Long-term evaluation of blood silicon and ostecalcin in operatively treated patients with benign bone tumors using bioactive glass and autogenous bone

In a study on 25 patients with verified benign bone tumors, bioactive glass (BG) and autogenous bone (AB) were used as bone-graft substitutes. The patients were randomized into two groups according to the filling material. Blood samples were taken both preoperatively, at 2 weeks, and 3, 8, 12, 24, and 36 months postoperatively, for evaluation of silicon concentration in blood. In the determination, direct current plasma atomic emission spectroscopy was used. No significant difference in blood silicon concentration between the BG group or the AB group could statistically be observed (p = 0.5400), and neither did the size of the bone tumor (p = 0.4259) nor the follow-up time affect the results (p = 0.2094). Concentration of osteocalcin in blood was significantly higher for large cysts (p < 0.0001). The filler material (BG or AB) did not affect the osteocalcin concentration level in blood.     

Clinical follow-up method for frontal sinus obliteration with bioactive glass S53P4

A clinical follow-up method was developed to investigate the behavior of a massive amount of bioactive glass S53P4 (BG) clinically used in frontal sinus obliteration. Two sizes of granules (0.63-0.8 mm or 0.8-1.0 mm) in 16 separate BG amounts, weight 25 g, were tested both in simulated body fluid (SBF) and in a buffer containing tris-hydroxymethyl aminomethane citric acid (TRIS-c.a) in standard conditions. The dissolution of silicon (Si) and phosphate (P) was detected with direct current plasma atom emission spectroscopy (DCP-AES) monthly up to 6 months. The BG masses were scanned both wet in the solutions and dried by computer tomography (CT), and the scans were analyzed by Region of Interest (ROI) technique. Calcium phosphate (CaP)- and silica (Si)-gel-layers were studied by scanning electron microscopy (SEM) at 1, 3, and 6 months. Cumulative loss of Si and P was stronger in TRIS-c.a than in SBF (p < 0.0001), and it was higher with smaller than with larger granules in both solutions (p < 0.0001). This was shown correspondingly by the decrease of Hounsfield units (HUs) in ROI analysis (p < 0.0001). The level of HUs was lower with dried than with wet BG (p < 0.0001). The results were compared for clinical ROI analysis of patients with obliterated frontal sinuses up to 48 months and they were parallel. The follow-up method seems to indirectly reveal the behavior of BG and the healing process in the obliterated cavity.     

Combined effect of BMP-2 gene transfer and bioactive glass microspheres on enhancement of new bone formation

Adenovirus-mediated recombinant human BMP-2 (RAdBMP-2) gene transfer has been found to have significant osteoinductive properties. The hypothesis of the current study was that bioactive glass surface could provide favorable osteoconductive conditions for cellular action of osteoinductive RAdBMP-2 gene transfer. In the rat proximal tibia, a portion of the medullary cavity was evacuated and filled with bioactive glass microspheres and injected with adenovirus carrying the human BMP-2 gene (BG/RAdBMP-2). Control defects filled with BG microspheres were injected with adenovirus carrying the LacZ reporter gene (BG/RAdLacZ) or saline (BG). Empty control defects were also used. Bone healing response was analyzed at 4 days, and at 2 and 8 weeks by radiography, peripheral quantitative computed tomography (pQCT), histomorphometry, and backscattered electron imaging of scanning electron microscopy (BEI-SEM) equipped with energy dispersive X-ray analysis (EDXA). In empty controls, the amount of intramedullary new bone peaked at 2 weeks, whereas defects filled with bioactive glass with and without RAdBMP-2 gene transfer showed a constant time-related increase of intramedullary new bone. At 8 weeks, there was significantly more new bone in defects treated with BG and RAdBMP-2 than in defects left to heal without filling (p < 0.001). Compared with the other controls (BG only or BG/RAdLacZ), the difference was not significant. In the current model, the osteopromotive effect of bioactive glass microspheres appears synergistic with the osteoinductive action of BMP-2 gene transfer, or one overshadows the other, as no additive effect was observed.     

In vivo model for frontal sinus and calvarial bone defect obliteration with bioactive glass S53P4 and hydroxyapatite

An in vivo model was developed to investigate the usability of a frontal sinus and a calvarial bone defect obliteration with bioactive glass S53P4 (BG) and hydroxyapatite (HA) granules. Roofs of 21 Elco rabbit frontal sinuses were drilled open from 4 separate holes using a standard method, and the sinuses, located in pairs, in frontal bone were filled with BG on one side and with HA on the other side. Two parallel posterior defects were covered with a pedicled periosteum flap, and 2 anterior defects with a free flap. The stability of materials, new bone, and connective tissue formation were observed with histomorphometry, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA), and X-ray pictures at 1, 3, 6, and 12 months postoperatively. The results showed more rapid resorption of filling material (p = 0.019) and new bone formation (p = 0.0001) in the defects filled with BG than in the corresponding HA-filled defects studied by histomorphometry throughout the study. New bone formation and resorption of materials were faster in defects covered by a pedicled flap than by a free periosteum flap. The results were supported by SEM histomorphometric and radiologic analysis. Both bioactive materials studied were well tolerated in frontal sinuses and in calvarial bone defects. The experimental model showed the influence of early periosteum vascularization on accurate frontal sinus filling and the healing process in rabbit frontal sinuses.     

In vitro model for frontal sinus obliteration with bioactive glass S53P4

An in vitro model was used to investigate the behavior of a massive frontal sinus obliteration with bioactive glass S53P4 (BG) for clinical purposes. Two sizes of granules (0.63-0.8 mm or 0.8-1.0 mm) in 16 separate BG amounts, weight 25 g, were tested both in simulated body fluid (SBF) and a buffer containing trishydroxymethyl aminomethane citric acid (TRIS-c.a) in standard conditions. The dissolution of silicon (Si) and phosphate (P) was detected with direct current plasma atom emission spectroscopy (DCP-AES) monthly up to 6 months. The BG masses were scanned by computer tomography (CT) and the scans analyzed by Region of Interest (ROI) technique. Calcium phosphate (CaP)- and silica (Si)-gel-layers were studied by scanning electron microscopy (SEM) at 1, 3, and 6 months. Cumulative loss of Si and P was stronger in TRIS -c.a than in SBF (p < 0.0001), and it was higher with smaller than with larger granules in both solutions (p < 0.0001). This was shown correspondingly by the decrease in Hounsfield units (HU) by ROI analysis (p < 0.0001). In SBF-soaked BG masses, the CaP-layer occurred on the uppermost granules, and in TRIS-c.a at 3-6 months, on the granules in the center and lower parts. The decrease of HU seems to reveal indirectly the resorption of BG.     

Application of a Novel Resorbable Membrane in the Treatment of Calvarial Defects in Rats

Diplen-Gam (DG) is a novel absorbable guided bone regeneration (GBR) membrane. This study was designed to evaluate the capacity of bone repair of DG compared with that of Bio-Gide (BG). Critical size defects were created in both sides of the calcarium of 36 Sprague–Dawley rats. Defects were assigned to six groups and each group was subjected to one of the following treatments: (A1) unfilled defects, (A2) Bio-Oss (BO) grafts, (B1) DG membrane, (B2) BG membrane, (C1) DG membrane + BO grafts and (C2) BG membrane + BO grafts. The animals were killed at 2, 4, 8 and 12 weeks after the operation. The defects and surrounding tissues were examined by gross observation and X-ray examination. The paraffin sections were subjected to HE (hematoxylin and eosin) staining and IHC (immunohistochemistry) for bone morphogenetic protein-2 (BMP-2). The X-rays showed that, at 12 weeks, the DG and BG group exhibited more new bone formation than CSD blank group did; the BG group exhibited more new bone formation than the DG group did (t = 5.240, P = 0.035), the BG + BO group showed no significant differences in bone formation compared with the DG + BO group (t = 1.246, P = 0.339). By IHC staining, BMP-2-positive results could be seen inside the DG membrane, on the surface of the new bone, and inside the new bone. It can be suggested that BG membrane achieved better effects in guided bone regeneration compared with DG membrane. No significant differences were found between the two membranes in their bone healing ability when they are used with BO. Therefore, DG membrane shows clinical effectiveness, but should be used in combination with bone substitute.     

Establishment and effects of allograft and synthetic bone graft substitute treatment of a critical size metaphyseal bone defect model in the sheep femur

Assessment of bone graft material efficacy is difficult in humans, since invasive methods like staged CT scans or biopsies are ethically unjustifiable. Therefore, we developed a novel large animal model for the verification of a potential transformation of synthetic bone graft substitutes into vital bone. The model combines multiple imaging methods with corresponding histology in standardized critical sized cancellous bone defect. Cylindrical bone voids (10 ml) were created in the medial femoral condyles of both hind legs (first surgery at right hind leg, second surgery 3 months later at left hind leg) in three merino‐wool sheep and either (i) left empty, filled with (ii) cancellous allograft bone or (iii) a synthetic, gentamicin eluting bone graft substitute. All samples were analysed with radiographs, MRI, μCT, DEXA and histology after sacrifice at 6 months. Unfilled defects only showed ingrowth of fibrous tissue, whereas good integration of the cancellous graft was seen in the allograft group. The bone graft substitute showed centripetal biodegradation and new trabecular bone formation in the periphery of the void as early as 3 months. μCT gave excellent insight into the structural changes within the defects, particularly progressive allograft incorporation and the bone graft substitute biodegradation process. MRI completed the picture by clearly visualizing soft tissue ingrowth into unfilled bone voids and presence of fluid collections. Histology was essential for verification of trabecular bone and osteoid formation. Conventional radiographs and DEXA could not differentiate details of the ongoing transformation process. This model appears well suited for detailed in vivo and ex vivo evaluation of bone graft substitute behaviour within large bone defects.     

FDG-PET and CT features of non-small cell lung cancer based on tumor type

We determined if specific tumor types of non-small cell lung cancer can be identified by variance in FDG-PET standard uptake value (SUV) in combination with characteristics on CT. Staging FDG-PET and CT scans of 81 patients (34 men and 47 women, average age 67+/-11 years) with 82 lung cancers were analyzed. Mean tumor SUV was calculated at the location of maximum FDG uptake. Tumor size, margins, and location were analyzed on CT. Statistical analysis compared SUV between tumor subtypes, assessed relationship between tumor subtype and features on CT and determined if combination of CT and SUV patterns predicted tumor type. In total 35 adenocarcinomas (AC); 15 bronchioloalveolar cell carcinomas (BAC), 23 squamous cell carcinomas and 9 large cell carcinomas were evaluated. Significant differences were found between SUV of all AC and squamous cell (p<0.0001); between all AC and large cell (p=0.03); between non-BAC AC and squamous cell types (p=0.0005); BAC and non-BAC AC (p=0.04), BAC and squamous cell (p<0.0001); BAC and large cell (p=0.004). Ground glass was the most significant CT feature in distinguishing tumor types, which was seen in BAC (p<0.0003). In conclusion, SUVs for non-small cell lung cancer were most significantly different between BAC and all other NCLC cell subtypes. The presence of ground glass in a nodule on CT is a significant feature for BAC and should raise the suspicion for this tumor type despite low FDG uptake.     

Bioactive glass microspheres as osteopromotive inlays in macrotextured surfaces of Ti and CoCr alloy bone implants: trapezoidal surface grooves without inlay most efficient in resisting torsional forces

We have tested the efficacy of porous bioactive glass (BG) inlays in enhancement of implant osseointegration. A total of 24 sheep underwent bilateral surgical implantation of three parallel implants on the anteromedial cortical surface of each tibia. The disc-shaped implants made of Ti6Al4V or cobalt chromium (CoCr) alloys had two parallel surface grooves (trapezoidal space with bottom widening) filled with sintered 100% bioactive glass microspheres or a selected mixture of bioactive and biocompatible glass microspheres. The surface of uncoated control implants was smooth, grit-blasted or had unfilled grooves. A subgroup of control smooth CoCr implants was coated with two or three BG layers. Implant incorporation with bone was evaluated using torque testing to failure, scanning electron microscopy and morphometry at 12 and 25 weeks. A total of 144 in vivo implants and 16 ex vivo cemented control implants were analyzed. Control Ti6Al4V implants with unfilled trapezoidal grooves showed highest torsional failure loads with excellent ingrowth of new bone and remodeling of ingrown bone into lamellar bone. Implants with BG inlays and microroughened control Ti6Al4V implants showed significantly lower torsional failure loads than control Ti6Al4V implants with unfilled grooves. In conclusion, BG inlays failed to enhance biological implant fixation. Macrotextured surface was more effective than grit-blasting in promotion of mechanical incorporation.     

Frontal sinus and skull bone defect obliteration with three synthetic bioactive materials. A comparative study

Three synthetic bioactive materials were studied in an experimental model to compare their usability in a frontal sinus and a skull bone defect obliteration. Bioactive glass number 9 (BAG(1)), bioactive glass number 13 (BAG(2)), and hydroxyapatite (HA) granules were investigated. BAG(1) and HA granules have been previously tested clinically. The clinical usefulness of BAG(2) granules has not been tested. Upper bony walls of 45 Elco rabbits' frontal sinuses were drilled open from four separate holes with the use of a standard method. The skull bone defects and the sinuses in frontal bone were filled with BAG(1) or BAG(2) on one side, and with HA on the other side. Two parallel posterior defects were covered with a pedicled periosteum flap, and two anterior defects with a free flap. The resorption of materials, new bone, and fibrous-tissue formation were observed with a histomorphometric method at 1, 3, and 6 months postoperatively. Scanning-electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) were done at 6 months. In histomorphometry, the new bone formation increased with all the investigated materials throughout the study (p < 0.001), but the results showed higher new bone formation in the defects filled with BAG(1) than in corresponding BAG(2)- or HA- filled defects. New bone formation and resorption of materials were faster in defects covered by pedicled than by free periosteum flaps (p < 0.001). Intimate contact between the used materials and new bone was confirmed by SEM. FTIR analysis of bone produced by BAG(1) and BAG(2) was of the same type as natural frontal bone. BAG(2) can be manufactured in various shapes, and thus, could possibly be used in clinical conditions requiring a special anatomical implant shape. However, more research is needed regarding this property of BAG(2).     

The in vivo behaviour of a sol-gel glass and a glass-ceramic during critical diaphyseal bone defects healing

The in vivo evaluation, in New Zealand rabbits, of a sol-gel glass 70% CaO-30% SiO2 (in mol%) and a glass-ceramic obtained from thermal treatment of the glass, both bioactive in Kokubo's simulated body fluid (SBF), is presented. Femoral bone diaphyseal critical defects were filled with: (i) sol-gel glass cylinders, (ii) glass-ceramic cylinders, or (iii) no material (control group). Osteosynthesis was done by means of anterior screwed plates with an associate intramedullar Kirschner wire. Each group included 10 mature rabbits, 9 months old. Follow-up was 6 months. After sacrifice, macroscopic study showed healing of bone defects, with bone coating over the cylinders, but without evidence of satisfactory repair in control group. Radiographic study showed good implant stability and periosteal growth and bone remodelling around and over the filled bone defect. The morphometric study showed minimum evidences of degradation or resorption in glass-ceramic cylinders, maintaining its original shape, but sol-gel glass cylinders showed abundant fragmentation and surface resorption. An intimate union of the new-formed bone to both materials was observed. Mechanical study showed the higher results in the glass-ceramic group, whereas sol-gel glass and control group showed no differences. The minimum degradation of glass-ceramic cylinders suggests their application in critical bone defects locations of transmission forces or load bearing. The performance of sol-gel glass cylinders suggests their usefulness in locations where a quick resorption should be preferable, considering the possibility of serving as drug or cells vehicle for both of them.     

硼酸盐生物玻璃和自体髂骨移植对新西兰兔桡骨大段骨缺损修复的对比研究

目的比较硼酸盐生物玻璃和自体髂骨移植对新西兰兔桡骨大段骨缺损的修复效果。方法取38只新西兰兔,制作桡骨干15 mm骨缺损动物模型,并将其随机分为空白组(8只)、对照组(15只)和实验组(15只),对照组和实验组分别植入自体髂骨和硼酸盐生物玻璃(borate glass, BG)。术后4、8和12周行X线检查,观察材料的降解和新生骨生成情况。术后6周和9周分别腹腔注射茜素红和钙黄绿素。术后12周取材行组织学和Micro-CT检查。结果影像学和组织学结果显示对照组和实验组新骨生成明显优于空白组,12周后对照组和实验组新骨完全修复缺损;实验组材料降解与新骨生成协调进行;术后12周缺损处组织学切片显示,对照组和实验组缺损处有大量的新生骨组织。结论硼酸盐生物玻璃可完全修复兔桡骨干大段骨缺损,其修复效果与自体髂骨移植接近,在骨组织工程领域有广阔的应用前景。     

Osteogenic effects of bioactive glass on bone marrow stromal cells

Bioactive glass (BG) is an effective synthetic bone graft material. BG granules of narrow size range (300-355 mum) have the ability to form new bone tissue inside excavations produced by in vivo resorption. Previously, we demonstrated that BG stimulates the differentiation of cultured osteoblast precursors if the glass surface was biomimetically modified by the formation of bone-like apatite and adsorption of serum proteins. We now report that modified BG can also increase the rate at which multipotential rat bone marrow stromal cells (rMSC) will undergo osteogenesis. BG promoted rMSC osteogenesis both when cells were plated in contact with BG and when cells were not directly in contact with the BG. Alkaline phosphatase activity, a marker of bone cell differentiation, was used as an indicator for osteogenesis. Alkaline phosphatase activity of rMSCs exposed to osteoinducers such as ascorbate, dexamethasone, and BMP-2 was enhanced in the presence of BG. The stimulatory effect of BG was more pronounced in rMSC cultures with low basal alkaline phosphatase activity than in those with higher activity. The enhanced differentiation of rMSCs was associated with both a change in rMSC morphology and altered chemical composition of the cell culture media. rMSCs cultured on BG in the presence of BMP or dexamethasone exhibited a more rounded osteoblast-like appearance as compared with cells grown on tissue culture plastic. In the presence of BG, elevated levels of calcium and silicon in the culture medium were observed throughout the 7-day culture period, suggesting a continuous dissolution of surface-modified BG and resulting release of BG dissolution products. The data suggest that both surface- and solution-mediated events play a role in the osteogenic effect of BG.     

Molecular biologic comparison of new bone formation and resorption on microrough and smooth bioactive glass microspheres

In a recent in vitro study, chemical microroughening of a bioactive glass surface was shown to enhance attachment of MG-63 osteoblastic cells to glass. The current study was designed to delineate the effects of microroughening on the gene expression patterns of bone markers during osteogenesis and new bone remodeling on bioactive glass surface in vivo. With the use of a rat model of paired comparison, a portion of the medullary canal in the proximal tibia was evacuated through cortical windows and filled with microroughened or smooth bioactive glass microspheres. The primary bone-healing response and subsequent remodeling were analyzed at 1, 2, and 8 weeks, respectively, by radiography, pQCT, histomorphometry, BEI-SEM, and molecular biologic analyses. The expression of various genes for bone matrix components (type I collagen, osteocalcin, osteopontin, osteonectin) and proteolytic enzymes (cathepsin K, MMP-9) were determined by Northern analysis of the respective mRNAs. Paired comparison showed significant differences in the mRNAs levels for specific bone matrix components at 2 weeks: osteopontin was significantly higher (p =.01) and osteonectin significantly lower (p =.05) in bones filled with microroughened microspheres than in those filled with smooth microspheres. Bones filled with microrough microspheres also showed significantly increased ratios of cathepsin K and MMP-9 (both markers of osteoclastic resorption) to type I collagen (p =.02 and p =.02, respectively) at 2 weeks and a significantly increased expression of MMP-9 at 8 weeks (p =.05). The pQCT, histomorphometric, and BEI-SEM analyses revealed no significant differences in the pattern of bone-healing response. Based on these results, microroughening of a bioactive glass surface could trigger temporal changes in the expression of specific genes especially by promoting the resorption part of new bone-remodeling processes. Future studies are needed to evaluate if the observed changes of gene expression are directly related to the microrough surface of any biomaterial or are biomaterial specific.     

Reduced bone formation in UK Gulf War veterans: a bone histomorphometric study

AIMS: Gulf War veterans report a high prevalence of musculoskeletal symptoms. The aim of this study was to establish whether there were abnormalities in bone turnover and remodelling in a group of symptomatic subjects who had served in the Gulf War. METHODS: Iliac crest bone biopsies were obtained from 17 Gulf War veterans who were seeking litigation and compared with those of 13 age and sex matched healthy controls. Bone histomorphometry was performed using image analysis. RESULTS: Cancellous bone area was significantly lower in Gulf War veterans than in control subjects (p = 0.027) and this was associated with a significantly reduced mineral apposition rate (p = 0.002), mean wall width (p < 0.0001), and bone formation rate at the tissue level (p < 0.0001). CONCLUSIONS: These results demonstrate that in this group of Gulf War veterans there was a significant reduction in bone formation at both the cellular and tissue level and this was associated with a reduction in cancellous bone area. The cause of these abnormalities is unknown but might be related to potentially harmful exposures during service in the Gulf War or to changes in life style as a result of chronic ill health. The clinical relevance of the observed reduction in bone formation remains to be established.     

Breast cancer metastasis to bone: evaluation of bioluminescent imaging and microSPECT/CT for detecting bone metastasis in immunodeficient mice

This study sought to determine if weekly X-ray exposure affected breast cancer cell metastasis to bone and to also evaluate the use of bioluminescent imaging (BLI) and microSPECT for detection of metastatic bone lesions. Five week old nude mice were randomly assigned to the CT exposed (n = 7) and no CT exposure (n = 6) treatment groups. Mice received an intracardiac injection of MDA-MB-435 human breast cancer cells transduced with luciferase, or a sham injection (saline). The CT exposed group of mice received CT irradiation once a week for 5 weeks. All mice underwent weekly BLI and select mice received Tc-99m-MDP followed by microSPECT imaging after 5 weeks. Pathological evaluation and histomorphometry were used to assess the affect of CT X-rays on bone metastasis and to evaluate BLI. BLI results found no significant difference in metastasis between animals that received CT and those that did not (P > 0.05); however, histomorphometry of the knee joints revealed a significant increase (P = 0.029) in tumor area of the leg bones in mice that received CT exposure (60% ± 7%) compared to animals that did not receive CT scans (33% ± 8%). Compared to histological analysis, BLI of the leg and spine was determined to have excellent sensitivity (100%), good specificity (80–90%) and accuracy (90–96%), a positive predictive value of 81–93% and a 100% negative predictive value. Thus, multi-modality imaging techniques can be very useful for monitoring bone metastasis, however microCT X-rays should be used judiciously in order to limit irradiation that may stimulate increased metastasis to specific regions of the skeleton. MicroSPECT imaging did not detect metastatic lesions in the legs of these young nude mice.     

Anabolic effects of bisphosphonates on peri-implant bone stock

The long-term durability of total joint replacements is critically dependent on adequate peri-implant bone stock, which can be compromised by wear debris-mediated osteolysis. This study investigated the effects of bisphosphonates on enhancing peri-implant bone in the presence of clinically relevant ultra-high molecular weight polyethylene (UHMWPE) wear debris. Fiber-mesh coated titanium-alloy plugs were implanted bilaterally in the femoral condyles of 36 New Zealand white rabbits. Implants in the left femora were covered with submicron UHMWPE particles during surgery. Rabbits were administered either no drug, subcutaneous alendronate weekly (1.0mg/kg/week) or a single dose of intravenous zoledronate (0.015mg/kg). A total of 6/12 rabbits in each group were sacrificed at 6 weeks and the remainder at 12 weeks postoperatively. Peri-implant bone stock was analyzed radiographically and histomorphometrically. Radiographically, both bisphosphonates significantly increased periprosthetic cortical thickness at 6 weeks (p<0.0001; alendronate: +18%; zoledronate: +11%) and at 12 weeks (p=0.001; alendronate: +17%; zoledronate:+19%). Histomorphometrically, alendronate and zoledronate raised peri-implant bone volume (BV/TV) up to 2-fold after 6 weeks without added wear debris and more than 3-fold when wear debris was present. Furthermore a 6-week bisphosphonate treatment increased osteoid thickness in the absence of wear debris (alendronate: +132%, p=0.007; zoledronate: +67%, p=0.51) and in the presence of wear debris (alendronate: +134%, p=0.023; zoledronate: +138%, p=0.016). In summary, alendronate and zoledronate treatment increased periprosthetic bone stock in a rabbit femoral model, particularly in the presence of UHMWPE wear debris. These new findings suggest that bisphosphonates may more than compensate for the well-documented negative effects of wear debris on peri-implant bone stock. The combined antiresorptive and osteoanabolic effects of bisphosphonates on periprosthetic bone stock may have an important role for critically improving the biological fixation and ultimate durability of total joint arthroplasty.     

Natural coral as bone-defect-filling material

Natural coral (NC) has been studied experimentally and clinically as a bone substitute, but its resorption rate and possible replacement by bone still need to be defined in humans. In this study bicortical bone was harvested from the iliac crest of 10 patients. The defect was filled with a NC block, and changes were monitored by X-rays and quantitative CT scans for a mean of 2.1 years. A biopsy was taken at 1 year. The purpose of the study was to investigate the resorption rate and pattern of NC (Porites) implants and the replacement, if any, of the implant by new bone. The blocks underwent centripetal resorption, but all the blocks still could be detected by X-rays and CT scans at the end of the follow-up period. The density of the remaining block did not change. Seven of the 10 implants were smaller than 50% of their original size at the end of the study. Bone ingrowth could be observed only in two of seven biopsies. One implant had to be removed after 1.7 years due to infection. The study shows that resorption of natural coral proceeds centripetally and apparently more rapidly when accompanied by tissue ingrowth. None of the blocks resorbed completely, and the defect at the iliac crest had not been restored by the end of the study.     

Peripheral quantitative computed tomography in evaluation of bioactive glass incorporation with bone

This laboratory study examined the feasibility of non-invasive, in vivo peripheral quantitative computed tomography (pQCT) method in evaluation of bioactive glass incorporation with bone. An intramedullary defect model of the rat tibia was applied. The defect was filled with bioactive glass microspheres (diameter of 250-315 microm) or was left to heal without filling (empty controls). The results of the pQCT analysis were compared with those of histomorphometry. In the control defects, there was a good correlation (r2 = 0.776, p < 0.001) between the pQCT density of the intramedullary space and the amount of new bone measured by histomorphometry. In the defects filled with bioactive glass, the use of thresholding techniques of the applied pQCT system (Stratec XCT Research M) failed in separation of new bone formation and bioactive glass particles. However, detailed analysis of the pQCT attenuation profiles showed time-related changes which well matched with the histomorphometric results of new bone formation both in control and bioactive glass filled defects. The biphasic pQCT attenuation profiles of bioactive glass filled defects could be separated into two distinct peaks. In statistical analysis of various variables, the center (i.e. the value of attenuation) of the major attenuation peak was found to be the most significant indicator of the incorporation process. The center of the peak initially decreased (during the first 4 weeks of healing) and thereafter increased. These two phases probably reflect the primary resorption and reactivity of the bioactive glass microspheres in vivo followed by secondary new bone formation on their surfaces. Based on these results, pQCT-method seems to be suitable for in vivo follow-up of the bioactive glass incorporation processes. Although the imaging technique is not able to discriminate the individual microspheres from invading new bone unambiguously, the attenuation profiling seems to give adequate information about the state of the incorporation process. This information may help to establish non-invasive imaging techniques of synthetic bone substitutes for preclinical and clinical testing of their efficacy.     

抗中性粒细胞胞浆抗体相关性血管炎的胸部CT表现

目的:探讨抗中性粒细胞胞浆抗体(antineutrophil cytoplasmic antibodies,ANCA)相关性血管炎(ANCA-associated small vessel vasculitis,AASV)的胸部CT表现.方法:回顾性分析2012年1月至2016年12月在苏州大学附属第一医院经血清学确诊的25例AASV患者的胸部CT表现.结果:25例患者中,男11例,女14例,年龄32～79岁(平均62)岁,其中胞浆型抗中性粒细胞胞浆抗体(cytoplasm antineutrophil cytoplasmic antibodies,c-ANCA)阳性5例,核周型抗中性粒细胞胞浆抗体(peripheral antineutrophil cytoplasmic antibodies,p-ANCA)阳性20例.胸部CT主要表现为间质性肺炎19例,斑片状磨玻璃影10例,结节及肿块7例,胸膜增厚5例,肺气肿肺大疱4例,支气管扩张4例,支气管充气征3例,空洞3例,胸腔积液3例,蜂窝肺1例,纵膈淋巴结肿大1例.在主要的3个影像学表现中,p-ANCA阳性患者中间质性肺炎的比例较高,较c-ANCA阳性患者而言,差异具有统计学意义(P<0.05),而斑片状磨玻璃影、结节及肿块两者比较差异并无统计学意义(P>0.05).结论:AASV患者胸部CT表现多样,以间质性肺炎、斑片状磨玻璃影、结节及肿块为主,p-ANCA阳性患者更易合并间质性肺炎.