Risk factors for cement leakage after percutaneous vertebral augmentation for osteoporotic vertebral compression fractures: a meta-analysis.

BACKGROUND: Osteoporotic vertebral compression fractures (OVCF) may necessitate percutaneous vertebral augmentation (PVA), a procedure not without its risks. One notable complication is cement leakage (CL), which can cause significant distress in patients. Despite its clinical importance, there remains a paucity of meta-analyses investigating these complications and their management in the existing literature. MATERIAL AND METHODS: We systematically reviewed PubMed, Cochrane Library, Embase, and Web of Science databases up to February 2024 to identify studies examining CL following PVA treatment in OVCF. We assessed the quality of eligible cohort studies using the Newcastle-Ottawa Scale (NOS), extracted data on incidence, identified risk factors for CL, and conducting meta-analysis with Revman 5.2 software. We calculated odd ratios (OR) and Mean Differences (MD) with 95% confidence interval (CI) applying random effects models. RESULTS: We identified twelve cohort studies that matched our strict inclusion criteria. These studies included a total of 2388 patients and 3392 vertebrae. CL was identified in 1132 vertebrae. Notable risk factors for CL included compromised cortical bone integrity (OR 5.00, 95% CI 3.01~8.29, P<0.00001), presence of intravertebral vacuum clefts (OR 1.68, 95% CI 1.07~2.65, P=0.03), basivertebral foramen sign (OR 1.77, 95% CI 1.09~2.89, P=0.02), and volume of cement used (MD 0.75, 95% CI 0.41~1.10, P<0.0001). CONCLUSION: Our findings underscore the significance of cortical bone integrity, intravertebral vacuum cleft, basivertebral foramen sign, and cement volume as principal determinants of CL risk in PVA for OVCF. These insights advocate for tailored surgical strategies to mitigate the risk of CL in this patient population.

[Percutaneous pedicle screw anchored vertebral augmentation for the treatment of Kümmell disease without neurological symptoms].

OBJECTIVE: To explore the clinical effect of percutaneous pedicle screw anchored vertebral augmentation(PPSAVA) in the treatment of asymptomatic Kümmell disease without neurological symptoms. METHODS: The clinical data of 20 patients with Kümmell disease without neurological symptoms treated with PPSAVA in our hospital from January 2019 to December 2021 were analyzed retrospectively, including 5 males and 15 females, aged 56 to 88 (74.95±9.93) years old. and the course of disease was 7 to 60 days with an average of (21.35±14.46) days. All patients were treated with PPSAVA. The time of operation, the amount of bone cement injected and the leakage of bone cement were recorded. The visual analogue scale(VAS), Oswestry disability index(ODI), vertebral body angle(VBA), anterior edge height and midline height of vertebral body were compared among the before operation, 3 days after operation and during the final follow-up. The loosening and displacement of bone cement were observed during the final follow-up. RESULTS: All the 20 patients completed the operation successfully. The operation time was 30 to 56 min with an average of (41.15±7.65) min, and the amount of bone cement injection was 6.0 to 12.0 ml with an average of (9.30±1.49) ml. Bone cement leakage occurred in 6 cases and there were no obvious clinical symptoms. The follow-up time was 6 to 12 months with an average of (8.43±2.82) months. The VBA, anterior edge height and midline height of of injured vertebral body were significantly improved 3 days after operation and the final follow-up(P<0.05), and the VBA, anterior edge height and midline height of of injured vertebral body were lost in different degrees at the final follow-up (P<0.05). The VAS and ODI at 3 days after operation and at the final follow-up were significantly lower than those at preoperatively(P<0.05), but the VAS score and ODI at the final follow-up were not significantly different from those at 3 d after operation(P>0.05). At the last follow-up, no patients showed loosening or displacement of bone cement. CONCLUSION: PPSAVA is highly effective in treating Kümmell disease without neurological symptoms, improving patients' pain and functional impairment, and reducing the risk of cement loosening and displacement postoperatively.

Effect of cervical spine motion on displacement of posterolateral annulus fibrosus in cervical spondylotic radiculopathy with contained posterolateral disc herniation: a three-dimensional finite element analysis.

BACKGROUND: Previous studies on dynamic impingement of nerve root in cervical spondylotic radiculopathy (CSR) have focused on effect of cervical spine motion (CSM) on dimensional changes of intervertebral foramen. However, there are few studies to investigate effect of CSM on displacement of posterolateral intervertebral disc until now. The present study aimed to investigate effect of CSM on displacement of posterolateral annulus fibrosus (AF) in CSR with contained posterolateral disc herniation. METHODS: A C5-C6 CSR finite element model with unilateral contained posterolateral disc herniation was generated based on validated C5-C6 normal finite element model. Forward and backward displacement distributions of posterolateral AFs in CSR model and normal model were compared. Changes in forward and backward displacement magnitudes of posterolateral AFs of the herniated side and the healthy side in CSR model, with respect to those of the ipsilateral posterolateral AFs in normal model, were compared. The comparisons were performed under flexion, extension, lateral bendings and axial rotations. RESULTS: There was no difference in deformation trend of posterolateral AF between CSR model and normal model. Bilateral posterolateral AFs mainly moved forward during flexion and backward during extension. Left posterolateral AF mainly moved backward and right posterolateral AF forward during left lateral bending and left axial rotation. Left posterolateral AF mainly moved forward and right posterolateral AF backward during right lateral bending and right axial rotation. However, with respect to forward and backward displacement magnitudes of the ipsilateral posterolateral AFs in normal model, those of the herniated side increased relatively significantly compared with those of the healthy side in CSR model. CONCLUSIONS: Flexion, lateral bending to the healthy side and axial rotation to the healthy side make posterolateral AF of the herniated side mainly move forward, whereas extension, lateral bending to the herniated side and axial rotation to the herniated side make it mainly move backward. These data may help select CSM or positions to diagnose and treat CSR with contained posterolateral disc herniation. Increase in deformation amplitude of posterolateral AF of the herniated side may also be the reason for dynamic impingement of nerve root in CSR with contained posterolateral disc herniation.

Investigating the mechanical effect of the sagittal angle of the cervical facet joint on the cervical intervertebral disc.

Background: Facet tropism is defined as the asymmetry between the left and right facet joints relative to the sagittal plane. Published clinical studies have found that facet tropism is associated with cervical disc herniation. However, the relationship between the facet orientation and the side of cervical disc herniation remains controversial. Therefore, this study used the finite-element technique to investigate the biomechanical effects of the sagittal angle of the cervical facet joints on the cervical intervertebral disc. Objective: The biomechanical effects of the sagittal angle of the cervical facet joint on the cervical disc and facet joint were investigated using the finite-element technique. Methods: The finite-element model was constructed using computed tomography scans of a 26-year-old female volunteer. First, a cervical model was constructed from C3 to C7. The model was verified using data from previously published studies. Second, the facet orientation at the C5-C6 level was altered to simulate different sagittal angles of cervical facet joints. Five models, F70, F80, F90, F100, and F110, were simulated with different facet joint orientations (70°, 80°, 90°, 100°, and 110° facet joint angles at the left side, respectively, and 90° facet joint angles at the right side) at the C5-C6 facet joints. In each model, annular fibres stress and facet cartilage pressure were studied under six pure moments and two combined moments. Results: Comparing the stress of the annulus fibres in flexion combined with right axial rotation and in flexion combined with left axial rotation in the same model, no difference in the maximum stress of the annulus fibres was noted between these two different moments in the F90 model, whereas differences of 12.80%, 8.84%, 14.95% and 33.32% were noted in the F70, F80, F100 and F110 models, respectively. The same trend was observed when comparing the maximum stress of the annulus fibres in each model during left and right axial rotation. No differences in annular fibres stress and facet cartilage pressure were noted among the five models in flexion, extension, lateral bending, left axial rotation, and flexion combined with left axial rotation in this study. However, compared with the F70 model in flexion combined with right axial rotation, the annulus fibres stress of the F80, F90, F100, and F110 models increased by 5.53%, 13.03%, 35.04%, and 72.94%, respectively, and the pressure of the left facet joint of these models decreased by 5.65%, 12.10%, 18.41%, and 25.74%, respectively. The same trend was observed in the right axial moment. Conclusion: Facet tropism leads to unbalanced stress distribution on the annulus fibres at the cervical intervertebral disc. The greater the sagittal angle of the facet joint, the greater the annular fibres stress on this side. We hypothesised that the side with the larger sagittal angle of the facet joint exhibits a greater risk of disc herniation.

Biomechanical evaluation of strategies for adjacent segment disease after lateral lumbar interbody fusion: is the extension of pedicle screws necessary?

BACKGROUND: Adjacent segment disease (ASD) is a well-known complication after interbody fusion. Pedicle screw-rod revision possesses sufficient strength and rigidity. However, is a surgical segment with rigid fixation necessary for ASD reoperation? This study aimed to investigate the biomechanical effect of different instrumentation on lateral lumbar interbody fusion (LLIF) for ASD treatment. METHODS: A validated L2~5 finite element (FE) model was modified for simulation. ASD was considered the level cranial to the upper-instrumented segment (L3/4). Bone graft fusion in LLIF with bilateral pedicle screw (BPS) fixation occurred at L4/5. The ASD segment for each group underwent a) LLIF + posterior extension of BPS, b) PLIF + posterior extension of BPS, c) LLIF + lateral screw, and d) stand-alone LLIF. The L3/4 range of motion (ROM), interbody cage stress and strain, screw-bone interface stress, cage-endplate interface stress, and L2/3 nucleus pulposus of intradiscal pressure (NP-IDP) analysis were calculated for comparisons among the four models. RESULTS: All reconstructive models displayed decreased motion at L3/4. Under each loading condition, the difference was not significant between models a and b, which provided the maximum ROM reduction (73.8 to 97.7% and 68.3 to 98.4%, respectively). Model c also provided a significant ROM reduction (64.9 to 77.5%). Model d provided a minimal restriction of the ROM (18.3 to 90.1%), which exceeded that of model a by 13.1 times for flexion-extension, 10.3 times for lateral bending and 4.8 times for rotation. Model b generated greater cage stress than other models, particularly for flexion. The maximum displacement of the cage and the peak stress of the cage-endplate interface were found to be the highest in model d under all loading conditions. For the screw-bone interface, the stress was much greater with lateral instrumentation than with posterior instrumentation. CONCLUSIONS: Stand-alone LLIF is likely to have limited stability, particularly for lateral bending and axial rotation. Posterior extension of BPS can provide reliable stability and excellent protective effects on instrumentation and endplates. However, LLIF with the use of an in situ screw may be an alternative for ASD reoperation.

The relationship between facet tropism and cervical disc herniation.

Many studies have demonstrated the association between facet tropism and disc herniation in the lumbar spine. Some of them found that lumbar disc herniation was on the side of the more sagittal facet joint interface. However, little is understood about the association of facet tropism with disc herniation in the cervical spine. As the relationship between the facet orientation and the side of cervical disc herniation (CDH) is unclear, the purpose of this study is to investigate that relationship. Ninety-six patients with single-level CDH (C4-C5, C5-C6 or C6-C7) were included in the CDH group of this study. Another 50 age-matched and gender-matched healthy participants who accepted physical examinations were enrolled as the control group. The cervical facet angles of two sides were measured using axial computed tomography (CT). The intersection angle of the midsagittal line of the vertebra to the facet line represents the facet angle. Facet tropism was defined as the angular difference of 7º between the left and the right sides. Facet tropism angle was recorded as the absolute value of the difference of facet angles between two sides. There were 20 herniations at C4-C5 level, 50 herniations at C5-C6 level and 26 herniations at C6-C7 level. The present study showed that more cases in the CDH group had facet tropism than did those in the control group at C4-C5, C5-C6 and C6-C7 level (p = .021, p = .001, p = .015, respectively). The facet tropism angles in the CDH group were significantly bigger than those in the control group at C4-C5, C5-C6 and C6-C7 level (p = .001, p = .002, p = .028, respectively). In the CDH group, the facet angles on the herniated side were found to be significantly bigger than those on the healthy side at C4-C5, C5-C6 and C6-C7 level (p = .000, p = .000, p = .037, respectively). The findings of this present study suggest that facet tropism is associated with the disc herniation in the cervical spine. We also found that cervical disc herniates towards the side of the bigger facet angle with respect to the sagittal plane. There is a need for future studies to verify the biomechanical impact of facet tropism on CDH.

Biomechanical Effects of Lateral Bending Position on Performing Cervical Spinal Manipulation for Cervical Disc Herniation: A Three-Dimensional Finite Element Analysis.

BACKGROUND: Most studies report that the common position of cervical spinal manipulation (CSM) for treating symptomatic cervical disc herniation (CDH) is lateral bending to the herniated side. However, the rationality of lateral bending position on performing CSM for CDH is still unclear. OBJECTIVE: The purpose of this study is to investigate the biomechanical effects of lateral bending position on performing CSM for CDH. METHODS: A finite element (FE) model of CDH (herniated on the left side) was generated in C5-6 segment based on the normal FE model. The FE model performed CSM in left lateral bending position, neutral position, and right lateral bending position, respectively. Cervical disc displacement, annulus fiber stress, and facet joint stress were observed during the simulation of CSM. RESULTS: The cervical disc displacement on herniated side moved forward during CSM, and the maximum forward displacements were 0.23, 0.36, and 0.45 mm in left lateral bending position, neutral position, and right lateral bending position, respectively. As the same trend of cervical disc displacement, the annulus fiber stresses on herniated side from small to large were 7.40, 16.39, and 22.75 MPa in left lateral bending position, neutral position, and right lateral bending position, respectively. However, the maximum facet stresses at left superior cartilage of C6 in left lateral bending position, neutral position, and right lateral bending position were 6.88, 3.60, and 0.12 MPa, respectively. CONCLUSION: Compared with neutral position and right lateral bending position, though the forward displacement of cervical disc on herniated side was smaller in left lateral bending position, the annulus fiber stress on herniated side was declined by sharing load on the left facet joint. The results suggested that lateral bending to the herniated side on performing CSM tends to protect the cervical disc on herniated side. Future clinical studies are needed to verify that.

Risk Factors for the Occurrence of Insufficient Cement Distribution in the Fractured Area after Percutaneous Vertebroplasty in Osteoporotic Vertebral Compression Fractures.

BACKGROUND: Insufficient cement distribution (ICD) in the fractured area has been advocated to be responsible for unsatisfied pain relief after percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fractures (OVCFs). However, little is known about risk factors for the occurrence of ICD. OBJECTIVE: The present study aimed to identify independent risk factors of the emergence of ICD. STUDY DESIGN: A retrospective cohort study. SETTING: Department of spinal surgery, an affiliated hospital of a medical university. METHODS: Patients who underwent PVP for single-level OVCF from January 2012 to September 2014 and met this study's inclusion criteria were retrospectively reviewed. Associations of ICD with co-variates (age, gender, bone mass density with a T-score, amount of injected cement, cement leakage, fracture level, fracture age, fracture severity grade, and location of the fractured area) and the influence of ICD on pain relief were analyzed. RESULTS: A total of 225 patients were included. ICD was found in 26 (11.6%) patients. Fractured area located in the superior portion of the index vertebra was significantly associated with occurrence of ICD. No further significant associations between the studied co-variates and emergence of ICD were seen in the adjusted analysis. In addition, patients with ICD had significantly higher immediate postoperative visual analog scale scores of back pain compared with those with sufficient cement distribution in the fractured area. LIMITATION: Location of the fractured area and cement distribution in the fractured area could not be evaluated quantitatively. CONCLUSIONS: The incidence of ICD is higher in patients with the fractured area located in the superior portion of the index vertebra and ICD might be responsible for unsatisfied pain relief after PVP for OVCFs. KEY WORDS: Percutaneous vertebroplasty, insufficient cement distribution, fractured area, risk factor, osteoporosis, vertebral compression fracture, spine, unsatisfied pain relief, cement augmentation.

Efficacy and safety of the target puncture technique for treatment of osteoporotic vertebral compression fractures with intravertebral clefts.

OBJECTIVE: To compare the efficacy and safety of our target puncture technique with the traditional technique during percutaneous kyphoplasty (PKP) for osteoporotic vertebral compression fractures (OVCFs) with intravertebral clefts (IVCs). METHODS: 104 patients treated with PKP for single OVCFs with IVCs were retrospectively reviewed. All patients were divided into three groups: cleft filling by the traditional technique (Group A, n=18); interdigitated filling (Group B, n=50); and overfilling by the target technique (Group C, n=36). Oswestry disability index (ODI) and visual analog scale (VAS) scores and radiological evidence of vertebral body height and kyphotic angle, cement leakage, and adjacent vertebral fractures were studied before and after surgery (immediate, 1 and 2 years). RESULTS: The ODI and VAS scores decreased for all patients and no significant difference was found between the three groups after treatment. However, 1 and 2 years after surgery a greater increase in ODI and VAS scores was observed in Group A compared with the other two groups. The initial correction of vertebral body height and kyphotic angle was not significant among the three groups. However, loss of correction was greater in Group A. No significant difference was found in cement leakage. The incidence of adjacent vertebral fractures in Group C was higher than in the other two groups. CONCLUSIONS: Different puncture techniques were initially effective for all patients with IVCs. However, cement cleft filling by the traditional technique was found to have less stability causing higher VAS/ODI scores and greater loss of correction. Hence, our target puncture technique was recommended in this study.

Intravertebral Vacuum Cleft and Its Varied Locations within Osteoporotic Vertebral Compression Fractures: Effect on Therapeutic Efficacy.

BACKGROUND: Previous studies have reported a high incidence of re-collapse of the augmented vertebrae after percutaneous vertebral augmentation (PVA) for osteoporotic vertebral compression fractures (OVCFs) with intravertebral vacuum cleft (IVC) during long-term follow-up. Previous IVC might be considered an important predisposing factor for re-collapse, but the prior studies could not find a significant correlation. OBJECTIVE: To determine the incidence and distribution characteristics of IVCs and to further assess IVCs in their varied locations. To assess the long-term therapeutic efficacy of PVA for OVCFs with IVC. STUDY DESIGN: A retrospective cohort study. SETTING: Department of spinal surgery, an affiliated hospital of a medical university. METHODS: A retrospective review was performed on 594 patients who underwent PVA to treat OVCFs from January 2010 to December 2013. Eighty-two patients with the IVC sign were enrolled in the study. The follow-up period was a minimum of 2 years. The difference between IVC and non-IVC patients was compared. Comparisons of the radiological and clinical findings at varied IVC locations were made pre-operatively and post-operatively (immediate, at one year, and at 2 years). RESULTS: IVC incidence correlated with older patient age and severe demineralization. Other baseline parameters showed no significant differences. The rate of cement leakage and vertebral fracture was significantly lower in the IVC groups than in the non-IVC groups intraoperatively. There was no significant difference in the incidence of cement leakage or adjacent vertebral fractures between the 3 IVC groups. In the immediate postoperative period, all patients benefited from significant improvement in vertebral body height and kyphotic angle correction. However, significant re-collapse was observed at the 2-year post-operative follow-up for the IVC patients when compared to the non-IVC patients. Among the 3 IVC groups, the most severe re-collapse was observed with inferior endplate IVCs. Superior endplate IVCs and IVCs extending to both endplates demonstrated only mild re-collapse at the 2-year follow-up. LIMITATION: Due to the infrequency of this process, the number of patients with IVCs was small. CONCLUSION: PVA treatment was initially effective in all patients with OVCFs. However, significant re-collapse of the augmented vertebrae with IVCs, especially those with inferior endplate IVCs, was found with long-term follow-up. Key words: Intravertebral vacuum cleft, percutaneous vertebral augmentation, osteoporotic vertebral compression fractures, affected vertebrae, augmented vertebrae.

The therapeutic effect of intravertebral vacuum cleft with osteoporotic vertebral compression fractures: A systematic review and meta-analysis.

BACKGROUND: To date, there has been ongoing debate over whether intravertebral vacuum cleft (IVC) has the effect of therapeutic efficacy in percutaneous vertebral augmentation (PVA) for the treatment of osteoporotic vertebral compression fractures (OVCFs). OBJECTIVE: The aim of this meta-analysis was to calculate a pooled estimate of the IVCs on the effect of therapeutic efficacy of PVA for the treatment of OVCFs. METHODS: A systematic electronic literature search was performed using the following databases: PubMed, Embase and Cochrane Library; the databases were searched from the earliest available records up to June 2016. Pooled risk ratio (RR) or a mean difference (MD) with 95% confidence interval (CI) was calculated using random- or fixed-effects models. The RevMan 5.2 was used to analyze the data. RESULTS: In the immediate postoperative period, pooled results showed that vertebral height and VAS scores of the IVC patients were significantly lower than those of the non-IVC patients. However, pooled results showed there was no significant difference in kyphotic angle and ODI indices between the two groups. At final follow-up period, significant difference was observed in all the radiological and clinical parameters for the IVC patients with compared to the non-IVC patients in our pooled results. Pooled results showed significant difference with respect to the rate of cement leakage between the two groups. CONCLUSION: The IVCs had an important effect of therapeutic efficacy in PVA for the treatment OVCFs. Therefore, we strongly recommend its strict observation and follow-up for the IVCs patients.

Risk factors for recollapse of the augmented vertebrae after percutaneous vertebroplasty for osteoporotic vertebral fractures with intravertebral vacuum cleft.

To determine risk factors related to recollapse of the augmented vertebrae after percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fractures (OVCFs) with intravertebral vacuum cleft (IVC).Fifty-two patients treated with PVP for single OVCFs with the IVC were retrospectively reviewed. The follow-up period was at least 2 years. Vertebral height loss ≥15% or kyphotic angle ≥10° at the final follow-up in relation to the immediately postoperative values were adopted as a definition of recollapse of the augmented vertebrae. Correlation analysis and multiple logistic regression analyses were performed to elucidate the related clinical or radiological factors for recollapse of the augmented vertebrae including age, gender, bone mineral density, preoperative fracture severity, locations of IVC sign, distribution patterns of polymethylmethacrylate (PMMA), reduction rate, and reduction angle.Assuming the increase of height loss more than 15% as a criterion of recollapse, only cleft filling pattern of PMMA in the IVC area was a significant risk factor for recollapse of the augmented vertebrae (P < 0.01). Assuming ≥10° progression of kyphotic angle as a criterion, cleft filling pattern of PMMA and higher values of reduction angle was as 2 significant risk factors for recollapse of the augmented vertebrae (P < 0.01). No significant difference was found in other clinical and radiological factors (P > 0.05).Cleft filling pattern of PMMA and higher values of reduction angle may play an important role in inducing recollapse of the augmented vertebrae after PVP for OVCFs with the IVC. Careful observation of patients with these conditions is necessary to prevent deterioration of their clinical course.

Pedicle screw fixation with kyphoplasty decreases the fracture risk of the treated and adjacent non-treated vertebral bodies: a finite element analysis.

Adjacent vertebral fractures are common in patients with osteoporotic vertebral compression fractures (OVCFs) after kyphoplasty. This finite element study was to examine whether short segment pedicle screw fixation (PSF) with kyphoplasty may decrease the fracture risk of the treated and adjacent non-treated vertebrae after kyphoplasty for OVCFs. By simulating cement augmentation with or without short segment pedicle screw fixation (PSF), two tridimensional, anatomically detailed finite element models of the T10-L2 functional spinal junction were developed. The insertion of pedicle screws into the intact vertebra apparently decreased the stress distribution of the treated vertebra in vertical compression and other load situations. The stress distribution in the bone structures of the intact vertebra adjacent to the intact-screwed vertebra was much less than that in the one adjacent to the treated vertebra. The insertion of pedicle screws into the intact vertebra greatly decreased the maximum displacement of the cortical bones and cancellous bones of the vertebrae. Our results indicated that short segment PSF with kyphoplasty may decrease the fracture risk of the treated and adjacent non-treated vertebrae in the management of OVCFs.

[COMPARISON OF EFFECTIVENESS BETWEEN PERCUTANEOUS VERTEBROPLASTY AND PERCUTANEOUS KYPHOPLASTY FOR TREATMENT OF OSTEOPOROTIC VERTEBRAL COMPRESSION FRACTURE WITH INTRAVERTEBRAL VACUUM CLEFT].

OBJECTIVE: To compare the clinical efficacy and safety between percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP) in the treatment of osteoporotic vertebral compression fracture (OVCF) with intravertebral vacuum cleft (IVC). METHODS: Between January 2010 and December 2013, 68 patients with single OVCF and IVC were treated, and the clinical data were retrospectively analyzed. Of 68 patients, 48 underwent PVP (PVP group) and 20 underwent PKP (PKP group). There was no significant difference in age, gender, disease duration, fracture level, bone mineral density (BMD), visual analogue scale (VAS), Oswestry disability index (ODI), and preoperative radiological parameters between 2 groups (P>0.05). The intraoperative incidence of cement leakage, cement volume, and operative time were compared between 2 groups; VAS score was used for evaluation of back pain and ODI for evaluation of dysfunction; the incidence of adjacent vertebral fracture was observed within 2 years. The vertebral height and kyphotic angle were measured on X-ray films; the rate of vertebral compression (CR), reduction rate (RR), progressive height loss (PHL), reduction angle (RA), and progressive angle (PA) were calculated. RESULTS: There was no significant difference in cement volume and the incidence of cement leakage between 2 groups (P>0.05). The operative time in PVP group was shorter than that in PKP group, showing significant difference (t=-8.821, P=0.000). The mean follow-up time was 2.4 years (range, 2.0-3.1 years). The VAS scores and ODI were significantly reduced at 1 day, 1 year, and 2 years after operation when compared with preoperative scores (P<0.05), but there was no significant difference between different time points after operation in 2 groups (P>0.05). Adjacent vertebral fracture occurred in 5 cases (10.4%) of PVP group and in 2 cases (10.0%) of PKP group, showing no significant difference (χ2=0.003, P=0.963). BMD was significantly increased at 1 year and 2 years after operation when compared with preoperative BMD (P<0.05), but no significant difference was found between 2 groups (t=0.463, P=0.642; t=0.465, P=0.646). The X-ray films showed that CR and kyphotic angle were significantly restored at immediate after operation in 2 groups (P<0.05); but vertebral height and kyphotic angle gradually aggravated with time, showing significant difference between at immediate and at 1 and 2 years after operation (P<0.05); there was no significant difference in CR and kyphotic angle between 2 groups at each time point (P>0.05). RR, RA, PHL, and PA showed no significant difference between 2 groups (P>0.05). CONCLUSIONS: There is similar clinical and radiological efficacy between PVP and PKP for treatment of OVCF with IVC. Re-collapse could happen after operation, so strict observation and follow-up are needed.

Biomechanical effects of cement distribution in the fractured area on osteoporotic vertebral compression fractures: a three-dimensional finite element analysis.

BACKGROUND: According to some clinical studies, insufficient cement distribution (ID) in the fractured area and asymmetrical cement distribution around the fractured area were thought to be the reasons for unrelieved pain and recollapse after percutaneous vertebral augmentation (PVA) in the treatment of symptomatic osteoporotic vertebral compression fractures. METHODS: Finite element methods were used to investigate the biomechanical variance among three patterns of cement distribution (ID and sufficient cement distribution in the fractured area and asymmetrical cement distribution around the fractured area including upward [BU] and downward [BD] cement distribution). RESULTS: Compared with fractured vertebra before PVA, distribution of von Mises stress in the cancellous bone was transferred to be concentrated at the cancellous bone surrounding cement after PVA, whereas it was not changed in the cortical bone. Compared with sufficient cement distribution group, maximum von Mises stress in the cancellous bone and cortical bone and maximum displacement of augmented vertebra increased significantly in the ID group, whereas asymmetrical cement distribution around the fractured area in BU and BD groups mainly increased maximum von Mises stress in the cancellous bone significantly. Similar results could be seen in all loading conditions. CONCLUSIONS: ID in the fractured area may lead to unrelieved pain after PVA in the treatment of symptomatic osteoporotic vertebral compression fractures as maximum displacement of augmented vertebral body increased significantly. Both ID in the fractured area and asymmetrical cement distribution around the fractured area are more likely to induce recollapse of augmented vertebra because they increased maximum von Mises stress in the cancellous bone and cortical bone of augmented vertebra significantly.

[VALUE OF SMART PHONE Scoliometer SOFTWARE IN OBTAINING OPTIMAL LUMBAR LORDOSIS DURING L4-S1 FUSION SURGERY].

OBJECTIVE: To investigate the value of smart phone Scoliometer software in obtaining optimal lumbar lordosis (LL) during L4-S1 fusion surgery. METHODS: Between November 2014 and February 2015, 20 patients scheduled for L4-S1 fusion surgery were prospectively enrolled the study. There were 8 males and 12 females, aged 41-65 years (mean, 52.3 years). The disease duration ranged from 6 months to 6 years (mean, 3.4 years). Before operation, the pelvic incidence (PI) and Cobb angle of L4-S1 (CobbL4-S1) were measured on lateral X-ray film of lumbosacral spine by PACS system; and the ideal CobbL4-S1 was then calculated according to previously published methods [(PI+9 degrees) x 70%]. Subsequently, intraoperative CobbL4-S1 was monitored by the Scoliometer software and was defined as optimal while it was less than 5 degrees difference compared with ideal CobbL4-S1. Finally, the CobbL4-S1 was measured by the PACS system after operation and the consistency was compared between Scoliometer software and PACS system to evaluate the accuracy of this software. In addition, value of this method in obtaining optimal LL was validated by comparing the difference between ideal CobbL4-S1 and preoperative one with that between ideal CobbL4-S1 and postoperative one. RESULTS: The CobbL4-S1 was (36.17 ± 1.53)degrees for ideal one, (22.57 ± 5.50)degrees for preoperative one, (32.25 ± 1.46)degrees for intraoperative one measured by Scoliometer software, and (34.43 ± 1.72)degrees for postoperative one, respectively. The observed intraclass correlation coefficient (ICC) was excellent [ICC = 0.96, 95% confidence interval (0.93, 0.97)] and the mean absolute difference (MAD) was low (MAD = 1.23) between Scoliometer software and PACS system. The deviation between ideal CobbL4-S1 and postoperative CobbL4-S1 was (2.31 ± 0.23)degrees, which was significantly lower than the deviation between ideal CobbL4-S1 and preoperative CobbL4-S1 (13.60 ± 1.85)degrees (t = 6.065, P = 0.001). CONCLUSION: Scoliometer software can help surgeon obtain the optimal LL and deserve further dissemination.

[Correlation analysis of cement leakage with volume ratio of intravertebral bone cement to vertebral body and vertebral body wall incompetence in percutaneous vertebroplasty for osteoporotic vertebral compression fractures].

OBJECTIVE: To investigate the risk factors of cement leakage in percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fracture (OVCF). METHODS: Between March 2011 and March 2012, 98 patients with single level OVCF were treated by PVP, and the clinical data were analyzed retrospectively. There were 13 males and 85 females, with a mean age of 77.2 years (range, 54-95 years). The mean disease duration was 43 days (range, 15-120 days), and the mean T score of bone mineral density (BMD) was -3.8 (range, -6.7- -2.5). Bilateral transpedicular approach was used in all the patients. The patients were divided into cement leakage group and no cement leakage group by occurrence of cement leakage based on postoperative CT. Single factor analysis was used to analyze the difference between 2 groups in T score of BMD, operative level, preoperative anterior compression degree of operative vertebrae, preoperative middle compression degree of operative vertebrae, preoperative sagittal Cobb angle of operative vertebrae, preoperative vertebral body wall incompetence, cement volume, and volume ratio of intravertebral bone cement to vertebral body. All relevant factors were introduced to logistic regression analysis to analyze the risk factors of cement leakage. RESULTS: All procedures were performed successfully. The mean operation time was 40 minutes (range, 30-50 minutes), and the mean volume ratio of intravertebral bone cement to vertebral body was 24.88% (range, 7.84%-38.99%). Back pain was alleviated significantly in all the patients postoperatively. All patients were followed up with a mean time of 8 months (range, 6-12 months). Cement leakage occurred in 49 patients. Single factor analysis showed that there were significant differences in the volume ratio of intravertebral bone cement to vertebral body and preoperative vertebral body wall incompetence between 2 groups (P < 0.05), while no significant difference in T score of BMD, operative level, preoperative anterior compression degree of operative vertebrae, preoperative middle compression degree of operative vertebrae, preoperative sagittal Cobb angle of operative vertebrae, and cement volume (P > 0.05). The logistic regression analysis showed that the volume ratio of intravertebral bone cement to vertebral body (P < 0.05) and vertebral body wall incompetence (P < 0.05) were the risk factors for occurrence of cement leakage. CONCLUSION: The volume ratio of intravertebral bone cement to vertebral body and vertebral body wall incompetence are risk factors of cement leakage in PVP for OVCF. Cement leakage is easy to occur in operative level with vertebral body wall incompetence and high volume ratio of intravertebral bone cement to vertebral body.