Fenestrated pedicle screws for cement-augmented purchase in patients with bone softening: a review of 21 cases

Background  

This prospective mixed cohort study was designed to evaluate the middle- to long-term purchase of cement-augmented pedicular screws in patients with poor bone quality. The growing number of surgical procedures performed in the spine has highlighted the problem of screws loosening in patients with poor bone stock due to osteoporosis and/or tumors. Different methods of increasing screw purchase have been reported in the literature, including polymethylmethacrylate (PMMA) augmentation.     

Reconstruction of bony facial contour deficiencies with polymethylmethacrylate implants: case report

Facial trauma can be considered one of the most serious aggressions found in the medical centers due to the emotional consequences and the possibility of deformity. In craniofacial surgery, the use of autologous bone is still the first choice for reconstructing bony defects or irregularities. When there is a shortage of donor bone or a patient refuses an intracranial operation, alloplastic materials such as polymethylmethacrylate (PMMA) can be used. The PMMA prosthesis can be pre-fabricated, bringing advantages such as reduction of surgical time, easy technical handling and good esthetic results. This paper describes the procedures for rehabilitating a patient with PMMA implants in the region of the face, recovering the facial contours and esthetics of the patient.     

椎体成形术的生物力学研究进展

椎体成形术,即经皮将骨水泥注入椎体内增强的手术,近年来被广泛用于骨质疏松性压缩性骨折的治疗。该手术止痛迅速可靠,并发症发生率低,早期临床疗效显著。但是随着临床病例的增多,术后邻近节段新发骨折也被陆续报道,究竟是因骨水泥的量、注射方式以及椎体骨密度、骨水泥材料特性等生物力学因素造成,还是人体骨质疏松椎体骨折的自然病程,目前尚有许多争议。     

椎体成形术中聚甲基丙烯酸甲酯引起犬急性肺栓塞

目的 观察椎体成形术中聚甲基丙烯酸甲酯(PMMA)静脉渗漏造成肺栓塞的严重程度与漏入量的关系.方法 15只成年家犬随机分为A、B、C三组,静脉麻醉后分别经股静脉注入PMMA骨水泥 0.5、1.0、2.0 ml;于注入前、后行胸部CT平扫、肺动脉造影,测肺动脉压,行血气分析,于术后2 h处死实验犬行病理检查.结果 C组氧分压在注入PMMA骨水泥10 min后显著下降,二氧化碳分压在注入1 min后显著上升;B、C组平均肺动脉压在注入1 min、10 min时显著上升,差异均有统计学意义(P<0.05);其余各组间差异无统计学意义(P>0.05).结论 PMMA进入下腔静脉导致肺栓塞的严重程度可能与漏入量有关,椎体成形术中大剂量的渗漏可导致呼吸功能障碍.     

Temperature Measurement During Polymerization of Bone Cement in Percutaneous Vertebroplasty: An In Vivo Study in Humans

Aim of the study was to “in vivo” measure temperature, during percutaneous vertebroplasty (PV), within a vertebral body injected with different bone cements. According to the declaration of Helsinki, 22 women (60–80 years; mean, 75 years) with painful osteoporotic vertebral collapse underwent bilateral transpedicular PV on 22 lumbar vertebrae. Two 10-G vertebroplasty needles were introduced into the vertebra under digital fluoroscopy; a 16-G radiofrequency thermoablation needle (Starburst XL; RITA Medical System Inc., USA), carrying five thermocouples, was than coaxially inserted. Eleven different bone cements were injected and temperatures were measured every 30 s until temperatures dropped under 45°C. After the thermocouple needle was withdrawn, bilateral PV was completed with cement injection through the vertebroplasty needle. Unpaired Student’s t-tests, Kruskal–Wallis test, and Wilcoxon signed rank test were used to evaluate significant differences (p < 0.05) in peak temperatures, variations between cements, and clinical outcome. All procedures were completed without complications, achieving good clinical outcomes (p < 0.0001). Regarding average peak temperature, cements were divided into three groups: A (over 60°C), B (from 50° to 60°C), and C (below 50°C). Peak temperature in Group A (86.7 ± 10.7°C) was significantly higher (p = 0.0172) than that in Groups B (60.5 ± 3.7°C) and C (44.8 ± 2.6°C). The average of all thermocouples showed an extremely significant difference (p = 0.0002) between groups. None of the tested cements maintained a temperature ≥45°C for more than 30 min. These data suggest that back-pain improvement is obtained not by thermal necrosis but by mechanical consolidation only. The relative necrotic thermal effect in vertebral metastases seems to confirm that analgesia must be considered the main intent of PV.     

Percutaneous Vertebroplasty and Bone Cement Leakage: Clinical Experience with a New High-Viscosity Bone Cement and Delivery System for Vertebral Augmentation in Benign and Malignant Compression Fractures

The aim of this study was to assess the feasibility of and venous leakage reduction in percutaneous vertebroplasty (PV) using a new high-viscosity bone cement (PMMA). PV has been used effectively for pain relief in osteoporotic and malignant vertebral fractures. Cement extrusion is a common problem and can lead to complications. Sixty patients (52 female; mean age, 72.2 ± 7.2) suffering from osteoporosis (46), malignancy (12), and angiomas (2), divided into two groups (A and B), underwent PV on 190 vertebrae (86 dorsal, 104 lumbar). In Group A, PV with high-viscosity PMMA (Confidence, Disc-O-Tech, Israel) was used. This PMMA was injected by a proprietary delivery system, a hydraulic saline-filled screw injector. In Group B, a standard low-viscosity PMMA was used. Postprocedural CT was carried out to detect PMMA leakages and complications. Fisher’s exact test and Wilcoxon rank test were used to assess significant differences (p < 0.05) in leakages and to evaluate the clinical outcome. PV was feasible, achieving good clinical outcome (p < 0.0001) without major complications. In Group A, postprocedural CT showed an asymptomatic leak in the venous structures of 8 of 98 (8.2%) treated vertebrae; a discoidal leak occurred in 6 of 98 (6.1%). In Group B, a venous leak was seen in 38 of 92 (41.3%) and a discoidal leak in 12 of 92 (13.0%). Reduction of venous leak obtained by high-viscosity PMMA was highly significant (p < 0.0001), whereas this result was not significant (p = 0.14) related to the disc. The high-viscosity PMMA system is safe and effective for clinical use, allowing a significant reduction of extravasation rate and, thus, leakage-related complications.     

Experimental Study of Different Laser Systems for PMMA Extraction Within the Scope of Revision Hip Arthroplasty

. Cement removal at revision hip arthroplasty forms a critical step for a successful operation. The removal of polymethymethacrylate (PMMA) with curet and chisel can cause major damage to the femoral shaft. The use of ultrasound or lithotripsy can cause perforation and microfractures to bone tissue. The goal of our study was to evaluate the application and practicability of different laser systems for cement removal. We examined and compared the effects of a diode laser (wavelength λ=800 nm), a Nd:YAG laser (λ=1064 nm), and an Er:YSSG laser (λ=2780 nm) on PMMA and the PMMA–bone interface. Whereas the Nd:YAG laser with a high ablation rate led to severe bone damage with extensive carbonisation, the Er:YSSG laser with a low ablation rate produced a defined cut at the PMMA–bone interface (max. depth 3.70 mm at 6.0 W laser power). Using the diode laser a defined high quality ablation of PMMA at the PMMA–bone interface was possible without any visible damage of adjacent tissue (max. depth 2.75 mm at 2.9 W laser power). However, sufficient ablation in an adequate operating time could not be realised with this power. The use of a laser tool for cement removal is insufficient. It only facilitated the manual removal of the remaining cement with chisel and curet. Paper received 5 November 1999; accepted after revision 27 April 2000.     

两种填充物在经皮椎体成形术中应用的临床比较

目的比较聚甲基丙烯酸酯(polymethylmethacrylate,PMMA)和锶羟磷灰石(strontium-containedhydroxyapatitece-ment,SrHAC)行经皮椎体成形术(percutaneousvertebroplasty,PVP)的临床应用。方法单椎体骨折29例,其中PMMA组16例,SrHAC组13例,对填充物注入量、术中患者血压、心率、血氧饱和度及术后疼痛、临床效果等指标进行对比。结果PMMA组平均注入量为(2.82±0.39)ml,SrHAC组为(3.75±0.52)ml,两组比较差异有显著性意义(P<0.01)。SrHAC组注入填充物时血压、心率、血氧饱和度稳定。两组VAS评分术后均较术前明显下降,差异有显著性意义(P<0.01);术后临床效果SC评价,优良率无显著性差异(P>0.05)。结论SrHAC是除PMMA外另一种可供选择的PVP填充材料。     

Biomechanical evaluation of kyphoplasty and vertebroplasty with calcium phosphate cement in a simulated osteoporotic compression fracture

 Kyphoplasty and vertebroplasty with polymethylmethacrylate (PMMA) have been used for the treatment of osteoporotic vertebral compression fractures. We performed kyphoplasty and vertebroplasty with α-tricalcium phosphate cement (CPC) and PMMA to compare the biomechanical properties. Thirty osteoporotic vertebrae were harvested from nine embalmed cadavers. We randomized the vertebrae into four treatment groups: (1) kyphoplasty with CPC; (2) kyphoplasty with PMMA; (3) vertebroplasty with CPC; and (4) vertebroplasty with PMMA. Prior to injecting the cement, all vertebrae were compressed to determine their initial strength and stiffness. They were then recompressed to determine their augmented strength and stiffness. Although the augmented strength was greater than the initial strength in all groups, there was no significant difference between the two bone cements for either kyphoplasty or vertebroplasty. The augmented stiffness was significantly less than the initial stiffness in the kyphoplasty groups, but the difference between the two cements did not reach significance. In the vertebroplasty groups, the augmented stiffness was not significantly different from the initial stiffness. There was no significant difference between the two bone cements for either procedure when cement volume and restoration of anterior height were assessed. We concluded that kyphoplasty and vertebroplasty with CPC were viable treatment alternatives to PMMA for osteoporotic vertebral compression fractures. Received: July 18, 2002 / Accepted: November 6, 2002 Offprint requests to: S. Tomita     

Giant Cell Tumor of Upper Thoracic Spine

Giant cell tumor (GCT) of the spine is a rare benign tumor, but can be aggressive and can exhibit a high local recurrence rate. Furthermore, GCT of the upper thoracic spine may pose diagnostic and management difficulties. Here, we report a rare case of GCT of the upper thoracic spine with soft tissue extension to the spinal canal. The patient was managed by decompressive laminectomy and posterolateral fusion followed by an injection of polymethylmethacrylate into the vertebral lesion. The patient recovered clinically and showed radiological improvement after surgical treatment without tumor recurrence at his last follow-up of postoperative 7 years. We present this unusual case of GCT and include a review of the literature.