Plastic surgery

<正>209277 Experimental study of PVPP/silicone composite automatic expanded material as implansts/Yin Weimin(Dept Plast Surg,Nanfang Hosp,Southern Med Univ,Guangzhou 510000)…∥Chin J Plast Surg.-2009,25(2).-140~145Objective To study the feasibility of Polyvinylpolypyrrolidone(PVPP)/silicone composite automatic expanded material as impants.Methods The PVPP hydrogel was mixed with silicone through the thiolocation at the high temperature.Implants with different ratio of PVPP to silicone were placed under the back and nose skin in 24 New Zealand rabbits.The surrounding tissue reaction,material and skin expansion were observed and compared with those with pure silicone implants.Results The study lasted for 200 days.Compared with pure silicone implants,the composite material could expand automatically and stop expanding at about 2weeks after implantation.Histological study showed similar infectional and foreign body reaction around the composite material and the pure silicone.Conclusion Compared with pure silicone,the PVPP/silicone composite implant has the advantage of automatic expansion,so as to expand the soft tissue.16 refs,5 figs,1 tab.     

Experimental Research on Ectopic Osteogenesis of BMP2-derived Peptide P24 Combined with PLGA Copolymers

To experimentally evaluate the ectopic osteogenetic capacity of synthesized BMP2-derived peptide P24 combined with poly lactic-co-glycolic acid (PLGA), Wistar rats were di- vided into two groups: group A, in which BMP2-derived peptide P24/PLGA complex was implanted, and group B which received simple PLGA implant. The complex was respectively implanted into the back muscles of rats. Samples were taken the 1st, 4th, 8th, and the 12th week after the implantation. Their bone formation was detected by X-ray examination, and tissue response was histologically ob- served. Western blotting was used for the detection of the expression of collagen Ⅰ (Col-Ⅰ) and osteopontin (OPN). There was acute inflammation in the tissue around both types of implants at early stage. The cartilage was found around implant areas 4 weeks after the implantation of BMP2-derived peptide p24/PLGA complex, 8 weeks after the implantation, osteoblasts were found, and 12 weeks after the implantation, typical trabecular bone structure was observed. In group B, after 12 weeks, no osteoblasts were found. It is concluded that PLGA is an ideal scaffold material for bone tissue engi- neering. BMP2-derived peptide can start endochondral ossification and is more effective in inducing ectopic osteogenesis.     

Transfect bone marrow stromal cells with pcDNA3.1-VEGF to construct tissue engineered bone in defect repair

Background  We previously showed that nano-hydroxyapatite/carboxymethyl chitosan (n-Ha/CMCS) displayed excellent mechanical properties, good degradation rates and exceptional biocompatibility, with negligible toxicity. The aim of this study was to determine the effect of the same composite with vascular endothelial growth factor (VEGF)- transfected bone marrow stromal cells (BMSCs) in a rabbit radial defect model.

Methods  The nano-hydroxyapatite was produced through co-precipitation. The n-HA/CMCS scaffold was produced by particle filtration and lyophilization followed by genipin crosslinking. Total RNA from rabbit bone was reverse-transcribed to synthesize VEGF165-pcDNA3.1 that was transfected into the BMSCs. The composite was implanted into a rabbit radial defect model, and the osteogenic activity examined by gross morphology, X-ray examination and hematoxylin and eosin (HE) staining.

Results  The microstructure and mechanical property of the n-HA/CMCS scaffold resembled natural cancellous bone. Compared with glutaric dialdehyde crosslinked scaffolds, the genipin crosslinked scaffold was less toxic, and displayed a higher capacity to promote cell adhesion and proliferation. Spontaneous fluorescence of the composite permitted visualization of the composite-bone interface and the adhesion behavior of cells on the scaffold under laser scanning confocal microscopy. The scaffold with VEGF-transfected BMSCs bridged the bony defect and promoted healing, with most of the implanted material being replaced by natural bone over time with little residual implant. Using X-ray, we noted obvious callus formation and recanalization of the bone marrow cavity. Furthermore, HE stained sections showed new cortical bone formation.

Conclusions  The n-HA/CMCS scaffold composite with VEGF-trasnfected BMSCs is biocompatible, nontoxic, promotes the infiltration and formation of the microcirculation, and stimulates bone defect repair. Furthermore, the degradation rate of the composite matched that of growing bone. Overall, this composite material is potentially useful for bone defect repair.

     

Experimental Study on Low Intensity Ultrasound and Tissue Engineering to Repair Segmental Bone Defects

In order to evaluate the efficacy of low intensity ultrasound and tissue engineering technique to repair segmental bone defects, the rabbit models of 1.5-cm long rabbit radial segmental os-teoperiosteum defects were established and randomly divided into 2 groups. All defects were implanted with the composite of calcium phosphate cement and bone mesenchymal stem cells, and additionally those in experimental group were subjected to low intensity ultrasound exposure, while those in control group to sham exposure. The animals were killed on the postoperative week 4, 8 and 12 respectively, and specimens were harvested. By using radiography and the methods of biome-chanics, histomorphology and bone density detection, new bone formation and material degradation were observed. The results showed that with the prolongation of time after operation, serum alkaline phosphatase (AKP) levels in both groups were gradually increased, especially in experimental group, reached the peak at 6th week (experimental group: 1.26 mmol/L; control group: 0.58 mmol/L), suggesting the new bone formation in both two group, but the amount of new bone formation was greater and bone repairing capacity stronger in experimental group than in control group. On the 4th week in experimental group, chondrocytes differentiated into woven bone, and on the 12th week, remodeling of new lamellar bone and absorption of the composite material were observed. The mechanical strength of composite material and new born density in experimental group were significantly higher than in control group, indicating that low intensity ultrasound could not only effectively increase the formation of new bone, but also accelerate the calcification of new bone. It was concluded that low intensity ultrasound could evidently accelerate the healing of bone defects repaired by bone tissue engineering.     

Fetal tissue grafts for cerebellar atrophy.

It has been shown in a rat model that surgical injury to the right cerebellum with resultant ataxia can be corrected by implantation of embryonic cerebellar tissue into the injured cerebellum. Histological examinations of the cerebellar tissue revealed that mitoses of Purkinje cells of the implanted group were increased substantially over the control group's. The surgically induced ataxia resolved more rapidly in the cerebellar implant group than the control group. Based on this experimental data, a similar technique was applied in 6 patients with severe hereditary cerebellar degenerative ataxia. The preliminary results in these 6 surgically implanted patients with heredity degenerative cerebellar disease show 2 with marked improvement, 3 with moderate improvement and 1 with improvement for 2 months followed by mild deterioration but still better than presurgery. We also studied immunological markers in the blood and CSF in an attempt to determine whether rejection of implanted tissue occurs.

     

Biocompatibility Studies on Fibrin Glue Cultured with Bone Marrow Mesenchymal Stem Cells in Vitro

By culturing bone marrow mesenchymal stem cells of rabbits with fibrin glue in vitro,the biocompatibility of fibrin glue was investigated to study whether this material can be used as scaffolds in bone tissue engineering. After 2-months old New Zealand rabbits had been anesthetized, about 4--6 ml of bone marrow were aspirated from rabbit femoral trochanter. The monocytes suspension was aspirated after bone marrow was centrifuged with lymphocyte separating medium and cultured primarily. Then the cells were divided into two groups: one was cultured with complete medium and the other with induced medium. The cells of the two groups were collected and inoculated to the culture plate containing fibrin glue. In the control group, cells were inoculated without fibrin glue. The implanted cells and materials were observed at different stages under a phase-contrast microscope and scanning electron microscope. MTT and alkaline phosphatase (ALP) were measured. Bone marrow mesenchymal stem cells grew on the surface of fibrin glue and adhered to it gradually. Cells light absorption value (A value) and the ALP content showed no significant difference. Fibrin glue had no inhibitory effect on cell morphology, growth, proliferation and differentiation. It has good biocompatibility and can be used as scaffold materials for bone marrow mesenchvmal stem cells in bone tissue engineering.     

In vivo testing of canine prosthetic femoral components with HA-Ti ladder-type coating on vacuum plasma-sprayed Ti substrate

The purpose of the present study was to observe the structure and functional change of the bone-coating-prosthesis interface in vivo and to evaluate the histocompatibility of self-made prosthetic femoral components in the body and the degree of their bonding with the surrounding bone tissues as well as their stability.Six mature beagle dogs underwent bilateral hip replacement with prosthetic femur components.Three groups were established in terms of different coating of prothesis (four joints in each group):atmosphere (A) plasma-sprayed pure titanium (Ti) prosthetic joint with hydroxyapatite (HA) coating (HA+Ti+A group);vacuum (V) plasma-sprayed pure Ti prosthetic joint with HA coating (HA+Ti+V group);vacuum plasma-sprayed pure Ti prosthetic joint with Ti-HA stepped coating (Ti+HAG+Ti+V group).The hip joints were functionally evaluated,and subjected to X-ray examination,biomechanics inspection,and histological examination.As a result,X-ray imaging revealed all prosthetic joints were in a good location and no dislocation of joint was found.Shear strength of interface was significantly higher in Ti+HAG+Ti+V group than in HA+Ti+V group (P<0.05) and HA+Ti+A group (P<0.05) at 28th week.Histological examination showed the amount of newborn bone in Ti+HAG+Ti+V group was more than in HA+Ti+V group and HA+Ti+A group after 28 weeks.It was suggested that vacuum plasma-sprayed pure Ti prosthetic joint with TI-HA stepped coating could improve the bonding capacity of bone-prosthesis,enhance the stability of prosthesis,and increase the fixion of prosthetic femoral components because of better bone growth.This new type of biological material in prosthetic femoral components holds promises for application in clinical practice.     

Evaluation of transforming growth factor beta and bone morphogenetic protein composite on healing of bone defects.

OBJECTIVE To evaluate the effect of transforming growth factor-beta/bone morphogenetic protein (TGF-beta/BMP) composite on the healing of large segmental bone defects and to discuss the interaction between TGF-beta and BMP during bone repair.

METHODS A 1.5 cm segmental defect was made in the mid-upper part of the radial shaft of 48 adult rabbits. The defects were filled with implants of TGF-beta/carrier, BMP/carrier or TGF-beta/BMP/carrier separately. 120 micrograms of purified bovine TGF-beta and 12 mg of BMP were used in the composite. The defects were examined radiographically and histologically at 4, 8, 12 and 16 weeks post-operation.

RESULTS In the group filled with TGF-beta/BMP composite, the defect areas were bridged at 4 weeks, with callus of uniform radiodensity. Cortices of the cut ends were obscured by new bone. By 16 weeks post-operation, the defects were bridged by uniform new bone and the cut ends of the cortex could not be seen in all groups. In group of BMP/carrier, the defects were filled with more irregular woven bone callus than in other two groups. TGF-beta/BMP implanted defects in animals killed at 16 weeks showed histologically new lamella and woven bone that was formed in continuity with the cut ends of the cortex. Medullar canal was recanalized and contained marrow elements with normal appearance.

CONCLUSIONS These data demonstrate not only the synergistic action between TGF-beta and BMP in the process of bone healing, but also a better effect of TGF-beta/BMP composite than single TGF-beta or BMP on bone repair, especially in the early stage of bone repair process.

     

Investigation of peri-implant status and risk variables for implant failure in body of maxilla after oral tumor surgery

The aim of this study was to assess the peri-implant parameters and evaluate the clinical status with the survival of dental implants in body of maxilla after treatments of oral tumor. A follow-up examination included 27 patients who underwent the ablative tumor and （or） reconstructive surgery during a 5-year period. The follow-up protocol included clinical examination, radiological evaluation, and an interview using a standardized questionnaire. The reasons related to implant failure were studied by comparing the amount of failure with the value of marginal bone resorption, probing pocket depth, and plaque index using statistical t-test. The relationship between smoking and implant failure was analyzed statistically by chi-square test. The results showed among the 112 implants observed after implant loading, 29 have failed with the failure rate being 22.14 %. There was no significant correlation between the peri-implant status and the implant failure （P〉0.05）, however, the association of smoking and implant failure was statistically tested （P〈0.05）. It was suggested that the association of peri-implant status and implant failure in the maxilla after tumor surgery can＇t be statistically tested, however smoking was still a mainly significant factor.     

FEASIBILITY OF WHOLE BODY DIFFUSION WEIGHTED IMAGING IN DETECTING BONE METASTASIS ON 3.0T MR SCANNER

Objective To evaluate the feasibility of whole body diffusion weighted imaging （DWI） in bone metastasis detection using bone scintigraphy as comparison.
Methods Forty-five patients with malignancy history were enrolled in our study. All the patients received the whole body DWI and bone scintigraphy scan within 1 week. The magnetic resonance （MR） examination was performed on 3.0T MR scanner using embedded body coil. The images were reviewed separately by two radiologists and two nuclear medicine physicians, who were blinded to the results of the other imaging modality. The sensitivity, specificity, positive predictive value （PPV） and negative predictive value （NPV） of the two techniques for detecting bone metastasis were analyzed.
Results A total of 181 metastatic lesions in 77 regions of 34 patients were detected by whole body DWI, and 167 metastatic lesions in 76 regions of 31 patients were identified by bone scintigraphy. The patient-based sensitivity and PPV of whole body DWI and bone scintigraphy were similar （89.5% vs. 81.6%, 97.1% vs. 91.2%）, whereas, the patient-based specificity and NPV of whole body DWI were obviously higher than those of bone scintigraphy （85.7% vs. 57.1%, 60.0% vs. 36.4%）. Ten regions negative in scintigraphy but positive in whole body DWI, mainly located in spine, pelvis, and femur; nine regions only detected by scintigraphy, mainly located in skull, sternum, clavicle, and scapula. The region-based sensitivity and specificity of whole body DWI were slightly higher than those of bone scintigraphy （89.5% vs. 88.4%, 95.6% vs. 87.6%）.
Conclusion Whole body DWI reveals excellent concordance with bone scintigraphy regarding detection of bone metastasis, and the two techniques are complementary for each other.     

PRELIMINARY APPLICATION OF WHOLE BODY DIFFUSION WEIGHTED IMAGING IN SCREENING METASTASIS

Objective To investigate the feasibility of whole body diffusion weighted imaging （WB-DWI） in screening metastasis.
Methods WB-DWI was performed in 24 patients diagnosed with various types of primary tumors. The three-dimensional maximum intensity projection reconstruction and black-and-white flip technique were used to observe metastatic lesions, and the results were compared with those of bone scintigraphy.
Results By WB-DWI scanning sequence at b = 800 s/mm^2, all the bone lesions found by bone scintigraphy in the cohort were well identified, and other lesions of soft tissue and organs were also well demonstrated. Its screening capability was equivalent with bone scintigraphy in screening metastases in bones （P = 0.062）.
Conclusion WB-DWI was practicable with the parameter settings attempted in metastases screening.     

COA:Intervertebral Disc Degeneration and Bone Density in Degenerative Lumbar Scoliosis: A Comparative Study between Patients with Degenerative Lumbar Scoliosis and Patients with Lumbar Stenosis

Objectives: To compare the intervertebral disc degeneration and bone density at major curve in degenerative lumbar scoliosis (DLS) and lumbar spinal stenosis. Methods: 96 patients with degenerative lumbar scoliosis(DLS) were retrospectively enrolled and 96 patients with lumbar spinal stenosis were selected as control group from Jan.2001 to Aug.2010. Cobb angle, the height of the apical disc and the contiguous disc superiorly and inferiorly in convex and concave side, the height of the convex and concave side of the apical and the contiguous vertebral body superiorly and inferiorly was measured in scoliosis group, the height of L2/L3, L3/L4, L4/L5 discs and the height of L2/L4 vertebral body was measured in control group. The grade of intervertebral disc degeneration was evaluated in T2WI sagittal image in both groups. The bone density of lumbar vertebrae was measured with dual-energy x-ray. Results: Scoliosis group: The intervertebral disc height in convex side was greater than the height in the concave side (P﹤0.001), The vertebral body height in convex side was greater than the height in the concave side (P=0.016). While there was significant statistically difference between the scoliosis group and the control groups (P=0.003). There was significant statistically difference of the T-value and the rate of osteoporosis between two groups (P﹤0.001, P﹤0.001). By using multiple linear regression analysis, the above results are further shown. Conclusion: In degenerative scoliotic major curves: the degeneration of intervertebral disc is more severe, bone density is lower in patients with DLS compared with lumbar spinal stenosis patients.     

Local changes in aluminium, calcium and phosphorus content of bone caused by alumina implant.

Thirty rabbits were divided equally into 5 groups randomly. A hole, 6 mm in diameter and 2 mm deep, was bored on each iliac crest. Two pieces of alumina were implanted into the hole of one side, while the opposite side served as control. These rabbits were killed on 10, 20, 40, 60 and 90 days after operation. Calcium, phosphorus and aluminium contents of iliac bone on both sides were determined by Inductively Coupled Plasma--Atomic Emission Spectrometry. The results showed that the aluminium content of the implanted side in each group was higher than that of the control and difference was significant in 10, 40 and 60 day groups (P < 0.05). This shows that the implant releases aluminium into the bone. Moreover, the calcium and phosphorus contents were significantly lower on the implanted side than on the control side in 10 and 20 day groups (P < 0.05-0.001). Apparently, the aluminium released from the implant in the early stage can interfere with the local calcium and phosphorus metabolism and delay the mineralization of the bone.

     

Repair of sheep metatarsus defects by using tissue-engineering technique

Tissue-engineering bone with porous β-tricalcium phosphate (β-TCP) ceramic and autologous bone marrow mesenchymal stem cells (MSC) was constructed and the effect of this composite on healing of segmental bone defects was investigated. 10-15 ml bone marrow aspirates were harvested from the iliac crest of sheep, and enriched for MSC by density gradient centrifugation over a Percoll cushion (1.073g/ml). After cultured and proliferated, tissue-engineering bones were constructed with these cells seeded onto porous β-TCP, and then the constructs were implanted in 8 sheep left metatarsus defect (25 mm in length) as experimental group. Porous β-TCP only were implanted to bridge same size and position defects in 8 sheep as control group, and 25 mm segmental bone defects of left metatarsus were left empty in 4 sheep as blank group. Sheep were sacrificed on the 6th, 12th, and 24th week postoperatively and the implants samples were examined by radiograph, histology, and biomechanical test. The 4 sheep in blank group were sacrificed on the 24th week postoperatively. The results showed that new bone tissues were observed either radiographic or histologically at the defects of experimental group as early as 6th week postoperatively, but not in control group, and osteoid tissue, woven bone and lamellar bone occurred earlier than in control group in which the bone defects were repaired in “creep substitution” way, because of the new bone formed in direct manner without progression through a cartilaginous intermediate. At the 24th week, radiographs and biomechanical test revealed an almost complete repair of the defect of experimental group, only partly in control group. The bone defects in blank group were non-healing at the 24th week. It was concluded that engineering bones constructed with porous β-TCP and autologous MSC were capable of repairing segmental bone defects in sheep metatarsus beyond “creep substitution” way and making it healed earlier. Porous β-TCP being constituted with autologous MSC may be a good option in healing critical segmental bone defects in clinical practice and provide insight for future clinical repair of segmental defect.     

Experimental study on the occlusion of arterial blood flow by the implantation of nitinol alloy stents.

To evaluate the occlusion of arteries, 6 conic intravaseular endoprosthetic stents of titanium-nickel alloy were implanted transluminally to the right external iliac arteries in 2 normal dogs and 4 normal pigs. The stent was characterized by ductility below 313 K (40℃) and restoration memory-shape between 313-319 K. The diameter of the large end of conic stent was 4.0 mm (dog) and 4.5 mm(pig). The topographic anatomy showed that the external iliac artery was near complete occlusion, with a very small residual lumen (about 1 mm in diameter) in dogs at 6 months, with complete occlusion in pigs at 8 months. The histopathological examination indicated that the arterial intima of the upper branch from the stented site was smooth, and that neither inflammatory cell infiltration nor foreign giant cell reaction was found. The newly formed granulation tissue inside the stent came from emboli organization. These results suggest that the shape-memory alloy stent has good biocompatibility and the conic intravascnla     

Extraskeletal chondrosarcoma. Report of 8 cases.

Eight cases of surgically and pathologically verified extraskeletal (soft tissue) chondrosarcoma were analyzed with regard to clinical and X-ray features. Their cardinal clinical aspects included presence of a local soft tissue mass and gradual enlargement of the mass accompanied by increasing pain. The X-ray signs were formation of a soft tissue mass, various forms of calcification in the central area of the tumor presence of saucer-like defect on the cortical surface of neighbouring bone in some cases, and bending deformity of the affected bone. The incidence and sites of predilection, the main X-ray findings, radiological diagnosis and differential diagnosis of the tumor were discussed.

     

Intervertebral disc degeneration and bone density in degenerative lumbar scoliosis: a comparative study between patients with degenerative lumbar scoliosis and patients with lumbar stenosis

Background  Degenerative lumbar scoliosis is common in older patients. Decreased bone density and the degeneration of intervertebral discs are considered to be correlated with degenerative lumbar scoliosis. A means of quantifying the relative signal intensity for degenerative disc disease has not been previously discussed. The purpose of this study was to compare bone mineral density and intervertebral disc degeneration between degenerative lumbar scoliosis and lumbar spinal stenosis patients in a nine-year retrospective study.

Methods  From January 2001 to August 2010, 96 patients with degenerative lumbar scoliosis were retrospectively enrolled and 96 patients with lumbar spinal stenosis were selected as controls. Cobb angle, height of the apical disc and the contiguous disc superiorly and inferiorly on convex and concave sides, the height of the convex and concave side of the apical and the contiguous vertebral body superiorly and inferiorly were measured in the scoliosis group. The height of L2/L3, L3/L4, L4/L5 discs and the height of L2/L4 vertebral body was measured in the control group. The grade of intervertebral disc degeneration was evaluated using T2WI sagittal images in both groups. The bone density of lumbar vertebrae was measured with dual-energy X-ray.

Results  In scoliosis group, the intervertebral disc height on the convex side was greater than the height on the concave side (P <0.001). The vertebral body height on the convex side was greater than the height on the concave side (P=0.016). There was a significant difference between the scoliosis group and the control group (P=0.003), and between T-value and the rate of osteoporosis between the two groups (both P <0.001). Results were verified using multiple linear regression analysis.

Conclusions  Degenerative lumbar scoliosis is accompanied by height asymmetry between the intervertebral disc and vertebral body regarding the convex and concave surfaces. There is a positive correlation between the angle of scoliosis and the disc index, the degree of degeneration of the intervertebral disc, and a negative correlation between the angle of scoliosis and bone density.

     

Experimental study of natural hydroxyapatite/chitosan composite on reconstructing bone defects

Objective:To study the possibility of natural hydroxyapatite/chitosan composite on repairing bone defects. Methods:We developed a natural hydroxyapatite/chitosan composite that could be molded into any desired shape. The powder component consists of natural hydroxyapatite, which is epurated from bone of pigs. The liquid component consists of malic acid and chitosan. Operations were performed on the left tibias of 15 white rabbits to create two square bone defects. One of the defects was reconstructed with the composite, while the other was not repaired and used as a blank control. Three of the animals were killed at the end of 2 weeks, 4 weeks, 8 weeks, 12 weeks and 16 weeks respectively and implants were evaluated anatomically and histologically. Results:No apparent rejection reaction was found, except for a mild inflammatory infiltration observed 2 weeks after surgery. Fibrous tissue became thinner 2～8 weeks after surgery and bony connections were detected 12 weeks after surgery. The new bone was the same as the recipient bone by the 16th postoperative week. Conclusion:The hydroxyapatite/chitosan composite has good biocompatibility and osteoconduction. It is a potential repairing material for clinical application.     

Effect of impaction on gene-modified cells seeded on granular bone allografts in vitro and in vivo

Background While attempting to restore bone stock, impaction bone grafting employed during revision joint surgery may result in slow and limited allograft incorporation into host bone. A new approach including gene-modified bone marrow stromal cells （BMSCs） in combination with impaction bone grafting may effectively restore bone stock and improve allograft incorporation. This study aimed to investigate the effect of impaction on gene-modified BMSCs seeded on granular bone allografts in vitro and in vivo.Methods Deep-frozen, granular, cancellous bone allografts from canines were prepared to serve as cell delivery scaffolds and were seeded with green fluorescent protein （GFP） genetically-modified BMSCs to construct cell-allograft composites. The composites were impacted in a simulative, in vitro impaction model and cultured for further analysis under standard conditions. Four Beagle dogs, treated with bilateral, uncemented proximal tibial joint hemiarthroplasty with a prosthesis, were implanted with autologous GFP gene-modified cell-allograft composites to repair the bone cavity around each prosthesis.Results A significant reduction in cell viability was observed after impaction by fluorescence microscopy in vitro.However, there remained a proportion of GFP-positive cells that were viable and functionally active, as evidenced by the secretion of GFP protein in vitro and in vivo.Conclusions Gene-modified BMSCs seeded on granular allografts were able to withstand the impaction forces and to maintain their normal functions in vitro and in vivo, in spite of a partial loss in cell viability.     

Validation of quantitative computed tomography-derived areal bone mineral density with dual energy X-ray absorptiometry in an elderly Chinese population

Background The performance of computed tomography X-ray absorptiometry （CTXA） against the dual energy X-ray absorptiometry （DXA） as standard has not been studied in Chinese population. The aim of this study was to evaluate the precision of this measurement and validate the value of quantitative computed tomography （QCT） by comparing CTXA results with DXA results in an elderly Chinese population. Methods One hundred and three females of 46 to 76 years old and 49 males of 52 to 76 years old were recruited from the Prospective Urban Rural Epidemiology study. All subjects underwent hip scans by both QCT and DXA on the same day. For precision determination, 30 subjects had duplicate DXA hip scans. The hip QCT data of a subset of 27 subjects were separately analyzed by two observers and reanalyzed by one observer at a different time. The inter- and intra-observer variations of CTXA measurement were assessed, and the difference and correlation between CTXA and DXA results were analyzed. Results The inter- and intra-observer variations of CTXA were 0.070 and 0.024 g/cm^2 in the femoral neck （FN）, and 0.030 and 0.012 g/cm2 in the total hip （TH）, which were comparable to the DXA inter-scan variations （0.013 g/cm2 for FN and 0.014 g/cm2 for TH）. The results of CTXA bone mineral density （BMD） were highly correlated with those of DXA （R2 = 0.810 for FN and R2 = 0.878 for TH）. The BMD values of CTXA in FN and TH were lower than those of DXA by 21.0% and 17.8% （P〈0.05）, respectively. However, after appropriate transformation, the difference was eliminated and a comparable T score could be obtained. Conclusions CTXA shows good agreement with DXA for the measurement of BMD in the proximal femur, which makes QCT suitable for the quantification of bone mineral content in the hip and helpful for the diagnosis of osteoporosis.