Complications following cranioplasty using autologous bone or polymethylmethacrylate—Retrospective experience from a single center

Objective

A decompressive hemicraniectomy is a potentially life-saving intervention following head trauma. Once performed patients are obliged to undergo a second procedure with cranioplasty. Two of the most commonly used materials are autologous bone and polymethylmethacrylate (PMMA). We have now evaluated complications following a cranioplasty using these materials.

Materials and methods

During a 7-year period (2002–2008) 49 patients were operated with a decompressive craniectomy following head trauma. Patients received a cranioplasty consisting of autologous bone (30 patients, 61.2%) or PMMA (19 patients, 38.8%) and were followed at least 24 months. Patient data were collected retrospectively.

Results

Twenty patients (20/49, 40.8%) experienced a complication that prompted a re-operation. There was a significantly higher rate of complications leading to a re-operation (53.3% vs. 21.1%, p = 0.03) and a shorter survival time of the cranioplasty (mean 48.1 ± 7.8 vs. 79.5 ± 9.0 months, p = 0.035) in patients with autologous bone compared to PMMA. Bone resorption and the presence of postoperative hematomas were significantly more common in patients with autologous bone. The material used for cranioplasty was the only variable that significantly correlated to the rate of complications.

Conclusions

In our series we had a high percentage of patients needing re-operation due to complications following a cranioplasty. Though generally considered a straightforward procedure, complications and associated morbidity in patients undergoing cranioplasty should not be underestimated.     

聚甲基丙烯酸甲酯强化椎弓根螺钉内固定对骨质疏松不稳定性胸腰椎损伤稳定性的影响

目的　评价聚甲基丙烯酸甲酯 (polymethylmethacrylate,PMMA)骨水泥强化椎弓根螺钉内固定对骨质疏松不稳定性胸腰椎损伤的即刻稳定性和反复载荷后的稳定性。　方法　 6具新鲜老年女性骨质疏松脊柱标本 (T1 0 ～L5) ,制备L1 椎体节段不稳定性损伤模型后 ,椎弓根螺钉系统固定 ,进行左 /右侧弯、左 /右旋转和前屈 /后伸 6个运动方向的稳定性测试 ,并在MTS 85 8型材料试验机上进行屈 /伸疲劳试验。比较完整脊柱标本 (a)、损伤模型钢板固定未强化疲劳前 (b)、钢板固定未强化疲劳后 (c)、钢板固定强化后疲劳前 (d)、钢板固定强化后疲劳后 (e) 5种状态下脊柱的稳定性变化。　结果　在b、d、e三种状态下 ,6个运动方向脊柱的稳定性差异不明显 (P >0 .0 5 ) ,但均强于a、c状态 (P <0 .0 1)。 2 0颗螺钉未强化疲劳后有 19颗出现松动 ,而强化螺钉疲劳后未见螺钉松动。　结论　PMMA强化骨质疏松椎弓根螺钉内固定能明显增强脊柱的稳定性和抗疲劳能力。     

应用国产药械行经皮椎体成形术治疗骨质疏松性椎体压缩骨折

目的：应用国产器械行椎体成形术治疗骨质疏松性椎体压缩骨折。观察其疗效。探讨椎体成形术操作技术和并发症的预防。方法：17例骨质疏松性椎体压缩骨折患者25个椎体应用国产器械经双侧椎弓根入路行椎体成形术。国产PMMA的粉、液及对比剂比例为3：2：1。操作在X线监测下进行。PMMA在浆糊期向椎体内注射。手术前后CT检查对照。随访患者5～24个月，观察临床疗效。结果：穿刺成功率100％，术后CT检查显示PMMA填充病灶均在50％以上。术后3d内患者的治疗效果为：CR15例，PR2例，临床治疗有效率达100％。17例患者随访5—24个月。未发现注射PMMA的椎体有新压缩出现，未发生由于PMMA外溢出现临床症状的并发症。结论：应用国产器械行椎体成形术治疗骨质疏松性椎体压缩骨折疗效良好，在浆糊期注射是预防PMMA外溢的重要措施。     

经皮椎体成形术的临床应用

目的　探讨经皮椎体成形术 (PVP)治疗椎体病变引起的压缩骨折的技术操作和临床效果。资料与方法　对 30例共 4 6个椎体行PVP ,其中骨质疏松 2 0例 ,血管瘤 1例 ,多发性骨髓瘤 1例 ,转移瘤 8例。年龄 31～ 98岁 ,平均 5 8岁。穿刺方法为患者俯卧 ,影像增强器向矢状面足侧成角 10°～ 15° ,椎体上下缘没有双边影 ,使欲穿刺侧的椎弓根投影在椎体的中外 1/ 3处 ,将穿刺针、X线管、椎弓根成一直线进针 ,穿刺成功后将聚甲基丙烯酸甲酯 (PM MA ,骨水泥 )按粉液比 3∶2 (g/ml)混合成糊状 ,在透视下用 1ml注射器均匀缓慢注入病变椎体。如骨水泥弥散不良再行对侧穿刺。术后当天、7天、1个月、3个月CT检查注射椎体 ,随访病情变化。结果　所有病例均成功施行了PVP ,单侧穿刺 32个椎体 (胸椎 8个 ,腰椎 2 4个 ) ,双侧穿刺 14个椎体 (胸椎 8个 ,腰椎 6个 )。单侧穿刺胸椎骨水泥平均用量 2 .5ml,腰椎 3.7ml;双侧穿刺胸椎骨水泥平均用量 3.2ml,腰椎 4 .7ml。治疗效果同骨水泥的注射量无关 ,同单双侧穿刺无关。 2 1例良性病例疼痛完全缓解 (CR) 14例 ,部分缓解 (PR) 7例 ;9例恶性病例中PR 7例 ,2例无效(NR) ;随访 6个月良性病例止痛效果良好 ,恶性病例 3个月后止痛效果下降。CT、X线随访骨水泥术后形态无变化 ,未见椎体     

Effect of cement pressure and bone strength on polymethylmethacrylate fixation

The effect of the quality of the bone and of the cement pressurization magnitude and duration on the fixation achieved with polymethylmethacrylate (PMMA) bone cement is studied in vitro. Seventy-one cementbone interface specimens, prepared under various conditions of pressurization of low-viscosity bone cement, are tested in tension. The load at failure and the maximum cement penetration are measured to assess the fixation achieved, and the quality of the bone is assessed by determining the compressive strength of each of the bone specimens. Statistical analysis of the data indicates that the pressure magnitude is the most influential of the factors considered in the cement penetration behavior and in the development of failure load capacity. The duration of the pressure does not appear to be a significant factor. The cement penetration is a decreasing function of the bone strength, reflecting a decrease in the porosity and an increase in the area fraction. Although not directly measured in these tests, these latter bone properties are indirectly measured by the bone compressive strength. The effect of increasing bone strength on the failure load is nonlinear. The development of adequate failure load capacity is the result of a balance between the cement penetration allowed by the porosity of the bone and the inherent strength of the cancellous bone itself. Weak bone, although adequately penetrated by cement, cannot provide strong fixation. Stronger, denser bone limits cement penetration, but pressurization enhances development of failure load capacity through more complete infusion and interlocking of the cement in the available pore space. The strength of the fixation achievable for any bone is limited by the intrinsic strength of the bone. An optimal depth of cement penetration of 4 mm and an optimal bone area fraction of 0.20 are suggested for the most effective fixation.     

纳米载银树脂基托体外抗菌效果的持久性

目的：研究纳米载银树脂基托在体外对变形链球菌和白色念珠菌抗菌效果的持久性。方法：制备含5mg／ml纳米载银抗菌剂STR-1的树脂基托片，分为不作处理的抗菌阳性对照组，57℃恒温水浴浸泡14d的恒温水浴浸泡组，经光照强度〉70μW／cm^2的紫外线照射8h的紫外线照射组，以及上述2种方式联合处理的联合处理组。用贴膜法检测各组在体外对变形链球菌和白色念珠菌的抗菌率。结果：阳性对照组、恒温水浴组、紫外线照射组以及联合处理组对变形链球菌的抗菌率分别为99％，96％，98％和90％；对白色念珠菌的抗菌率分别为91％，82％，90％、80％。结论：含5mg／ml纳米载银抗菌剂STR-1的树脂基托片在体外对变形链球菌和白色念珠菌具有抗菌持久性。     

Antibiotic-releasing porous polymethylmethacrylate/gelatin/antibiotic constructs for craniofacial tissue engineering

An antibiotic-releasing porous polymethylmethacrylate (PMMA) construct was developed to maintain the bony space and prime the wound site in the initial step of a two-stage regenerative medicine approach toward reconstructing significant bony or composite craniofacial tissue defects. Porous PMMA constructs incorporating gelatin microparticles (GMPs) were fabricated by the sequential assembly of GMPs, the antibiotic colistin, and a clinically used bone cement formulation of PMMA powder and methylmethacrylate liquid. PMMA/gelatin/antibiotic constructs with varying gelatin incorporation and drug content were investigated to elucidate the relationship between material composition and construct properties (porosity and drug release kinetics). The porosity of PMMA/gelatin/antibiotic constructs ranged between 7.6 ± 1.8% and 38.4 ± 1.4% depending on the amount of gelatin incorporated and the drug solution added for gelatin swelling. The constructs released colistin over 10 or 14 days with an average release rate per day above 10 μg/ml. The porosity and in vitro colistin release kinetics of PMMA/gelatin/antibiotic constructs were tuned by varying the material composition and fabrication parameters. This study demonstrates the potential of gelatin-incorporating PMMA constructs as a functional space maintainer for both promoting tissue healing/coverage and addressing local infections, enabling better long-term success of the definitive regenerated tissue construct.     

Minimally invasive decompression with posterior column reinforcement for the treatment of symptomatic osteoporotic fracture with spinal stenosis in lumbar vertebrae

An osteoporotic fracture (OF) in the second to fifth lumbar vertebrae with spinal stenosis may be an indication for surgical treatment, but carries the risks of instability or instrumentation failure. Modified surgical procedures have been developed to manage patients with challenging OF. We retrospectively studied 12 patients (three male, nine female; mean age±standard deviation=73.5±7.2 years) who underwent minimally invasive decompression and posterior column reinforcement with polymethylmethacrylate. During a mean follow-up period of 24.8±3.1 months, pain severity and functional impairment were both significantly reduced, as measured by the visual analog scale and the Oswestry disability index. Nine patients (75%) experienced a satisfactory outcome while the other three (25%) were unchanged. Plain radiographs showed stable spinal alignment and immobilization of flexion-extension within the PMMA construct. Five complications were managed successfully, including one by revision surgery. These procedures are a feasible surgical option in the elderly population studied.     

Comparison of polymethylmethacrylate versus expandable cage in anterior vertebral column reconstruction after posterior extracavitary corpectomy in lumbar and thoraco-lumbar metastatic spine tumors

Single-stage posterior corpectomy for the management of spinal tumors has been well described. Anterior column reconstruction has been accomplished using polymethylmethacrylate (PMMA) or expandable cages (EC). The aim of this retrospective study was to compare PMMA versus ECs in anterior vertebral column reconstruction after posterior corpectomy for tumors in the lumbar and thoracolumbar spine. Between 2006 and 2009 we identified 32 patients that underwent a single-stage posterior extracavitary tumor resection and anterior reconstruction, 16 with PMMA and 16 with EC. There were no baseline differences in regards to age (mean: 58.2 years) or performance status. Differences between groups in terms of survival, estimated blood loss (EBL), kyphosis reduction (decrease in Cobb’s angle), pain, functional outcomes, and performance status were evaluated. Mean overall survival and EBL were 17 months and 1165 ml, respectively. No differences were noted between the study groups in regards to survival (p = 0.5) or EBL (p = 0.8). There was a trend for better Kyphosis reduction in favor of the EC group (10.04 vs. 5.45, p = 0.16). No difference in performance status or VAS improvements was observed (p > 0.05). Seven patients had complications that led to reoperation (5 infections). PMMA or ECs are viable options for reconstruction of the anterior vertebral column following tumor resection and corpectomy. Both approaches allow for correction of the kyphotic deformity, and stabilization of the anterior vertebral column with similar functional and performance status outcomes in the lumbar and thoracolumbar area.