Screw-Related Complications After Instrumentation of the Osteoporotic Spine: A Systematic Literature Review With Meta-Analysis

Application of radiomics model based on lumbar computed tomography in diagnosis of elderly osteoporosis

A metabolic bone disease characterized by decreased bone formation and increased bone resorption is osteoporosis. It can cause pain and fracture of patients. The elderly are prone to osteoporosis and are more vulnerable to osteoporosis. In this study, radiomics are extracted from computed tomography (CT) images to screen osteoporosis in the elderly. Collect the plain scan CT images of lumbar spine, cut the region of interest of the image and extract radiomics features, use Lasso regression to screen variables and adjust complexity, use python language to model random forests, support vector machines, K nearest neighbor, and finally use receiver operating characteristic curve to evaluate the performance of the model, including precision, recall, accuracy and area under the curve (AUC). For the model, 14 radiolomics features were selected. The diagnosis performance of random forest model and support vector machine is good, all around 0.9. The AUC of K nearest neighbor model in training set and test set is 0.828 and 0.796, respectively. We selected the plain scan CT images of the elderly lumbar spine to build radiomics features model, which has good diagnostic performance and can be used as a tool to assist the diagnosis of osteoporosis in the elderly.

A Biomechanics-Aware Robot-Assisted Steerable Drilling Framework for Minimally Invasive Spinal Fixation Procedures

In this paper, we propose a novel biomechanics-aware robot-assisted steerable drilling framework with the goal of addressing common complications of spinal fixation procedures occurring due to the rigidity of drilling instruments and implants. This framework is composed of two main unique modules to design a robotic system including (i) a Patient-Specific Biomechanics-aware Trajectory Selection Module used to analyze the stress and strain distribution along an implanted pedicle screw in a generic drilling trajectory (linear and/or curved) and obtain an optimal trajectory; and (ii) a complementary semi-autonomous robotic drilling module that consists of a novel Concentric Tube Steerable Drilling Robot (CT-SDR) integrated with a seven degree-of-freedom robotic manipulator. This semi-autonomous robot-assisted steerable drilling system follows a multi-step drilling procedure to accurately and reliably execute the optimal hybrid drilling trajectory (HDT) obtained by the Trajectory Selection Module. Performance of the proposed framework has been thoroughly analyzed on simulated bone materials by drilling various trajectories obtained from the finite element-based Selection Module using Quantitative Computed Tomography (QCT) scans of a real patient's vertebra.

Biomechanical Properties of Novel Porous Scaffold Core and Hollow Lateral Hole Pedicle Screws: A Comparative Study in Bama Pigs

OBJECTIVE

Screw loosening is a common complication of internal fixation of pedicle screw. Therefore, the development of a pedicle screw with low loosening rate and high biosafety is of great clinical significance. This study aimed to investigate whether the application of a porous scaffold structure can improve the stability of pedicle screws by comparing the biomechanical properties of novel porous scaffold core pedicle screws (PSCPSs) with those of hollow lateral hole pedicle screws (HLHPSs) in a porcine lumbar spine.

METHODS

Thirty-two pedicle screws of both types were implanted bilaterally into the L1-4 vertebrae of four Bama pigs, with our newly designed PSCPSs on the right and HLHPSs on the left. All the Bama pigs were sacrificed 16 weeks postoperatively, and the lumbar spine was freed into individual vertebrae. Biomechanical properties of both the pedicle screws were evaluated using pull-out tests, as well as cyclic bending and pull-out tests, while the mechanical properties were assessed using three-point bending tests. The data generated were statistically analyzed using paired-sample t-tests and two independent sample t-tests.

RESULTS

We found that the maximal pull-out forces before and after cyclic bending of the PSCPSs (1161.50 ± 337.98 N and 1075.25 ± 223.33 N) were significantly higher than those of the HLHPSs (948.38 ± 194.32 N and 807.13 ± 242.75 N) (p < 0.05, p < 0.05). In 800 cycles of the bending tests, neither PSCPS nor HLHPS showed loosening or visible detachment, but their maximal pull-out forces after cyclic bending tests decreased compared to those in cycles without cyclic bending tests (7.43% and 14.89%, respectively), with no statistical significance (p > 0.05 and p > 0.05, respectively). Additionally, both screws buckled rather than broke in the three-point bending tests, with no statistically significant differences between the maximal bending load and modulus of elasticity of the two screws (p > 0.05 and p > 0.05, respectively).

CONCLUSIONS

Compared with the HLHPSs, the PSCPSs have greater pull-out resistance and better fatigue tolerance with appropriate mechanical properties. Therefore, PSCPSs theoretically have significant potential for clinical applications in reducing the incidence of loosening after pedicle screw implantation.

Effect of bone density on the drill-hole diameter made by a cannulated drill bit in cancellous bone

BACKGROUND

When a pilot hole is made prior to a screw's insertion into bone, the same drill bit is used irrespective of the bone quality. However, osteoporotic bone is fragile and this may affect the hole diameter, which is of particular concern in cancellous bone. In this study, the relationship between bone density and drill-hole diameter was investigated assuming a pre-drilling process in screw-only osteosynthesis in the metaphysis and epiphysis.

METHODS

Two types of drill bit (triple-flute [T] and quadruple-flute [Q]) with different shapes and diameters were prepared: type T bits with 3.5 mm and 4.4 mm diameters, and type Q bits with 3.5 mm and 4.2 mm diameters. Drilling was performed manually in simulated bones with four densities: 5, 10, 15, and 20 pounds per cubic foot. We measured the hole diameters with a coordinate measuring machine and analyzed the relationship between the drill-hole diameters and the densities of the simulated bones. We then compared the screw pull-out strength between the two 3.5-diameter drill bits.

RESULTS

In all cases, the diameters of the drill holes were larger than those of the drill bits. The relationship between the drill-hole diameters and the bone densities was a negative linear correlation. Enlarging the hole diameter decreased the screw pull-out strength.

CONCLUSIONS

For cannulated drill bits of 3.5, 4.2 and 4.4 mm diameter, the diameter of the drill hole in cancellous bone obtained by the manual drilling technique tends to be larger in low-density (e.g., osteoporotic) compared to high-density (e.g., healthy) bone.

[Osteoporotic vertebral fractures of the thoracic and lumbar spine]

The frequency of osteoporotic vertebral fractures in the clinical routine is increasing due to the demographic change. They are the most frequent fractures associated with osteoporosis and affect an especially morbid and vulnerable group of patients. These fractures often occur after minor trauma or spontaneously. Pain is the predominant symptom, whereas mechanical stability is mostly sufficient, in comparison to vertebral fractures after high-energy trauma, and is not a predominant indication for surgery. These fractures can be described using the classification for fractures associated with osteoporosis and the corresponding treatment recommendations are guided by them. Besides the specific treatment of osteoporotic vertebral fractures, a holistic treatment of patients taking pre-existing comorbidities into consideration is decisive. A mobilization as quickly as possible and treatment of the underlying osteoporosis are important to prevent further fractures.

Zinc based biodegradable metals for bone repair and regeneration: Bioactivity and molecular mechanisms

Bone fractures and critical-size bone defects are significant public health issues, and clinical treatment outcomes are closely related to the intrinsic properties of the utilized implant materials. Zinc (Zn)-based biodegradable metals (BMs) have emerged as promising bioactive materials because of their exceptional biocompatibility, appropriate mechanical properties, and controllable biodegradation. This review summarizes the state of the art in terms of Zn-based metals for bone repair and regeneration, focusing on bridging the gap between biological mechanism and required bioactivity. The molecular mechanism underlying the release of Zn ions from Zn-based BMs in the improvement of bone repair and regeneration is elucidated. By integrating clinical considerations and the specific bioactivity required for implant materials, this review summarizes the current research status of Zn-based internal fixation materials for promoting fracture healing, Zn-based scaffolds for regenerating critical-size bone defects, and Zn-based barrier membranes for reconstituting alveolar bone defects. Considering the significant progress made in the research on Zn-based BMs for potential clinical applications, the challenges and promising research directions are proposed and discussed.

Torque forces of expandable titanium vertebral body replacement cages during expansion and subsidence in the osteoporotic lumbar spine

BACKGROUND

The application of expandable titanium-cages has gained widespread use in vertebral body replacement for indications such as burst fractures, tumors and infectious destruction. However, torque forces necessary for a satisfactory expansion of these implants and for subsidence of them into the adjacent vertebrae are unknown within the osteoporotic spine.

METHODS

Six fresh-frozen human, osteoporotic, lumbar spines were dorsally instrumented with titanium implants (L2-L4) and a partial corpectomy of L3 was performed. An expandable titanium-cage was inserted ventrally and expanded by both residents and senior surgeons until fixation was deemed sufficient, based on haptic feedback. Torque forces for expansion were measured in Nm. Expansion was then continued until cage subsidence occurred. Torque forces necessary for subsidence were recorded. Strain of the dorsal rods during expansion was measured with strain gauges.

FINDINGS

The mean torque force for fixation of cages was 1.17 Nm (0.9 Nm for residents, 1.4 Nm for senior surgeons, p = .06). The mean torque force for subsidence of cages was 3.1 Nm (p = .005). Mean peak strain of the dorsal rods was 970 μm/m during expansion and 1792 μm/m at subsidence of cages (p = .004).

INTERPRETATION

The use of expandable titanium-cages for vertebral body replacement seems to be a primarily safe procedure even within the osteoporotic spine as torque forces required for subsidence of cages are nearly three times higher than those needed for fixation. Most of the expansion load is absorbed by straining of the dorsal instrumentation. Rod materials other than titanium may alter the torque forces found in this study.

Clinical and Economic Outcomes of Patients with Osteoporosis Undergoing Spine Fusion Surgery in Japan

Introduction

Spinal fusion surgery with instrumentation is a treatment of choice for many spinal disorders; however, there is little data related to factors associated with early and late outcomes, especially among patients with poor bone quality (e.g., osteoporosis). We conducted this study to characterize the epidemiology and outcomes of patients undergoing spinal fusion surgery with instrumentation in Japan, especially in patients with poor bone quality and those needing additional fixation methods.

Methods

This retrospective observational study used real-world health insurance claims data from the Japanese Medical Data Vision. Adult patients undergoing an index spinal fusion procedure from April 1, 2010, to September 30, 2017, with procedural details, length of stay (LOS), total in-hospital costs, spine-related reoperation, all-cause readmission, and postoperative complications recorded. Data were summarized descriptively overall, by osteoporosis status, and additional fixation method used, and were analyzed in bivariate analyses. Multivariate logistic and linear regressions were used to explore associations between covariates and variables of interest.

Results

A total of 22,932 patients (mean age, 67.3 years; 51.2% male) met the study criteria and were included. A total of 5,288 (23.0%) patients had osteoporosis, and 2,507 (10.9%) needed additional fixation methods; these patients were older, more frequently female, and had higher Elixhauser comorbidity index scores. Osteoporosis and additional fixation use were also associated with longer LOS, higher hospital costs, and higher rates of complications.

Conclusions

Patients with osteoporosis and those needing additional fixation methods have a higher risk for procedural and postoperative complications, reoperation, longer LOS, and higher total hospital costs.

Longitudinal Study on Pre- and Post-Operation CT Imaging for Predicting Pedicle Screw Loosening in Patients with Lumbar Degenerative Disease

Purpose

We conducted a longitudinal study to examine the predictive role of risk factors in the occurrence of pedicle screw loosening, assessed through pre- and post-operative computed tomography (CT) scans.

Methods

A total of 103 patients with degenerative lumbar disease who had undergone L4/5 pedicle screw fixation (involving 412 screws) were included in this study. They were subsequently categorized into two groups-the "loosening group" and the "non-loosening group". The axial and sagittal angles of the screw trajectory in pre- and post-operative CT images were measured, and the deviation angles were computed. Additionally, measurements were taken of the Hounsfield unit (HU) within the screw entry point area, the pedicle, and the vertebral body in preoperative CT images. Logistic regression analysis was employed to ascertain the risk factors influencing the occurrence of screw loosening.

Results

Elderly patients who experienced screw loosening tended to have bilateral screw issues at the L5 level (p < 0.005). The HU of the pedicle (p < 0.001), age (p < 0.001), and the axial deviation angle (p = 0.014) were identified as independent factors predicting screw loosening. Additionally, when HU of the pedicle < 126.5 or age ≥ 53.5 years, the axial deviation angle was found to be smaller in the group experiencing screw loosening (p = 0.018 and p = 0.019).

Conclusion

Loosening of screws positioned at L5 was found to be more prevalent in elderly patients, particularly exhibiting a bilateral occurrence. Independent predictors of this phenomenon included a low HU value in the pedicle, advanced age in patients, and a substantial axial deviation angle. In the case of elderly patients with a low HU value in the pedicle, a reduced axial surgical deflection was necessitated to prevent the occurrence of screw loosening.

Skeletal Status in Patients Scheduled for Elective Lumbar Spine Surgery: Comparison of Discectomy, Decompression, Fusion, and Revision

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVES

To investigate and compare the prevalence of low bone mineral density (BMD) and abnormal laboratory bone metabolism parameters in patients undergoing elective primary discectomy, decompression, and fusion and to outline possible differences in these parameters between patients undergoing revision for skeletal vs non-skeletal complications.

METHODS

We retrospectively evaluated BMD measurements by dual-energy x-ray absorptiometry (DXA) in 389 consecutive patients scheduled for elective lumbar spine surgery. Next to demographic characteristics, laboratory bone metabolism parameters were assessed. Group comparisons were performed between primary discectomy, decompression, and fusion. In patients scheduled for revision surgery after fusion, potential differences in the skeletal status between those with skeletal vs non-skeletal complications were analyzed.

RESULTS

Osteoporosis by T-score was detected in 6.7%, 11.0% and 14.7% of the patients undergoing discectomy, decompression and fusion, respectively. While vitamin D deficiency (67.6%) and hyperparathyroidism (16.4%) were frequently detected, no differences in laboratory bone metabolism markers could be found between the groups. Female sex (P<.001), higher age (P=.01) and lower BMI (P<.001) were associated with lower BMD. In the cohort of patients undergoing revision surgery due to complications after fusion, those with skeletal complications did not differ in BMD or bone metabolism from those with non-skeletal complications.

CONCLUSIONS

Osteoporosis represents a relevant comorbidity in patients scheduled for elective spine surgery, which is why DXA should be routinely performed in these patients. However, DXA may provide limited information in identifying patients at increased risk for skeletal complications after fusion.

Increased stability due to symmetric cement volume in augmented pedicle screws? A biomechanical study

Pedicle screw instrumentation has become "state of the art" in surgical treatment of many spinal disorders. Loosening of pedicle screws due to poor bone mineral density is a frequent complication in osteoporotic patients. As prevalence of osteoporosis and spinal disorders are increasing with an aging demographic, optimizing the biomechanical properties of pedicle screw constructions and therefore outcome after spinal surgery in osteoporotic patients is a key factor in future surgical therapy. Therefore, this biomechanical study investigated the stability of polymethylmethacrylate (PMMA)-augmented pedicle screw-rod constructions under a deviating distribution of PMMA applied to the instrumentation in osteoporotic human cadaveric vertebrae. We showed that PMMA-augmented pedicle screw-rod constructions tend to be more stable than those with non-augmented pedicle screws. Further, there appears to be a larger risk of screw loosening in unilateral augmented pedicle screws than in non-augmented, therefore a highly asymmetrically distributed PMMA should be avoided.

Biomechanical Study of 3 Osteoconductive Materials Applied in Pedicle Augmentation and Revision for Osteoporotic Vertebrae: Allograft Bone Particles, Calcium Phosphate Cement, Demineralized Bone Matrix

OBJECTIVE

This study assessed biomechanical properties of pedicle screws enhanced or revised with 3 materials. We aimed to compare the efficacy of these materials in pedicle augmentation and revision.

METHODS

One hundred twenty human cadaveric vertebrae were utilized for in vitro testing. Vertebrae bone density was evaluated. Allograft bone particles (ABP), calcium phosphate cement (CPC), and demineralized bone matrix (DBM) were used to augment or revise pedicle screw. Post the implantation of pedicle screws, parameters such as insertional torque, pullout strength, cycles to failure and failure load were measured using specialized instruments.

RESULTS

ABP, CPC, and DBM significantly enhanced biomechanical properties of the screws. CPC augmentation showed superior properties compared to ABP or DBM. ABP-augmented screws had higher cycles to failure and failure loads than DBM-augmented screws, with no difference in pullout strength. CPC-revised screws exhibited similar strength to the original screws, while ABP-revised screws showed comparable cycles to failure and failure loads but lower pullout strength. DBM-revised screws did not match the original screws' strength.

CONCLUSION

ABP, CPC, and DBM effectively improve pedicle screw stability for pedicle augmentation. CPC demonstrated the highest efficacy, followed by ABP, while DBM was less effective. For pedicle revision, CPC is recommended as the primary choice, with ABP as an alternative. However, using DBM for pedicle revision is not recommended.

The Effect of Halo-Pelvic Traction on Bone Mineral Density of Vertebrae and Corresponding Risk Factors

OBJECTIVES

Decreased bone mineral density (BMD) is associated with complications in implantation surgery for severe spinal deformity. In this quantitative study, we aimed to investigate the impact of halo-pelvic traction on vertebral bone mineral density (BMD) and identify the risk factors for a decrease in BMD.

METHODS

Patients who underwent halo-pelvic traction at our hospital between 2019 and 2022 were included in the study. Patients' data, including height, weight, and BMD pre- and post-traction, were collected and analyzed. Quantitative computed tomography (QCT) was used to determine the BMD. The paired rank sum test was used to evaluate the changes in each measurement parameter. Linear regression was used to identify risk factors for a decrease in BMD.

RESULTS

Fifteen patients were included in the study, nine women and six men, with an average age of 21.2 ± 7.3 years. Eleven patients had severe rigid scoliosis, while four had tuberculotic kyphosis. One expert measured the BMD values of 345 vertebrae using QCT. The average traction time was 143.3 ± 44.4 days. The average pre-traction BMD was 183.1 ± 73.8 mg/cm3 , and the average post-traction BMD was 140.5 ± 61.3 mg/cm3 (p < 0.01) Patients' height increased from an average of 151.3 ± 12.8 cm pre-traction to 165.5 ± 13.7 cm post-traction (p < 0.01), with traction length averaging 14.3 ± 6.2 cm (p < 0.01). The Cobb angle of the main curve declined from an average of 112.5° ± 24.4° pre-traction to 67.7° ± 19.8° post-traction (p < 0.01). Linear regression revealed a positive correlation between BMD loss and traction length and a negative correlation between BMD loss and correction rate.

CONCLUSIONS

Halo-pelvic traction can lead to a decrease in the BMD of the spinal vertebrae, with traction length positively correlated with BMD loss and correction rate negatively correlated with BMD loss. To prevent osteoporosis, physicians should ensure a limited traction length while utilizing better management techniques.

Enhanced Recovery After Surgery Protocols and Spinal Deformity

The authors outline a review of preoperative, intraoperative, and postoperative considerations surrounding adult spinal deformity. Preoperative management topics include imaging, hemoglobin A1c levels before spine surgery, osteoporotic management, and prehabilitation. Topics surrounding intraoperative management include the use of antibiotics, liposomal bupivacaine, and Foley catheters. The authors also discuss postoperative questions surrounding analgesia, nausea and vomiting, thromboembolic prophylaxis, and early mobilization. Throughout their discussion, the authors incorporate enhanced recovery after surgery protocols to hopefully lead to future discussions regarding optimizing complex spinal patients.

Effect of Zoledronic Acid on the Vertebral Body Bone Mineral Density After Instrumented Intervertebral Fusion in Postmenopausal Women With Osteoporosis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To evaluate the effect of zoledronic acid, an anti-osteoporosis treatment, during the perioperative period on vertebral body bone mineral density (BMD) after spinal fusion surgery in postmenopausal women with osteoporosis.

METHODS

The medical records of postmenopausal patients with osteoporosis who underwent instrumented intervertebral fusion for lumbar degenerative disease between July 2016 and May 2018 were reviewed. Patients with comorbidities or condition which might affect bone metabolism were excluded. Forty-six patients did not receive anti-osteoporosis treatment before surgery and during the postoperative follow-up (untreated group). Another 46 patients who was treated with zoledronic acid perioperatively were matched for age and body mass index to patients in the untreated group. Preoperative and postoperative dual-energy X-ray absorptiometry (DEXA) records and lumbar BMD values of the involved spinal segments and of the cephalad levels, as well as of the femoral neck were recorded.

RESULTS

A significant decrease of cephalad vertebral BMD values was observed in the untreated group (-11.47%, P < 0.001), with a slight decrease of the femoral neck (-1.28%, P > 0.05). Zoledronic acid prevented rapid bone loss after instrumented intervertebral fusion surgery, with a bone loss in the cephalad levels of -0.76 ± 4.71% compared to -11.47 ± 16.45% in the untreated group (P < 0.001). while the change in BMD of the femoral neck in the treated group was 1.52 ± 5.88% compared to -1.28 ± 6.58% in the untreated group (P = 0.036).

CONCLUSIONS

Perioperative zoledronic acid treatment may offer protection against a significant decrease in BMD of cephalad vertebrae after spinal fusion surgery among postmenopausal women with osteoporosis.

Pedicle screw augmentation in posterior constructs of the thoracolumbar spine: How many pedicle screws should be augmented?

BACKGROUNDS

To evaluate the effects of different pedicle screw augmentation strategies on screw loosening and adjacent segment collapse at the proximal end of long-segment instrumentation.

METHODS

Eighteen osteoporotic (9 male, 9 female donors; mean age: 74.7 ± 10.9 [SD] years) thoracolumbar multi-segmental motion segments (Th11 - L1) were assigned as follows: control, one-level augmented screws (marginally), and two-level augmented screws (fully augmented) groups (3 × 6). Pedicle screw placement was performed in Th12 and L1. Cyclic loading in flexion started with 100-500 N (4 Hz) and was increased by 5 N every 500 cycles. Standardized lateral fluoroscopy images with 7.5 Nm loading were obtained periodically during loading. The global alignment angle was measured to evaluate the overall alignment and proximal junctional kyphosis. The intra-instrumental angle was used to evaluate screw fixation.

FINDINGS

Considering screw fixation as a failure criterion, the failure loads of the control (683 N), and marginally (858 N) and fully augmented (1050 N) constructs were significantly different (ANOVA p = 0.032).Taking the overall specimen alignment as failure criteria, failure loads of the three groups (control 933 ± 271.4 N, marginally 858 N ± 196 N, and full 933 ± 246.3 N were in the same range and did not show any significance (p = 0.825).

INTERPRETATION

Global failure loads were comparable among the three groups and unchanged with augmentation because the adjacent segment and not the instrumentation failed first. Augmentation of all screws showed significant improved in screw anchorage.

Georg Schmorl prize of the German spine society (DWG) 2022: current treatment for inpatients with osteoporotic thoracolumbar fractures-results of the EOFTT study

AIM

Osteoporotic thoracolumbar fractures are of increasing importance. To identify the optimal treatment strategy this multicentre prospective cohort study was performed.

PURPOSE

Patients suffering from osteoporotic thoracolumbar fractures were included. Excluded were tumour diseases, infections and limb fractures. Age, sex, trauma mechanism, OF classification, OF-score, treatment strategy, pain condition and mobilization were analysed.

METHODS

A total of 518 patients' aged 75 ± 10 (41-97) years were included in 17 centre. A total of 174 patients were treated conservatively, and 344 were treated surgically, of whom 310 (90%) received minimally invasive treatment. An increase in the OF classification was associated with an increase in both the likelihood of surgery and the surgical invasiveness.

RESULTS

Five (3%) complications occurred during conservative treatment, and 46 (13%) occurred in the surgically treated patients. 4 surgical site infections and 2 mechanical failures requested revision surgery. At discharge pain improved significantly from a visual analogue scale score of 7.7 (surgical) and 6.0 (conservative) to a score of 4 in both groups (p < 0.001). Over the course of treatment, mobility improved significantly (p = 0.001), with a significantly stronger (p = 0.007) improvement in the surgically treated patients.

CONCLUSION

Fracture severity according to the OF classification is significantly correlated with higher surgery rates and higher invasiveness of surgery. The most commonly used surgical strategy was minimally invasive short-segmental hybrid stabilization followed by kyphoplasty/vertebroplasty. Despite the worse clinical conditions of the surgically treated patients both conservative and surgical treatment led to an improved pain situation and mobility during the inpatient stay to nearly the same level for both treatments.

Treatment and Outcome of Osteoporotic Thoracolumbar Vertebral Body Fractures With Deformation of Both Endplates With or Without Posterior Wall Involvement (OF 4): Short-Term Results from the Prospective EOFTT Multicenter Study

STUDY DESIGN

Multicenter prospective cohort study.

OBJECTIVE

To analyse therapeutical strategies applied to osteoporotic thoracolumbar OF 4 injuries, to assess related complications and clinical outcome.

METHODS

A multicenter prospective cohort study (EOFTT) including 518 consecutive patients who were treated for an Osteoporotic vertebral compression fracture (OVCF). For the present study, only patients with OF 4 fractures were analysed. Outcome parameters were complications, Visual Analogue Scale, Oswestry Disability Questionnaire, Timed Up & Go test, EQ-5D 5L, and Barthel Index after a minimum follow-up of 6 weeks.

RESULTS

A total of 152 (29%) patients presented with OF 4 fractures with a mean age of 76 years (range 41-97). The most common treatment was short-segment posterior stabilization (51%; hybrid stabilization in 36%). Mean follow up was 208 days (±131 days), mean ODI was 30 ± 21. Dorsoventral stabilized patients were younger compared to the other groups (P < .001) and had significant better TuG compared to hybrid stabilization (P = .049). The other clinical outcomes did not differ in the therapy strategies (VAS pain: P = 1.000, ODI: P > .602, Barthel: P > .252, EQ-5D 5L index value: P > .610, VAS-EQ-5D 5L: P = 1.000). The inpatient complication rate was 8% after conservative and 16% after surgical treatment. During follow-up period 14% of conservatively treated patients and 3% of surgical treated patients experienced neurological deficits.

CONCLUSIONS

Conservative therapy of OF 4 injuries seems to be viable option in patients with only moderate symptoms. Hybrid stabilization was the dominant treatment strategy leading to promising clinical short-term results. Stand-alone cement augmentation seems to be a valid alternative in selected cases.

Treatment and Outcome of Osteoporotic Thoracolumbar Vertebral Fractures With Anterior or Posterior Tension Band Failure (OF 5): Short-Term Results From the Prospective EOFTT Multicenter Study

STUDY DESIGN

Subgroup analysis of a multicenter prospective cohort study.

OBJECTIVE

To analyse surgical strategies applied to osteoporotic thoracolumbar osteoporotic fracture (OF) 5 injuries with anterior or posterior tension band failure and to assess related complications and clinical outcome.

METHODS

A multicenter prospective cohort study (EOFTT) was conducted at 17 spine centers including 518 consecutive patients who were treated for an osteoporotic vertebral fracture (OVF). For the present study, only patients with OF 5 fractures were analysed. Outcome parameters were complications, Visual Analogue Scale (VAS), Oswestry Disability Questionnaire (ODI), Timed Up & Go test (TUG), EQ-5D 5L, and Barthel Index.

RESULTS

In total, 19 patients (78 ± 7 years, 13 female) were analysed. Operative treatment consisted of long-segment posterior instrumentation in 9 cases and short-segment posterior instrumentation in 10 cases. Pedicle screws were augmented in 68 %, augmentation of the fractured vertebra was performed in 42%, and additional anterior reconstruction was done in 21 %. Two patients (11 %) received short-segment posterior instrumentation without either anterior reconstruction or cement-augmentation of the fractured vertebra. No surgical or major complications occurred, but general postoperative complications were observed in 45%. At a follow-up of mean 20 ± 10 weeks (range, 12 to 48 weeks), patients showed significant improvements in all functional outcome parameters.

CONCLUSIONS

In this analysis of patients with type OF 5 fractures, surgical stabilization was the treatment of choice and lead to significant short-term improvement in terms of functional outcome and quality of life despite a high general complication rate.

Avoiding Spinal Implant Failures in Osteoporotic Patients: A Narrative Review

STUDY DESIGN

Narrative review.

OBJECTIVES

With an aging population, the prevalence of osteoporosis is continuously rising. As osseous integrity is crucial for bony fusion and implant stability, previous studies have shown osteoporosis to be associated with an increased risk for implant failure and higher reoperation rates after spine surgery. Thus, our review's purpose was to provide an update of evidence-based solutions in the surgical treatment of osteoporosis patients.

METHODS

We summarize the existing literature regarding changes associated with decreased bone mineral density (BMD) and resulting biomechanical implications for the spine as well as multidisciplinary treatment strategies to avoid implant failures in osteoporotic patients.

RESULTS

Osteoporosis is caused by an uncoupling of the bone remodeling cycle based on an unbalancing of bone resorption and formation and resulting reduced BMD. The reduction in trabecular structure, increased porosity of cancellous bone and decreased cross-linking between trabeculae cause a higher risk of complications after spinal implant-based surgeries. Thus, patients with osteoporosis require special planning considerations, including adequate preoperative evaluation and optimization. Surgical strategies aim towards maximizing screw pull-out strength, toggle resistance, as well as primary and secondary construct stability.

CONCLUSIONS

As osteoporosis plays a crucial role in the fate of patients undergoing spine surgery, surgeons need to be aware of the specific implications of low BMD. While there still is no consensus on the best course of treatment, multidisciplinary preoperative assessment and adherence to specific surgical principles help reduce the rate of implant-related complications.

Vertebral Augmentation in Spine Surgery

Vertebral augmentation has been a well-studied adjunct percutaneous procedure in spine surgery. Cement augmentation has been used in the treatment of compression fractures through kyphoplasties or vertebroplasties. Historically, data have shown no difference between treating compression fractures conservatively versus with percutaneous cement augmentation procedures. Recent literature has shown improvement in patient outcomes and increase in mobility with percutaneous cement augmentation procedures. Cement augmentation has been used in treating patients with spinal column fractures in higher energy trauma. Cement augmentation has shown to have a reduction in local kyphosis, improved pain, and significant height restoration of the anterior column in patients with burst fractures. Augmentation has been used in spinal deformity surgery, specifically to attempt to reduce the risk of proximal junctional kyphosis and to decrease the risk of screw pullout with cement augmented fenestrated screws in patients with osteoporosis. In pathologic compression fractures, cement augmentation is a safe, viable intervention to improve pain control in these patients. This review will go into the new advances of vertebral augmentation and indications for use in treatment today.

Use of MRI-based vertebral bone quality score (VBQ) of S1 body in bone mineral density assessment for patients with lumbar degenerative diseases

PURPOSE

To evaluate the use of the modified and simplified vertebral bone quality (VBQ) method based on T1-weighted MRI images of S1 vertebrae in assessing bone mineral density (BMD) for patients with lumbar degenerative diseases.

METHODS

We reviewed the preoperative data of patients with lumbar degenerative diseases undergoing lumbar spine surgery between January 2019 and June 2022 with available non-contrast T1-weighted magnetic resonance imaging (MRI), computed tomography (CT) images and dual-energy X-ray absorptiometry (DEXA). S1 vertebral bone quality scores (S1 VBQ) and S1 CT Hounsfield units were measured with picture archiving and communication system (PACS). One-way ANOVA was applied to present the discrepancy between the S1 VBQ of patients with normal bone density (T-score ≥ - 1.0), osteopenia (- 2.5 < T-score < - 1.0) and osteoporosis (T-score ≤ - 2.5). The receiver operating characteristic curve (ROC) was drawn to analyze the diagnostic performance of S1 VBQ in distinguishing low BMD. Statistical significance was set at p < 0.05.

RESULTS

A total of 207 patients were included. The S1 VBQ were significantly different between groups (p < 0.001). Interclass correlation coefficient for inter-rater reliability was 0.86 (95% CI 0.78-0.94) and 0.94(95% CI 0.89-0.98) for intra-rater reliability. According to the linear regression analysis, the S1 VBQ has moderate-to-strong correlations with DEXA T-score (r = - 0.48, p < 0.001). The area under the ROC curve indicated a predictive accuracy of 82%. A sensitivity of 77.25% with a specificity of 70% could be achieved for distinguishing low BMD by setting the S1 VBQ cutoff as 2.93.

CONCLUSIONS

The S1 VBQ was a promising tool in distinguishing poor bone quality in patients with lumbar degenerative diseases, especially in cases where the previously reported VBQ method based on L1-L4 was not available. S1 VBQ score could be useful as opportunistic assessment for screening and complementary evaluation to DEXA T-score before surgery.

Clinical Trial for the Safety and Feasibility of Pedicle Screws Coated with a Fibroblast Growth Factor-2-Apatite Composite Layer for Posterior Cervical Fusion Surgery

To solve the instrument loosening problem, we developed a fibroblast growth factor-2-calcium phosphate composite layer as a novel coating material to improve screw fixation strength. The primary aim of the present study was to demonstrate the safety and feasibility of screws coated with the FGF-2-calcium phosphate composite layer for posterior instrumented surgery of the cervical spine. The trial design was a single-arm, open-label, safety and feasibility study. Patients receiving fusion of the cervical spine from C2 (or C3) to C7 (or T1) were recruited. The primary endpoint to confirm safety was any screw-related adverse events. Seven patients who underwent posterior fusion surgery of the cervical spine were enrolled in the present study. The coated pedicle screws were inserted bilaterally into the lowest instrumented vertebrae. There was only one severe adverse event unrelated with the coated screw. Three out of the fourteen coated screws showed loosening. The present results prove the safety and feasibility of pedicle screws coated with the FGF-2-calcium phosphate composite layer for fusion surgery in the cervical spine. This is the first step to apply this novel surface coating in the field of spine surgery.

Computed Tomography-Based Prediction of Lumbar Pedicle Screw Loosening

Objective

Pedicle screw loosening is one of the main complications after pedicle screw fixation. However, there are few reliable measures for prediction of screw loosening. The current study was carried out to find an effective method to use preoperative CT scanning as a predictor of screw loosening in the elderly patients and provide guidance for preoperative surgical planning.

Methods

Patients who were treated with lumbar pedicle screw fixation procedure in our department for degenerative lumbar disorders between January 2015 and January 2021 were retrospectively included in the current study. CT scan attenuation of each vertebra was measured with Hounsfield units (HU). Screw loosening was determined in postoperatively X-ray tests. One-way analysis of variance (ANOVA) and receiver operating characteristic (ROC) curve analysis were carried out with IBMSPSS 24.00 software.

Results

Screw loosening was observed in 44 of 215 patients (124 male, 91 female, average age 58.4 ± 7.6 years) during a mean follow-up time of 19.0 ± 11.2 months (range 12-32 months). No significant differences were found among the patients concerning patient gender, BMI, habit of smoking, and whether or not the patient had diabetes or suffered from spondylolisthesis (P > 0.05). The average HU value of lumbar vertebra was 122.4 ± 32.8 HU in the screw loosening group and 142.4 ± 38.2 HU in the control group, and the difference was significant (P < 0.01). ROC curve analysis revealed that the average HU value of L1-L5 has a relatively larger area under the curve (AUC) of 0.689 (95% CI: 0.605-0.773). With the sensitivity of 68% and specificity of 57%, a HU cut-off value of ≤124 HU is a plausible cut-off point to predict screw loosening.

Conclusions

A prospective CT scan HU value-based prediction can be used to decide whether or not to use screw augmentation methods. A cut-off L1-L5 average HU value of 124 HU can be used as an independent risk factor for screw loosening in instrumented lumbar vertebra. More predictive indexes should be involved to achieve higher sensitivity and specificity in future clinical practice.

MRI-Based Score for Assessment of Bone Mineral Density in Operative Spine Patients

STUDY DESIGN

Retrospective comparison.

OBJECTIVE

The aim was to determine whether a previously developed magnetic resonance imaging (MRI)-derived bone mineral density (BMD) scoring system can differentiate between healthy and osteoporotic vertebrae and to validate this scoring system against quantitative computed tomography measurements.

SUMMARY OF BACKGROUND DATA

BMD is an important preoperative consideration in spine surgery. Techniques to measure BMD are subject to falsely elevated values in the setting of spondylosis (dual-energy X-ray absorptiometry) or require significant exposure to radiation [quantitative computed tomography (QCT)]. Previous studies have shown that MRI may be utilized to measure bone quality using changes in the bone marrow signal observed on T1-weighted MRIs.

MATERIALS AND METHODS

Retrospective study of patients who underwent operative lumbar procedures at a single tertiary institution between 2016 and 2021 (n=61). Vertebral bone quality (VBQ) scores were measured by dividing the median signal intensities of L1-L4 by the signal intensity of cerebrospinal fluid on noncontrast T1W MRI. Demographic data, comorbidities, VBQ scores, and QCT-derived T scores and BMD of the lumbar spine were compared between healthy ( T score ≥-1; n=21), osteopenic (-2.5 < T score < -1; n=21), and osteoporotic ( T score ≤-2.5; n=19) cohorts using analysis of variance with post hoc Tukey test. Linear regression and receiver operating characteristic curve analyses were performed to assess the predictive value of VBQ scores. Pearson correlation test was used to evaluate the association between VBQ scores and QCT-derived measurements.

RESULTS

VBQ differentiated between healthy and osteoporotic groups ( P =0.009). Receiver operating characteristic curve analysis revealed that a greater VBQ score was associated with presence of osteoporosis (area under the curve=0.754, P =0.006). Cutoff VBQ for osteoporosis was 2.6 (Youden index 0.484; sensitivity: 58%; specificity: 90%). VBQ scores weakly correlated with QCT-derived BMD ( P =0.03, r =-0.27) and T scores ( P =0.04, r =-0.26).

CONCLUSION

This study attempted to further validate a previously developed MRI-based BMD scoring system against QCT-derived measurements. VBQ score was found to be a significant predictor of osteoporosis and could differentiate between healthy and osteoporotic vertebrae.

Comparison of cervical, thoracic, and lumbar vertebral bone quality scores for increased utility of bone mineral density screening

PURPOSE

To evaluate the associations among the validated lumbar vertebral bone quality (VBQ) score, and cervical and thoracic VBQ scores.

METHODS

Radiographic records of 100 patients who underwent synchronous MRI of the cervical, thoracic, and lumbar spine were retrieved. DEXA-validated lumbar VBQ was calculated using median signal intensity (MSI) of the L1-L4 vertebrae and L3 CSF. VBQ was derived as the quotient of MSI_L1-L4 divided by MSI_CSF. Cervical and thoracic VBQ were similarly obtained using C3-C6 and C5 CSF, and T5-T8 and T7 CSF, respectively. Paired sample t-tests were used to evaluate differences among regional VBQ scores. Independent sample t-tests were used to identify sex differences in VBQ. Regression models with one-way analysis of variance (ANOVA) were constructed to identify associations among all permutations of anthropometric and regional VBQ measures.

RESULTS

Mean cervical, thoracic, and lumbar VBQ scores were 3.06 ± 0.89, 2.60 ± 0.77, and 2.47 ± 0.61, respectively. Mean differences of .127 (p = 0.045) and - 0.595 (p < 0.001) were observed between thoracic and lumbar, and cervical and lumbar VBQ scores. Correlations of 0.324, 0.356, and 0.600 (p < 0.001) were found between cervical and lumbar, cervical and thoracic, and thoracic and lumbar VBQ scores. Regression with ANOVA predicting lumbar VBQ in relation to cervical and thoracic VBQ demonstrated R Square values of 0.105 and 0.360 (p < 0.001), and β coefficient values of 0.471 and 0.217 (p < 0.001), respectively.

CONCLUSION

Thoracic VBQ provides values representative of the validated lumbar VBQ score. Cervical VBQ scores are distinct from lumbar VBQ scores and do not provide adequate surrogate values of lumbar VBQ.

Evaluation of an Injectable Biphasic Calcium Sulfate/Hydroxyapatite Cement for the Augmentation of Fenestrated Pedicle Screws in Osteoporotic Vertebrae: A Biomechanical Cadaver Study

Cement augmentation of pedicle screws is one of the most promising approaches to enhance the anchoring of screws in the osteoporotic spine. To date, there is no ideal cement for pedicle screw augmentation. The purpose of this study was to investigate whether an injectable, bioactive, and degradable calcium sulfate/hydroxyapatite (CaS/HA) cement could increase the maximum pull-out force of pedicle screws in osteoporotic vertebrae. Herein, 17 osteoporotic thoracic and lumbar vertebrae were obtained from a single fresh-frozen human cadaver and instrumented with fenestrated pedicle screws. The right screw in each vertebra was augmented with CaS/HA cement and the un-augmented left side served as a paired control. The cement distribution, interdigitation ability, and cement leakage were evaluated using radiographs. Furthermore, pull-out testing was used to evaluate the immediate mechanical effect of CaS/HA augmentation on the pedicle screws. The CaS/HA cement presented good distribution and interdigitation ability without leakage into the spinal canal. Augmentation significantly enhanced the maximum pull-out force of the pedicle screw in which the augmented side was 39.0% higher than the pedicle-screw-alone side. Therefore, the novel biodegradable biphasic CaS/HA cement could be a promising material for pedicle screw augmentation in the osteoporotic spine.

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.

Incidence and risk factors for early and late reoperation following lumbar fusion surgery

STUDY DESIGN

Retrospective cohort study.

PURPOSE

The aim of our study was to determine the rates and indications of reoperations following primary lumbar fusion, as well as the independent risk factors for early and late reoperation.

METHODS

We retrospectively reviewed patients who underwent lumbar fusion surgery between January 2017 and March 2020. All patients were followed up for more than 2 years. Characteristics, laboratory tests, primary diagnosis and surgery-related variables were compared among the early reoperation (< 3 months), the late reoperation (> 3 months) and the non-reoperation groups. Multivariable logistic regression analysis was used to identify independent risk factors for early and late reoperations.

RESULTS

Of 821 patients included in our studies, 34 patients underwent early reoperation, and 36 patients underwent late reoperation. The cumulative reoperation rate was about 4.1% (95% CI 3.8-4.5%) at 3 months, 6.2% (95% CI 5.9-6.5%) at 1 year and 8.2% (95% CI 8.0-8.5%) at 3 years. Multivariable analysis indicated that osteoporosis (odds ratio [OR] 3.6, 95% CI 1.2-10.5, p = 0.02) and diabetes (OR 2.1, 95% CI 1.1-4.5, p = 0.04) were independently associated with early reoperation and multilevel fusion (OR 2.4, 95% CI 1.1-5.4, p = 0.03) was independently associated with late reoperation.

CONCLUSIONS

The most common reasons for early reoperation and late operation were surgical site infection and adjacent segment diseases, respectively. Osteoporosis and diabetes were independent risk factors for early reoperation, and multilevel fusion was independent risk factor for late reoperation. Surgeons should pay more attention to these patients, and future studies should consider the effects of follow-up periods on results.

[Cement augmentation in spinal surgery]

Bone cement has been used in spinal surgery for as long as 50 years. In contemporary spinal surgery, cement augmentation of fractured osteoporotic vertebrae in the form of vertebroplasty/kyphoplasty as well as cement augmentation of pedicle screws in instrumented procedures of any etiology are established as standard procedures. Both procedures are very effective, although the benefits of vertebroplasty/kyphoplasty procedures have been controversially discussed in the past. Overall, complications rarely occur. The most relevant complication is cement leakage, which is asymptomatic in the majority of cases but in the worst case might lead to neurological deficits, embolic events and even circulatory collapse. Prevention of cement leakage is therefore crucial. Risk factors for cement leakage and preventive measures are presented in a comprehensive review based on the available literature.

Impact of Sarcopenia and Bone Mineral Density on Implant Failure after Dorsal Instrumentation in Patients with Osteoporotic Vertebral Fractures

Background and Objectives: Age-related loss of bone and muscle mass are signs of frailty and are associated with an increased risk of falls and consecutive vertebral fractures. Management often necessitates fusion surgery. We determined the impacts of sarcopenia and bone density on implant failures (IFs) and complications in patients with spondylodesis due to osteoporotic vertebral fractures (OVFs). Materials and Methods: Patients diagnosed with an OVF according to the osteoporotic fracture classification (OF) undergoing spinal instrumentation surgery between 2011 and 2020 were included in our study. The skeletal muscle area (SMA) was measured at the third lumbar vertebra (L3) level using axial CT images. SMA z-scores were calculated for the optimal height and body mass index (BMI) adjustment (zSMA_HT). The loss of muscle function was assessed via measurement of myosteatosis (skeletal muscle radiodensity, SMD) using axial CT scans. The bone mineral density (BMD) was determined at L3 in Hounsfield units (HU). Results: A total of 68 patients with OVFs underwent instrumentation in 244 segments (mean age 73.7 ± 7.9 years, 60.3% female). The median time of follow-up was 14.1 ± 15.5 months. Sarcopenia was detected in 28 patients (47.1%), myosteatosis in 45 patients (66.2%), and osteoporosis in 49 patients (72%). The presence of sarcopenia was independent of chronological age (p = 0.77) but correlated with BMI (p = 0.005). The zSMA_HT was significantly lower in patients suffering from an IF (p = 0.0092). Sarcopenia (OR 4.511, 95% CI 1.459–13.04, p = 0.0092) and osteoporosis (OR 9.50, 95% CI 1.497 to 104.7, p = 0.014) increased the likelihood of an IF. Using multivariate analysis revealed that the zSMA_HT (p = 0.0057) and BMD (p = 0.0041) were significantly related to IF occurrence. Conclusion: Herein, we established sarcopenic obesity as the main determinant for the occurrence of an IF after instrumentation for OVF. To a lesser degree, osteoporosis was associated with impaired implant longevity. Therefore, measuring the SMA and BMD using an axial CT of the lumbar spine might help to prevent an IF in spinal fusion surgery via early detection and treatment of sarcopenia and osteoporosis.

Prevention of Compression Fracture in Osteoporosis Patients under Minimally Invasive Trans-Foraminal Lumbar Interbody Fusion with Assistance of Bone-Mounted Robotic System in Two-Level Degenerative Lumbar Disease

Background and Objectives: Minimally invasive spine surgery reduces destruction of the paraspinal musculature and improves spinal stability. Nevertheless, screw loosening remains a challenging issue in osteoporosis patients receiving spinal fixation and fusion surgery. Moreover, adjacent vertebral compression fracture is a major complication, particularly in patients with osteoporosis. We assessed long-term imaging results to investigate the outcomes of osteoporosis patients with two-level degenerative spine disease receiving minimally invasive surgery with the assistance of a robotic system. Materials and Methods: We retrospectively analyzed consecutive osteoporosis patients who underwent minimally invasive surgery with the assistance of a robotic system at our institution during 2013–2016. All patients were diagnosed with osteoporosis according to the World Health Organization criteria. All patients were diagnosed with two levels of spinal degenerative disease, including L34, L45, or L5S1. The study endpoints included screw-loosening condition, cage fusion, and vertebral body heights of the adjacent, first fixation segment, and second fixation segments before and after surgery, including the anterior, middle, and posterior third parts of the vertebral body. Differences in vertebral body heights before and after surgery were evaluated using the F-test. Results: Nineteen consecutive osteoporosis patients were analyzed. A lower rate of screw loosening was observed in osteoporosis patients in our study. There were no significant differences between the preoperative and postoperative vertebral body heights, including adjacent and fixation segments. Conclusions: According to our retrospective study, we report that minimally invasive surgery with the assistance of a robotic system provided better screw fixation, a lower rate of screw loosening, and a lesser extent of vertebral compression fracture after spinal fixation and fusion surgery in osteoporosis patients.

Temporary Monosegmental Fixation Using Multiaxial Percutaneous Pedicle Screws for Surgical Management of Bony Flexion-Distraction Injuries of the Thoracolumbar Spine: A Technical Note

Introduction

The efficacy of minimally invasive surgeries for thoracolumbar flexion-distraction injuries (FDIs) has been reported, but those surgeries were monosegmental fusion surgeries of two adjacent vertebrae with bone grafts or temporary fixations using percutaneous pedicle screws (PPSs) that were at least bisegmental. Our idea was to fuse the fracture itself, not to fuse the fractured vertebra with an adjacent vertebra or to stabilize the fractured vertebra by bridging rostrally/caudally adjacent intact vertebrae, specifically when the displacement is minimal. This study aimed to present the surgical techniques of reduction and temporary monosegmental fixation of neurologically intact thoracolumbar bony FDIs using multiaxial PPSs, which can minimize the surgical invasiveness and preserve all motion segments, as well as report three cases treated with this procedure.

Technical Note

When the fracture extended from the vertebral body to the spinous process at the same level, screws were placed into the fractured vertebra rostrally to the fracture along the rostral endplate, and the caudally adjacent vertebra was instrumented beyond the fracture line. When the fracture extended from the vertebral body to the spinous process of the rostrally adjacent vertebra, screws were placed into the fractured vertebra caudally to the fracture line, and the rostrally adjacent vertebra was instrumented. The kyphotic deformity was reduced through ligamentotaxis by using MPPSs in the rostral vertebra as rigid joysticks to apply direct buttress leverage to the rostral endplate. Intraoperative blood loss was minimal. The correction of kyphotic deformity and its durability were acceptable, and the segmental range of motion of the two affected vertebrae from flexion to extension was maintained after implant removal.

Conclusions

This surgery can act as the least-invasive option for the management of thoracolumbar bony FDIs to allow early ambulation without external bracing and to preserve all the motion segments.

Biomechanical Evaluation of Semi-rigid Junctional Fixation Using a Novel Cable Anchor System to Prevent Proximal Junctional Failure in Adult Spinal Deformity Surgery

STUDY DESIGN

A porcine cadaveric biomechanical study.

OBJECTIVE

To biomechanically evaluate a novel Cable Anchor System as semi-rigid junctional fixation technique for the prevention of proximal junctional failure after adult spinal deformity surgery and to make a comparison to alternative promising prophylactic techniques.

SUMMARY OF BACKGROUND DATA

The abrupt change of stiffness at the proximal end of a pedicle screw construct is a major risk factor for the development of proximal junctional failure after adult spinal deformity surgery. A number of techniques that aim to provide a gradual transition zone in range of motion (ROM) at the proximal junction have previously been studied. In this study, the design of a novel Cable Anchor System, which comprises a polyethylene cable for rod fixation, is assessed.

METHODS

Ten T6-T13 porcine spine segments were subjected to cyclic 4 Nm pure-moment loading. The following conditions were tested: uninstrumented, 3 level pedicle screw fixation (PSF), and PSF with supplementary Cable Anchors applied proximally at 1-level (Anchor1) or 2-levels (Anchor2), transverse process hooks (TPH), and 2-level sublaminar tapes (Tape2). The normalized segmental range of motion in the junctional zone was compared using one-way analysis of variance and linear regression.

RESULTS

Statistical comparison at the level proximal to PSF showed significantly lower ROMs for all techniques compared to PSF fixation alone in all movement directions. Linear regression demonstrated a higher linearity for Anchor1 (0.820) and Anchor2 (0.923) in the junctional zone in comparison to PSF (1-level: 0.529 and 2-level: 0.421). This linearity was similar to the compared techniques (TPH and Tape2).

CONCLUSION

The Cable Anchor System presented in this study demonstrated a gradual ROM transition zone at the proximal end of a rigid pedicle screw construct similar to TPH and 2-level sublaminar tape semi-rigid junctional fixation constructs, while providing the benefit of preserving the posterior ligament complex.Level of Evidence: 5.

Bone-Mounted Robotic System in Minimally Invasive Spinal Surgery for Osteoporosis Patients: Clinical and Radiological Outcomes

Purpose

Severe complications, including screw loosening events and low fusion rates, in spinal fusion surgery using the traditional open method are problematic. This retrospective study aimed to evaluate the rate of screw loosening and the clinical outcomes of bone-mounted miniature robot-assisted pedicle screw placement in patients treated for degenerative spinal disease.

Patients and Methods

Data were collected from the medical records of 118 patients (mean age, 69 years). Differences in clinical outcomes, including the Oswestry disability index, visual analog scale score, screw loosening rate, cage fusion rate, and complications, were evaluated among different bone mineral densities.

Results

The screw loosening and cage fusion rates for all patients, normal bone mineral density, osteopenia, and osteoporosis groups were 12%, 8.6%, 13.1%, and 14%, respectively, and 85.3%, 93%, 82.5%, and 81.4%, respectively. There was a higher screw loosening rate and a lower cage fusion rate in the osteopenia and osteoporosis groups than in the normal bone density group. The accuracy of the screw placement was 97.3%. There were no statistically significant differences in the Oswestry disability index and visual analog scale scores, and no major complications for dural tear or vascular or visceral injury.

Conclusion

Our study demonstrated an acceptable screw loosening rate in patients with osteoporosis compared to that in patients with normal bone mineral density. The robotic system resulted in accurate screw placement in patients with osteoporosis.

Intra- and inter-observer reliability of the novel vertebral bone quality score

PURPOSE

To assess the intra- and inter-observer reliability of the novel vertebral bone quality (VBQ) scoring system.

METHODS

Four orthopedic surgery residents at various levels of training (PGY1-4) evaluated 100 noncontrast, T1-weighted MRIs of the lumbar spine. VBQ was calculated as quotient of the median of L1-L4 average signal intensity (SI) and the L3 cerebral spinal fluid (CSF) SI, as described by Ehresman et al. All measurements were repeated 2 weeks later. We performed a stratified analysis based on patient history of instrumentation, pathology, and MRI manufacturer/magnet strength to determine their effect on VBQ reliability. Spinal pathologies included compression fracture, burst fracture, vertebral osteomyelitis, epidural abscess, or neoplasm. The interclass correlation coefficient (ICC) two-way mixed model on absolute agreement was used to analyze inter-rater and intra-rater reliability. ICC less than 0.40 was considered poor, 0.40-0.59 as fair, 0.60-0.74 as good, and greater than 0.75 as excellent.

RESULTS

Intra-observer reliability was excellent (≥ 0.75) for all four observers. When stratified by history of spinal instrumentation or spinal pathology, all raters showed excellent intra-observer reliability except one (0.71 and 0.69, respectively). When stratified by MRI manufacturer, intra-observer reliability was ≥ 0.75 for all raters. Inter-observer reliability was excellent (0.91) and remained excellent (≥ 0.75) when stratified by history of spinal instrumentation, spinal pathology, or MRI-manufacturer.

CONCLUSIONS

VBQ scores from spine lumbar MRIs demonstrate excellent intra-observer and inter-observer reliability. These scores are reliably reproduced in patients regardless of previous instrumentation, spinal pathology, or MRI manufacturer/magnetic field strength.

Effect of Preoperative Opiate Use on Outcomes After Posterior Lumbar Surgery

Introduction

The prescription opioid epidemic and widespread use of narcotic medications have introduced new challenges when treating patients undergoing spine surgery. Given the ubiquity of preoperative opioid consumption amongst patients undergoing spine surgery, further research is needed to characterize perioperative risks. Our goal is to compare outcomes following primary lumbar decompression, instrumentation, and fusion based on preoperative opioid prescriptions.

Methods

Patients older than 18 years of age who underwent a primary one- to two-level lumbar decompression, instrumentation, and fusion were included in the study. Patients with known malignancy, surgery involving three or more lumbar levels, current or previous use of neuromodulation, revision surgery, anterior or far lateral interbody fusions, acute fractures, or other concurrent procedures were excluded. Patients were divided into chronic opioid therapy (COT; over six months), acute opioid therapy (AOT; up to six months), and opiate-naïve groups. Opioid prescriptions, demographics, smoking status, readmission rates within one year, and reoperation rates within two years were recorded based on electronic medical record documentation.

Results

Out of 416 patients identified, 114 patients met the inclusion criteria. Thirty-eight patients (33.3%) were on COT, 38 patients (33.3%) were on AOT, and 38 patients (33.3%) were opioid naïve preoperatively. Readmission rates within one year for COT, AOT, and opioid naïve patients were 34.2%, 26.3%, and 10.5%, respectively (p=0.047). Reoperation rates within two years for COT, AOT, and opioid naïve patients were 34.2%, 15.8%, and 13.2%, respectively (p=0.049). We also found current or former smokers were more likely to be on AOT or COT than never smokers (78.4% vs. 57.1%; p=0.017). 

Conclusion

Long-term opiate use is associated with an increased risk for readmission within one year and revision within two years. Physicians should discuss the increased risks of readmission and revision surgery associated with lumbar decompression and fusion seen in patients on preoperative opioid therapy.

Full-endoscopic spine surgery treatment of lumbar foraminal stenosis after osteoporotic vertebral compression fractures: A case report

BACKGROUND

Few reports have described lumbar foraminal stenosis-induced radiculopathy after treatment by full-endoscopic spine surgery (FESS) combined with percutaneous vertebroplasty (PVP) in patients with vertebral compression fractures. We herein report such a case, including the patient’s treatment process and doctor’s surgical experience.

CASE SUMMARY

A 79-year-old man presented with symptoms of radiculopathy after sustaining L4 vertebral compression fractures. Imaging and physical examination revealed L4 vertebral compression fractures combined with L3/4 Lumbar foraminal stenosis (LFS). The patient’s symptoms were low back pain with pain in the lateral left leg. Although many reports have described radiculopathy induced by osteoporotic vertebral compression fractures, the use of FESS combined with PVP has rarely been reported. This case report indicates that the combination of FESS and PVP is a safe and effective approach for the treatment of LFS-induced radiculopathy after vertebral compression fractures. This minimally invasive technique has great potential to replace traditional lumbar fixation and decompression surgery. Thus, we suggest the continued accumulation of similar cases to discuss the wider application of FESS.

CONCLUSION

For patients with osteoporotic vertebral compression fracture (OVCF) and LFS, PVP and FESS can be used to restore the vertebral height and reduce the pressure around the intervertebral foramen. Additionally, the combination of FESS and PVP can treat the pain or numbness of the low back and lower limbs and allow for recovery in a short time with excellent postoperative effects. In general, FESS is a good treatment for radiculopathy caused by foraminal stenosis after OVCF.

Posterior spinal stabilization: A biomechanical comparison of Laminar Hook Fusion to a Pedicle Screw System

BACKGROUND

Several spine instrumentation techniques have been introduced to correct inter-segmental alignment, or provide long-term stability. Whilst pedicle screws are considered the intervention of reference, we hypothesize that the week hold of osteoporotic bone, might be a clinical indicator for an alternative surgical approach.

METHODS

To put this to the test, a non-linear Finite Element model, of a ligamentous lumbosacral spine, was employed to examine a stabilization spanning over L3-L5. Two different immobilization techniques (a Pedicle Screw System and Laminar Hook Fusion) are compared as to their biomechanical response during 7.5 Nm flexion, lateral flexion and torsion, while considering a 280 N follower load. Fifteen analyses performed in total, simulating patients of healthy and osteoporotic Bone Mineral Density.

FINDINGS

Range of Motion was significantly reduced after instrumentation for both implant systems. This trend was more pronounced in the Pedicle Screw models, which were stressed to a higher degree. To evaluate implant loosening risk, we introduce the consideration of strain energy patterns around the screw tract. The notably higher intensity of these, for the osteoporotic model, taken into consideration with the weaker strength of the tissue and inconsistencies in the stress allocation between implant and bone, affirmed an increased risk for loosening of the Pedicle Screws in osteoporotic patients.

INTERPRETATION

The analysis provided refined insight as to the treatment of osteoporotic patients as well as to their postoperative care, as restriction of specific movements (e.g. through bracing), could significantly restrict the stress values in the bone-implant interface and thus, reduce implant failure.

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.

A guide to assessing post-operative complications following en bloc spinal resection

En-bloc resection of spinal tumours is a complex procedure with significant morbidity and mortality. The extensive resection leaves a large soft tissue and osseous defect requiring reconstruction. Following en-bloc resection, there may be complications relating to both the removal of the tumour and the subsequent reconstruction. This paper outlines the imaging appearances of the frequently encountered complications in our experience. The primary aim is to improve the confidence of the radiologist when reporting imaging following spinal en-bloc resection, however we believe this is also useful for the spinal and orthopaedic surgeons in assessing the patients following en block resection.

Hybrid versus total sublaminar wires in patients with spinal muscular atrophy undergoing scoliosis surgery

Background

Early versions of spinal muscular atrophy (SMA) scoliosis correction surgery often involved sublaminar devices. Recently, the utilization of pedicle screws has gained much popularity. Pedicle screws are generally believed to provide additional deformity correction, but pedicle size and rotational deformity limit their application in the thoracic spine, resulting in a hybrid construct involving pedicle screws and sublaminar wire. Studies of the efficacy of hybrid instrumentation in SMA scoliosis are often limited by the scarcity of the disease itself. In this study, we aimed to compare the surgical outcomes between hybrid constructs involving pedicle screws and sublaminar wire and sublaminar wire alone in patients with SMA scoliosis.

Methods

We retrospectively reviewed the clinical records and radiographic assessments of patients with SMA scoliosis who underwent corrective surgery between 1993 and 2017. The radiographic assessments included deformity correction and progressive changes in the major curve angle, pelvic tilt (PT) and coronal balance (CB). The correction of deformities was observed postoperatively and at the patient’s 2-year follow-up to test the efficacy of each type of construct.

Results

Thirty-three patients were included in this study. There were 14 and 19 patients in the wiring and hybrid construct groups, respectively. The hybrid construct group demonstrated a higher major curve angle correction (50.5° ± 11.2° vs. 36.4° ± 8.4°, p < 0.001), a higher apical vertebral rotation correction (10.6° ± 3.9° vs. 4.8° ± 2.6°, p < 0.001), and a reduced progression of the major curve angle at the 2-year follow-up (5.1° ± 2.9° vs. 8.7° ± 4.8°, p < 0.001). A moderate correlation was observed between the magnitude of correction of the apical vertebral rotation angle and the major curve (r = 0.528, p = 0.002).

Conclusion

This study demonstrated that hybrid instrumentation can provide a greater magnitude of correction in major curve and apical rotation as well as less major curve progression than sublaminar wire instrumentation alone in patients with SMA scoliosis. Level of evidence III

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04737-0.

Novel Biodegradable Composite of Calcium Phosphate Cement and the Collagen I Mimetic P-15 for Pedicle Screw Augmentation in Osteoporotic Bone

Osteoporotic vertebral fractures often necessitate fusion surgery, with high rates of implant failure. We present a novel bioactive composite of calcium phosphate cement (CPC) and the collagen I mimetic P-15 for pedicle screw augmentation in osteoporotic bone. Methods involved expression analysis of osteogenesis-related genes during osteoblastic differentiation by RT-PCR and immunostaining of osteopontin and Ca²⁺ deposits. Untreated and decalcified sheep vertebrae were utilized for linear pullout testing of pedicle screws. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DEXA). Expression of ALPI II (p < 0.0001), osteopontin (p < 0.0001), RUNX2 (p < 0.0001), and osteocalcin (p < 0.0001) was upregulated after co-culture of MSC with CPC-P-15. BMD was decreased by 28.75% ± 2.6%. Pullout loads in untreated vertebrae were 1405 ± 6 N (p < 0.001) without augmentation, 2010 ± 168 N (p < 0.0001) after augmentation with CPC-P-15, and 2112 ± 98 N (p < 0.0001) with PMMA. In decalcified vertebrae, pullout loads were 828 ± 66 N (p < 0.0001) without augmentation, 1324 ± 712 N (p = 0.04) with PMMA, and 1252 ± 131 N (p < 0.0078) with CPC-P-15. CPC-P-15 induces osteoblastic differentiation of human MES and improves pullout resistance of pedicle screws in osteoporotic and non-osteoporotic bone.

Comparison of clinical effectiveness of fenestrated and conventional pedicle screws in patients undergoing spinal surgery: a systematic review and meta-analysis

INTRODUCTION

Pedicle screws are commonly used for spinal procedures for fusion stability, which is particularly important in osteoporotic patients, who are at an increased risk of requiring revision procedures.

AREAS COVERED

A systematic review and meta-analysis were conducted to compare clinical effectiveness of conventional pedicle screws (CPS) vs fenestrated pedicle screws (FPS) in patients undergoing spinal surgery. Primary outcomes included screw loosening, revision surgeries (involving an implant) and reoperations (not involving intervention on an implant) in patients treated with CPS vs FPS, sub-stratified by with and without osteoporosis. Secondary outcomes included changes in pain scores. Forty-eight studies with 8,302 patients were included, with 1,565 (19.18%) treated with FPS and 6,710 (80.82%) treated with CPS. FPS was associated with a lower risk of screw loosening (p = 0.001) vs CPS. In the general population, there was a non-significant trend of lower revision rate, but no difference in reoperation rate, between patients treated with FPS vs CPS. In osteoporotic patients, revision rates were significantly lower for FPS vs CPS (p = 0.009).

EXPERT OPINION

This review suggests that FPS are effective for surgical fixation and reduce rates of screw loosening, and in osteoporotic patients, revision surgeries, compared to CPS.

Interrater and Intrarater Reliability of the Vertebral Bone Quality Score

BACKGROUND

Vertebral bone quality had a significant impact on postoperative outcomes in spinal fusion surgery. New magnetic resonance imaging-based measures, such as the Vertebral Bone Quality (VBQ) score, may allow for bone quality assessment without the radiation associated with conventional testing. In the present study, we sought to assess the intrarater and interrater reliability of VBQ scores calculated by medical professionals and trainees.

METHODS

Thirteen reviewers of various specialties and levels of training were recruited and asked to calculate VBQ scores for 30 patients at 2 time points separated by 2 months. Scored volumes were acquired from patients treated for both degenerative and oncologic indications. Intrarater and interrater agreement, quantified by intraclass correlation coefficient (ICC), was assessed using 2-way random effects modeling. Square-weight Cohen κ and Kendall Tau-b were used to determine whether raters assigned similar scores during both evaluations.

RESULTS

All raters showed moderate to excellent reliability for VBQ score (ICC 0.667-0.957; κ0.648-0.921) and excellent reliability for all constituent components used to calculate VBQ score (ICC all ≥0.97). Interrater reliability was also found to be good for VBQ score on both the first (ICC = 0.818) and second (ICC = 0.800) rounds of assessment; scores for the constituent component all had ICC values ≥0.97 for the constituent components.

CONCLUSIONS

The VBQ score appears to have both good intrarater and interrater reliability. In addition, there appeared to be no correlation between score reliability and level of training. External validation and further investigations of its ability to accurately model bone biomechanical properties are necessary.

Osteoporosis and Spine Surgery: A Critical Analysis Review

Despite being part of the aging process, early and adequate management of osteoporosis mitigates adverse outcomes associated with low bone mineral density. Although the health-care burden of osteoporosis is on the rise, screening and management of osteoporosis are not yet an integral part of preoperative patient evaluation in spine surgery. Patients with osteoporosis should undergo multidisciplinary evaluation and management, including lifestyle modifications and initiation of multiple therapeutic modalities. Integrating osteoporosis in preoperative optimization and surgical planning for patients undergoing spine surgery has the potential to mitigate osteoporosis-related postoperative complications.

The Value of Cement Augmentation in Patients With Diminished Bone Quality Undergoing Thoracolumbar Fusion Surgery: A Review

STUDY DESIGN

Systematic review.

OBJECTIVES

Osteoporosis predisposes patients undergoing thoracolumbar (TL) fusion to complications and revision surgery. Cement augmentation (CA) improves fixation of pedicle screws to reduce these complications. The goal of this study was to determine the value and cost-effectiveness of CA in TL fusion surgery.

METHODS

A systematic literature review was performed using an electronic database search to identify articles discussing the cost or value of CA. As limited information was available, the review was expanded to determine the mean cost of primary TL fusion, revision TL fusion, and the prevalence of revision TL fusion to determine the decrease of revision surgery necessary to make CA cost-effective.

RESULTS

Two studies were identified discussing the cost and value of CA. The mean cost of CA for two vertebral levels was $10 508, while primary TL fusion was $87 346 and revision TL fusion was $76 825. Using a mean revision rate of 15.4%, the use of CA for TL fusion would need to decrease revision rates by 13.7% to be cost-effective. Comparison studies showed a decreased revision rate of 11.3% with CA, which approaches this value.

CONCLUSION

CA for TL fusion surgery improves biomechanical fixation of pedicle screws and decreases complications and revision surgery in patients with diminished bone quality. The costs of CA are substantial and reported decreases in revision rates approach but do not reach the calculated value to be a cost-effective technique. Future studies will need to focus on the optimal CA technique to decrease complications, revisions, and costs.

Engineered collagen-binding bone morphogenetic protein-2 incorporated with platelet-rich plasma accelerates lumbar fusion in aged rats with osteopenia

In aged individuals, osteopenia is a great concern for achieving solid spinal fusion. Spinal malunion could lead to various implant-related complications and reduce postoperative quality of life. This study aims to investigate the efficacy of collagen-binding bone morphogenetic protein-2 (CBD-BMP-2) on the treatment of lumbar inter-transverse defects and to explore whether platelet-rich plasma could help CBD-BMP-2 to achieve a better outcome in terms of osteogenesis in senile rats with osteopenia. In vitro experiment proved the angiogenic function of platelet-rich plasma and osteogenic effect of CBD-BMP-2. Rats were performed posterolateral lumbar inter-transverse fusion. Rats implanted with CBD-BMP-2 + platelet-rich plasma were assigned to Group A (n = 20), rats implanted with CBD-BMP-2 were assigned to Group B (n = 20), and those with platelet-rich plasma were assigned to Group C (n = 20). Four weeks after implantation, radiographic assessment, manual palpation, and histological evaluation were performed. In vivo experiments showed satisfactory therapeutic effect on lumbar inter-transverse fusion in both Groups A and B and better results of bone microarchitecture in Group A. Solid fusion rate was 77.8% in Group A, 66.7% in Group B, and 0% in Group C (P < 0.001). Our study indicated that CBD-BMP-2 could effectively facilitate the lumbar inter-transverse fusion in aged rats with osteopenia and platelet-rich plasma could help CBD-BMP-2 to enhance the bone healing of vertebral defects.