Cement-augmented Pedicle Screw Fixation Research Articles

Biomechanical Effect of Different Posterior Fixation Techniques on Stability and Adjacent Segment Degeneration in Treating Thoracolumbar Burst Fracture With Osteoporosis: A Finite Element Analysis.

Finite element analysis. To investigate the biomechanical effect of four posterior fixation tcehniques on stability and adjacent segment degeneration in treating thoracolumbar burst fractures with osteoporosis. In terms of stability and adjacent segment degeneration, there remains no consensus or guidelines on the optimal technique for the treatment of thoracolumbar burst fractures in patients with osteoporosis. Images of CT scans were imported into MIMICS and further processed by Geomagic to build 3-dimensional models of the T10-L5 region. A v-shaped osteotomy was performed on the L1 vertebral body to simulate a burst fracture in the setting of osteoporosis. Subsequently, four fixation techniques were designed using SolidWorks software. Range of motion (ROM) of the global spine, ROM distribution, ROM of adjacent segment, Von Mises stress on adjacent intervertebral discs and facet joints were analyzed. Among the four groups, the cortical bone screw fixation (CBT) showed the highest global ROM at 1.86°, while long-segmented pedicle screw fixation (LSPS) had the lowest global ROM at 1.25°. The LSPS had the smallest percentage of ROM of fractured vertebral body to fixed segment at 75.04%, suggesting the highest stability after fixation. The maximum ROM of the adjacent segment was observed in the CBT at 1.32°, while the LSPS exhibited the smallest at 0.89°. However, the LSPS group experienced larger maximum stress on the adjacent intervertebral discs (9.60MPa) and facet joints (3.36MPa), indicating an increasing risk of adjacent segment disease. LSPS provided the greatest stability, while CBT provided the smallest amount of stability. However, the elevated stress on adjacent intervertebral discs and facet joints after LSPS fixation increased the possibility of adjacent segment degeneration. Cement-augmented pedicle screw fixation (CAS) and combined cortical bone screw and pedicle screw fixation (CBT-PS) demonstrated significant biomechanical advantages in providing moderate fixation strength while reducing stress on the intervertebral discs and facet joints.

Anatomic distribution of basivertebral foramen with a magistral form in vertebral bodies of T10~L5 and its clinical significance for extensive epidural cement leakage in cement-augmented pedicle screw fixation: a multicenter case–control study

BackgroundThere are no reports discussing anatomic distribution of basivertebral foramen (BVF) in the osteoporotic vertebral body, which is critical in the analysis of the risk of epidural cement leakage (ECL) after cement-augmented pedicle screw fixation (CAPSF).Methods371 osteoporotic patients using 1898 cement-augmented screws were included. Preoperative computed tomography (CT) was used to determine the frequency, width, height, and depth of magistral BVF in T10~L5. Additionally, we measured the distance between BVF and the left/right borders of vertebral body as well as the distance between BVF and upper/lower endplates. Following CAPSF, the severity of ECL and the position of pedicle screws were determined by postoperative CT. Finally, significant risk factors for extensive ECL were identified through binary logistic regression analysis.ResultsOf 2968 vertebral bodies ranging from T10 to L5, 801 (42.2%) had a magistral BVF. From T10 to L5, the frequency of magistral BVF appeared to gradually increase. The magistral BVF was much closer to the upper endplate and the depth accounted for about a quarter of anteroposterior diameter of vertebral body. Overall, there were 19 patients (5.1%) and 32 screws (1.7%) with extensive ECL, nine of whom had neurological symptoms. The independent risk factors for extensive ECL were the magistral BVF (OR = 8.62, P < 0.001), more volume of cement injected (OR = 1.57, P = 0.031), reduced distance from screw tip to vertebral midline (OR = 0.76, P = 0.003) and vertebral posterior wall (OR = 0.77, P < 0.001) respectively.ConclusionWhen planning a CAPSF procedure, it is important to consider anatomical distribution of BVF and improve screw implantation methods.

The incidence and risk factors for extensive epidural cement leakage in cement-augmented pedicle screw fixation: a multicenter retrospective study.

In cement-augmented pedicle screw fixation (CAPSF), epidural cement leakage (CL) is a frequently reported complication with the potential for neural injury, especially when it is extensive. To date, there has been no reports discussing basivertebral foramen morphology and pedicle screw placement, which is critical in the analysis of the risk of extensive epidural CL. Thus, this study aimed to identify the incidence and risk factors for extensive epidural CL in osteoporotic patients with CAPSF. 371 osteoporotic patients using 1898 cement-augmented screws were included. Preoperative computed tomography (CT) was utilized to characterize basivertebral foramen morphology. Following CAPSF, the severity of epidural CL, the implantation position of pedicle screw and cement extension within the vertebral body were determined by postoperative CT. In this study, significant risk factors for extensive epidural CL were identified through logistic regression analysis. There were 19 patients (5.1%) and 32 screws (1.7%) with extensive epidural CL. Nine patients (involving 19 screws) had neurological symptoms. The independent risk factors for patients with extensive epidural CL were decreased BMD and increased number of augmented screws. Significant predictors for extensive epidural CL were a magistral type of basivertebral foramen, more volume of cement injected, solid screw, a shallower screw implantation, and the smaller distance between the tip of the screw and the midline of vertebral body. Extensive epidural CL risk was significant in CAPSF when a magistral basivertebral foramen was present; solid screws and more volume of cement were used; and screw tip was implanted shallower or closer to the midline.

Efficacy of cement-augmented pedicle screw fixation for osteoporotic mid-thoracic vertebral fractures.

Osteoporotic mid-thoracic vertebral fractures (OmTVF), often result in severe pain, and neurological deficits secondary to cord compression. Cement-augmented pedicle screw (CaPS) fixation with posterior spinal decompression (PSD) offers simultaneous decompression with stabilization of these osteoporotic vertebral fractures. The study involved 32 patients (2022-2023) with T8-T10 osteoporotic vertebral compression fractures resulting in cord compression. All patients underwent CaPS surgery with PSD. Pain reduction was measured using the visual analog scale (VAS), and outcomes with the Oswestry Disability Index, and the American Spinal Injury Association Grades. The local kyphotic angle was also tracked with computed tomography studies performed 1, 3, and 6 months post-operatively. The average pre-operative VAS score was 8.56 mm; this decreased at 1, 3, and 6 months post-operatively to 2.72 mm, 2.03 mm, and 1.44 mm, respectively. In addition, 31 of 32 patients fully recovered within 6 postoperative months. For 31 of 32 patients with T8-T10 osteoporotic vertebral fractures, CaPS fixation with PSD successfully alleviated pain and resulted in significant post-operative neurological recovery.

Treatment of stage Ⅱ-Ⅲ Kümmell disease with robot-assisted bone cement-augmented pedicle screw fixation

To evaluate the early clinical efficacy of robot-assisted percutaneous short-segment bone cement-augmented pedicle screw fixation in the treatment of stageⅡ-Ⅲ Kümmell disease. The clinical data of 20 patients with stageⅡ-Ⅲ Kümmell's disease who underwent robot-assisted percutaneous bone cement-augmented pedicle screw fixation between June 2017 and January 2021 were retrospectively analyzed. There were 4 males and 16 females, aged from 60 to 81 years old with an average age of (69.1±8.3) years. There were 9 cases of stageⅡand 11 cases of stage Ⅲ, all of which were single vertebral lesions, including 3 cases of T11, 5 cases of T12, 8 cases of L1, 3 cases of L2, and 1 case of L3. These patients did not exhibit symptoms of spinal cord injury. The operation time, intraoperative blood loss, and complications were recorded. The position of pedicle screws and the filling and leakage of bone cement in gaps were observed using postoperative CT 2D reconstruction. The data of the visual analogue scale (VAS), Oswestry disability index (ODI), kyphosis Cobb angle, wedge angle of the diseased vertebra, and anterior and posterior vertebral height on lateral radiographs were statistically analyzed preoperatively, 1 week postoperatively, and at the final follow-up. Twenty patients were followed up for 10 to 26 months, with an average follow-up of (16.0±5.1) months. All operations were successfully completed. The surgical duration ranged from 98 to 160 minutes, with an average of (122±24) minutes. The intraoperative blood loss ranged from 25 to 95 ml, with an average of (45±20) ml. There were no intraoperative vascular nerve injuries. A total of 120 screws were inserted in this group, including 111 screws at grade A and 9 screws at grade B according to the Gertzbein and Robbins scales. Postoperative CT indicated that the bone cement was well-filled in the diseased vertebra, and cement leakage occurred in 4 cases. Preoperative VAS and ODI were (6.05±0.18) points and (71.10±5.37)%, respectively, (2.05±0.14) points and (18.57±2.77)% at 1 week after operation, and (1.35±0.11) points and (15.71±2.12) % at final follow-up. There were significant differences between postoperative 1 week and preoperative, and between final follow-up and postoperative 1 week(P<0.01). Anterior and posterior vertebral height, kyphosis Cobb angle, and wedge angle of the diseased vertebra were(45.07±1.06)%, (82.02±2.11)%, (19.49±0.77) °, and (17.56±0.94) ° preoperatively, respectively, (77.00±0.99)%, (83.04±2.02)%, (7.34±0.56) °, and (6.15±0.52) ° at 1 week postoperatively, and (75.13±0.86)%, (82.39±0.45)%, (8.38±0.63) °, and (7.09±0.59) ° at the final follow-up. Robot-assisted percutaneous short-segment bone cement-augmented pedicle screw fixation demonstrates satisfactory short-term efficacy in treating stageⅡ-Ⅲ Kümmell's disease as an effective minimally invasive alternative. However, longer operation times and strict patient selection criteria are necessary, and long-term follow-up is required to determine its lasting effectiveness.

High Rate of Pulmonary Cement Embolism after Cement-Augmented Pedicle Screw Fixation: A 12-Year Single-Center Study.

The global trend toward increased life expectancy because of remarkable improvements in health care quality has drawn increased attention to osteoporotic fractures and degenerative spine diseases. Cement-augmented pedicle screw fixation has been established as the mainstay treatment for patients with poor bone quality. This study aimed to determine the number of patients with cement leakage and pulmonary cement embolism (PCE) as detected on thoracic computed tomography (CT), and to assess the potential risk factors for PCE. Patients undergoing cement-augmented pedicle screw placement in our institution between May 2008 and December 2020 were included. Data regarding baseline characteristics, complications, and cement leakage rates were collected. Indications for the performance of a postoperative thoracic CT due to the suspicion of PCE were intra- or postoperative complications, or postoperative oxygen supplementation. Moreover, PCE was accidently diagnosed because the thoracic CT was performed for medical reasons other than the suspicion of PCE (tumor staging, severe pneumonia, or exacerbated chronic pulmonary obstructive disease). A total of 104 patients with a mean age of 72.8 years (standard deviation of 6.7) were included. Of 802 screws, 573 were cement augmented. Of the 104 patients, 44 (42.3%) underwent thoracic CT scans to diagnose PCE; additionally, 67 (64.4%) demonstrated cement leakage, of whom 27 developed PCE and 4 were symptomatic. Cement-augmented thoracic screws were a risk factor for PCE (odds ratio: 1.5; 95% confidence interval: 1.2-2.1; p = 0.004). This study showed a high prevalence of cement leakage after cement-augmented pedicle screw insertion, with a relatively frequent incidence of PCE, as tracked by thoracic CT scans. Cement-augmented thoracic screw placement was a unique risk factor for PCE.

Cardiopulmonary Cement Embolism Following Cement-Augmented Pedicle Screw Fixation: A Narrative Review.

Fixation using cement-augmented pedicle screws (CAPS) is being increasingly performed. However, CAPS-associated cement leakage is a critical problem that can lead to cardiopulmonary cement embolism (CPCE). This narrative review aimed to explore the incidence of and risk factors and treatment strategies for CPCE and cement leakage-related complications after CAPS fixation. Data were extracted from each article, including characteristics of CPCE after CAPS fixation (incidence, location, diagnostic method and criteria, treatment, and outcome and prognosis). Overall, 28 case series and 14 case reports that met the inclusion criteria were included. Of the 1974 cases included in the review, CPCE was noted in 123, symptomatic CPCE in 35, and death in six, respectively. The frequencies of PCE and symptomatic PCE after CAPS fixation were 6% (range: 0-28.6%) and 1.3% (range: 0-26%), respectively. The range of frequencies of PCE and symptomatic PCE after CAPS fixation may have been wide because the definition of CPCE and data collection methods differed among the reports analyzed. Since PCE due to large cement emboli may be primarily related to the surgical technique, improved technique, such as minimizing the number of CAPSs by injecting low-volume high-viscosity cement at low velocity and pressure, and careful observation of cement leakage during CAPS insertion may reduce PCE associated with cement leakage. Spinal surgeons should pay more attention to the occurrence of CPCE during and after CAPS insertion, which can cause serious complications in some patients.

Comparison of pedicle screw fixation with or without cement augmentation for treating single-segment isthmic spondylolisthesis in the osteoporotic spine

The present study examined the necessity of cement-augmented pedicle screw fixation in osteoporotic patients with single-segment isthmic spondylolisthesis.Fifty-nine cases were reviewed retrospectively. Thirty-three cases were in the polymethylmethacrylate-augmented pedicle screw (PMMA-PS) group, and the other 26 cases were in the conventional pedicle screw (CPS) group. Evaluation data included operation time, intraoperative blood loss, hospitalization cost, hospitalization days, rates of fusion, screw loosening, bone cement leakage, visual analogue scale (VAS) scores, Oswestry disability index (ODI), lumbar lordosis (LL), pelvic tilt (PT) and sacral slope (SS).The operation time and blood loss in the CPS group decreased significantly compared to those in the PMMA-PS group. The average hospitalization cost of the PMMA-PS group was significantly higher than that of the CPS group. There was no significant difference in the average hospital stay between the 2 groups. The initial and last follow-up postoperative VAS and ODI scores improved significantly in the two groups. There were no significant differences in VAS and ODI between the 2 groups at each time point. The last postoperative spine-pelvic parameters were significantly improved compared with those preoperatively. In the PMMA-PS group, the fusion rate was 100%. The fusion rate was 96.15% in the CPS group. No significant difference was found between the two groups for the fusion rate. Nine patients in the PMMA-PS group had bone cement leakage. There was no screw loosening in the PMMA-PS group. There were 2 cases of screw loosening in the CPS group. There were no significant differences in screw loosening, postoperative adjacent segment fractures, postoperative infection or postoperative revision between the 2 groups. The use of PMMA-PS on a regular basis is not recommended in posterior lumbar interbody fusion for the treatment of single-segment isthmic spondylolisthesis with osteoporosis.

Biomechanical Comparison and Three-Dimensional Analysis of Cement Distribution Patterns for Different Pedicle Screw Designs.

The purpose of this study to explore strategies for reducing cement leakage during cement-augmented pedicle screw fixation, we compared the cement distribution patterns and biomechanical strengths of different types of cement-augmented fenestrated screws and traditional cement-augmented techniques. We compared five screw groups in this study: (1) Cannulated screws (Cann); (2) distal one-hole screws (D1); (3) distal two-hole screws (D2); (4) middle two-hole screws (M2); and (5) traditional screws with a traditional cement injection technique (Trad). The screws were inserted into cancellous bone blocks using a controlled, adequate cement injection pressure (1.6–2.0 kg), and an appropriate cement viscosity. Center to screw tip distance, three-dimensional distribution, and pull-out strength for cement were compared between groups. The average distance between the cement center and the screw tip was highest in the M2 group, suggesting a higher risk of cement leakage into the spinal canal. The Trad group had the highest migration distance in the z-axis, also reflecting a higher risk of leakage into the spinal canal. The D1 group had the highest pull-out strength (253 ± 48.82 N and 797 ± 58.31 N) in bone blocks representing different degrees of osteoporosis, and the D2 group had the second highest pull-out strength in the severe osteoporosis model. Overall, D1 screws appeared to be the best option for optimizing biomechanical function and minimizing the risk of cement leakage into the spinal canal in patients with osteoporotic bone undergoing spinal surgery.

An Experimental Study on the Biomechanical Effectiveness of Bone Cement-Augmented Pedicle Screw Fixation with Various Types of Fenestrations.

To analyze the effects of the number and shape of fenestrations on the mechanical strength of pedicle screws and the effects of bone cement augmentation (BCA) on the pull-out strength (POS) of screws used in conventional BCA. For the control group, a conventional screw was defined as C1, a screw with cannulated end-holes was defined as C2, a C2 screw with six pinholes was defined as C3, and the control group type was set. Among the experimental screws, T1 was designed using symmetrically placed thru-hole type fenestrations with an elliptical shape, while T2 was designed with half-moon (HM)-shaped asymmetrical fenestrations. T3 and T4 were designed with single HM-shaped fenestrations covering three pitches and five pitches, respectively. T5 and T6 were designed with 0.6-mm and 1-mm wider fenestrations than T3. BCA was performed by injecting 3 mL of commercial bone cement in the screw, and mechanical strength and POS tests were performed according to ASTM F1717 and ASTM F543 standards. Synthetic bone (model #1522-505) made of polyurethane foam was used as a model of osteoporotic bone, and radiographic examinations were performed using computed tomography and fluoroscopy. In the fatigue test, at 75% ultimate load, fractures occurred 7781 and 9189 times; at 50%, they occurred 36122 and 82067 times; and at 25%, no fractures occurred. The mean ultimate load for each screw type was 219.1±52.39 N for T1, 234.74±15.9 N for T2, 220.70±59.23 N for T3, 216.45±32.4 N for T4, 181.55±54.78 N for T5, and 216.47±29.25 N for T6. In comparison with C1, T1, T2, T3, T4, and T6 showed significantly different ultimate load values (p<0.05). However, when the values for C2 and the fenestrated screws were evaluated with an unpaired t test, the ultimate load value of C2 significantly differed only from that of T2 (p=0.025). The ultimate load value of C3 differed significantly from those of T1 and T2 (C3 vs. T1 : p=0.048; C3 vs. T2 : p<0.001). Linear correlation analysis revealed a significant correlation between the fenestration area and the volume of bone cement (Pearson's correlation coefficient r=0.288, p=0.036). The bone cement volume and ultimate load significantly correlated with each other in linear correlation analysis (r=0.403, p=0.003). Fenestration yielded a superior ultimate load in comparison with standard BCA using a conventional screw. In T2 screws with asymmetrical two-way fenestrations showed the maximal increase in ultimate load. The fenestrated screws can be expected to show a stable position for the formation of the cement mass.

Pulmonary Infarction and Acute Respiratory Distress Syndrome Resulted from Small Amount of Peripheral Pulmonary Cement Embolism following Cement-Augmented Pedicle Screw Fixation: A Rare Case and Literature Review

The information about symptomatic pulmonary cement embolism (PCE) following vertebroplasty and cement-augmented pedicle screw fixation is limited. To our knowledge, this is the first reported case of severe acute respiratory distress syndrome (ARDS) caused by a relatively small amount of peripheral PCE, which resulted in mortality.

Long-term efficacy and safety of bone cement-augmented pedicle screw fixation for stage III K\xfcmmell disease

This study aimed to evaluate the efficacy and safety of bone cement-augmented pedicle screw fixation for stage III Kümmell disease. Twenty-five patients with stage III Kümmell disease who received bone cement-augmented pedicle screw fixation at the First Affiliated Hospital of Guangzhou University of Chinese Medicine between June 2009 and December 2015 were enrolled. All patients were females with a history of osteoporosis. The vertebral Cobb angle (V-Cobb angle), the fixed segment Cobb Angle (S-Cobb angle), pelvic parameters, visual Analogue Scale (VAS) score, and Oswestry Disability Index (ODI) were assessed preoperatively, postoperatively and at the final follow-up. Complications, loosening rate, operation time, and intraoperative bleeding were recorded. The average lumbar vertebral density T-value was − 3.68 ± 0.71 SD, and the average age was 71.84 ± 5.39. The V-Cobb angle, S-Cobb angle, and Sagittal Vertical Axis (SVA) were significantly smaller postoperatively compared to the preoperative values. The VAS and ODI at 1 month after surgery were 3.60 ± 1.00 and 36.04 ± 6.12%, respectively, which were both significantly lower than before surgery (VAS: 8.56 ± 1.04, ODI: 77.80 ± 6.57%). Bone cement-augmented pedicle screw fixation is a safe and effective treatment for stage III Kümmell disease. It can effectively correct kyphosis, restore and maintain sagittal balance, and maintain spinal stability.

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

High-grade metastatic epidural spinal cord compression from radioresistant tumor histologies is often treated with separation surgery and adjuvant stereotactic body radiation therapy. Historically, long-segment fixation is performed during separation surgery with posterior transpedicular fixation of a minimum of 2 spinal levels superior and inferior to the decompression. Previous experience with minimal access surgery techniques and percutaneous stabilization have highlighted reduced morbidity as an advantage to the use of shorter fixation constructs. Cement augmentation of pedicle screws is an attractive option for enhanced stabilization while performing shorter fixation. Herein, the authors describe their initial experience of open separation surgery using short-segment cement-augmented pedicle screw fixation for spinal reconstruction. The authors performed a retrospective chart review of patients undergoing open (i.e., nonpercutaneous, minimal access surgery) separation surgery for high-grade epidural spinal cord compression using cement-augmented pedicle screws at single levels adjacent to the decompression level(s). Patient demographics, treatment data, operative complications, and short-term radiographic outcomes were evaluated. Overall, 44 patients met inclusion criteria with radiographic follow-up at a mean of 8.5 months. Involved levels included 19 thoracic, 5 thoracolumbar, and 20 lumbar. Cement augmentation through fenestrated pedicle screws was performed in 30 patients, and a vertebroplasty-type approach was used in the remaining 14 patients to augment screw purchase. One (2%) patient required an operative revision for a hardware complication. Three (7%) nonoperative radiographic hardware complications occurred, including 1 pathologic fracture at the index level causing progressive kyphosis and 2 incidences of haloing around a single screw. There were 2 wound complications that were managed conservatively without operative intervention. No cement-related complications occurred. Open posterolateral decompression utilizing short-segment cement-augmented pedicle screws is a viable alternative to long-segment instrumentation for reconstruction following separation surgery for metastatic spine tumors. Studies with longer follow-up are needed to determine the rates of delayed complications and the durability of these outcomes.

Can cavity-based pedicle screw augmentation decrease screw loosening? A biomechanical in vitro study

PurposeIn an osteoporotic vertebral body, cement-augmented pedicle screw fixation could possibly be optimized by the creation of an initial cavity. The aim of this study is to compare three test groups with regard to their loosening characteristics under cyclic loading.MethodsEighteen human, osteoporotic spine segments were divided in three groups. Flexibility tests and cyclic loading tests were performed with an internal fixator. The screws were fixed after creation a cavity and with cement (cavity-augmented group), without cavity and with cement (augmented group), and without cavity and without cement (control group). Cyclic loading up to 100,000 cycles was applied with a complex loading protocol. Screw loosening was measured with flexibility tests after implantation and after cyclic loading. Cement distribution was visualized from CT scans.ResultsIn all groups, range of motion increased during cyclic loading, representing significant screw loosening after 100,000 cycles. In both augmented groups, screw loosening was less pronounced than in the control group. The cavity-augmented group showed only a slight tendency of screw loosening, but with smaller variations compared to both other groups. This may be explained with a trend for a more equal and homogeneous cement volume around each tip for the cavity-augmented group.ConclusionThis study demonstrated that creating a cavity may allow a more equal fixation of all pedicle screws with slight reduction of loosening. However, augmentation only through a cannulated screw is almost equivalent, if care is taken that enough cement volume can be pushed out around the tip of the screw.

Effect and potential risks of using multilevel cement-augmented pedicle screw fixation in osteoporotic spine with lumbar degenerative disease

BackgroundThe increase of augmented level and bone cement dose are accompanied by the rising incidence of cement leakage (CL) of cement-augmented pedicle screw instrumentation (CAPSI). But the effect and potential risks of the application of CAPSI to osteoporotic lumbar degenerative disease (LDD) have not been studied in the case of multilevel fixation. This study aimed to investigate the effectiveness and potential complications of using multilevel CAPSI for patients with osteoporotic LDD.MethodsA total of 93 patients with multilevel LDD were divided into the CAPSI group (46 subjects) and the conventional pedicle screw (CPS) group (47 subjects), including 75 cases for three levels and 18 cases for four levels. Relevant data were compared between two groups, including baseline data, clinical results, and complications.ResultsIn the CAPSI group, a total of 336 augmented screws was placed bilaterally. The CL was observed in 116 screws (34.52%). Three cemented screws (0.89%) were found loosened during the follow-up and the overall fusion rate was 93.47%. For perioperative complications, two patients (4.35%) experienced pulmonary cement embolism (PCE), one patient augmented vertebral fracture, and three patients (6.52%) wound infection. And in the CPS group, thirty-three screws (8.46%) suffered loosening in cranial and caudal vertebra with a fusion rate of 91.49%. The operation time and hospital stay of CAPSI group were longer than the CPS group, but CAPSI group has a lower screw loosening percentage (P<0. 05). And in terms of blood loss, perioperative complications, fusion rate, and VAS and ODI scores at the follow-up times, there were no significant differences between the two groups.ConclusionsPatients with osteoporotic LDD underwent multilevel CPS fixation have a higher rate of screw loosening in the cranial and caudal vertebra. The application of cemented pedicle screws for multilevel LDD can achieve better stability and less screw loosening, but it also accompanied by longer operating time, higher incidence of CL, PCE and wound infections. Selective cement augmentation of cranial and caudal pedicle screws may be a worthy strategy to decrease the complications.

Clinical outcome of bone cement-augmented pedicle screw fixation for thoracolumbar refractures after percutaneous kyphoplasty

Objective To investigate the clinical therapeutic effects of bone cement-augmented pedicle screw fixation for cement vertebrae refractures with lower limb neurological symptoms after percutaneous kyphoplasty (PKP) in elderly patients with osteoporotic thoracolumbar compression fractures. Methods A total of 123 elderly patients with osteoporotic thoracolumbar compression fractures underwent PKP from December 2013 to December 2016 were retrospectively analyzed by case series study. Twelve patients had vertebral refracture with compression of the spinal cord or cauda equina which resulted in lumbosacral and leg pain, numbness and disability of ambulation and there were five males and seven females, with age of (69.2±7.1)years. Injured vertebrae was located at T12in five cases, at L1 in five and at L2 in two. Bone cement-augmented pedicle screw fixation through a standard posterior approach was utilized to treat all the 12 patients. Visual analogue scale (VAS), Oswestry disability index (ODI), anterior vertebral height compression ratio, and kyphotic angle at the preoperative time, one week postoperatively and last follow-up were recorded and compared. Intraoperative and postope-rative complications were also recorded. Results The mean duration of follow-up in all the patients was 26.7 months (range, 12-36 months). Intraoperative nerve injury, dural tear, leakage of bone cement, bone cement toxicity reaction, and pulmonary embolism were not observed during the surgery. The postoperative radiographs for all the 12 patients showed that the bone cement was distributed in cancellous bone and around the screw appropriately where there was no cement leakage out of the vertebral body or pedicle. Compared with preoperative scores, the average low back pain VAS, leg pain VAS and ODI at postoperative one week were improved by (2.2±0.7)points, (2.2±0.4)points and (33.2±8.9)points, respectively (P 0.05). Conclusion For elderly patients with spinal cord or cauda equina nerve compression symptoms after PKP for osteoporotic thoracolumbar compression fractures, the usage of posterior approach bone cement-augmented pedicle screw fixation can effectively correct kyphosis, relieve neurological symptoms and restore spinal stability. Key words: Spinal fractures; Thoracic vertebrae; Lumbar vertebrae; Internal fixators; Vertebral refracture

Posterior Vertebrectomy and Circumferential Fusion for the Treatment of Advanced Thoracolumbar Kümmell Disease with Neurologic Deficit.

Study DesignSingle-center, retrospective case series.PurposeTo investigate the effectiveness of posterior vertebrectomy and circumferential fusion in patients with advanced Kümmell disease with neurologic deficit.Overview of LiteratureVarious surgical options exist for the treatment of Kümmell disease, and determination of the appropriate treatment is based on the clinical and radiologic status of the patient. However, surgical intervention is required for patients with advanced Kümmell disease accompanied by neurologic deficit.MethodsWe retrospectively analyzed 22 neurologically compromised patients with advanced Kümmell disease who were treated surgically at Ewha Womans Hospital between January 2011 and January 2014. The surgical approach used by us was a posterior vertebrectomy with mesh cage insertion and segmental cement-augmented pedicle screw fixation. The tissue from the corpectomy was histopathologically examined. Anterior vertebral height, kyphotic angle, visual analog scale (VAS) score, and the Frankel classification were used to evaluate the efficacy of the procedure.ResultsThe mean follow-up period was 26 months (range, 13–40 months). VAS score, anterior vertebral height, kyphotic angle, and neurologic state were significantly improved immediately postoperatively and at the last follow-up compared with preoperatively (p<0.05). Most patients exhibited intravertebral clefts on imaging, and postoperative pathology revealed bone necrosis.ConclusionsPosterior vertebrectomy with mesh cage insertion and segmental cement-augmented pedicle screw fixation is an effective approach for treating patients with advanced Kümmell disease with neurologic deficit.

Corpectomy and circumferential fusion for advanced thoracolumbar Kümmell's disease.

The aim of this study was to investigate the surgical treatment of neurologically compromised advanced Kümmell's disease. The surgical treatment of Kümmell's disease has various options according to clinical and radiologic status. Far collapsed Kümmell's disease patients with neurological deficit need to be treated surgically. We retrospectively analyzed 22 patients operated to our hospital with neurologically compromised Kümmell's disease between January 2011 and January 2014. Surgical approach was vertebrectomy, mesh cage insertion and segmental cement-augmented pedicle screw fixation. Corpectomy tissue was examined histopathologically. Anterior vertebral heights, kyphotic angle, the visual analog scale (VAS) and the Frankel classification were used to evaluate the effects of the surgery. The mean time of follow-up was 26months (range, 13-40months). The VAS, anterior vertebral heights, kyphotic angle and neurological state were improved significantly immediate postoperatively and at the last follow-up compared with the preoperative examinations (P<0.05). Most of the patients in this study exhibited intravertebral clefts, and postoperative pathology revealed bone necrosis. Posterior vertebrectomy with mesh cage insertion and segmental cement-augmented pedicle screw fixation is an effective option for advanced Kümmell's disease with neurological deficits.

Risk of cement leakage and pulmonary embolism by bone cement-augmented pedicle screw fixation of the thoracolumbar spine

BackgroundCement-augmented pedicle screw instrumentation (CAPSI) of the thoracolumbar spine is indicated in osteoporosis or osteopenia to improve pullout strength and biomechanical stability of pedicle screws (PS). Only a few studies report on the incidence of pulmonary cement embolism or other complications associated with CAPSI. PurposeThe aim of this retrospective study was to assess the rate of CAPSI-associated complications. Study DesignRetrospective cohort study. Patient SamplePatients who underwent CAPSI due to spinal tumors or degenerative spine disease. Outcome MeasuresCement leakage, pulmonary cement embolism (PCE), mortality rate. MethodsOur clinical database was reviewed for patients who underwent CAPSI between January 2012 and June 2015. A total of 165 patients (mean age 71±11.2; range: 46 to 93 years; m=62, f=103) were included. Indications were osteoporotic fractures (n=40), spinal metastases (n=57), degenerative (n=49) or infectious spine disease (n=5), and traumatic vertebral fractures (n=14) with an associated osteoporosis. Every patient received between 2 and 21 (mean 8±3.3) cement-augmented pedicle screws in the thoracolumbar and lumbosacral spine. Both intraoperative cement leakage in prevertebral veins, the inferior vena cava, and/or pulmonary arteries, and leakage detected on postoperative imaging were evaluated. We assessed the incidence of clinically symptomatic and asymptomatic events. ResultsIn 29 of 31 patients with intraoperative suspicion of cement leakage into prevertebral veins or the inferior vena cava on lateral fluoroscopy, which were without hemodynamic relevance, cement extrusion was confirmed on postoperative X-ray or computed tomography (CT) scan. In three of eight patients with suspicion of PCE, PCE was verified on thoracic CT. Four patients experienced life-threatening intraoperative hemodynamic reactions, either due to cement embolism (n=2; 1.2%) or anaphylactic shock (n=2; 1.2%) with need for intraoperative cardiopulmonary resuscitation in three cases. Two patients died due to fulminant PCE. Three patients with dyspnea 1 day after surgery were also confirmed with PCE on chest CT. In five patients, an asymptomatic PCE was found incidentally on postoperative imaging. In addition, 68 patients with cement leakage into prevertebral veins or the ascending cava vein were found incidentally on postoperative spine X-ray or CT. Two of 10 patients with intraspinal epidural cement leakage required revision surgery. One hundred ten of 165 patients (66.7%) had clinically asymptomatic cement leakage. Thirteen patients had PCE (7.9%), of whom five (3.0%) were symptomatic. Two patients experienced intraoperative cement-induced anaphylaxis (1.2%). The overall symptomatic complication rate was 5.5% (n=9). The 30-day mortality rate was 1.8% (n=3). ConclusionsCAPSI bears a high risk of asymptomatic cement leakage. The risk for associated severe complications was also relatively high and probably underestimated considering the retrospective nature of the present study. A strict indication for cement augmentation, especially in patients with cardiac predisposition, should be the consequence. We doubt that technical aspects of cement application and/or different types of cement are capable of reducing the risk of these complications substantially.

Unilateral Augmented Pedicle Screw Fixation for Foraminal Stenosis

The purpose of this study is to evaluate the effectiveness of unilateral decompression and pedicle screw fixation for the unilateral symptomatic foraminal stenosis. The study group comprises consecutive 16 patients who underwent unilateral decompression and bone cement augmented pedicle screw fixation from May 2003 to January 2006. The patients were evaluated by visual analog scale (VAS) for pain and the scoring system of the Japanese Orthopedic Association (JOA) for low back pain. The result of surgery was also evaluated with McNab's classification. Excellent or good outcome was considered as successful. The patients were followed at postoperative 1 month, 3 month, 6 month, and 1 year with standing AP and lateral films. The average VAS and JOA score of the 16 patients were 7.8 (range, 6-9) and 5.8 (range, 3 - 10) before surgery and 2.2 (range, 0 - 5) and 12.3 (range, 9 - 15) at the time of last follow up. Both VAS and JOA score improved significantly after the surgery (p < 0.05, t-test). All patients improved after the operation and no revision surgery was required. No metal failure or pseudoarthrosis was observed during the follow-up. The success rate was 87.5%. Our data suggest that unilateral decompression and pedicle screw fixation for the unilateral symptomatic foraminal stenosis is an effect method for obtaining satisfactory clinical outcome. Its possible advantage is shorter operation time and reduced surgical extent. We believe that the reduced stiffness of unilateral fixation was compensated by pedicle screw augmentation and interbody fusion.