery and assess the predictive performance of VBQ for osteoporosis and osteoporotic vertebral fracture (VCF).

DESIGN

A nested case‒control study based on an ongoing prospective cohort study of patients undergoing spine surgery.

PATIENT SAMPLE

All older patients (men aged > 60 years and postmenopausal women) with available DXA, QCT and MR images within one month were included.

OUTCOME MEASURES

VBQ score, DXA T-score, and QCT derived vBMD.

METHODS

The osteoporotic classifications recommended by the World Health Organization and American College of Radiology were used to categorize the DXA T-score and QCT-derived BMD, respectively. For each patient, the VBQ score was calculated using T1-weighted MR images. Correlation analysis between VBQ and DXA/QCT was performed. Receiver operating characteristic (ROC) curve analysis, including determination of the area under the curve (AUC), was performed to assess the predictive performance of VBQ for osteoporosis.

RESULTS

A total of 452 patients (98 men aged > 60 years and 354 postmenopausal women) were included in the analysis. Across different BMD categories, the correlation coefficients between the VBQ score and BMD ranged from -0.211 to -0.511, and the VBQ_1.5T score and QCT BMD demonstrated the strongest correlation. The VBQ score was a significant classifier of osteoporosis detected by either DXA or QCT, with VBQ_1.5T showing the highest discriminative power for QCT-osteoporosis (AUC = 0.744, 95% CI = 0.685-0.803). In ROC analysis, the VBQ_1.5T threshold values ranged from 3.705 to 3.835 with a sensitivity between 48% and 55.6% and a specificity between 70.8% and 74.8%, while the VBQ_3.0T threshold values ranged from 2.59 to 2.605 with a sensitivity between 57.6% and 67.1% and a specificity between 67.8% and 69.7%.

CONCLUSIONS

VBQ_1.5T exhibited better discriminability between patients with and without osteoporosis than VBQ_3.0T. Considering the nonnegligible difference in osteoporosis diagnosis threshold values between the VBQ_1.5T and VBQ_3.0T scores, it is essential to clearly distinguish the magnetic field strength when assessing the VBQ score.

Posterior instrumentation for osteoporotic fractures in the thoracic or lumbar spine: Cement-augmented pedicle screws vs hybrid constructs

BACKGROUND

Cement-augmented pedicle screws (CPS) and hybrid construct (HC), consisting of pedicle screws and additional hooks, are common fixation methods for osteoporotic spine fracture. No study has compared surgical results of CPS and HC for treating osteoporotic spine fracture. The aim of the study was to compare surgical results using CPS or HC for osteoporotic fractures of the thoracic or lumbar spine.

METHODS

This retrospective cohort study included 84 patients who received surgical treatment with CPS (n = 43) or HC (n = 41) for osteoporotic spine fractures from January 2011 to December 2015, with a mean follow-up of 67 months. Sixty-five patients with neurological deficits received long posterior instrumentation, short posterior decompression, and posterolateral fusion. The 19 patients without neurologic deficits received long posterior instrumentation without posterior decompression and fusion. Radiographic, clinical, and neurologic outcomes were evaluated.

RESULTS

The HC group had significantly shorter operative times (231 vs 258 minutes), greater blood loss (497 vs 427 mL), better immediate postoperative kyphosis reduction (10.6° vs 9.1°), and greater final reduction loss (9.8° vs 7.1°) than the CPS group. In both groups, significant loss of the kyphotic angle was apparent during follow-up. Improved ambulation after surgery occurred in 51.2% and 58.5% of patients in the CPS and HC groups, respectively. Neurologic function after surgery improved 0.5 and 0.7 grades in the CPS and HC groups, respectively. Implants failed in 2.3% and 2.4% of patients in the CPS and HC groups, respectively. The incidence of cement leakage from screw augmentation was 38.9%.

CONCLUSION

The CPS and HC techniques for treating osteoporotic fractures of the thoracic or lumbar spine did not differ statistically in terms of improved radiologic and clinical outcomes, final neurologic and ambulatory function, or implant failure rates, making them equally comparable alternatives.

Reversed windshield-wiper effect leads to failure of cement-augmented pedicle screw: Biomechanical mechanism analysis by finite element experiment

The failure mode of cement-augmented pedicle screw (CAPS) was different from common pedicle screw. No biomechanical study of this failure mode named as "reversed windshield-wiper effect" was reported. To investigate the mechanisms underlying this failure mode, a series of finite element models of CAPS and PS were modified on L4 osseous model. Nine models were created according to the cement volume at 0.5 mL interval (range: 1-5 mL). Pullout load and cranio-caudal loads were applied on the screws. Stress and instantaneous rotation center (IRC) of the vertebra were observed. Under cranio-caudal load, the stress concentrated on the screw tip and pedicle region. The maximal stress (MS) at the screw tip region was +2.143 MPa higher than pedicle region. With cement volume increasing, the maximal stress (MS) at the screw tip region decreased dramatically, while MS at pedicle region was not obviously affected. As dose increased to 1.5 mL, the MS at pedicle region became higher than screw tip region and the maximal stress difference was observed at 3.5 mL. IRC of the vertebra located at the facet joint region in PS model. While IRC in CAPS models shifted anteriorly closer to the vertebral body with the increasing of cement volume. Under axial pull-out load, the maximal stress (MS) of cancellous bone in CAPS models was 29.53-50.04% lower than that 2.228 MPa in PS model. MS in the screw-bone interface did not change significantly with cement volume increasing. Therefore, the possible mechanism is that anterior shift of IRC and the negative difference value of MS between screw tip and pedicle region due to cement augmentation, leading to the screw rotate around the cement-screw complex as the fulcrum point.

Posterior Stabilization Without Neural Decompression in Osteoporotic Thoracolumbar Fractures With Dynamic Cord Compression Causing Incomplete Neurological Deficits

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

Management of osteoporotic vertebral compression fracture (OVCF) remains an unsolved problem for a spine surgeon. We hypothesize that instability at the fracture site rather than neural compression is the main factor leading to a neurological deficit in patients with OVCF.

METHODS

In this study, the prospective data of patients with osteoporotic fractures with incomplete neurological deficits from January 2015 to December 2017 was analyzed in those who underwent posterior instrumented fusion without neural decompression.

RESULTS

A total of 61 patients received posterior indirect decompression via ligamentotaxis and stabilization only. Of these 17 patients had polymethylmethacrylate (PMMA) augmented screws and in 44 patients no PMMA augmentation was done. The mean preoperative kyphosis was 27.12° ± 9.63°, there was an improvement of 13.5° ± 6.87° in the immediate postoperative period and at the final follow-up, kyphosis was 13.7° ± 7.29° with a loss of correction by 2.85° ± 3.7°. The height restoration at the final follow-up was 45.4% ± 18.29%. In all patients, back pain was relieved, and neurological improvement was obtained by at least 1 American Spinal Injury Association Impairment Scale in all except 3 patients.

CONCLUSION

We propose that neural decompression of the spinal cord is not always necessary for the treatment of neurological impairment in patients with osteoporotic vertebral collapse with dynamic mobility. Dynamic magnetic resonance imaging is a valuable tool to make an accurate diagnosis and determine precise surgical plan and improving the surgical strategy of OVCF.

The Biomechanical Properties of Cement-Augmented Pedicle Screws for Osteoporotic Spines

STUDY DESIGN

This is a broad, narrative review of the literature.

OBJECTIVE

In this review, we describe recent biomechanics studies on cement-augmented pedicle screws for osteoporotic spines to determine which factors influence the effect of cement augmentation.

METHODS

A search of Medline was performed, combining the search terms "pedicle screw" and ("augmentation" OR "cement"). Articles published in the past 5 years dealing with biomechanical testing were included.

RESULTS

Several factors have been identified to impact the effect of cement augmentation in osteoporotic spines. These include the type of augmentation material, the volume of injected cement, the timing of augmentation, the severity of osteoporosis, the design of the pedicle screw, and the specific augmenting technique, among others.

CONCLUSIONS

This review elaborates the biomechanics of cement-augmented pedicle screws, determines which factors influence the augmentation effect, and identifies the risk factors of cement leakage in osteoporotic bone, which might offer some guidance when using this technique in clinical practice. Further, we provide information about newly designed screws and recently developed augmentation materials that provide higher screw stability as well as fewer cement-related complications.

A meta-analysis of complications associated with the use of cement-augmented pedicle screws in osteoporosis of spine

PURPOSE

Our study aimed to provide updated and comprehensive evidence on the complications associated with the use of cement-augmented pedicle screws (CAPS) in osteoporosis patients undergoing spinal instrumentation.

METHODS

Databases of PubMed, Embase, Ovoid, and Google Scholar were screened from January 2000-February 2020 for studies reporting complications of CAPS in osteoporosis patients. Pooled estimates (with 95% confidence intervals) were calculated.

RESULTS

Twenty studies were included. The pooled risk of screw loosening, screw breakage and screw migration was 2.0% (0.2%-4.9%), 0.6% (0%-2.0%) and 0.2% (0%-1.2%) respectively. On pooling of data from 1277 patients, we found the risk of all cement leakage to be 21.8% (6%-43.1%). However, data from 1654 patients indicated the risk of symptomatic cement leakage was 1.2% (0.6%-1.9%). The incidence of pulmonary embolism was 3.0% (0.5%-6.8%) while the risk of symptomatic pulmonary embolism was 0.8% (0.2%-1.5%). Pooled risk of neurovascular complications was 1.6% (0.3%-3.6%), adjacent compression fracture was 3.3% (1.2%-6.2%) and infectious complications was 3.1% (1.1%-5.7%). There were high heterogeneity and variability in the study outcomes.

CONCLUSION

The incidence of screw-related complications like loosening, breakage, and migration with the use of CAPS in spinal instrumentation of osteoporotic patients is low. The risk of cement leakage is high and variable but the incidence of symptomatic cement leakage and related neurovascular or pulmonary complications is low. Further studies using homogenous methods of reporting are needed to strengthen current evidence.

LEVEL OF EVIDENCE

II, Systematic Review and Meta-analysis.

Safety and efficacy studies of kyphoplasty, mesh-container-plasty, and pedicle screw fixation plus vertebroplasty for thoracolumbar osteoporotic vertebral burst fractures

Background

Percutaneous kyphoplasty (PKP), percutaneous mesh-container-plasty (PMCP), and pedicle screw fixation plus vertebroplasty (PSFV) were three methods for osteoporotic vertebral burst fractures (OVBF). The purpose of the current study was to evaluate the clinical safety and efficacy of PKP, PMCP, and PSFV for OVBFs.

Methods

This retrospective study included 338 consecutive patients with thoracolumbar OVBFs who underwent PKP (n = 111), PMCP (n = 109), or PSFV (n = 118) and compared their epidemiological data, surgical outcomes, and clinical and radiological features. Clinical evaluations of VAS and ODI and radiological evaluations of height restoration, deformity correction, cement leakage, and canal compromise were calculated preoperatively, postoperatively, and 2 years postoperatively.

Results

Cement leakage (31/111 vs. 13/109 and 16/118, P < 0.05) was significantly higher in group PKP than in groups PSFV and PMCP. VAS and ODI scores improved postoperatively from 7.04 ± 1.15 and 67.11 ± 13.49 to 2.27 ± 1.04 and 22.00 ± 11.20, respectively, in group PKP (P < 0.05); from 7.04 ± 1.29 and 67.26 ± 12.79 to 2.17 ± 0.98 and 21.01 ± 7.90, respectively, in group PMCP (P < 0.05); and from 7.10 ± 1.37 and 67.36 ± 13.11 to 3.19 ± 1.06 and 33.81 ± 8.81, respectively, in the PSFV group (P < 0.05). Moreover, postoperative VAS and ODI scores were significantly higher in group PSFV than in groups PKP and PMCP (P < 0.05). However, VAS scores were not significantly different in the three groups 2 years postoperatively (P > 0.05). Postoperative anterior (81.04 ± 10.18% and 87.51 ± 8.94% vs. 93.46 ± 6.42%, P < 0.05) and middle vertebral body height ratio (83.01 ± 10.16% and 87.79 ± 11.62% vs. 92.38 ± 6.00%, P < 0.05) were significantly higher in group PSFV than in groups PMCP and PKP. Postoperatively, Cobb angle (10.04 ± 4.26° and 8.16 ± 5.76° vs. 4.97 ± 4.60°, P < 0.05) and canal compromise (20.76 ± 6.32 and 19.85 ± 6.18 vs. 10.18 ± 6.99, P < 0.05) were significantly lower in group PSFV than in groups PMCP and PKP.

Conclusion

Despite relatively worse radiological results, PMCP is a safe and minimally invasive surgical method that can obtain better short-term clinical results than PKP and PSFV for OVBFs.

Fenestrated pedicle screws for thoracolumbar instrumentation in patients with poor bone quality: Case series and systematic review of the literature

OBJECTIVE

To describe the results of a single-surgeon series and systematically review the literature on cement-augmented instrumented fusion with fenestrated pedicle screws.

METHODS

All patients treated by the senior surgeon using fenestrated screws between 2017 and 2019 with a minimum of 6-months of clinical and radiographic follow-up were included. For the systematic review, we used PRISMA guidelines to identify all prior descriptions of cement-augmented instrumented fusion with fenestrated pedicle screws in the English literature. Endpoints of interest included hardware loosening, cement leakage, and pulmonary cement embolism (PCE).

RESULTS

Our series included 38 patients (mean follow-up 14.8 months) who underwent cement-augmented instrumentation for tumor (47.3%), deformity/degenerative disease (39.5%), or osteoporotic fracture (13.2%). Asymptomatic screw lucency was seen in 2.6%, cement leakage in 445, and pulmonary cement embolism (PCE) in 5.2%. Our literature review identified 23 studies (n = 1526 patients), with low reported rates of hardware loosening (0.2%) and symptomatic PCE (1.0%). Cement leakage, while common (55.6%), produced symptoms in fewer than 1% of patients. Indications for cement-augmentation in this cohort included: spine metastasis with or without pathologic fracture (n = 18; 47.3%), degenerative spine disease or fixed deformity with poor underlying bone quality (n = 15; 39.5%), and osteoporotic fracture (n = 5; 13.2%).

CONCLUSION

Cement-augmented fusion with fenestrated screws appears to be a safe, effective means of treating patients with poor underlying bone quality secondary to tumor or osteoporosis. High-quality evidence with direct comparisons to non-augmented patients is needed.

Effectiveness and reliability of cannulated fenestrated screws augmented with polymethylmethacrylate cement in the surgical treatment of osteoporotic vertebral fractures

Background

Implants' stability, especially in osteoporosis patients, is a challenging matter. Nowadays, the adoption of cannulated fenestrated screws augmented with polymethylmethacrylate cement (PMMA CSF) is described by some authors. This single-center, retrospective observational study aims to evaluate the long-term effectiveness, reliability, and mechanical performances of this type of screws in osteoporotic fractures.

Materials and Methods

All the patients surgically treated from January 2009 to December 2019 with PMMA CSF were evaluated and submitted to the inclusion and exclusion criteria. Clinical and radiological evaluations were performed at pre- and post-surgery time and at the follow-up (FU). Loss of correction in the sagittal plane (bisegmental Cobb angle), kyphosis angle of the fracture (fractured vertebral angle), loosening of pedicle screws (screw's apex vertebral body's anterior cortex mean gap called SAAC gap and screw's apex vertebral body's superior endplate mean gap called SASE gap), visual analog scale, and Oswestry disability index scores were evaluated.

Results

One hundred and sixty-three patients (58 males and 105 females) aged over 65 years affected by vertebral osteoporotic fractures were included in the study. At FU, we do not found significant differences in radiological items in respect to the postoperative period. Only one case of loosening and 18 cases of cement leaking (without neurological impairments) were found. Clinical scores improvement was significant in the interval between preoperative and FU.

Conclusions

PMMA CSF seems to can guarantee good efficacy and effectiveness in the surgical treatment of vertebral fractures in osteoporosis.

Selective cement augmentation of cranial and caudal pedicle screws provides comparable stability to augmentation on all segments in the osteoporotic spine: a finite element analysis

Background

Cement-augmented pedicle screw instrumentation (CAPSI) has been proven to significantly increase the biomechanical stability in the osteoporotic lumbar spine. However, besides the merits, it is responsible for the inevitable cement leakage growing with more instrumented segments and volumes involved. This study aimed to compare the biomechanical performance of pedicle screws augmented on all segments with those augmented only on the cranial and caudal vertebrae selectively.

Methods

The finite element model of L3-S1 was modeled with the CT data of a healthy volunteer, the solid/fenestrated pedicle screws from micro-CT scans of physical screws, and bone cement from the CT scans of a postoperative patient with CAPSI. Three different augmented strategies for pedicle screws were taken into consideration: augmentation at each pedicle trajectory (Model A), selective augmentation at the cranial and caudal pedicle trajectories (Model B), and pedicle trajectories without augmentation (Model C). A total of six surgical models were constructed: Models A, B, and C were subdivided into double segmental fusion from L4 to S1 (Models A1, B1, and C1) and multi-segment fusion from L3 to S1 (Models A2, B2, and C2). The Range of motion (ROM), stress on the cage, and stress on the fixed segments were compared among the six models.

Results

The ROM at the fusion segments decreased in all instrumentation models. The ROMs of Model B and Model A are similar in each direction, while that of Model C is significantly larger. The differences in the ROMs between Model A and Model B were noted to be less than 0.1°. Compared with Models A1 and A2, the peak Von Mise stress on the cage-endplate interface and pedicle screws were slightly higher in Models B1 and B2. In contrast, the stress of Models C1 and C2 increased significantly. The compressive stress was concentrated in the screw head, the cranial and caudal screws, and rods.

Conclusions

The selective augmentation of pedicle screws is capable of providing reliable stability in short-segment posterior fixation (2- or 3-level). It could be a potential optimal procedure to minimize the associated complications of CAPSI.

Long versus Short Segment Instrumentation in Osteoporotic Thoracolumbar Vertebral Fracture

Study Design

Retrospective comparative study.

Purpose

This study aimed to compare clinical and radiological data and rate of mechanical complications in elderly patients treated with short segment (SSS) or long segment stabilization (LSS) for thoracolumbar junction osteoporotic vertebral fractures (OVFs).

Overview of Literature

A fervent debate is now focused on the treatment of OVF using SSS or LSS. High rate of complications is associated with pedicle screw fixation because of poor bone quality.

Methods

Patients over 65 years old with a T-score of <−2.5, affected by (T10–L2) vertebral fracture treated with LSS or SSS pedicle screw fixation, with at least 24 months of follow-up were evaluated. All patients were analyzed with conventional X-ray to evaluate bisegmental kyphotic angle (BKA) and clinically with Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and rate of mechanical complications at 2, 6, 12, and 24 months. Data were expressed as mean±standard deviation. Student t-test was used to compare clinical scores between populations. Mann-Whitney U-test was used to analyze clinical and radiological variable, whereas Fisher’s exact test was used to identify differences in the rate of complications between groups.

Results

A total of 37 patients met the inclusion criteria. Mean follow-up was 33.97±9.26 months. For both groups, ODI and VAS significantly decreased over time with good results (p<0.00001). At the final follow-up, no significant differences were found in terms of ODI and VAS. There was no difference in correction of BKA between groups; however, a significant difference was found in LSS group between pre- and postoperative BKA (p=0.046), whereas no difference was found in SSS group. A significant difference in the rate of mechanical complications was found between groups (p=0.011).

Conclusions

Both treatments showed good clinical and radiological results; however, LSS group showed better BKA correction and lower mechanical complications than SSS group.

Effect of Fenestrated Pedicle Screws with Cement Augmentation in Osteoporotic Patients Undergoing Spinal Fusion

OBJECTIVE

Osteoporosis is a well-known risk factor for instrumentation failure and subsequent pseudoarthrosis after spinal fusion. In the present systematic review, we analyzed the biomechanical properties, clinical efficacy, and complications of cement augmentation via fenestrated pedicle screws in spinal fusion.

METHODS

We conducted a systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Reports appearing in the PubMed database up to March 31, 2020 were queried using the key words "cement," "pedicle screw," and "osteoporosis." We excluded non-English language studies, studies reported before 2000, studies that had involved use of cement without fenestrated pedicle screws, nonhuman studies, technical reports, and individual case reports.

RESULTS

Twenty-five studies met the inclusion criteria. Eleven studies had tested the biomechanics of cement-augmented fenestrated pedicle screws. The magnitude of improvement achieved by cement augmentation of pedicle screws increased with the degree of osteoporosis. The cement-augmented fenestrated pedicle screw was superior biomechanically to the alternative "solid-fill" technique. Fourteen studies had evaluated complications. Cement extravasation with fenestrated screw usage was highly variable, ranging from 0% to 79.7%. However, cement extravasation was largely asymptomatic. Thirteen studies had assessed the outcomes. The use of cement-augmented fenestrated pedicles decreased screw pull out and improved fusion rates; however, the clinical outcomes were similar to those with traditional pedicle screw placement.

CONCLUSIONS

The use of cement-augmented fenestrated pedicle screws can be an effective strategy for achieving improved pedicle screw fixation in patients with osteoporosis. A potential risk is cement extravasation; however, this complication will typically be asymptomatic. Larger comparative studies are needed to better delineate the clinical efficacy.

Sublaminar fixation versus hooks and pedicle screws in scoliosis surgery for Marfan syndrome

Background:

In patients with Marfan syndrome (MFS), surgical correction of spinal deformities with hooks and/or pedicle screws involves a higher rate of complications than in patients with adolescent idiopathic scoliosis. Therefore, sublaminar instrumentation is often a last resort option. This study wants to assess the ability of sublaminar fixation to achieve three-dimensional scoliosis correction and spine stabilization compared with hook and/or pedicle screw systems.

Methods:

Twenty-one MFS patients who underwent posterior spinal fusion at a highly specialized medical center in 1995–2017 were divided into two different groups retrospectively evaluated at a minimum follow-up of 2 years. Group 1 (8 patients) was composed by hooks and screws instrumentation, while Group 2 (13 patients) was composed by hook or pedicle screw system associated to sublaminar wires/bands. Radiological (correction and long-term stability) and general endpoints (mean blood loss, surgery time, and complications) were compared between the groups.

Results:

The degree of correction compared with the preoperative status was satisfactory with both approaches, although the difference between them was not significant. No significant differences were found for general endpoints between groups.

Conclusion:

Our data suggest that scoliosis correction with sublaminar fixation is not inferior to treatment with hooks and/or pedicle screws.

Level of Evidence:

III.

Surgical Trend Analysis for Use of Cement Augmented Pedicle Screws in Osteoporosis of Spine: A Systematic Review (2000-2017)

STUDY DESIGN

Systematic review.

OBJECTIVES

(1) Study indications for cement-augmented pedicle screws (CAPS) in patients with osteoporosis. Have they changed over the years (2000-2017)? Are there any differences in usage of CAPS based on the geographical region? (2) What were the outcome of the studies? (3) What are the complications associated with this technique?

METHODS

Electronic database and reference list of desired articles were searched from the database (2000-2017). Articles were selected discussing indications, clinical and radiological outcomes, and complications in cases of preexistent osteoporosis treated surgically using CAPS.

RESULTS

Seventeen studies were identified; 3 were comparative studies and had a control arm (cemented vs noncemented screws). Most studies originated from Europe (10) or Asia (7). Painful vertebral fracture with or without neurological deficit, Kummell's lesion, deformity and failure to respond to conservative treatment are the common indications for cement augmentation. Visual analogue scale score was the most commonly used to assess pain and average improvement after surgery was 6.1. Average improvement in kyphosis was 13.21° and average loss of correction at the end of the study was 3°. Cement leak was the most common complication observed and pulmonary cement embolism was the most dreaded complication. Nevertheless, majority of cement leaks discussed in studies were asymptomatic.

CONCLUSION

CAPS are being increasingly used in osteoporotic spine. Pain scores, functional quality of life, and neurological function indices were studied. CAPS improved anchorage in osteoporotic vertebra and helped improve/maintain clinical and radiological improvement. Common risks of cement leak were observed.

Treatment of Aggressive Vertebral Hemangiomas with Poly Vinyl Alcohol (PVA) Microparticles Embolization, PMMA, and Short Segment Stabilization: Preliminary Results with at Least 5 Years of Follow-up

OBJECTIVE

Vertebral hemangiomas (VHs) are the most common incidental lesions of vertebral body, but they are very challenging to treat if they become symptomatic. Several treatments have been proposed but none was superior to others. The aim of this study is to analyze blood loss and long-term clinical and neurological results of aggressive VHs treated with arterial embolization the day before operation, followed by vertebroplasty, posterior decompression, and short segment stabilization.

METHODS

Ten patients (4 males and 6 females) were treated for aggressive VHs with polyvinyl alcohol microparticles embolization, posterior short segment stabilization, and poly methyl methacrylate. Clinical and neurological outcomes were assessed with visual analog, Nurick, and American Spinal Injury Association (ASIA) scales.

RESULTS

At last follow-up mean, visual analog scale was 1.8 ± 1.3, with a significant difference with preoperative values (P = 0.00018). Neurological deficits persisted in 4 patients (ASIA scale: C in 1 patient [10%], D in 3 patients [30%]), but they improved from baseline in all cases. Also, Nurick scale rating improved in all patients (0 in 3 patients [30%], 1 in 4 patients [40%], 2 in 2 patients [20%], and 3 in the last one [10%]). A statistically significant difference between pre- and postoperative values was observed for both scores (ASIA, P = 0.0102; Nurick, P = 0.026). Relapse of pathology was recorded in 2 patients.

CONCLUSIONS

Polyvinyl alcohol microparticles embolization, short segment fixation, and vertebroplasty is an effective treatment option for aggressive VHs, with a fast surgical time, poor blood loss, and improvement of preoperative clinical and neurological outcomes.

Over 70° thoracic idiopathic scoliosis: Results with screws or hybrid constructs

BACKGROUND

Adolescent idiopathic scoliosis is the most common type of scoliosis. High degrees curve can be treated with the anterior, posterior, or combined anterior-posterior approach. Contrarily to the anterior approach, the posterior one is widely used nowadays for its good correction outcomes and relatively low-complication rate.

MATERIALS AND METHODS

We evaluated retrospectively 27 patients, treated with posterior approach. Patients were divided into two groups, namely pedicle screws group (PSG) and hybrid group (pedicle screws + sublaminar bands). Radiographic measurements, including thoracic and lumbar Cobb° measurements of primary and secondary curves, coronal balance and sagittal balance, kyphosis and lordosis, curve flexibility, first and last vertebra included in the arthrodesis, and implant density were evaluated. Clinical patients' satisfaction was also evaluated with Scoliosis Research Society (SRS) 24 questionnaire.

RESULTS

Considering both groups, on preoperative X-rays, the average primary scoliotic curve angle was 83.56° ± 10.96° (range 70°-112°), whereas the global flexibility was 64° ± 7.63 (range 46°-72°). The curves were classified following the Lenke classification: 17 Type 1, 2 Type 2, and 8 Type 3. The primary curve resulted to be well corrected in both groups. In T0, the groups were homogeneous, but in T1 and follow-up, PSG stated a better mean value. No other significative differences can be found between groups for all other items (P > 0.05). Clinical results of SRS 24 were excellent in both groups.

CONCLUSIONS

The posterior approach proved to be an excellent technique for obtaining good clinical and radiographic results if the surgeon adopts the third-generation high-density implants.

LEVEL OF EVIDENCE

III.

Surgical Intervention for Osteoporotic Vertebral Burst Fractures in Middle-low Lumbar Spine with Special Reference to Postoperative Complications Affecting Surgical Outcomes

The purpose of this study was to investigate the clinical and radiological features of osteoporotic burst fractures affecting levels below the second lumbar (middle-low lumbar) vertebrae, and to clarify the appropriate surgical procedure to avoid postoperative complications. Thirty-eight consecutive patients (nine male, 29 female; mean age: 74.8 years; range: 60-86 years) with burst fractures affecting the middle-low lumbar vertebrae who underwent posterior-instrumented fusion were included. Using the Magerl classification system, these fractures were classified into three types: 16 patients with superior incomplete burst fracture (superior-type), 11 patients with inferior incomplete burst fracture (inferior-type) and 11 patients with complete burst fracture (complete-type). The clinical features were investigated for each type, and postoperative complications such as postoperative vertebral collapse (PVC) and instrumentation failure were assessed after a mean follow-up period of 3.1 years (range: 1-8.1 years). All patients suffered from severe leg pain by radiculopathy, except one with superior-type fracture who exhibited cauda equina syndrome. Nineteen of 27 patients with superior- or inferior-type fracture were found to have spondylolisthesis due to segmental instability. Although postoperative neurological status improved significantly, lumbar lordosis and segmental lordosis at the fused level deteriorated from the postoperative period to the final follow-up due to postoperative complications caused mainly by PVC (29%) and instrument failure (37%). Posterior-instrumented fusion led to a good clinical outcome; however, a higher incidence of postoperative complications due to bone fragility was inevitable. Therefore, short-segment instrument and fusion with some augumentation techniqus, together with strong osteoporotic medications may be required to avoid such complications.

Clinical comparison between simple laminectomy and laminectomy plus posterior instrumentation in surgical treatment of cervical myelopathy

BACKGROUND

Posterior stabilization in patients treated with laminectomy for spondylotic cervical myelopathy is still a debate. Despite both being reported in literature by several authors, some controversies still exist. The aim of this study is to compare clinical and radiological outcomes in patients treated with laminectomy or laminectomy with posterior stabilization.

MATERIAL AND METHODS

We retrospectively evaluated 42 patients affected by cervical myelopathy (mean age 70.43 ± 5.03 years), 19 treated with laminectomy (group A) and 23 with laminectomy and posterior instrumentation (group B). Neurological status was assessed with Nurick scale, pain with VAS and radiological parameters with C2-C7 SVA, T1 slope and C2-C7 lordosis, clinical function with modified Japanese Orthopaedic Association score (JOA). Also, surgery time and blood loss were recorded. Student's t test was used for continuous variables, while Kruskal-Wallis test was used for categorical values.

RESULTS

No differences were found in postoperative Nurick scale (p = 0.587), VAS (p = 0.62), mJOA (p = 0.197) and T1 slope (p = 0.559), while laminectomy with fusion showed better postoperative cervical lordosis (p = 0.007) and C2-C7 SVA (p < 0.00001), but higher blood loss (p < 0.00001) and surgical time (p < 0.00001). Both groups showed better Nurick scale (p = 0.00017 for group A and p = 0.00081 for group B), VAS (p = 0.02 for group A and p = 0.046 for group B) and mJOA (p < 0.00001 for both groups) than preoperative values.

CONCLUSIONS

Both treatments are a valuable choice, offering some benefits and disadvantages against each other. Each procedure must be carefully evaluated on the basis of patients' general status, preoperative pain, signs of instability and potential benefits from cervical alignment correction.

Is cast an option in the treatment of thoracolumbar vertebral fractures?

Background:

Thoracolumbar vertebral fractures are common in high-energy trauma and often are associated to other concomitant injuries. Currently, brace and Closed Reduction and Casting (CRC) are the two conservative treatments proposed by literature. Despite CRC was widely used in the past, today brace is preferred. The aim of our study is to evaluate clinical and radiographic outcomes of thoracolumbar type A fractures, not associated with other injuries, treated with CRC.

Materials and Methods:

We retrospectively evaluated all patients treated from 2008 to 2015, with a mean age of 26.69 years (range 15–45). All patients were affected by AO type A fracture: 26 type A1, 17 type A2, and 21 type A3. All patients were evaluated by X-ray, computed tomography, and magnetic resonance imaging. Radiological evaluations included vertebral kyphosis (VK), segmental kyphosis (SK), regional kyphosis (RK) angle, and vertebral ratio (VR) measures. Patients were clinically assessed through visual analog scale, Oswestry Disability Index, Roland–Morris Disability Questionnaire, and Short Form 36 Health Survey.

Results:

Seventy-four patients (41 males and 33 females) were included in the study. At follow-up (mean 28.48 months ± 5.16), we found significant improvements in VK (P = 0.000013), SK (P = 0.000455), and RK (P = 0.000016). No significant differences were observed in VR (P = 0.26). Good clinical results were reported in patients in all scores and 90.7% of patients returned to work.

Conclusions:

Closed reduction and casting is still a reliable treatment option in selected thoracolumbar fractures without spinal cord involvement. A correct fracture evaluation, patient compliance, and motivation are essentials.

Level of evidence:

IV.

Surgical treatment of spinal deformities in Marfan syndrome: Long-term follow-up results using different instrumentations

Background:

Scoliosis is the most frequent spinal deformity related to Marfan syndrome (MFS). Treatment with a brace is often ineffective, and surgical treatment is very challenging; many instrumentations were used along the years. Our retrospective study has the purpose of identifying the reliability of different devices in three-dimensional correction of the spine deformities in MFS.

Materials and Methods:

We reviewed retrospectively the records of patients surgically treated, in a single institution between 1999 and 2016, for spinal deformities in MFS. X-rays were reviewed for analyzing the magnitude of the curves in preoperative time (T0), the amount of correction in the immediate after surgery period (T1), and it's stability at follow-up (FU) (T2). The clinical outcomes were also evaluated with the Scoliosis Research Society 24.

Results:

A total of 21 patients with a mean age at surgery of 16 years met inclusion and exclusion criteria. Four different construct types were identified: hooks with sublaminar wires (G1), hooks and pedicle screws (G2), pedicle screws (G3), and pedicle screws with sublaminar wires (G4). The mean FU time was 8 years. The average major scoliosis curve had a mean value of 63.48° at T0 and was corrected to 28.81° at T2. Furthermore, minor curve, thoracic lordosis, and lumbar kyphosis (when associated to scoliosis) were also corrected. Student t-test showed significative differences (P < 0.05) for all curves between T0–T1 and T0–T2 while between T1 and T2, no differences were found. We also evaluated separately the results of each instrumentation, and G3 obtained the best performances.

Conclusions:

Our results shows that screws may guarantee a better correction of the deformities.

Level of Evidence:

III

Effects of polymethylmethacrylate on the stability of screw fixation in mandibular angle fractures: A study on sheep mandibles

Aim: Malfixed miniplates can impair fracture healing, and the screw pilot holes may widen during repeated fixation trials. This in vitro study explored the extent to which screw fixation of mandibular angle fractures could be improved by augmenting the drilling holes with polymethylmethacrylate (PMMA). Materials and Methods: We measured stabilization by recording specimen displacement under a vertical force of 50 N applied using a hydraulic tester. We included 20 hemimandibles from sheep (average weight 40 kg). The specimens were randomly divided into two groups of 10 and pilot holes were created in the angulus region using a drill 1.2 mm in diameter. Next, we performed osteotomies simulating angulus fracture repair. In group 1, the fracture site was fixed using non-compression miniplates and four screws were inserted to the maximal possible extent employing a mechanical screwdriver. In group 2, the pilot drill holes were filled with PMMA prior to miniplate fixation. Then vertical forces of 50 N were applied to the molar region and the displacements were measured. The Shapiro-Wilks test was used to compare the two groups. Result: The maximum average displacement in the experimental group was significantly lower than that in the control group (p=0.026). Thus, PMMA-augmented screws better stabilized bone, affording reliable fixation.

Clinical and radiological union rate evaluation of type 2 odontoid fractures: A comparison between anterior screw fixation and halo vest in elderly patients

Purpose:

Odontoid fracture is a very common cervical injury, especially in elderly patients. Despite the high frequency, the appropriate management is still debated. The aim of this study is to evaluate clinical and radiological outcomes after anterior screw fixation or halo vest (HV) in type II odontoid fracture in elderly patients.

Materials and Methods:

Between January 2013 and December 2015, 135 consecutive patients affected by odontoid process were found. According to inclusion and exclusion criteria, 57 patients were included in the study. Patients were evaluated with visual analog scale (VAS), Smiley–Webster Scale (SWS), Italian Version of the Neck Disability Index (NDI), and patient satisfaction during follow-up. Furthermore, radiological data were evaluated for bone healing. Student's t-test or Fisher's exact test was used between groups, analyzing radiological and clinical results, and level of statistical significance was set at P < 0.05.

Results:

Seventeen patients were female and 40 were male. Twenty-seven patients were included in surgical group (SG) while 30 were included in HV group with a mean follow-up of 37.74 ± 10.52 months. A significant difference (P < 0.05) between groups was found for pseudoarthrosis, with a lower rate for SG. No significant differences in term of VAS, NDI, and SWS were found between groups (P > 0.05); SG reached higher satisfaction than HV group (P = 0.0271).

Conclusions:

Both treatments are equivalent in terms of clinical outcomes, and they are a valuable choice in the management of type II odontoid fracture. However, it must be considered that patients could slightly tolerate HV and may need a change of treatment.