Kyphoplasty for treatment of osteoporotic vertebral fractures

Cement reinforcement for the treatment of osteoporotic vertebral fractures is efficient mean with high success in pain release and prevention of further sintering of the reinforced vertebrae; however, the technique does not allow to address the kyphotic deformity. Kyphoplasty was designed to address the kyphotic deformity and help to realign the spine. It involves the percutaneous placement of an inflatable bone tamp into a vertebral body. Restoration of VB height and kyphosis correction is achieved by inflation of the bone tamp with liquid. After deflation, a cavity is created that eases the cement application. The potential of kyphosis reduction is given in fresh fractures with a range of 0–90% for height restoration and absolute correction of the kyphotic angle of 8.5°. The cavity formation, on one hand, and the different cementing technique leads to lower risk for cement extravasation. An alternative method for kyphosis correction represents the so-called lordoplasty where the adjacent vertebrae are reinforced first and with the cannulas in place acting as a lever the reduction of the collapsed vertebra can be performed. The results with respect to kyphosis correction are superior in comparison with a kyphoplasty procedure.     

Lordoplasty: report on early results with a new technique for the treatment of vertebral compression fractures to restore the lordosis

Cement augmentation using PMMA cement is known as an efficient treatment for osteoporotic vertebral compression fractures with a rapid release of pain in most patients and prevention of an ongoing kyphotic deformity of the vertebrae treated. However, after a vertebroplasty there is no chance to restore vertebral height. Using the technique of kyphoplasty a certain restoration of vertebral body height can be achieved. But there is a limitation of recovery due to loss of correction when deflating the kyphoplastic ballon and before injecting the cement. In addition, the instruments used are quite expensive. Lordoplasty is another technique to restore kyphosis by indirect fracture reduction as it is used with an internal fixateur. The fractured and the adjacent vertebrae are instrumented with bone cannulas bipediculary and the adjacent vertebrae are augmentated with cement. After curing of the cement the fractured vertebra is reduced by applying a lordotic moment via the cannulas. While maintaining the pretension the fractured vertebra is reinforced. We performed a prospective trial of 26 patients with a lordoplastic procedure. There was a pain relief of about 87% and a significant decrease in VAS value from 7.3 to 1.9. Due to lordoplasty there was a significant and permanent correction in vertebral and segmental kyphotic angle about 15.2° and 10.0°, respectively and also a significant restoration in anterior and mid vertebral height. Lordoplasty is a minimal invasive technique to restore vertebral body height. An immediate relief of pain is achieved in most patients. The procedure is safe and cost effective.     

Kyphosis recurrence after posterior short-segment fixation in thoracolumbar burst fractures

OBJECT: Recurrent kyphosis has been commonly seen after posterior short-segment pedicle instrumentation for a thoracolumbar fracture, but studies on this issue are relatively scarce, and the clinical significance of recurrent deformity is uncertain. No study has addressed the associations between the reduction of a burst fracture vertebra and the final recurrent kyphosis after implant removal. The aim of this study was to investigate the recurrent kyphosis after short-segment pedicle screw fixation in thoracolumbar burst fractures and to evaluate the effect of the degree of a vertebral reduction on the recurrent kyphotic deformity after implant removal. METHODS: Twenty-seven patients who had undergone posterior short-segment pedicle screw fixation for thoracolumbar junction burst fractures (T12-L2) were investigated retrospectively. The minimum follow-up period was 2 years (mean 2.7 years). Pain status was evaluated using the Denis pain scale. Changes in the anterior vertebral height ratio, vertebral wedge angle, upper intervertebral angle, lower intervertebral angle, Cobb angle, regional angle, and sagittal index were measured preoperatively, postoperatively, before implant removal, and at final follow-up. The correlation between the reduction of a fractured vertebra and the recurrent kyphotic deformity was also analyzed. RESULTS: After the initial surgical correction, the reduced vertebral body (VB) height (anterior vertebral height ratio and vertebral wedge angle) remained stable until final follow-up, whereas the intervertebral disc space (the upper and lower intervertebral angles) collapsed, resulting in a progressive kyphotic deformity (Cobb angle, regional angle, and sagittal index). No significant correlation was found between the final kyphosis and pain scale, but the 8 patients with a sagittal index > 15 degrees showed a higher incidence of moderate to severe pain (P3-5 on the Denis pain scale) compared with the remaining 19 patients with a sagittal index < 15 degrees . Significant positive correlation was found between recurrent kyphosis and vertebral wedge angle (r = 0.850, p < 0.001) and the reduced vertebral height (r = -0.727, p < 0.001). CONCLUSIONS: Given that the correction loss occurs primarily through disc space collapse, the amount of the final kyphotic deformity was predictable by the degree of the fractured vertebral reduction as seen on the lateral x-ray study. Surgeons who perform posterior reduction and fixation procedures should pay more attention to reducing the fractured vertebral wedge angle to its intact condition, rather than the segmental angular parameters. If the wedge angle of the fractured VB is unacceptable after reduction, additional reconstruction of the anterior column may be necessary.     

Altered disc pressure profile after an osteoporotic vertebral fracture is a risk factor for adjacent vertebral body fracture

This study investigated the effect of endplate deformity after an osteoporotic vertebral fracture in increasing the risk for adjacent vertebral fractures. Eight human lower thoracic or thoracolumbar specimens, each consisting of five vertebrae were used. To selectively fracture one of the endplates of the middle VB of each specimen a void was created under the target endplate and the specimen was flexed and compressed until failure. The fractured vertebra was subjected to spinal extension under 150 N preload that restored the anterior wall height and vertebral kyphosis, while the fractured endplate remained significantly depressed. The VB was filled with cement to stabilize the fracture, after complete evacuation of its trabecular content to ensure similar cement distribution under both the endplates. Specimens were tested in flexion-extension under 400 N preload while pressure in the discs and strain at the anterior wall of the adjacent vertebrae were recorded. Disc pressure in the intact specimens increased during flexion by 26 ± 14%. After cementation, disc pressure increased during flexion by 15 ± 11% in the discs with un-fractured endplates, while decreased by 19 ± 26.7% in the discs with the fractured endplates. During flexion, the compressive strain at the anterior wall of the vertebra next to the fractured endplate increased by 94 ± 23% compared to intact status (p < 0.05), while it did not significantly change at the vertebra next to the un-fractured endplate (18.2 ± 7.1%, p > 0.05). Subsequent flexion with compression to failure resulted in adjacent fracture close to the fractured endplate in six specimens and in a non-adjacent fracture in one specimen, while one specimen had no adjacent fractures. Depression of the fractured endplate alters the pressure profile of the damaged disc resulting in increased compressive loading of the anterior wall of adjacent vertebra that predisposes it to wedge fracture. This data suggests that correction of endplate deformity may play a role in reducing the risk of adjacent fractures.     

椎体后凸成形术治疗多发性老年骨质疏松脊柱骨折

目的 探讨应用球囊扩张椎体后凸成形术(Kyphoplasty)治疗多发性老年骨质疏松性脊柱骨折的疗效和安全性。方法 治疗8例17椎多发性老年骨质疏松性脊柱骨折,患者均不伴神经损伤,术前X线及MRI检查证实多发性脊柱骨折,手术在C型臂X线机透视下进行,经皮穿刺,置入可扩张球囊于伤椎塌陷终板前下方,扩张球囊提升终板以恢复椎体高度,在持续X线监视下注入骨水泥强化椎体,同法完成各伤椎的操作。结果 8例17椎均顺利完成手术,术后无脊髓神经根受损表现,48h内疼痛均缓解。X线片复查示伤椎高度基本恢复,后凸畸形大部矫正,未发现并发症。结论 球囊扩张椎体后凸成形术治疗多发性老年骨质疏松脊柱骨折安全有效。     

Biomechanical changes after the augmentation of experimental osteoporotic vertebral compression fractures in the cadaveric thoracic spine.

BACKGROUND CONTEXT: Osteoporotic compression fractures are an important public health concern, leading to significant morbidity, mortality and economic burden. Cement augmentation procedures used to treat these fractures alter the biomechanics of the fractured segment, which could promote adjacent failure. However, if alignment is improved or restored, there will be less risk of adjacent failure. PURPOSE: To determine the effects of load (compression/flexion), adjacent vertebral location (superior/inferior) and augmentation on vertebral segment stiffness and adjacent vertebral strain in the upper and lower thoracic spine. STUDY DESIGN: Human cadaveric thoracic spine segments were tested under load control before and after the creation of experimentally augmented vertebral compression fractures. METHODS: Six T1-T5 and six T8-T12 segments were obtained from eight thoracic spines with known bone mineral density (BMD). Rosette strain gauges were applied to T2, T4, T9 and T11 to measure strain adjacent to the experimental fracture sites T3 and T10. Two compression fractures were created in succession, the first in flexion preceded by a weakening defect in T3 and T10 and the second created in an adjacent vertebra in compression without prior weakening. The first fracture was reduced with the inflatable bone tamp (IBT) and augmented with cement. Compression and flexion tests were performed before and after the first fracture while measuring vertebral cortical shear strain on T2, T4, T9 and T11 and stiffness of the entire segment. Strain and stiffness were compared by using a repeated measures analysis using adjacent vertebral location (superior/inferior), augmentation and load (compression/flexion) as factors. RESULTS: The mean BMD was 0.61+/-0.11 g/cm(2) (T1-T5) and 0.78+/-0.07 g/cm(2) (T8-T12). Stiffness in compression and flexion increased with load (p<.05, and p>.27, respectively). Augmentation reduced compressive and bending stiffness (p=.23, and p=.19, respectively), whereas the adjacent vertebral strain increased (p>.11). The adjacent strain in flexion was much greater than in compression (p<.03). Cement augmentation caused greater amounts of inferior than superior adjacent strain (p>.19). The applied moment at first fracture was 2.98+/-1.28 Nm (T1-T5) and 8.44+/-1.02 Nm (T8-T12). The compressive load at second fracture was 1122+/-993 N (T1-T5) and 2906+/-1008 N (T8-T12). Adjacent vertebral strain during the second compression and flexion tests exceeded that during the first compression and flexion tests (p=.11). Adjacent vertebral strain at second fracture exceeded that at first fracture (p=.007) and was greater on the superior adjacent vertebra than the inferior (p=.47). CONCLUSION: With axial compressive loads, the addition of flexion increases fracture risk. Cement augmentation of a fractured vertebral segment reduces stiffness while increasing both the superior and inferior adjacent cortical strain. This increment in strain that is greatest on the inferior adjacent vertebra effectively redistributes loads from the superior adjacent vertebra to the inferior adjacent vertebra, sparing the superior adjacent vertebra from failure.     

Intervertebral disc degeneration can predispose to anterior vertebral fractures in the thoracolumbar spine.

Mechanical experiments on cadaveric thoracolumbar spine specimens showed that intervertebral disc degeneration was associated with reduced loading of the anterior vertebral body in upright postures. Reduced load bearing corresponded to locally reduced BMD and inferior trabecular architecture as measured by histomorphometry. Flexed postures concentrated loading on the weakened anterior vertebral body, leading to compressive failure at reduced load. INTRODUCTION: Osteoporotic fractures are usually attributed to age-related hormonal changes and inactivity. However, why should the anterior vertebral body be affected so often? We hypothesized that degenerative changes in the adjacent intervertebral discs can alter load bearing by the anterior vertebral body in a manner that makes it vulnerable to fracture. MATERIALS AND METHODS: Forty-one thoracolumbar spine "motion segments" (two vertebrae and the intervertebral disc) were obtained from cadavers 62-94 years of age. Specimens were loaded to simulate upright standing and flexed postures. A pressure transducer was used to measure the distribution of compressive "stress" inside the disc, and stress data were used to calculate how compressive loading was distributed between the anterior and posterior halves of the vertebral body and the neural arch. The compressive strength of each specimen was measured in flexed posture. Regional volumetric BMD and histomorphometric parameters were measured. RESULTS: In the upright posture, compressive load bearing by the neural arch increased with disc degeneration, averaging 63 +/- 22% (SD) of applied load in specimens with severely degenerated discs. In these specimens, the anterior half of the vertebral body resisted only 10 +/- 8%. The anterior third of the vertebral body had a 20% lower trabecular volume fraction, 16% fewer trabeculae, and 28% greater intertrabecular spacing compared with the posterior third (p < 0.001). In the flexed posture, flexion transferred 53-59% of compressive load bearing to the anterior half of the vertebral body, regardless of disc degeneration. Compressive strength measured in this posture was proportional to BMD in the anterior vertebral body (r2 = 0.51, p < 0.001) and inversely proportional to neural arch load bearing in the upright posture (r2 = 0.28, p < 0.001). CONCLUSIONS: Disc degeneration transfers compressive load bearing from the anterior vertebral body to the neural arch in upright postures, reducing BMD and trabecular architecture anteriorly. This predisposes to anterior fracture when the spine is flexed.     

Changes of the adjacent discs and vertebrae in patients with osteoporotic vertebral compression fractures treated with or without bone cement augmentation

BACKGROUND CONTEXTAlthough vertebral augmentation with bone cement has been commonly used to treat symptomatic osteoporotic vertebral compression fractures, relatively little is known about the impact of augmentation on the adjacent spinal components.PURPOSETo determine the imaging effects of vertebral augmentation on the adjacent discs, the augmented vertebra, and the involved spinal segment.STUDY DESIGNRetrospective radiographic study.PATIENT SAMPLEPatients with acute osteoporotic vertebral compression fractures who underwent vertebral augmentation or nonoperative treatments.OUTCOME MEASURESOn baseline and follow-up mid-sagittal T2W magnetic resonance images, quantitative measurements of disc degeneration, including disc height, bulging, and signal, vertebral height, wedge angle, and segmental kyphotic angle were acquired.METHODSLumbar spine magnetic resonance images of patients with acute osteoporotic vertebral compression fractures at a local hospital in Eastern China between 2010 and 2017 were reviewed. Student's t-tests and χ² tests were used to examine the differences of baseline and changes over time between vertebrae underwent vertebral augmentation and those did not. Paired t-tests were used to examine the differences between baseline and follow-up to study the changes of adjacent disc degeneration, creep deformity of the vertebra and progression of segmental kyphosis.RESULTSThere were 112 acute vertebral compression fractures (72 treated with kyphoplasty and 40 with nonoperative treatments) in 101 subjects. At final follow-up (mean 21.5 months), the cranial disc of the augmented vertebra decreased in height (p<.001), and both cranial and caudal discs decreased in signal intensity (p≤.02). The discs in the nonoperative group did not undergo such degenerative changes. For the fractured vertebra, vertebral height significantly decreased (p<.01 for both) and vertebral wedge angle significantly increased (p≤.01 for both), regardless of augmentation treatment or not. Segmental kyphotic angle significantly increased in vertebral fractures that underwent vertebral augmentation (p<.001), but not in those underwent nonoperative treatments.CONCLUSIONSPatients that underwent vertebral augmentation had more advanced disc degeneration at adjacent disc levels as compared to those without augmentation. The fractured vertebral body height decreased and the wedge angle increased, regardless of vertebral augmentation treatment or not. Vertebral augmentation may be associated with increased creep deformity of the adjacent vertebra and the progression of segmental kyphosis.     

Ergebnisse der Ballonkyphoplastie in der Behandlung von osteoporotischen Wirbelkörperfrakturen

The aim of this study was to evaluate the reduction of pain, improvement of sagittal alignment, complications and intermediate term results of balloon kyphoplasty in the treatment of osteoporotic vertebral compression fractures (VCF).The study group consisted of 87 patients with 145 VCFs which were not responsive to non-operative treatment. All data were collected prospectively. Improvement of sagittal alignment (Cobb and kyphotic angles, anterior, middle and posterior height) was determined from CT scans. Pain was evaluated by means of a visual analogue scale (VAS).Postoperative CT scans revealed a significant reduction of the mean kyphotic angle of 5.7 degrees (range 2-24 degrees ) and a significant reduction of pain from 7.8+/-2.4 to 2.0+/-1.5 in the VAS (improvement of pain in 95.5% of patients). An asymptomatic leakage of cement was observed in 28 out of 145 vertebrae (19.3%). The outcome of 35 patients with 51 VCFs was evaluated after a mean of 13 (range 12-70) months (CT and VAS) and there was a persisting reduction of pain and no loss of reduction. In this group of patients new symptomatic fractures were evident in 4 and clinically asymptomatic (only seen on CT) fractures were detected in 5 out of 35 patients, 7 fractures were adjacent to and 2 fractures were remote from the initially treated level. In two patients an asymptomatic moderate loss of reduction was detected.These intermediate term results indicate that kyphoplasty reduces pain and improves sagittal alignment in patients with VCF. However, in 26% of patients new fractures occurred, predominantly in adjacent levels but approximately 50% of these fractures were clinically asymptomatic.     

Does spinal kyphotic deformity influence the biomechanical characteristics of the adjacent motion segments? An in vivo animal model.

STUDY DESIGN: In an in vivo sheep model, the effects of spinal fusion and kyphotic deformity on the neighboring motion segments were analyzed. OBJECTIVES: To investigate the effects of spinal fusion and kyphotic deformity on the adjacent motion segment. SUMMARY OF BACKGROUND DATA: The in vivo effects of kyphotic deformity on the neighboring motion segments have not been investigated in any studies. METHODS: Eighteen sheep were equally randomized into three groups based on surgical procedure: L3-L5 in situ posterolateral fusion (n = 6) L3-L5 kyphotic posterolateral fusion (n = 6), and surgical exposure alone (n = 6). After a 16-week survival period, the adjacent motion segment changes were analyzed radiographically, biomechanically, and histologically. RESULTS: The kyphosis group showed 5.0 degrees +/- 2.6 degrees and 1.7 degrees +/- 1.8 degrees compensatory hyperlordosis at L2-L3 and L5-L6, respectively, compared with surgical exposure and in situ posterolateral fusion, the kyphotic posterolateral fusion significantly influenced cranial adjacent motion segment biomechanics by inducing more stiffness in the posterior ligamentous complex (P < 0.05) and increasing lamina strain under flexion-extension loading (P < 0.05). Results of histologic analysis showed significant degenerative changes of the L2-L3 facet joints in the kyphosis group. CONCLUSIONS: It is inferred that in the kyphosis group, compensatory hyperlordosis at the cranial adjacent level leads to lordotic contracture of the posterior ligamentous complex. The increased lamina strain, exhibited by the in situ group under flexion-extension, was further increased in the kyphosis group, indicating higher load transmission through the posterior column. Significant degenerative changes of the cephalad adjacent facet joints observed in the kyphosis group served to corroborate the biomechanical data. These results indicate that a kyphotic deformity may lead to facet joint contracture and facet arthritis and may serve as the origin of low back pain at the cranial adjacent level.     

Vertebral locking lesion following cervical spine fracture in ankylosing spondylitis

Spine fractures in patients with ankylosing spondylitis frequently extend to all 3 columns, which can lead to displacement and deformity with severe instability. Cervical spine fractures occasionally cause severe kyphotic deformities, such as chin-on-chest deformities. In such cases, the patients typically exhibit a chronic progression of hyperkyphosis after the traumatic event. This article describes a unique case of ankylosing spondylitis associated with an acute chin-on-chest deformity following a spine fracture due to a vertebral locking lesion.A 60-year-old man fell while walking and sustained a compression fracture of the C6 vertebra. Two weeks later, the patient acutely developed an inability to raise his head, difficulties with chewing and swallowing, and a horizontal gaze. Radiographs demonstrated a severe kyphosis in the cervical spine with a locking lesion between the anterior wall of the C5 and C6 vertebrae. The patient also presented with neurological impairment in his hands. Because the anterior approach to the spine was anatomically impossible, halo traction was initially applied under a close observation of neurological symptoms. Three days after halo traction, release of the vertebral locking lesion and realignment of the spine were seen. The patient subsequently underwent spinal fusion using a combined anterior-posterior approach.Postoperatively, neurological dysfunction improved, and solid fusion was confirmed at 6 months. In cases of acute kyphotic deformity following cervical spine fracture in ankylosing spondylitis patients, halo traction followed by circumferential spine fusion is a safe and effective approach for improving the alignment and stability of the spine.     

单双入路后凸成形术治疗胸腰椎压缩骨折比较

目的：探讨单入路与双入路球囊扩张椎体后凸成形术治疗老年骨质疏松性胸腰椎压缩性骨折在疗效和安全性上的差异。方法：52例患者随机分为单入路组和双入路组。单入路组16例,经皮伤椎单侧入路穿刺建立工作通道,放置单枚球囊于伤椎内,行球囊扩张椎体后凸成形术 双入路组36例,经皮伤椎双侧入路穿刺建立工作通道,在双侧分别放置球囊于伤椎内,行球囊扩张椎体后凸成形术。结果：52例患者均未发现神经损伤等并发症,两组背痛缓解程度、脊柱后凸畸形矫正度、伤椎前缘高度恢复比较,差异无显著性（P〉0.05） 两组手术时间和透视次数比较,差异有显著性（P〈0.05）。结论：单入路与双入路椎体后凸成形术治疗老年骨质疏松性胸腰椎压缩性骨折疗效相似,单入路较双入路能明显减少手术时间和放射暴露。     

Predictors of kyphotic deformity in osteoporotic vertebral compression fractures: a radiological study

Purpose

To report the radiological predictors of kyphotic deformity in osteoporotic vertebral compression fractures (OVCF).

Methods

This is a retrospective study of 64 consecutive patients with OVCF. We studied the radiographic features in the immediate post-injury image of patients, who developed significant (more than 30°) segmental kyphotic deformity at final follow-up and compared them with those patients who did not.

Results

Thirty-three (82.5 %) out of 40 patients with fracture at thoracolumbar (TL) junction, 5 (33.3 %) patients out of 15 with fracture at lumbar (L) spine and 7 (77.7 %) patients out of 9 with fracture at thoracic (T) spine developed significant segmental kyphotic deformity. Forty-one (75.9 %) [TL-33 (80.5 %), L-4 (33.33 %) and T-4 (80 %)] out of 54 [TL-37 (68.51 %), L-12 (22.23 %) and T-5 (9.26 %)] patients with superior endplate fracture developed significant segmental kyphotic deformity. Forty patients (86.9 %) [TL-28 (70 %), L-6 (15 %) and T-6 (15 %)] out of 46 [TL-32 (69.56 %), L-8 (17.4 %) and T-6 (13.04 %)] with anterior cortical wall fracture developed significant segmental kyphotic deformity. Five patients (71.42 %) [TL-2 (40 %) and T-3 (60 %)] out of 7 [TL-02 (28.58 %), L-01 (14.28 %), T-04 (57.14 %)] with adjacent level fracture developed significant segmental kyphotic deformity. The average immediate post-injury kyphosis of 11° (5°–25°) increased to 29° (15°–50°) at final follow-up.

Conclusion

Progressive segmental kyphotic collapse following an OVCF seems unavoidable. Patients with TL junction and superior endplate fracture are probably at the highest risk for significant segmental kyphotic deformity.     

椎体后凸成形术治疗骨质疏松性脊柱压缩骨折

[目的]分析椎体后凸成形术治疗骨质疏松性椎体压缩骨折的临床和影像学结果,评价其临床效果。[方法]本组43例骨质疏松性椎体压缩骨折均接受经皮椎体球囊扩张后凸成形术。其中男19例,女24例;年龄56~85岁,平均68·2岁。本组共61个椎体骨折,其中单椎体26例,两椎体骨折11例,三椎体骨折4例,四椎体骨折2例。椎体骨折部位T7~L5。术后对患者的疼痛、日常功能以及影像学结果进行了分析。[结果]所有患者随访1a以上,平均18·8个月(12~36个月)。平均VAS评分由术前8·6到术后2·3和最终随访2·7(P<0·001),Oswestry评分由术前55到术后30和最终随访35(P<0·01)。手术椎体前、中柱平均高度由术前的12·20mm到术后的25·38mm和最终随访26·36mm。脊柱矢状位后凸畸形改善平均9·9°(4·3~22°),随访丢失平均1·6°(0·8~1·7°)。4例发生骨水泥渗漏,但无严重并发症发生。最终随访时有3例患者发生3个临近节段椎体压缩骨折。[结论]球囊扩张椎体后凸成形术可有效恢复骨质疏松性骨折椎体的高度、迅速缓解疼痛、改善病人的功能,明显减少骨水泥的渗漏率,是一种安全、有效的治疗方法。     

Radiographic parameters for evaluating the neurological spaces in experimental thoracolumbar burst fractures

It is important to know the condition of neural spaces during the nonoperative treatment of thoracolumbar burst fractures. The goals of the current study were to identify the correlation between the degree of deformity of a fractured vertebra and the encroachment of neural spaces, and to determine how the encroachment and the deformity can be improved by the extension posture simulating the postural reduction. Experimental burst fractures were produced in L1 vertebrae of nine human thoracolumbar spine segments (T11-L3) with neural spaces lined with tiny steel balls. Lateral radiographs were taken in neutral and extended posture before and after the trauma. Anterior vertebral height, posterior vertebral height, vertebral height ratio, vertebral kyphotic angle, posterior vertebral body angle, and the cross diagonal angle were the geometric parameters used to describe the vertebral deformity. The canal diameter and superior and inferior intervertebral foramen areas were defined as the neural spaces. All parameters were measured on the scanned images of radiographs, as seen on the computer screen. Among the vertebral body parameters, the posterior vertebral height, posterior vertebral body angle, and cross diagonal angle showed significantly higher correlations with the canal encroachment. The extended posture did not improve the canal and intervertebral foramen encroachments. The kyphotic deformity (vertebral kyphotic angle and anterior vertebral height) was improved but the deformity of the vertebral posterior wall (posterior vertebral height and posterior vertebral body angle) was not improved because of the extended posture.     

Anterior radical debridement and anterior instrumentation in tuberculosis spondylitis

The conventional procedure in the treatment of vertebral tuberculosis is drainage of the abscess, curettage of the devitalized vertebra and application of an antituberculous chemotherapy regimen. Posterior instrumentation results are encouraging in the prevention or treatment of late kyphosis; however, a second-stage operation is needed. Recently, posterolateral or transpedicular drainage without anterior drainage or posterior instrumentation following anterior drainage in the same session has become the preferred treatment, in order that kyphotic deformity can be avoided. Information on the use of anterior instrumentation along with radical debridement and fusion is scarce. This study reports on the surgical results of 63 patients with Pott's disease who underwent anterior radical debridement with anterior fusion and anterior instrumentation (23 patients with Z-plate and 40 patients with CDH system). Average age at the time of operation was 46.8+/-13.4 years. Average duration of follow-up was 50.9+/-12.9 months. Local kyphosis was measured preoperatively, postoperatively and at the last follow-up visit as the angle between the upper and lower end plates of the collapsed vertebrae. Vertebral collapse, destruction, cold abscess, and canal compromise were assessed on magnetic resonance (MR) images. It was observed that the addition of anterior instrumentation increased the rate of correction of the kyphotic deformity (79.7+/-20.1%), and was effective in maintaining it, with an average loss of 1.1 degrees +/-1.7 degrees. Of the 25 patients (39.7%) with neurological symptoms, 20 (80%) had full and 4 (16%) partial recoveries. There were very few intraoperative and postoperative complications (major vessel complication: 3.2%; secondary non-specific infection: 3.2%). Disease reactivation was not seen with the employment of an aggressive chemotherapy regimen. It was concluded that anterior instrumentation is a safe and effective method in the treatment of tuberculosis spondylitis.     

Mechanical modulation of growth for the correction of vertebral wedge deformities.

This study tested the following hypotheses: (a) a vertebral wedge deformity created by chronic static asymmetrical loading will be corrected by reversal of the load asymmetry; (b) a vertebral wedge deformity created by chronic static asymmetrical loading will remain if the load is simply removed; and (c) vertebral longitudinal growth rates, altered by chronic static loading, will return to normal after removal of the load. An external fixator was used to impose an angular deformity (Cobb angle of 30 degrees) and an axial compression force (60% body weight) on the ninth caudal (apical) vertebra in two groups of 12 5-week-old Sprague-Dawley rats. This asymmetrical loading was applied to all rats for 4 weeks to create an initial wedge deformity in the apical vertebra. The rats from group I (load reversal) then underwent 1 week of distraction loading followed by 4 weeks of asymmetrical compressive loading with the imposed 30 degree Cobb angle reversed. The rats from group II (load removal) had the apparatus removed and were followed for 5 weeks with no external loading. Weekly radiographs were obtained and serial fluorochrome labels were administered to follow vertebral wedging. After the initial 4-week loading period, the combined average wedge deformity that developed in the apical vertebra of the animals in both groups was 10.7 +/- 4.4 degrees. The group that underwent load reversal showed significant correction of the deformity with the wedging of the apical vertebra decreasing to, on average, 0.1 +/- 1.4 degrees during the 4 weeks of load reversal. Wedging of the apical vertebra in the group that underwent load removal significantly decreased to 7.3 +/- 3.9 degrees during the first week after removal of the load, but no significant changes in wedging occurred after that week. This indicated a return to a normal growth pattern following the removal of the asymmetrically applied loading. The longitudinal growth rate of the apical vertebra also returned to normal following removal of the load. Vertebrae maintained under a load of 60% body weight grew at a rate that was 59.4 +/- 17.0% lower than that of the control vertebrae, whereas after vertebrae were unloaded their growth averaged 102.4 +/- 31.8%. These findings show that a vertebral wedge deformity can be corrected by reversing the load used to create it and that vertebral growth is not permanently affected by applied loading.     

Presence or absence of adjacent vertebral fractures has no effect on long-term global alignment and quality of life in patients with osteoporotic vertebral fractures treated with balloon kyphoplasty

BackgroundGlobal sagittal malalignment after osteoporotic vertebral fracture is correlated with decreased quality of life. Balloon kyphoplasty promotes short-term global alignment, but long-term correction is difficult in patients with such fractures. Adjacent vertebral fracture is one of the major complications of balloon kyphoplasty. We investigated the correlation of the incidence of adjacent vertebral fracture with the loss of global alignment correction after balloon kyphoplasty.MethodsForty patients were enrolled in this retrospective study. Adjacent vertebral fracture occurred in 17 patients. Sagittal vertical axis, the angle between the two vertebrae above and below the balloon kyphoplasty site (local alignment angle), and the vertebral kyphotic angle at the kyphoplasty site were measured pre- and post-operatively. Clinical results were assessed.ResultsThere were no significant differences between the sagittal vertical axis before and after balloon kyphoplasty in groups with (+) or without (−) adjacent vertebral fracture. Local alignment angles decreased soon after balloon kyphoplasty, but increased during follow-up in both groups. Vertebral kyphotic angles decreased significantly soon after balloon kyphoplasty in both groups; although this increased significantly in the adjacent vertebral fracture (−) group, but not in the adjacent vertebral fracture (+) group, during follow-up. Correction loss of alignment was found in both adjacent vertebral fracture (+) and (−) groups, attributed to adjacent vertebral fracture in the former and re-collapse of the balloon kyphoplasty site in the latter. No significant differences in clinical results were observed between the groups, although these were strongly correlated with sagittal vertical axis before balloon kyphoplasty.ConclusionsThe adjacent vertebral fracture (+) and (−) groups exhibited similar correction loss of alignment and improved quality of life. The presence or absence of adjacent vertebral fractures had no effect on long-term global alignment and patient quality of life.     

Biomechanical evaluation of kyphoplasty with calcium phosphate cement in a 2-functional spinal unit vertebral compression fracture model

BACKGROUND CONTEXT: Kyphoplasty is used to treat vertebral compression fractures (VCFs) by inflating a balloon within the vertebral body (VB) to create a void, thereby reducing the fracture, and then depositing polymethylmethacrylate (PMMA) into that void to augment the VB. Calcium phosphate (CaP) may be preferable to PMMA because it is resorbable and nontoxic, although there are concerns about its compressive strength during the setting process. PURPOSE: To evaluate the ability of a particular self-setting CaP cement to restore the structural integrity of a VCF in a 2-functional spinal unit (2FSU) cadaver model under physiologically relevant loading. STUDY DESIGN/SETTING: Repeated-measures compressive testing on a cadaver thoracolumbar 2FSU VCF model. METHODS: Ten 2FSU thoracolumbar specimens were tested to evaluate structural integrity under compressive loading during initial anterior VCF creation (in the central VB), after fracture, and after kyphoplasty treatment. Bipedicular kyphoplasty treatment was performed in a 37 degrees C chamber to reduce the fracture and create a void, which was filled with CaP (n=5) or PMMA (n=5) and allowed to cure for at least 15 minutes. Using fluoroscopic imaging, the sagittal area of the VB (SAVB), the minimum central VB height (MCVBH), and the wedge angle were measured on the central VB for each condition at a 1,000-N compressive load. A repeated-measures linear model was used to determine if the differences in these parameters among the various experimental conditions were statistically significant (p< .05). RESULTS: Compared with the fractured condition, there was a significant improvement in the SAVB, MCVBH, and wedge angle under a physiologically relevant 1,000-N compressive load applied after kyphoplasty. There was no statistically significant difference between treatment with CaP or PMMA. CONCLUSIONS: The structural properties of CaP-augmented VBs are similar to those of PMMA-augmented VBs. Our study indicated that, after at least 15 minutes of setting, a fractured 2FSU specimen treated with kyphoplasty with PMMA or CaP could withstand physiologically relevant loading.     

椎体后凸成形术治疗重度骨质疏松性椎体压缩骨折

目的 探讨应用椎体后凸成形术治疗重度骨质疏松性椎体压缩骨折的可行性和疗效.方法 2003年8月至2008年6月,治疗椎体后壁完整的重度骨质疏松性椎体压缩骨折35例(48椎),男2例,女33例;年龄64～86岁,平均74.2岁.患椎压缩程度为75.8%～80.1%,平均77.0%.在"C"型臂X线机引导下经皮穿刺进针,建立工作通道后放入可扩张球囊,行"扩张-放松-再扩张"渐进式复位,扩张压力不超过150 psi(1 psi=6.89 kPa).复位基本满意或球囊达椎体皮质时停止扩张,取出球囊,在"C"型臂X线机监视下将可显影骨水泥低压注入椎体.结果 35例患者均顺利完成手术.椎体前缘、中部及后缘平均高度分别由术前(0.8±0.1)cm、(0.8±0.2)cm和(2.1±0.8)cm增至术后第3天(1.2±0.3)cm、(1.3±0.2)cm和(2.3±1.0)cm,手术前后椎体前缘、中部高度差异有统计学意义.矢状面Cobb角由术前28.2°±5.2°矫正至术后19.1°±4.9°.疼痛视觉模拟评分(visual analogue scale,VAS)由术前(7.4±1.7)分(5.5～9.4分)降至术后第3天(1.8±1.1)分(0～3.0分).SF-36健康调查评分由术前(33.2±7.1)分提高至术后第3天(42.7±7.9)分.结论 通过改进穿刺复位方法及控制球囊扩张压力,椎体后凸成形术对重度骨质疏松性椎体压缩骨折患者可行且有效.