Aspiration of osteoprogenitor cells for augmenting spinal fusion: comparison of progenitor cell concentrations from the vertebral body and iliac crest

BACKGROUND: Successful arthrodesis in challenging clinical scenarios is facilitated when the site is augmented with autograft bone. The iliac crest has long been the preferred source of autograft material, but graft harvest is associated with frequent complications and pain. Connective tissue progenitor cells aspirated from the iliac crest and concentrated with allograft matrix and demineralized bone matrix provide a promising alternative to traditional autograft harvest. The vertebral body, an even larger reservoir of myeloproliferative cells, should provide progenitor cell concentrations similar to those of the iliac crest. METHODS: Twenty-one adults (eleven men and ten women with a mean age of 59 +/- 14 years) undergoing posterior lumbar arthrodesis and pedicle screw instrumentation underwent transpedicular aspiration of connective tissue progenitor cells. Aspirates were obtained from two depths within the vertebral body and were quantified relative to matched, bilateral aspirates from the iliac crest that were obtained from the same patient at the same time. Histochemical analysis was used to determine the prevalence of vertebral progenitor cells relative to the depth of aspiration, the vertebral level, age, and gender, as compared with the iliac crest standard. The cell count, progenitor cell concentration (cells/cc marrow), and progenitor cell prevalence (cells/million cells) were calculated. RESULTS: Aspirates of vertebral marrow demonstrated comparable or greater concentrations of progenitor cells compared with matched controls from the iliac crest. Progenitor cell concentrations were consistently higher than matched controls from the iliac crest (p = 0.05). The concentration of osteogenic progenitor cells was, on the average, 71% higher in the vertebral aspirates than in the paired iliac crest samples (p = 0.05). With the numbers available, there were no significant differences relative to vertebral body level, the side aspirated, the depth of aspiration, or gender. An age-related decline in cellularity was suggested for the iliac crest aspirates. CONCLUSIONS: The vertebral body is a suitable site for aspiration of bone marrow for graft augmentation during spinal arthrodesis.     

Optimal aspiration volume of vertebral bone marrow for use in spinal fusion

Background context

Bone marrow aspirate (BMA) has shown promise as a bone graft option in spinal fusion. The vertebral body is a convenient source for marrow aspirate as it is accessed in routine course of pedicle screw instrumentation. Studies have relied on data from the iliac crest to determine optimal aspiration volume from the vertebral body.

Purpose

This study is designed to determine the optimal aspiration volume for BMA taken from the vertebral body.

Study design

Prospective clinical study.

Patient sample

Data are drawn from 18 pedicles and 180 aspirations. The average age of the subjects was 50.3 years, and the subject pool comprised five men and seven women.

Outcome measures

Nucleated cell count and alkaline phosphatase staining colony forming units.

Methods

Ten 1 mL aliquots of BMA were incrementally aspirated through a cannulated pedicle tap for each instrumented vertebral body. The numbers of nucleated cells per mL of BMA were analyzed with a hemocytometer, and the percentage of osteoprogenitor cells per mL aspirate were estimated by an alk phos production assay. The study was funded through departmental funds, and none of the authors have any conflicts of interest to report related to the study.

Results

Nucleated cell count decreased with increasing aspirate number (p<.001). The average cell count for the first mL was 45.8 million cells. Cell counts did not differ by age or sex (p=.943 and p=.685, respectively). Likewise, osteoprogenitor cell percentage decreased with increasing aspirate number (p<.001).

Conclusions

The 2 mL aspirate volume has been defined as ideal for the iliac crest, but there has been no analogous assessment of the effect of aspiration volume for other sources such as the vertebral body. This information is important for the clinical implementation of vertebral body aspirations if volume, cells, and presumably performance, of this potential bone graft option are to be optimized for spine cases. Our data show a direct relationship between increasing aspiration number and decreasing osteoprogenitor cellular concentration, with a drop to 50% of the original aspirate cell count by the 4th mL aspirate. The vertebral body is a potentially exciting source of osteoprogenitor cells that can be implemented for a variety of spinal uses.     

Anatomical considerations for cervical pedicle screw insertion: the use of multiplanar computerized tomography measurements in 122 consecutive clinical cases

Background contextSuccessful placement of pedicle screws in the cervical spine requires a sufficient three-dimensional understanding of pedicle morphology to allow accurate identification of the screw axis.PurposeThe goal of the present study was to assess morphologic trends from one level to the next with respect to linear and angular parameters associated with the subaxial cervical pedicles.Study design/settingWe evaluated the pedicle morphology of cervical spine using axial and sagittal computed tomography (CT) imaging. The C3–C7 vertebrae in 122 patients (610 vertebrae) were evaluated (age range, 14–93; mean, 48 years).MethodsThin cut (2.5 mm thickness) axial CT images were measured. Sagittal reconstructions were obtained using 1.25-mm thickness slices. The following pedicle parameters were assessed: pedicle width (PW, the mediolateral diameter of the pedicle isthmus, perpendicular to the pedicle axis), pedicle height (PH, rostro-caudal dimension of the pedicle determined on the sagittal image), maximal screw length (MSL, distance from the posterior cortex of the lateral mass to the anterior wall of the vertebral body along the pedicle axis), and pedicle transverse angle (PTA, angle between the pedicle axis and the midline vertebral body).ResultsThe overall mean PW and PH ranged from 4.7 to 6.5 mm and 6.4 to 7.0 mm, respectively. For both these parameters there was a trend toward increasing size proceeding caudally in the cervical spine. The mean PW and PH was greater in males than in females, and this difference was statistically significant at all levels (p<.0001). The overall mean MSL ranged from 29.9 to 32.9 mm. All intersections of the pedicle axis and the posterior cortex of the lateral mass were located at the most lateral portion of the lateral mass for the C3–C6 vertebrae. The overall mean PTA ranged from 37.8° to 45.3°. The overall mean PTA was approximately 44° from C3 to C6 and 37.8° at C7.ConclusionThe findings of our radiological anatomical study suggest that the preoperative CT scans of patients undergoing cervical transpedicular fixation should be thoroughly analyzed and close attention paid to the pedicle size and its angulation. The placement of cervical pedicle screws should be individualized for each patient and based on detailed preoperative planning.     

When does intraoperative 3D-imaging play a role in transpedicular C2 screw placement?

IntroductionThe stabilization of an atlantoaxial (C1-C2) instability is demanding due to a complex atlantoaxial anatomy with proximity to the spinal cord, a variable run of the vertebral artery (VA) and narrow C2 pedicles. We perfomed the Goel & Harms fusion in combination with an intraoperative 3D imaging to ensure correct screw placement in the C2 pedicle. We hypothesized, that narrow C2 pedicles lead to a higher malposition rate of screws by perforation of the pedicle wall. The purpose of this study was to describe a certain pedicle size, under which the perforation rate rises.Patients and methodsIn this retrospective study, all patients (n = 30) were operated in the Goel & Harms technique. The isthmus height and pedicle diameter of C2 were measured. The achieved screw position in C2 was evaluated according to Gertzbein & Robbin classification (GRGr).ResultsA statistically significant correlation was found between the pedicles size (isthmus height/pedicle diameter) and the achieved GRGr for the right (p = 0.002/p = 0.03) and left side (p = 0.018/p = 0.008). The ROC analysis yielded a Cut Off value for the pedicle size to distinguish between an intact or perforated pedicle wall (GRGr 1 or ≥2). The Cut-Off value was identified for the isthmus height (right 6.1 mm, left 5.4 mm) and for the pedicle diameter (6.6 mm both sides).ConclusionThe hypothesis, that narrow pedicles lead to a higher perforation rate of the pedicle wall, can be accepted. Pedicles of <6.6 mm turned out to be a risk factor for a perforation of the pedicle wall (GRGr 2 or higher). Intraoperative 3D imaging is a feasible tool to confirm optimal screw position, which becomes even more important in cases with thin pedicles. The rising risk of VA injury in these cases support the additional use of navigation.     

Additional vertebral augmentation with posterior instrumentation for unstable thoracolumbar burst fractures

BackgroundTo investigate the role of vertebral augmentation in kyphosis reduction, vertebral fracture union, and correction loss after surgical management of thoracolumbar burst fracture.DesignRetrospective chart and radiographic review.SettingLevel 1 trauma center.MethodsThe analysis included patients treated between April 2007 and June 2015, who received pedicle-screw-rod distraction and reduction within two days following acute traumatic thoracolumbar burst fracture with a load sharing score >6. Medical records were retrospectively reviewed for data regarding operative details, imaging and laboratory findings, neurological function, and functional outcomes.InterventionNot applicable.Main outcome measuresSagittal index, pain score, loss of correction, and implant failure rate.ResultsNineteen patients were enrolled in this study (mean age, 37.2 ± 13 years; age range, 17–62 years; female/male ratio: 10/9). Of the five patients who received only reduction (no augmentation), one underwent revision surgery because of implant failure and pedicle screw backing out. Compared to patients who received only reduction, those who received both reduction and augmentation showed better sagittal alignment after the operation, with better sagittal index immediately postoperatively and during the follow-up (p < 0.05).ConclusionsTranspedicular vertebral augmentation with calcium sulfate/phosphate-based bone cement may reinforce thoracolumbar burst fracture stability, partially restore vertebral body height, and reduce pedicle screw bending and movement, thereby preventing early implant failure and late loss of correction, especially in patients with excellent fracture reduction.Level of evidence: Therapeutic level III, retrospective chart review     

Only prolonged time from abstraction found to affect viable nucleated cell concentrations in vertebral body bone marrow aspirate

Background contextVertebral body–derived bone marrow aspirate (BMA, with an appropriate carrier) is a potential alternative to traditional iliac crest bone graft for use in spinal fusion surgery. No studies have looked at the effect of different temporary handling/storage conditions on the osteoprogenitor potential of BMA. This is especially important because aspirate, as with cancellous and/or cortical grafts, may be extracted some time before actual implementation in regular clinical use.PurposeTo characterize factors that affect BMA cell concentration during routine spinal instrumentation, this study examined whether cell counts change significantly between the second pedicle aspirated and the first pedicle harvested at the same vertebral level. This study also aims to examine the optimal perioperative storage conditions for BMA obtained from the vertebral body.Study designIn vitro concentrations of viable cells were determined in BMA harvested from the first and second pedicles on every vertebral level, and after 1 hour of storage in different perioperative conditions.Patient sampleBMA was harvested from 28 pedicles from seven patients undergoing lumbar instrumented fusion surgeries.Outcome measuresThe outcome measure included viable nucleated cell concentrations in BMA.MethodsAfter obtaining HIC approval from our institution, 28 vertebral marrow aspirates (obtained from seven patients) were evaluated. Based on prior work, 4-mL aspirates from each pedicle were evaluated. BMA was aspirated from both pedicles of two vertebral levels per patient. Samples were divided and placed in different storage conditions to examine the effect of laterality (first versus second pedicle aspirated per level), temperature, media, and time, on nucleated cell counts. No funding was received for this study, and the authors disclose no study specific conflicts of interest.ResultsCell count was not significantly different between the first or second side aspirated for each vertebral level. Similarly, no significant differences were found for samples after 1 hour of storage at different temperatures (0°C, room temperature, or 37°C) or media (none, saline, essential media). Of the conditions examined, time from aspiration was the only variable found to have an impact on nucleated cell counts (p=.003). The viable cell count decreased to less than half by 4 hours.ConclusionAs vertebral BMA is increasingly considered as a bone grafting option, the field would be remiss not to consider factors that could affect cell viability after abstraction and before implementation. We expected a greater effect of perioperative storage conditions than was observed. Although the variables evaluated might show small effects on cell viability in a larger study, this would not be expected to be significant. In the current study, only prolonged time from abstraction could be shown to have a significant effect on cell viability.     

单侧枢椎椎板螺钉在椎动脉变异的上颈椎不稳中的临床应用

目的：探讨后路寰椎侧块螺钉联合单侧枢椎椎板螺钉＋对侧枢椎椎弓根螺钉固定、自体双皮质骨加压植骨融合术治疗上颈椎不稳伴椎动脉变异的临床疗效。方法：2008年6月至2012年12月,行后路寰椎侧块螺钉联合单侧枢椎椎板螺钉＋对侧枢椎椎弓根螺钉固定、自体双皮质骨加压植骨融合术12例,男8例,女4例,年龄16—77岁,平均47．5岁。术前患者枕颈部活动受限伴或不伴疼痛,VAS评分0-7分,平均3．50±2．71;椎动脉造影或颈椎CTA示单侧椎动脉明显狭窄。观察术中有无神经及血管损伤;术后7d内行X线和CT检查,了解内固定位置;术后随访观察有无内固定松动、断裂失败并发症、复位丢失,以及植骨融合率等。结果：12例单侧枢椎椎板螺钉固定,术中未发生神经和椎动脉损伤。患者颈部VAS评分0．92±0．90,较术前明显减轻（P=0．01）。术后x线示12例患者颈椎序列恢复良好,CT示1例枢椎椎板腹侧皮质侵犯,余位置均良好。12例患者均获得随访,时间6个月～3年;未见内固定松动、断裂和复位丢失等并发症;术后6个月12例均骨性融合。结论：后路寰椎侧块螺钉联合单侧枢椎椎板螺钉＋对侧枢椎椎弓根螺钉固定、自体双皮质骨加压植骨融合术,既避免了传统螺钉固定椎动脉损伤的同时,又克服了部分病例双侧枢椎椎板螺钉时植骨床的不足,在保证良好力学稳定的情况下,可以取得良好的骨性融合率。单侧枢椎椎板螺钉可以作为一种安全有效的补充固定措施应用于椎动脉变异的上颈椎不稳患者中。     

The vertebral interbody grafting site’s low concentration in osteogenic progenitors can greatly benefit from addition of iliac crest bone marrow

The ability of bone substitutes to promote bone fusion is contigent upon the presence of osteoinductive factors in the bone environment at the fusion site. Osteoblast progenitor cells are among these environmental osteoinductive factors, and one of the most abundant and available sources of osteoblastic cells is the bone marrow. As far as biological conditions are concerned, the vertebral interbody space appears as a favorable site for fusion, as it is surrounded by spongy bone, theoretically rich in osteogenic cells. This site may, however, not be as rich in osteogenic precursor cells especially at the time of grafting, because decortication of the vertebral end plates during the grafting process may modifiy cell content of the surrounding spongy bone. We tested this hypothesis by comparing the abundance of human osteogenic precursor cells in bone marrow derived from the iliac crest, the vertebral body, and the decorticated intervertebral body space. The number of potential osteoblast progenitors in each site was estimated by counting the alkaline phosphatase–expressing colony-forming units (CFU-AP). The results, however, demonstrate that the vertebral interbody space is actually poorer in osteoprogenitor cells than the iliac crest (P<0.001) and vertebral body (P<0.01), especially at the time of graft implantation. In light of our results, we advocate addition of iliac crest bone marrow aspirate to increase the success rate of vertebral interbody fusion.     

Pedicle screw placement at the sacrum: anatomical characterization and limitations at S1.

Anatomical and biomechanical data have suggested that pedicle screw fixation at the sacrum is optimum in the anteromedial direction into the S1 vertebral body, yet the possibility of posterior iliac crest interference with this screw pathway has been considered but not defined. This study aimed to determine if the anteromedial direction of screw placement into the vertebral body is possible in all cases at S1 and to assess the limiting effect of the posterior iliac crest. Computed tomography scans of the upper sacrum at the S1 pedicle parallel to the sacral endplate were examined in 100 patients. Analysis using a digitizer allowed characterization of an ideal screw pathway with variable screw and screw head diameters in an anteromedial direction into the S vertebral body. The effects of the posterior iliac crest upon these pathways were studied. The study demonstrated that anteromedial placement with bicortical fixation at the vertebral body was theoretically possible in almost all (98.5%) cases. Because the sacral body is often wider than the sacral spinal canal, a straight-ahead screw direction will often achieve placement into the S1 vertebral body, if the starting point for the screw allows screw placement adjacent to the medial border of the S1 pedicle with only 1.5 mm of cortical bone separating the canal and the screw. The space between the posterior iliac crest and the lateral aspect of the screw corridor ranges from a maximum of 52.4 mm to a minimum of 12.8, 6.2, and 0 mm for the 7-, 10-, and 12.5-mm screw corridors. On only three occasions (1.5%) was the ideal screw corridor not possible because of posterior iliac crest overlap. In each case, this occurred only unilaterally and when the widest of the screw corridors (12.5 mm) was used. Both the distance between the posterior iliac crests and the space available for optimum screw placement are greater in females than males.     

Ⅰ期手术经后路病灶清除内固定治疗儿童胸椎结核

目的:探讨Ⅰ期手术经后路结核病灶清除植骨融合内固定治疗儿童胸椎结核的效果.方法:2005年6月至2010年12月采用病灶清除植骨融合内固定治疗儿童胸椎结核9例,其中男7例,女2例;年龄3～12岁,平均7岁;病史3个月～1年,平均6个月.患儿均有不同程度胸背痛、肋间神经痛以及脊柱后凸畸形,同时伴有低热、盗汗、消瘦等全身症状.术前X线片、CT、MRI检查提示病变部位多发生于T4-T9节段.胸段后凸角35°～72°,平均48.2°.术前脊髓功能ASIA分级:B级2例,C级5例,D级2例.术后定期复查X线片了解后凸角变化和椎间植骨融合情况,采用ASIA分级评定术后脊髓功能恢复情况.结果:术中无大血管或脊髓损伤,术后随访16～38个月,平均24个月.所有患儿结核症状消失,无结核复发、切口感染、窦道形成或内固定失败等并发症,复查血沉正常.术后4～8个月复查X线片提示椎间植骨均获骨性愈合,内固定位置正常.最后随访后凸角12°～30°,平均19.5°,脊髓功能ASIA分级:C级2例,D级2例,E级5例.脊髓功能均有不同程度改善.结论:Ⅰ期经后路清除胸椎结核病灶彻底,椎管减压可靠,矫形效果显著,行自体或同种异体骨植骨钉棒系统内固定可有效重建胸段脊柱的稳定性.     

Biological modalities for treatment of acute spinal cord injury: a pilot study and review of the literature

Objective： Paraplegia due to traumatic spinal cord injuries is one of the devastating effects of dorsolumbar vertebral fractures. Treatment modalities for such fractures, such as stabilization, have no effect on the neurological recovery. Thus, various pharmacological and biological treatment modalities have been used. The more recent trend of using autologous stem cells from the iliac crest has been used in some clinical trials with varying success. Thus, more clinical studies are required to study the effect of this novel approach Methods： This is a prospective hospital-based cohort study （level IV）. The study was conducted in the Dept. of Orthopaedics, University College of Medical Sciences and GTB Hospital, Delhi from November 2010 to March 2012. Ten patients who had sustained traumatic dorsolumbar vertebral fractures with complete paraplegia were recruited for this study. Under suitable anaesthesia, at the beginning of surgery, 100 ml of bone marrow was aspirated. This was centrifuged and buffy coat isolated and then transferred into a sterile tube and sent to the operating room on ice packs. After surgical decompression and stabilization, the buffy coat isolate was injected into the dural sleeve at the site of the injury using a 21G needle. All the patients were evaluated for neurological improvement using the American Spinal Injury Association （ASIA） score and Frankel grade at 6 weeks and 3 months postoperatively. Results： The evaluation at 6 weeks showed some improvement in terms of the ASIA scores in 2 patients but no improvements in their Frankel Grade. The other 8 patients showed no improvements in their ASIA scores or their Frankel Grades. The current pilot study has shown that there has been no improvement in most of the recipients of the transplant （n=8）. Some patients （n=2） who did show some improvement in their sensory scores proved to be of no significant functional value as depicted by no change in their Frankel Grades. Conclusion： The outcome of current study shows th     

Error rate of multi-level rapid prototyping trajectories for pedicle screw placement in lumbar and sacral spine

Objective：Free-hand pedicle screw placement has a high incidence of pedicle perforation which can be reduced with fluoroscopy,navigation or an alternative rapid prototyping drill guide template.In our study the error rate of multi-level templates for pedicle screw placement in lumbar and sacral regions was evaluated.Methods：A case series study was performed on 11 patients.Seventy-two screws were implanted using multilevel drill guide templates manufactured with selective laser sintering.According to the optimal screw direction preoperatively defined,an analysis of screw misplacement was performed.Displacement,deviation and screw length difference were measured.The learning curve was also estimated.Results：Twelve screws （17％） were placed more than 3.125 mm out of its optimal position in the centre of pedicle.The tip of the 16 screws （22％） was misplaced more than 6.25 mm out of the predicted optimal position.According to our predefined goal,19 screws （26％） were implanted inaccurately.In 10 cases the screw length was selected incorrectly：1 （1％） screw was too long and 9 （13％） were too short.No clinical signs of neurovascular lesion were observed.Learning curve was insignificantly noticeable （P=0.129）.Conclusion：In our study,the procedure of manufacturing and applying multi-level drill guide templates has a 26％ chance of screw misplacement.However,that rate does not coincide with pedicle perforation incidence and neurovascular injury.These facts along with a comparison to compatible studies make it possible to summarize that multi-level templates are satisfactorily accurate and allow precise screw placement with a clinically irrelevant mistake factor.Therefore templates could potentially represent a useful tool for routine pedicle screw placement.     

改良漏斗椎弓根植骨治疗胸腰椎骨折疗效分析

目的:分析改良漏斗经椎弓根伤椎内植骨治疗胸腰椎骨折的临床疗效。方法:自2006年5月至2011年11月,采用后路椎弓根螺钉固定、复位并联合改良椎弓根漏斗伤椎内植入自体髂骨治疗胸腰椎骨折患者35例(严重压缩性骨折9例、爆裂性骨折26例),男19例,女16例;年龄21～66岁,平均34.6岁。术后通过X线片动态测量伤椎前缘高度及Cobb角;CT评估植骨效果并最终测定植骨区CT值;神经功能采用Frankel分级评定;疼痛按照视觉模拟评分。结果:32例均获得随访,时间18～37个月,平均19.7个月。无神经损伤加重,术前11例神经功能部分损害者有至少1级的恢复;无内固定松动或断裂,伤椎内植骨填充良好,6个月内全部融合,植骨区无贯通式腔隙。伤椎前缘高度比由术前(50.17±8.26)%恢复至术后(90.79±4.85)%,末次随访时(内固定取除后6个月)为(90.34±4.03)%;Cobb角由术前(28.70±6.24)°恢复到术后(7.26±3.79)°,末次随访时为(7.34±4.05)°。末次随访伤椎植骨区平均CT值均明显高于邻椎;疼痛视觉模拟评分平均为1.06分。结论:后路椎弓根固定、复位并联合改良漏斗伤椎内植骨治疗胸腰椎爆裂性骨折简便、安全且经济,伤椎空腔内植骨效果良好,可有效防止伤椎高度再丢失和进行性后凸畸形,最大程度地保留脊柱运动功能。     

Traumatic loss of talus: A rare injury

BackgroundTraumatic loss of talus during a compound injury of ankle is an unusual injury.ObjectiveWe report a 55 years old woman who sustained an open ankle injury with complete extrusion of talus and loss at the injury site.MethodA tricortical bone graft was obtained from iliac crest and talar dimensions carved with 5 cm length and 3 cm height given by buttressing fibular graft between them. These grafts are made in the shape of talus by fixing them together with cortical screw and binding them together with Ethibond No. 5. By anterior approach ankle was opened and talar graft was placed in between the raw surfaces of tibia and calcaneus to facilitate ankle arthrodesis.ResultPatient had solid fusion at the ankle joint after 4 months with no pain on walking.ConclusionThe definitive treatment of this serious lower extremity injury remains controversial we have attempted this novel way of treatment as the patient was unable to afford talar prosthesis and facilities of allogenic bone grafts were not there.     

Demineralized bone matrix composite grafting for posterolateral spinal fusion

In a prospective series, the 24-month fusion status was evaluated radiographically among patients undergoing instrumented posterolateral lumbosacral spinal fusion. Seventy-three patients had a diagnosis of degenerative disk disease or degenerative spondylolisthesis and had supplemental bone grafting with demineralized bone matrix (DBM) putty (Grafton DBM; Osteotech, Eatontown, NJ) enriched with aspirated bone marrow (DBM bone marrow), DBM putty combined with iliac crest autograft (DBM autograft), or autograft. Overall, approximately 63% (12 of 19) of DBM bone marrow, 70% (19 of 27) of DBM autograft, and 67% (18 of 27) of autograft patients were fused at 24 months (P = .875). These findings suggest that both DBM composites offer similar performance to autograft in posterolateral spinal fusion.     

Validation of marrow fat assessment using noninvasive imaging with histologic examination of human bone samples

PurposeThe marrow composition throughout the body is heterogeneous and changes with age. Due to heterogeneity, invasive biopsies of the iliac crest do not truly represent the complete physiological status, impeding the clinical effectiveness of this method. Therefore, we aim to provide verification for an in vivo imaging technique using co-registered histologic examinations for assessment of marrow adiposity.MethodsFive recently expired (i.e. < 24 h) human cadavers were scanned with a dual source CT (DECT) scanner in order to measure marrow fat in the lumbar vertebrae. These donors were also imaged using water–fat MRI (wfMRI) which was used to estimate the fraction of yellow marrow. After imaging, lumbar columns were excised and the superior and inferior aspects of 21 vertebrae were removed. The remaining center section was processed for histological examination to find the ratio of adipocyte volume per tissue volume (AV/TV).ResultsResults of DECT and wfMRI had a high correlation (r = 0.88). AV/TV ranged from 0.18 to 0.75 with a mean (SD) of 0.36 (0.18). Inter-evaluator reliability for AV/TV was r > 0.984. There were similar correlations between AV/TV and the imaging modalities, DECT-derived MF and wfMRI (r = 0.802 and 0.772, respectively).ConclusionsA high MF variation was seen among the 25 vertebrae imaged. Both DECT and wfMRI have a good correlation with the histologic adipocyte proportion and can be used to measure MF. This makes longitudinal studies possible without painful, less-effective, invasive biopsies.     

经伤椎椎弓根植骨联合椎弓根钉内固定系统治疗胸腰椎爆裂性骨折

目的探讨经伤椎椎弓根植骨联合椎弓根钉内固定系统治疗胸腰椎爆裂性骨折的临床效果。方法 2014年5月—2016年1月,共收治胸腰椎单节段爆裂性骨折患者73例,其中前期35例采用椎弓根钉内固定系统进行治疗(A组),后期38例采用经伤椎椎弓根植骨联合椎弓根钉内固定系统治疗(B组)。记录并比较2组患者术前、术后伤椎前缘高度、后凸Cobb角、美国脊髓损伤协会(ASIA)分级以及腰痛情况。结果所有患者均顺利完成手术。末次随访时,B组伤椎前缘高度显著高于A组,Cobb角显著小于A组,远期椎体高度及Cobb角丢失率显著低于A组,差异均有统计学意义(P 0.05)。末次随访时,B组患者术后ASIA分级情况显著优于A组,差异有统计学意义(P 0.05)。B组术后腰痛整体情况优于A组,其中无痛例数显著多于A组,中度疼痛例数显著少于A组,差异均有统计学意义(P 0.05)。结论经伤椎椎弓根植骨联合椎弓根钉内固定系统治疗胸腰椎爆裂性骨折,可有效恢复伤椎椎体高度,改善伤椎稳定性,有助于神经功能的恢复,减少腰痛等并发症的发生,疗效显著,值得推广。     

椎弓根钉棒系统不对称撑开治疗齿突合并单侧关节面压缩性骨折

目的 探讨椎弓根钉棒系统不对称撑开治疗齿突合并单侧关节面压缩骨折的临床疗效.方法 2005年12月～2011年4月共治疗此类患者12例,2例为陈旧骨折,其余均为新鲜骨折.患者均有不同程度的颈枕区疼痛,活动受限,疼痛视觉模拟量表（visual analogue scale,VAS）评分平均6.3分.所有患者实施颈后路寰枢椎椎弓根钉棒系统固定,两侧不对称撑开,行自体髂骨植骨,根据手术前后临床及影像学检查评价手术疗效.结果 所有患者均获得随访,随访8～22个月,平均11.2个月,术后未出现螺钉松动、断裂,钉棒移位.术中未出现椎动脉或脊髓损伤.术后VAS评分平均1.1分,冠状面CT重建示头颈部骨性力线恢复良好,斜颈矫正率达83%,6个月随访见寰枢椎达到骨性融合.结论 椎弓根钉棒系统不对称撑开治疗齿突合并单侧关节面骨折是一种固定牢固、安全可靠的方法.     

Vertebral body fracture after anterolateral instrumentation and interbody fusion in two osteoporotic patients

Background contextThe XLP plate is an anterolateral instrumentation system developed as a part of the eXtreme Lateral Interbody Fusion (XLIF) system for lateral transpsoas interbody fusion, an alternative to anterior interbody fusion.PurposeTo report two cases of atraumatic coronal plane vertebral body fractures in the early postoperative period after interbody fusion using XLIF cages, lateral plating using the XLP plate, and unilateral posterior pedicle screw instrumentation.Study designCase report.Methods/summariesBoth patients were septuagenarian women with normal body mass indices and osteoporosis. The patients underwent L4–L5 XLIF with anterolateral instrumentation followed by posterior decompression and fusion using unilateral pedicle screws. In the early postoperative period (≤6 weeks), the patients developed acute onset of severe low back pain without history of trauma. Imaging demonstrated coronal plane vertebral body fracture through the screw hole of the XLP plate in the superior vertebral body in one case and the inferior vertebral body in the other. One patient required kyphoplasty at the L4 level for pain relief. The other was treated conservatively. The nondisplaced fractures went on to union with pain resolution and successful fusion in both patients.ResultsCoronal plane fractures occurred in 2 of 13 patients treated by the senior author using XLIF, the XLP plate, and unilateral pedicle screw instrumentation. Osteoporosis was likely a contributing factor in both patients. One potential mechanism for this unusual fracture pattern is subsidence of the cage with resultant cut-through of the fixed-angle screws through the osteoporotic vertebral body. Alternately, the fracture could have resulted from the stress riser created by the screw hole traversing an area of relative stress concentration directly adjacent to the cage.ConclusionCoronal plane vertebral fracture may occur in osteoporotic patients treated with XLIF and XLP lateral instrumentation. Unilateral pedicle screw instrumentation does not prevent this complication.     

Posterior spinal fusion using a pedicle nail system with polymethylmethacrylate in a paraplegic patient after vertebral collapse caused by osteoporosis

Background contextBecause posterior decompression and fusion for vertebral collapse in an osteoporotic spine sometimes results in a pullout of the pedicle screw. Several authors reported that fixation of pedicle screws in severely osteoporotic bone could be improved by inserting polymethylmethacrylate (PMMA) into the hole before inserting the screw. However, pedicle screws were not designed to be used with PMMA.PurposeTo report a patient with vertebral collapse who were treated using a novel-concept, pedicle nail using with PMMA.Study designCase report.MethodsThe patient was a 74-year-old female who experienced back pain after some heavy lifting 3 months before. She was laid up for 2 months because of the back pain and weakness of her lower legs. Radiographs and magnetic resonance imaging showed vertebral collapse and neural severe compression from the posterior wall of vertebra T12. The pedicle nail consists of an outer sheath with evenly spaced holes and an internal, removable, threaded component. The outer sheath and the internal component were connected before insertion. The pedicle nail attaches to and is bound by the PMMA through the holes of the outer sheath. We performed a T11–L1 posterior fusion and laminectomy using the pedicle nail, and we used a hydroxyapatite block to perform a transpedicular vertebroplasty of T12.ResultsBone union was observed on a lateral radiograph without pedicle nail loosening.ConclusionsThe authors speculate that posterior spinal fusion and vertebroplasty using the pedicle nail will be a reasonable choice for delayed paraplegia after osteoporotic vertebral fracture.