[Bone metabolism by the secondary osteon--study of resorption rate of the longitudinal bone and bone formation in each region].
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Animals↗
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[Data on the tissue metabolism of cortical bone, spongious bone and red bone marrow].
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Animals↗
[Detection of bone metastases from bronchogenic carcinoma by bone scintigraphy with 99mTc-phosphorous compounds. I. Incidence of bone metastases from bronchogenic carcinoma and their prognosis (author's transl)].
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Adenocarcinoma↗
Effect of recombinant human bone morphogenetic protein-2, -4, and -7 on bone formation in rat calvarial defects.
BACKGROUND: Currently, more than 20 bone morphogenetic proteins (BMPs) have been identified, and many trials have been carried out using recombinant human BMPs (rhBMPs) for bone tissue engineering. However, comparative analyses on bone formative activities of rhBMP using a preclinical model have been limited. Therefore, the aim of this study was to evaluate and compare the osteogenic potential of rhBMP-2, -4, and -7 delivered with absorbable collagen sponge (ACS) upon early (2 weeks) and complete (8 weeks) wound healing phases in a critical sized rat calvarial defect model. METHODS: Eight-millimeter critical sized calvarial defects were created in 30 male Sprague-Dawley rats. The animals were divided into three groups of 10 animals each. The defects were treated with 0.025 mg/ml rhBMP-2/ACS, rhBMP-4/ACS, or rhBMP-7/ACS. The rats were sacrificed at either 2 (five rats) or 8 (five rats) weeks after surgery, and the results were evaluated histologically, histomorphometrically, and immunohistometrically. RESULTS: The surgical implantation of rhBMP-2/ACS, rhBMP-4/ACS, or rhBMP-7/ACS resulted in enhanced local bone formation in the rat calvarial defect model at both 2 and 8 weeks. The amount of defect closure, new bone area, and bone density were similar in the three groups at each time point (P > 0.05). In terms of bone density and new bone area, there were statistically significant differences between results obtained at 2 weeks and those obtained at 8 weeks in all groups (P < 0.05). Two-way analysis of variance (ANOVA) revealed that there was no correlation between the time and conditions (P > 0.05), but time was found to have a strong influence on defect closure, new bone area, and bone density (P < 0.05). Irrespective of rhBMP type, positive immunoreactions of osteopontin (OPN) and osteocalcin (OCN) were evident at 2 and 8 weeks. Intense OPN and OCN staining was observed near the newly formed bone as well as in some cells within the new bone. CONCLUSIONS: Within the rhBMP types used, rhBMP concentration, and the observation interval, there appears to be no specific differences in bone regenerative potential. All rhBMPs used in this study may be considered effective factors for inducing bone formation.
Absorbable Implants↗
Bone metabolic markers as gauges of metastasis to bone: a review.
Currently, imaging techniques are the leading methods used to diagnose of metastasis to bone. However, these techniques are expensive, expose patients to toxic and radioactive compounds, and monitor response to treatment poorly; these drawbacks have prompted the search for alternative screening methods. Therefore, bone metabolic markers have been evaluated as possible methods to diagnose and monitor the development and progression of metastatic bone disease. Although bone metabolic markers are often grouped as either resorption or formation markers, studies have revealed that each marker has its own biologic meaning and clinical relevance. Recent milestones in the use of bone metabolic markers as screening methods for metastatic bone disease and as evaluation methods for treatment response are shown in the following lists. 1. Bone metabolic marker measurements provide insight into mechanisms of metastasis to bone. 2. Although promising data have been reported, bone metabolic markers are not yet considered to be reliable screening methods for metastasis to bone. 3. Bone metabolic markers are reliable indicators of response to both conventional and bisphosphonate therapies. 4. Preliminary results indicate bone metabolic markers might be an independent prognostic factor in patients whose tumors metastasize to bone. 5. New or refined assays for bone metabolic markers are expected to improve the sensitivity and specificity of bone metabolic marker use in diagnosing and monitoring metastasis to bone.
Biomarkers, Tumor↗
Comparison of assay of total and bone-specific alkaline phosphatase in the assessment of osteoblast activity in patients with metastatic bone disease.
The evaluation of response of osseous metastases to systemic treatments is often low as a consequence of the different radiologic appearances that make objective assessment not only difficult but sometimes impossible. Radiographic evidence of recalcification, the UICC criterion of response, is often evident for 6 months and sometimes may be delayed even more. This accounts for lower response rates in bone with respect to other metastatic sites in clinical trials. A transient rise in bone formation indices may provide an early indication of bone healing and, along with measurement of symptomatic changes, could ameliorate the response evaluation. Among the biochemical markers of bone formation, total alkaline phosphatase (TALP) is widely employed, but it lacks specificity. Estimation of bone isoenzyme (E-BALP) by electrophoretic techniques is time consuming and semiquantitative. The immunoradiometric assay (I-BALP) seems to overcome these limitations. In this study, we compared the two methods of bone isoenzyme estimation with each other and with the levels of bone gla protein (BGP) and carboxyterminal propeptide of type I procollagen (PICP) in a group of 136 cancer patients with bone metastases stratified as having lytic or mixed and blastic lesions at X-ray, and in 62 cancer patients without apparent bone involvement. The same indices were also evaluated prospectively in a patient subset submitted to chemotherapy associated with pamidronate. The aims of the study were to evaluate whether I-BALP is superior to E-BALP and whether both methods of bone isoenzyme estimation are more advantageous than TALP, BGP, and PICP in the assessment of osteoblast activity either in baseline conditions or in response to treatment. In bone metastatic patients with lytic appearances, values above the cut-off limit were observed in 32.1%, 23.3%, 48.9%, 32.9%, and 14% for, TALP, E-BALP, I-BALP, PICP, and BGP, while the corresponding percentages in those with blastic/mixed appearances were 74.0%, 84.8%, 76.9%, 51.9%, and 43.8%, respectively. In the patients without bone involvement, values within the normal range were 90.2%, 98.2%, 89.6%, 71.7%, and 90.2%, respectively. Levels of TALP, E-BALP, and I-BALP were reciprocally correlated in the three groups examined. In bone metastatic patients, however, the degree of correlation of the enzymes with PICP and BGP was weak. Liver isoenzyme of alkaline phosphatase (LALP) was found to correlate with E-BALP, but not with I-BALP, in patients with mixed/blastic lesions. Thirty-eight patients were submitted to pamidronate therapy (60 mg every 3 weeks, administered 4 times) in association with cytotoxic treatment. Osteoblastic markers were determined before any administration. Serum TALP, E-BALP, and I-BALP showed a transient rise in 9 cases, a progressive reduction in 12, no change in 2, and a progressive increase in 6. Changes in E-BALP and I-BALP from baseline were greater than those of TALP. A divergent pattern between TALP and both I-BALP and E-BALP was found in 9 patients, whereas a divergent temporal profile between the two methods of bone isoenzyme estimation was recorded in only 3 patients. Eight out of 38 cases obtained a partial recalcification of lytic and mixed lesions. Seven of them showed the concomitant early increase in TALP, E-BALP, and I-BALP followed by a gradual decline (osteoblastic flare), whereas 1 patient demonstrated the flare of E-BALP and I-BALP but not of TALP. No relationship was found between response and temporal changes in in BGP and PICP serum levels. We conclude that I-BALP is a useful marker for detecting excess osteoblastic activity in patients who have at imaging "pure" lytic bone metastases. In the longitudinal evaluation of patients receiving multiple pamidronate infusions plus chemotherapy, TALP, E-BALP, and I-BALP, but not BGP and PICP, appeared to be useful to identify responders in bone. (ABSTRACT TRUNCATED)
Adult↗
Age-related changes in cortical bone in women: metacarpal bone mass measurement study.
The mechanism of age-related cortical bone loss was investigated in 229 Japanese women, 41-94 years of age, by metacarpal bone mass measurement. While no significant correlation was found between bone width and age, a significant increase in bone marrow width, and significant decreases in cortical bone density and total bone mass were observed in association with aging (P < 0.0001). There was a significant negative correlation between total bone mass and bone marrow width (r = -0.239; P < 0.0005), and significant positive correlations between both total bone mass and cortical bone density (r = 0.539; P < 0.0001) and cortical bone width (r = 0.839; P < 0.0001). The findings suggested that age-related cortical bone loss in middle-aged and elderly women resulted from two different factors; a decrease in cortical bone density caused by progression of intracortical porosity, and a decrease in cortical bone width as a result of bone loss on the endosteal surface. The latter had a greater influence on an age-related cortical bone loss than the former.
Absorptiometry, Photon↗
Expression of bone sialoprotein and osteopontin in breast cancer bone metastases.
Bone sialoprotein (BSP) and osteopontin (OPN) are prominent, mineral-associated proteins in the extracellular matrix of bone that have been implicated in the metastatic activity of cancer cells. The expression of BSP, which is normally restricted to mineralizing tissues, has been observed in cancers with a high propensity for forming bone metastases. To investigate the relationship between BSP expression and the formation of bone metastases we have conducted an initial study of the expression of BSP in 10 intraductal breast carcinoma bone metastases using immunostaining and in situ hybridization, and compared the expression with OPN. The metastases were characterized by the infiltration of tumour cells into bone with extensive bone resorption evident. Moderate to strong staining for BSP was observed in all (100%) carcinomas, which also expressed BSP mRNA as determined by in situ hybridization. Variable staining for BSP was also observed in the mineralized bone and expression of BSP mRNA could be observed in osteoblastic cells on the bone surface and in some osteocytes at sites of bone remodelling. Contrary to a previous report, BSP expression could be demonstrated by PCR in three breast cancer cell lines, MCF-7, T47-D and MDA-MB-231. Moreover, in sub-cutaneous tumours formed by MDA-MB-231 breast cancer cells injected into athymic mice, higher immunostaining for BSP was seen in large ulcerating tumours in which mineral deposits were formed. In contrast to BSP, staining for OPN in bone metastases was generally restricted to the interface between tumor cells and bone surface of the carcinomas. While OPN staining was also observed in the cytoplasm of osteoclasts, which showed strong hybridization to a digoxygenin-labelled OPN cRNA probe, expression of OPN was not clearly detectable in the tumour cells. These studies provide the first demonstration of BSP expression by tumour cells in bone metastases and support the concept that BSP may have a role in targeting metastatic cells to bone. Expression of OPN in bone metastases appears to be related to increased bone resorptive activity by osteoclasts.
Animals↗
[A new method to optimize the adhesion between bone cement and acetabular bone in total hip arthroplasty].
AIM: In cemented total hip arthroplasty cup loosening occurs earlier than stem loosening in most of the cases. This is mainly caused by the lack of stabile adhesion between the hydrophobic bone cement and the hydrophilic bone surface of the acetabulum. The aim of this study was to develop a multilayer amphiphilic bonding system which prevents the hydrolytic debonding at the bone cement-bone interface, thus optimizing the compound stability. METHOD: In a first series of tests a standardized three-point-bending test was performed to determine the compound stability of the bone cement-bone interface. The bony test specimens were immersed into physiologic NaCl solution to simulate the hydrolytic in situ conditions and contaminated with blood to simulate the intraoperative bleeding of prepared acetabular bone surfaces. In a second series of tests polyethylene cups were implanted into the acetabular cavity of sheep using the current cementing technique. Acetabular bone stock was prepared differently (subchondral sclerotic zone preserved vs. removed, additional drilling into the acetabular roof, with vs. without the multilayer bonding system) in intra-individual comparison of both acetabular sides. To ascertain the bone cement-bone stability a torsional-turn out test was performed on an universal testing machine. RESULTS: In the three-point-bending tests the compound stability between bone cement and bone was 50- to 100-times higher with the use of the multilayer system. In the torsional-turn out tests the compound stability showed in mean a 1.8-fold increase of the interface strength in case of preconditioned acetabular cavities with the multilayer bonding system. CONCLUSION: The developed multilayer bonding system optimizes the interface strength between acetabular bone stock and bone cement significantly for cemented cups in total hip arthroplasty. In contrast to cementing techniques with complete removal of the subchondral sclerotic zone (in order to optimize micro-interlocking) the biologically effective and load bearing acetabular bone stock can be preserved using the newly developed multilayer bonding system. This aspect might be highly important especially with regard to possible acetabular bone defects caused by the process of aseptic cup loosening.
Acetabulum↗
Stimulation of bone formation and prevention of bone loss by prostaglandin E EP4 receptor activation.
Bone remodeling, comprising resorption of existing bone and de novo bone formation, is required for the maintenance of a constant bone mass. Prostaglandin (PG)E2 promotes both bone resorption and bone formation. By infusing PGE2 to mice lacking each of four PGE receptor (EP) subtypes, we have identified EP4 as the receptor that mediates bone formation in response to this agent. Consistently, bone formation was induced in wild-type mice by infusion of an EP4-selective agonist and not agonists specific for other EP subtypes. In culture of bone marrow cells from wild-type mice, PGE2 induced expression of core-binding factor alpha1 (Runx2/Cbfa1) and enhanced formation of mineralized nodules, both of which were absent in the culture of cells from EP4-deficient mice. Furthermore, administration of the EP4 agonist restored bone mass and strength normally lost in rats subjected to ovariectomy or immobilization. Histomorphometric analysis revealed that the EP4 agonist induced significant increases in the volume of cancellous bone, osteoid formation, and the number of osteoblasts in the affected bone of immobilized rats, indicating that activation of EP4 induces de novo bone formation. In addition, osteoclasts were found on the increased bone surface at a density comparable to that found in the bone of control animals. These results suggest that activation of EP4 induces bone remodeling in vivo and that EP4-selective drugs may be beneficial in humans with osteoporosis.
Animals↗
Functional heterogeneity of osteoclasts: matrix metalloproteinases participate in osteoclastic resorption of calvarial bone but not in resorption of long bone.
Data in the literature suggest that site-specific differences exist in the skeleton with respect to digestion of bone by osteoclasts. Therefore, we investigated whether bone resorption by calvarial osteoclasts (intramembranous bone) differs from resorption by long bone osteoclasts (endochondral bone). The involvement of two major classes of proteolytic enzymes, the cysteine proteinases (CPs) and matrix metalloproteinases (MMPs), was studied by analyzing the effects of selective low molecular weight inhibitors of these enzymes on bone resorption. Mouse tissue explants (calvariae and long bones) as well as rabbit osteoclasts, which had been isolated from both skeletal sites and subsequently seeded on bone slices, were cultured in the presence of inhibitors and resorption was analyzed. The activity of the CP cathepsins B and K and of MMPs was determined biochemically (CPs and MMPs) and enzyme histochemically (CPs) in explants and isolated osteoclasts. We show that osteoclastic resorption of calvarial bone depends on activity of both CPs and MMPs, whereas long bone resorption depends on CPs, but not on the activity of MMPs. Furthermore, significantly higher levels of cathepsin B and cathepsin K activities were expressed by long bone osteoclasts than by calvarial osteoclasts. Resorption of slices of bovine skull or cortical bone by osteoclasts isolated from long bones was not affected by MMP inhibitors, whereas resorption by calvarial osteoclasts was inhibited. Inhibition of CP activity affected the resorption by the two populations of osteoclasts in a similar way. We conclude that this is the first report to show that significant differences exist between osteoclasts of calvariae and long bones with respect to their bone resorbing activities. Resorption by calvarial osteoclasts depends on the activity of CPs and MMPs, whereas resorption by long bone osteoclasts depends primarily on the activity of CPs. We hypothesize that functionally different subpopulations of osteoclasts, such as those described here, originate from different sets of progenitors.
Amides↗
Bone marrow involvement by non-Hodgkin's lymphoma: the clinical significance of morphologic discordance between the lymph node and bone marrow. Nebraska Lymphoma Study Group.
Bone marrow specimens from 317 patients with non-Hodgkin's lymphoma (NHL) obtained at initial staging were evaluated for the presence of lymphoma or benign lymphoid aggregates. Thirty-two percent (102 patients) had lymphoma in their bone marrow, and 9% had benign lymphoid aggregates. Bone marrow lymphoma was present in 39% of low-grade, 36% of intermediate-grade, and 18% of high-grade lymphomas. The bone marrow was involved in 25% of patients with diffuse large-cell or immunoblastic NHL (ie, diffuse histiocytic lymphoma of Rappaport). Bone marrow involvement did not affect survival of patients with low-grade NHL, but survival was significantly shorter (P = .03) for patients with intermediate- and high-grade NHL with bone marrow involvement. Bone marrow involvement was equally common in B-cell and T-cell NHL (31% v 32%). However, patients with T-cell NHL and bone marrow involvement had shorter survival than B-cell NHL with marrow involvement (P = .02) or T-cell NHL without marrow involvement (P = .05). A high incidence of morphologic discordance between lymph node and bone marrow was observed (ie, 40%), always with a more aggressive subtype in the lymph node than in the bone marrow. Presence of large-cell lymphoma in the bone marrow predicted for short survival. Survival for patients with small-cell lymphoma in their bone marrow did not differ significantly from patients with negative bone marrows. We conclude that bone marrow involvement in large-cell NHL, especially in those of T-cell origin, portends a poor prognosis. However, the subgroup of patients with an aggressive histologic subtype of NHL in a lymph node biopsy and small-cell NHL in the bone marrow do not have a poorer outlook than those without bone marrow involvement.
Actuarial Analysis↗
Bone marrow and peripheral blood leptin levels in lymphoproliferative diseases--relation to the bone marrow fat and infiltration.
Leptin is a nonglycosylated protein produced mostly by adipocytes. The role ofleptin in body weight regulation through its anorectic effect in hypothalamus is very well known. Less known are other leptin effects such as the stimulation of hematopoesis and some parts of immunity system. The role of leptin in the pathogenesis of some malignant tumors is discussed. Only a little is known about bone marrow adipocyte leptin production. We examined leptin concentrations in the sera from peripheral blood and bone marrow, the percentage of bone marrow fat, the degree of bone marrow infiltration, the body mass index (BMI) in 42 patients with lymphoproliferative diseases. We found that bone marrow has significantly lower leptin levels (6,6+/-10,9 ng/ml) than peripheral blood (9,1+/-11,5 ng/ml) (p < 0.0001). Bone marrow and peripheral blood leptin levels have also a significant thin correlation (r = +0.91, p < 0.0001). Bone marrow (r = +0.55, p < 0.0005) and peripheral blood (r = +0.52, p < 0.0005) leptin concentrations are significantly correlated to BMI. Blood serum leptin (r = +0.46, p < 0.003) and bone marrow leptin (r = +0.40, p < 0.01) are related to the bone marrow fat percentage. In addition we found a negative correlation of blood serum leptin (r = -0.59, p < 0.0001) and bone marrow leptin (r = -0.42, p < 0.005) to bone marrow malignant infiltration. When we divided the patients into groups with bone marrow infiltration more than 10% and without or less than 10% infiltration, the first group had significantly lower peripheral blood (p < 0.001) and bone marrow (p < 0.02) leptin. We also confirmed a relation of bone marrow fat and infiltration (r = +0.49, p < 0.001). Our results suggest a relationship among leptin levels in blood or bone marrow and bone marrow infiltration in lymphoproliferative diseases. This fact needs further investigation and an evaluation of its application in clinical practice.
Adipose Tissue↗
[Percutaneous autogenous bone marrow grafting for repairing bone defect: an experimental study in rabbits].
OBJECTIVE: To observe osteogenesis of percutaneous autogenous bone marrow into cicatrix of bone defect. METHODS: 18 rabbits were used to observe the osteogenesis of percutaneous autogenous bone marrow into cicatrix of bone defect. A 1 cm bone defect model was made in each side of the radius. And 2 ml autogenous bone marrow was injected in the right radial bone defect after 6 weeks, and 2 ml peripheral blood in the left side. The animals were sacrificed in 1, 2, 3, 4, 12 weeks after injection. Bone formation was studied with histologic technique, X-ray examination and Ca-P quantitative estimates. RESULTS: After 1 week of injection, a big shadow of softtissue was found around the bone defect in the right side(bone marrow). Histologically a lot of new cartilage like tissues were found. In the left side(peripheral blood), no change was seen. After 4 weeks of injection, many of new bone-like shadows were observed around the defect by X-ray examination in the right side. The defect was smaller(average 1.5 mm) and bone formation was found. But in the left side, no signs for osteogenesis were noted. In 12 weeks defect was smaller(average 1 mm). Histologic sections proved well-developed bone tissue. In the left side, no bone formation found. CONCLUSION: Autogenous bone marrow can induce osteogenesis in cicatric bone defect, whereas no osteogenesis is found in the peripheral blood injection side.
Animals↗
Biochemical picture of bone metabolism in breast cancer patients with bone metastases.
A panel of bone turn-over markers was assessed in 75 normocalcemic patients bearing bone metastases from breast cancer (BC), and in 25 advanced/metastatic BC patients without clinical appearance of bone involvement. 115 healthy women, stratified in three subgroups according to age served as controls. Bone formation was investigated by measuring serum carboxyterminal propeptide of type I procollagen (PICP), Bone Gla Protein (BGP, osteocalcin), bone isoenzyme of alkaline phosphatase (BALP); bone resorption by measuring serum carboxyterminal telopeptide of type I collagen (ICTP), fasting urinary hydroxyproline/creatinine (OHPro/Cr) and calcium/creatinine (Ca/Cr). In patients with bone metastases the percent of supranormal values (higher than mean plus 2 SD of the age-matched controls) ranged between 25% and 40% for indices of bone formation, about 73% for both ICTP and OHPro/Cr and about 30% for Ca/Cr. The median levels of all bone turn-over markers were higher in bone metastatic patients than in those without apparent skeletal involvement, but significance was attained only for OHPro/Cr, Ca/Cr and BALP. Supranormal levels of ICTP and OHPro/Cr were also found in about 65-70% of patients without apparent skeletal involvement. ICTP and Ca/Cr significantly correlated with bone pain score, BALP, ICTP, Ca/Cr significantly correlated with the number of tumour appearances in bone. In conclusion, the bone resorption indices, ICTP and OHPro/Cr, are much more frequently elevated than bone formation indices in BC patients with or without skeletal involvement. Their potential use in the early detection of bone metastases is hampered by the insufficient knowledge on specificity. Among the biochemical markers evaluated, Ca/Cr, ICTP and BALP, due to correlation with clinical aspects, appear the most interesting for follow-up studies.
Adult↗
[Relation between common allelic variation in a cross-sectional longitudinal population study. Vitamin D receptor locus, bone mineral density and postmenopausal bone loss].
The aim of this study was to determine whether common allelic variation at the vitamin D receptor locus is related to bone mineral density and postmenopausal bone loss. Five hundred and ninety-nine healthy women aged 27 to 72 and 125 women with low bone mass aged 55-77 were measured once in a cross-sectional design. Furthermore, 136 women aged 45-54 were followed longitudinally for 18 years. The vitamin D receptor genotypes were determined using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism analysis for three different polymorphic restriction sites (BsmI, ApaI and TaqI). Bone mineral density was measured by photon and X-ray absorptiometry. The cross-sectional study showed no significant relationship between vitamin D receptor genotype and bone mineral density. The maximum difference between homozygotes was 1.3%, P = 0.33, N = 723. The low bone mineral density group had virtually the same genotype frequencies as the normal bone mineral density group. The results of the longitudinal study showed that vitamin D receptor genotype was neither related to early postmenopausal bone loss: age 51-53 (total bone loss at the lower forearm: -3.6% [3.6%], mean [standard deviation]), late postmenopausal bone loss: age 63-69 (total bone loss at the hip: -6.2% [8.7%]) nor to long term postmenopausal bone loss: age 51-69 (total bone loss at the lower forearm: -24.5% [11.4%]). Using analysis of variance to test for differences in the rates of bone loss between the vitamin D receptor genotypes, P values ranged from 0.07 to 0.79. We conclude that common allelic variation at the vitamin D receptor locus as defined by the endonucleases ApaI, BsmI and TaqI is neither related to bone mineral density nor to the rate of bone loss in healthy postmenopausal Danish women.
Adult↗
Bioactive bone cement: effect of the amount of glass-ceramic powder on bone-bonding strength.
We examined the influence of the proportion of glass-ceramic powder in a bioactive bone cement of our formula on the bone-bonding ability of cement. Changes in cement bonding with time also were examined. The bioactive bone cement consisted of MgO-CaO-SiO2-P2O5-CaF2 glass-ceramic powder (AW-GC powder) and bisphenol-alpha-glycidyl methacrylate (Bis-GMA)-based resin. AW-GC powder was added to the cement as 0%, 30%, 50%, 70%, and 80% w/w. Rectangular plates (2 x 10 x 15 mm) of each cement with polished surfaces were implanted into the proximal metaphysis of the tibiae of male rabbits, and the failure load was measured by detaching tests 10 and 25 weeks after implantation. The failure loads of each cement were 0% = 0.03, 30% = 1.52, 50% = 2.67, 70% = 3.56, and 80% = 5.59 kg at 10 weeks, and 0% = 0.05, 30% = 1.68, 50% = 2.77, 70% = 3.80, and 80% = 6.37 kg at 25 weeks. Observation of the cement-bone interface revealed that all bioactive bone cements (30%-80%) formed direct contact with bone whereas intervening fibrous tissue was observed in all specimens of the 0% group. By scanning electron microscopy, all bioactive bone cements (30%-80% groups) showed direct contact with bone at the cement-bone interface. In the 0% group, direct contact with bone at the cement-bone interface was not observed. By electron-probe microanalysis, a Ca-P-rich layer was not detected at the cement-bone interfaces of the 30%-70% bioactive bone cements, but in some samples of the 80% cement specimens a thin Ca-P-rich layer (3 microns thick) was observed at the interface at 10 and 25 weeks after implantation. These results show that all of the bioactive bone cements tested had the ability to bond to bone and to function as bioactive composites of ceramics and polymers.
Animals↗
Evaluation of bone healing enhancement by lyophilized bone grafts supplemented with platelet gel: a standardized methodology in patients with tibial osteotomy for genu varus.
Orthopedic practice may be adversely affected by an inadequate bone repair that might compromise the success of surgery. In recent years, new approaches have been sought to improve bone healing by accelerating the rate of new bone formation and the maturation of the matrix. There is currently great interest in procedures involving the use of platelet gel (PG) to improve tissue healing, with satisfactory results both in vitro and in maxillofacial surgery. Otherwise, to our knowledge, only a preliminary clinical study was undertaken in the orthopedic field [Kitoh et al., Bone 2004;35:892-898] and the efficacy of PG is still controversial. Our paper focuses on the effect on bone regeneration by adding PG to lyophilized bone chips used for orthopedic applications. The clinical model and the laboratory methodology were standardized. As a clinical model, we employed the first series of patients of a randomized case-control study undergoing high tibial osteotomy (HTO) for genu varus. Ten subjects were enrolled: in 5 patients lyophilized bone chips supplemented with PG were inserted during tibial osteotomy (group A); 5 patients were used as a control (group B) and lyophilized bone chips without gel were applied. Forty-five days after surgery, computed tomography scan guided biopsies of grafted areas were obtained and the bone maturation was evaluated by a standardized methodology: the osteogenic and angiogenic processes were semi-quantitatively characterized by using histomorphometry, and the mineral component of the lyophilized and host bone was analyzed by using X-ray diffraction technique with sample microfocusing and microradiography. Lyophilized bone with PG seems to accelerate the healing process, as shown by new vessel formation and deposition of newly formed bone, with no evidence of inflammatory cell infiltrate, when compared with lyophilized bone without gel. On the contrary, lyophilized bone undergo a resorption process, and a fibrous tissue often fills the spaces between chips. A histiocytic/giant-cell reaction is sometimes present. Otherwise, no differences have been found concerning microstructure. Our findings show the reliability of the methodology used to monitor early bone repair. The completion of the study and the evaluation of the ultimate clinical outcome are necessary in order to verify PG in vivo effects in orthopedic surgery.
Adult↗