Degree Of Bone Formation Research Articles

Potentiating effect of AMD3100 on bone morphogenetic protein-2 induced bone regeneration

BackgroundAMD3100, a CXCR4 antagonist, is currently prescribed for activating the mobilization of hematopoietic stem cells. Recently, AMD3100 was shown to potentiate bone morphogenetic protein-2 (BMP-2)-induced bone formation by stimulating the trafficking of mesenchymal cells. However, optimization of the strategic combination of AMD3100 and BMP-2 has not yet been clearly established. The purpose of this study was to evaluate the effect of AMD3100 on BMP-2-induced bone regeneration in vitro and in a mouse calvarial defect healing model.MethodsIn vitro osteoblastic differentiation and cell migration after sequential treatments with AMD3100 and BMP-2 were analyzed by alkaline phosphatase (ALP) activity, ALP staining, and calcium accumulation. Migration capacity was evaluated after treating mesenchymal cells with AMD3100 and/or BMP-2. A critical-size calvarial defect model was used to evaluate bone formation after sequential or continuous treatment with AMD3100 and BMP-2. The degree of bone formation in the defect was analyzed using micro-computed tomography (micro-CT) and histological staining.ResultsCompared with single treatment using either AMD3100 or BMP-2 alone, sequential treatment with AMD3100 followed by BMP-2 on mesenchymal cells increased osteogenic differentiation. Application of AMD3100 and subsequent BMP-2 significantly activated cell migration on mesenchymal cell than BMP-2 alone or AMD3100 alone.Micro-CT and histomorphometric analysis showed that continuous intraperitoneal (IP) injection of AMD3100 resulted significantly increased new bone formation in BMP-2 loaded scaffold in calvarial defect than control groups without AMD3100 IP injection. Additionally, both single IP injection of AMD3100 and subsequent BMP-2 injection to the scaffold in calvarial defect showed pronounced new bone formation compared to continuous BMP-2 treatment without AMD3100 treatment.ConclusionOur data suggest that single or continuous injection of AMD3100 can potentiate BMP-2-induced osteoblastic differentiation and bone regeneration. This strategic combination of AMD3100 and BMP-2 may be a promising therapy for bone regeneration.

Early Osteogenic-Induced Adipose-Derived Stem Cells and Canine Bone Regeneration Potential Analyzed Using Biodegradable Scaffolds.

The complex process of bone regeneration is influenced by factors such as inflammatory responses, tissue interactions, and progenitor cells. Currently, multiple traumas can interfere with fracture healing, causing the prolonging or failure of healing. In these cases, bone grafting is the most effective treatment. However, there are several drawbacks, such as morbidity at the donor site and availability of suitable materials. Advantages have been provided in this field by a variety of stem cell types. Adipose-derived stem cells (ASCs) show promise. In the radiological examination of this study, it was confirmed that the C/S group showed faster regeneration than the other groups, and Micro-CT also showed that the degree of bone formation in the defect area was highest in the C/S group. Compared to the control group, the change in cortical bone area in the defect area decreased in the sham group (0.874), while it slightly increased in the C/S group (1.027). An increase in relative vascularity indicates a decrease in overall bone density, but a weak depression filled with fibrous tissue was observed outside the compact bone. It was confirmed that newly formed cortical bone showed a slight difference in bone density compared to surrounding normal bone tissue due to increased distribution of cortical bone. In this study, we investigated the effect of bone regeneration by ADMSCs measured by radiation and pathological effects. These data can ultimately be applied to humans with important clinical applications in various bone diseases, regenerative, and early stages of formative differentiation.

Dental implants with electrochemical nanopattern formation to increase osseointegration

An electrochemical nanopattern formation (ENF) surface treatment was developed to overcome the limitations of conventional surface treatments. This study aimed to evaluate the cytocompatibility and preclinical efficacy of the newly developed ENF surfaces in comparison to conventional surfaces. The cytocompatibility of human mesenchymal stem cells, degree of bone formation, bone-to-implant contact (BIC) ratio, and implant stability quotient (ISQ) were investigated using rabbit and beagle models. Overall, the ENF surfaces showed greater cytocompatibility than other surfaces. The ISQs of implants in rabbit tibias showed that ENF surfaces provided greater stability than other surfaces. In contrast, the ISQs of implants in beagle mandibles were similar for ENF and sandblasted large-grit acid-etched (SLA) surfaces. In the rabbit model, the degree of bone formation and BIC ratio were significantly higher for ENF surfaces than for other surfaces. However, the removal torque (RT) during implant removal was significantly higher for SLA surfaces than ENF surfaces. Thus, it was confirmed that ENF-treated dental implants can replace conventional implants, but further research is required to improve the surface roughness to increase the RT.

Spontaneous intranasal tumours in degus (Octodon degus): 20 cases (2007-2020).

The objective of this retrospective study was to describe the clinical and histopathological findings associated with intranasal tumours in degus. Medical records of degus diagnosed with intranasal neoplasms on histopathological examination between the years 2007 and 2020 at one hospital were included in the study. Twenty degus (10 males and 10 females) were eligible for inclusion. Initial clinical signs included sneezing, abnormal nasal sounds, and nasal discharge, followed by anorexia and frequent nose rubbing. On radiography, 15 out of 20 animals showed space-occupying lesions in the nasal cavity. CT was performed in 16 animals and revealed various degrees of changes, including abnormal radiopacity within the nasal cavity and damaged nasal septum. Rhinostomy and excisional biopsy was performed in all 20 animals. Six out of 20 patients died during the perioperative period. Six and seven degus survived for 3 months and 1 year, respectively. One animal was lost to follow-up. In 16 cases the histological diagnosis was consistent with fibromas, while in 4 cases with osteomas. Intranasal neoplasms in degus are mostly benign mesenchymal tumours with various degrees of bone formation, which is unique to this animal species. This occurrence should be considered as an important differential diagnosis for upper respiratory tract disease in degus.

Burn and thoracic trauma alters fracture healing, systemic inflammation, and leukocyte kinetics in a rat model of polytrauma

BackgroundSingular traumatic insults, such as bone fracture, typically initiate an appropriate immune response necessary to restore the host to pre-insult homeostasis with limited damage to self. However, multiple concurrent insults, such as a combination of fracture, blunt force trauma, and burns (polytrauma), are clinically perceived to result in abnormal immune response leading to inadequate healing and resolution. To investigate this phenomenon, we created a model rat model of polytrauma.MethodsTo investigate relationship between polytrauma and delayed healing, we created a novel model of polytrauma in a rat which encompassed a 3-mm osteotomy, blunt chest trauma, and full-thickness scald burn. Healing outcomes were determined at 5 weeks where the degree of bone formation at the osteotomy site of polytrauma animals was compared to osteotomy only animals (OST).ResultsWe observed significant differences in the bone volume fraction between polytrauma and OST animals indicating that polytrauma negatively effects wound healing. Polytrauma animals also displayed a significant decrease in their ability to return to pre-injury weight compared to osteotomy animals. Polytrauma animals also exhibited significantly altered gene expression in osteogenic pathways as well as the innate and adaptive immune response. Perturbed inflammation was observed in the polytrauma group compared to the osteotomy group as evidenced by significantly altered white blood cell (WBC) profiles and significantly elevated plasma high-mobility group box 1 protein (HMGB1) at 6 and 24 h post-trauma. Conversely, polytrauma animals exhibited significantly lower concentrations of plasma TNF-alpha (TNF-α) and interleukin 6 (IL-6) at 72 h post-injury compared to OST.ConclusionsFollowing polytrauma with burn injury, the local and systemic immune response is divergent from the immune response following a less severe singular injury (osteotomy). This altered immune response that follows was associated with a reduced capacity for wound healing.

Development of an experimental model for radiation-induced inhibition of cranial bone regeneration

BackgroundRadiation therapy is widely employed in the treatment of head and neck cancer. Adverse effects of therapeutic irradiation include delayed bone healing after dental extraction or impaired bone regeneration at the irradiated bony defect. Development of a reliable experimental model may be beneficial to study tissue regeneration in the irradiated field. The current study aimed to develop a relevant animal model of post-radiation cranial bone defect.MethodsA lead shielding block was designed for selective external irradiation of the mouse calvaria. Critical-size calvarial defect was created 2 weeks after the irradiation. The defect was filled with a collagen scaffold, with or without incorporation of bone morphogenetic protein 2 (BMP-2) (1 μg/ml). The non-irradiated mice treated with or without BMP-2-included scaffold served as control. Four weeks after the surgery, the specimens were harvested and the degree of bone formation was evaluated by histological and radiographical examinations.ResultsBMP-2-treated scaffold yielded significant bone regeneration in the mice calvarial defects. However, a single fraction of external irradiation was observed to eliminate the bone regeneration capacity of the BMP-2-incorporated scaffold without influencing the survival of the animals.ConclusionThe current study established an efficient model for post-radiation cranial bone regeneration and can be applied for evaluating the robust bone formation system using various chemokines or agents in unfavorable, demanding radiation-related bone defect models.

Systemic and local zoledronic acid treatment with hydroxyapatite bone graft: A histological and histomorphometric experimental study.

In this study, the aim was to compare the relative efficacy of systemic and local zoledronic acid (ZA) on a hydroxyapatite (HA) bone graft in a rat critical-size calvarial bone defect. In total, 84 female rats were divided into four groups: Empty control (EC) group with no treatment applied; HA group, in which only HA bone graft material was used in the calvarium; and HA plus local ZA (HA+LZA) and HA plus systemic ZA (HA+SZA) groups, in which animals received ZA locally or systemically, respectively, with HA bone graft material in the calvarium. A 5-mm standardised critical-size calvarial bone defect was created with a standard trephine drill and the respective treatment was applied. Rats were sacrificed 7, 14 and 28 days later. The numbers of osteoclasts and osteoblasts, and degree of bone formation were evaluated histopathologically and histomorphometrically. Statistically significant differences were detected between the HA, HA+LZA and HA+SZA groups and the EC group for new bone formation (P<0.05). Osteoblast numbers in the HA+LZA and HA+SZA groups were significantly higher compared with those in the EC and HA groups (P<0.05). No statistically significant difference was detected between the HA+LZA and HA+SZA groups in new bone formation or osteoblast number (P>0.05). Bone formation was significantly higher in the HA group than in the EC group (P<0.05). The numbers of osteoclasts in the HA+LZA and HA+SZA groups were significantly higher than those in the groups EC and HA (P<0.05); however, there was no significant difference between groups HA+LZA and HA+SZA (P>0.05). Within the limitations of this study, systemic or local administration of ZA enhanced new bone formation with a HA bone graft in a rat critical-size calvarial defect model.

Effect of dual treatment with SDF-1 and BMP-2 on ectopic and orthotopic bone formation.

PurposesThe potent stem cell homing factor stromal cell-derived factor-1 (SDF-1) actively recruits mesenchymal stem cells from circulation and from local bone marrow. It is well established that bone morphogenetic protein-2 (BMP-2) induces ectopic and orthotopic bone formation. However, the exact synergistic effects of BMP-2 and SDF-1 in ectopic and orthotopic bone regeneration models have not been fully investigated. The purpose of this study was to evaluate the potential effects of simultaneous SDF-1 and BMP-2 treatment on bone formation.Materials and MethodsVarious doses of SDF-1 were loaded onto collagen sponges with or without BMP-2.These sponges were implanted into subcutaneous pockets and critical-size calvarial defects in C57BL/6 mice. The specimens were harvested 4 weeks post-surgery and the degree of bone formation in specimens was evaluated by histomorphometric and radiographic density analyses. Osteogenic potential and migration capacity of mesenchymal cells and capillary tube formation of endothelial cells following dual treatment with SDF-1 and BMP-2 were evaluated with in vitro assays.ResultsSDF-1-only-treated implants did not yield significant in vivo bone formation and SDF-1 treatment did not enhance BMP-2-induced ectopic and orthotopic bone regeneration. In vitro experiments showed that concomitant use of BMP-2 and SDF-1 had no additive effect on osteoblastic differentiation, cell migration or angiogenesis compared to BMP-2 or SDF-1 treatment alone.ConclusionsThese findings imply that sequence-controlled application of SDF-1 and BMP-2 must be further investigated for the enhancement of robust osteogenesis in bone defects.

Demineralized bone matrix, as a graft enhancer of auto-local bone in posterior lumbar interbody fusion.

Study DesignA case controlled study with prospective data collection.PurposeTo evaluate the early influence and the final consequence of demineralized bone matrix (DBM) on auto-local bone as a graft enhancer in posterior lumbar interbody fusion (PLIF).Overview of LiteratureDBM is known as an osteoinductive material; however, it has not been clearly recognized to enhance auto-local bone with a small amount.MethodsPatients who had a PLIF were allocated into two groups. Group I (70 cases) used auto-local bone chips and group II (44 cases) used DBM as an additive to auto-local bone, 1 mL per a segment. Group selection was alternated. Early assessment was performed by computed tomography at 6 months and final assessment was done by simple radiography after 24 months at least. The degree of bone formation was assessed by 4 grade scale.ResultsThe subjects of both groups were homogenous and had similar Oswestry Disability Index at final assessment. The ratio of auto-local bone chips and DBM was 6:1. The degree of bone formation at 6 months after surgery was superior in group II. However, there was no significant difference between the two groups at the final assessment.ConclusionsDBM was not recognized to enhance auto-local bone with small amount.

Dasatinib Therapy Affects Bone Homeostasis in Patients with Chronic Myelogenous Leukemia in Chronic Phase Independently of Molecular Response

AbstractAbstract 1682 BackgroundWith the success of targeted oral tyrosine kinase inhibitor (TKI) therapy, long-term/life-long therapy for patients with chronic myelogenous leukemia (CML) can now be envisaged. Dasatinib is a second generation TKI, which in a phase I clinical trial was found to be 100–300 times more potent at inhibiting tyrosine kinases than imatinib. In vitro data suggest that dasatinib therapy also may have a direct effect on bone metabolism by interfering with c-FMS, c-SRC and the PDGF-R pathways (Boufker et al, BMC Cancer 2010, 10:298). In this study, we evaluated the effects of dasatinib monotherapy on bone homeostasis of CML patients treated at our center between 2006 and 2011. The levels of traditional biomarkers of bone health, namely serum bone specific alkaline phosphatase isoenzyme (BAP) and osteoprotegerin (OPG) were measured and were correlated with morphometric assessment of bone marrow biopsy specimens (BM Bx). We also assessed for any correlations between bone homeostasis and the results of conventional cytogenetics and molecular analysis with respect to treatment response. MethodsThe study group included 23 patients with chronic phase CML without evidence of clonal evolution who were treated with dasatinib. The median age was 51 years (range, 25–63) with a male to female ratio of 1.5: 1. Four different treatment groups were assessed (20mg/day, 40 mg/day, 80 mg/day and 100 mg/day). We compared paired BM specimens, obtained at initial diagnosis and 12–51 months (mos) after commencing dasatinib therapy. We performed whole slide imaging (Philips) on routinely stained BM Bx and specimen compartments were quantified using an area pixel count algorithm (Image Pro Plus system Version 6.3, MediaCybernetics, Bethesda, MD, USA) to calculate trabecular bone volume as a percentage area. The morphometric results were correlated with the results of conventional cytogenetics and molecular analysis obtained every 3 mos after enrollment. We also performed competitive inhibition ELISA assays to measure serum levels of OPG (baseline and after 12/18 mos) and BAP (every 4 mos), respectively. ResultsWith a median follow up of 24 mos (range 12–51mo), a significant increase in trabecular bone volume (TBV) was noted (p=0.022, Figure 1); 74% (17 pts) showed an increase in TBV on therapy, with an absolute increase of 5.2% (mean). Twelve of 16 pts (75%) evaluated had a decrease in OPG after 18 mos, which correlated in 90% of pts with an increase in TBV using a linear regression model (p= 0.0017, Figure 2). No significant difference was detected in TBV changes among the four dose groups. There was no significant trend in serum BAP levels, thus no statistical correlation was performed at this time point. All patients treated with dasatinib showed cytogenetic and molecular BCR-ABL1 response. There was no correlation between the degree of TBV change and either cytogenetic or molecular response (Figure 3) Conclusions:Our results indicate that within the therapeutic range for CML patients, dasatinib therapy promotes bone formation. However, there was no correlation between the dose levels studied and degree of bone formation and no correlation between TBV change and either cytogenetic or molecular response. The combination of digital image analysis and bone biomarkers enhances our understanding of bone homeostasis in patients on dasatinib. Further studies in a larger cohort of patients will be helpful to further validate our results.Figure 1: mean and standard deviation of TBV for each visit.Figure 2: correlation between “percent change TBV between visit 1 and visit 2” and 18 months OPG levels (linear regression model R2 =0.292, p= 0.0017)Figure 3: association between “percent change in TBV between visit 1 and visit 2” and “Rate of PCR response change between 3 and 12 months” (Spearman correlation coefficient = −0.05; p =0.81) [Display omitted] [Display omitted] [Display omitted] Disclosures:Cortes:Ariad: research support and consulting, research support and consulting Other; Pfizer: research support and consulting, research support and consulting Other; Novartis: research support and consulting, research support and consulting Other; BMS: research support and consulting Other.

Retrospective study of two biochemical markers for the risk assessment of oral bisphosphonate-related osteonecrosis of the jaws: can they be utilized as risk markers?

the purpose of this retrospective study was to examine the possibility of utilizing serum C-terminal telopeptide cross-link of type I collagen (s-CTX) and serum osteocalcin (s-OC) as risk markers for oral bisphosphonate-related osteonecrosis of the jaws (BRONJ). the s-CTX values and the s-OC values were measured from 23 patients (one male, 22 females) diagnosed with BRONJ using clinical and radiographic examinations. The two biochemical markers were evaluated during a regular checkup for osteoporosis management. For the control group of s-CTX study, s-CTX values were obtained from 61 independently recruited postmenopausal women who have been on bisphosphonate therapy for >6 months. The s-CTX values of the ONJ group and the control group were compared. Because of retrospective nature of this study, the control group for s-OC study could not be established. A single sample t-test was performed for the s-OC value from the ONJ group. twenty-three ONJ patients had taken alendronate for osteoporosis treatment, and the s-CTX testing results were low levels of 10-192 pg/ml (mean: 93.2 ± 49.4 pg/ml). Mean of s-CTX of the control (n=61) was 125 ± 85.7 pg/ml. The duration of BP therapy ranged between 1 and 10 years (4.82 ± 2.6). The s-OC level was estimated between 0.2 and 5.4 ng/ml (1.91 ± 1.51 ng/ml). The mean s-CTX value of the control group was higher but without significance (P=0.12). The s-OC values of the ONJ group were significantly lower than the lowest value of the reference range (P<0.001). as a result of the s-CTX and s-OC testings at the diagnosis of BRONJ, the values of the two markers were decreased. The decrease of the s-OC values implies a problem during the bone-formation process. Therefore, we can assume that in this patient group, invasive dental surgery contributes to an increase in the risk of BRONJ incidence. This result may imply that, during bisphosphonate therapy, simultaneous consideration of s-CTX showing inhibition of bone resorption and s-OC indicating the degree of bone formation might be a set of risk markers assessing risk prediction for BRONJ before invasive dental surgery.

The Effect of Varying the Particle Size of Beta Tricalcium Phosphate Carrier of Recombinant Human Bone Morphogenetic Protein‐4 on Bone Formation in Rat Calvarial Defects

Beta tricalcium phosphate (beta-TCP) has been developed as one of the carriers of recombinant human bone morphogenetic protein (rhBMP). However, it is not known whether the particle size of beta-TCP is related to its resorption rate and the degree of bone formation. The purpose of this study was to evaluate the effect of using beta-TCP with different particle sizes on the ability of rhBMP-4 to enhance bone formation in the rat calvarial defect model. Calvarial, 8-mm-diameter, critical-size defects were created in 100 male Sprague-Dawley rats. Five groups of 20 animals each received either rhBMP-4 (2.5 microg) using beta-TCP with a particle size of 50 to 150 microm, rhBMP-4 (2.5 microg) using beta-TCP with a particle size of 150 to 500 microm, a beta-TCP control with a particle size of 50 to 150 microm, a beta-TCP control with a particle size of 150 to 500 microm, or a sham-surgery control, respectively, and were evaluated by measuring their histologic and histometric parameters following a 2- and 8-week healing interval. There were no significant differences in the defect closure, new bone area, or augmented area between either the two rhBMP-4/beta-TCP groups or between the two beta-TCP control groups at 2 and 8 weeks. rhBMP-4 combined with either small- or large-particle beta-TCP had a significant effect on the induction of bone formation compared to either a small- or large-particle beta-TCP control or a sham-surgery control. Within the parameters of this study, varying the particle size of beta-TCP did not seem to have a significant effect on bone formation.

Tissue-engineered bone formation in vivo using a novel sintered polymeric microsphere matrix

We have evaluated in vivo a novel, polymer-based, matrix for tissue engineering of bone. A segmental defect of 15 mm was created in the ulna of New Zealand white rabbits to determine the regenerative properties of a porous polylactide-co-glycolide matrix alone and in combination with autogenous marrow and/or the osteoinductive protein, BMP-7. In this study four implant groups were used: 1) matrix alone; 2) matrix with autogenous marrow; 3) matrix with 20 microg of BMP-7; and 4) matrix with 20 microg of BMP-7 and autogenous marrow. The results showed that the degree of bone formation was dependent on the properties of the graft material. The osteoconductive sintered matrix structure showed significant formation of bone at the implant-bone interface. The addition of autogenous marrow increased the penetration of new bone further into the central area of the matrix and also increased the degree of revascularisation. The osteoinductive growth factor BMP-7 induced penetration of new bone throughout the entire structure of the implant. The most effective treatment was with the combination of marrow cells and osteoinductive BMP-7.

Solcoseryl, a tissue respiration stimulating agent, significantly enhances the effect of capacitively coupled electric field on the promotion of bone formation around dental implants.

In the present study we examined the combined effect of application of a capacitively coupled electric field (CCEF) and the tissue respiration stimulating agent, Solcoseryl, on the promotion of bone formation around dental implants histologically and mechanically. After a dental implant was inserted into each femur of Japanese white rabbits, Solcoseryl (2 ml/kg) was administered intravenously in the ear vein and a CCEF was applied for 4 h per day for 14 days. The degree of bone formation on microscopic observation, bone contact ratio, bone surface area ratio, and the level of removal torque of the implant in the Solcoseryl- and CCEF-treated group were significantly higher than the respective value in the control group, which had not been treated with Solcoseryl nor CCEF. Thus, the combination of CCEF stimulation and Solcoseryl effectively promoted the formation of new bone. It is suggested that the clinical use of a combination of CCEF stimulation and Solcoseryl for dental implants promotes osseointegration.

Focal adhesion kinase expression during mandibular distraction osteogenesis: evidence for mechanotransduction.

Distraction osteogenesis is an established treatment strategy in the reconstruction of the craniofacial skeleton. The underlying mechanisms that drive bone formation during this process are largely unknown, but a regulatory role for mechanical force is believed to be critical. The integrin-mediated signal transduction cascade is a primary pathway by which signal transduction of mechanical stimuli (i.e., mechanotransduction) occurs. Focal adhesion kinase (FAK) is a significant regulator in this pathway. The authors hypothesize that mechanical forces created during distraction osteogenesis are responsible for the osteogenic response that takes place, and that these changes arise through integrin-dependent mechanotransduction. Using a rat model of distraction osteogenesis, the authors examined the expression of FAK in critical size defects (n = 15), subcritical size defects (n = 15), and mandibles undergoing distraction osteogenesis (n = 15). Their findings demonstrated FAK immunolocalization in mandibles undergoing distraction osteogenesis, but not in the critical size defects or in subcritical size defects, despite varying degrees of bone formation in the latter two groups. Furthermore, bone sialoprotein mRNA in situ hybridization patterns were found to mirror FAK immunolocalization patterns in mandibles undergoing distraction osteogenesis, demonstrating an association of FAK expression with the osteogenic process specific to distraction osteogenesis. These findings suggest that the bone formation in distraction osteogenesis is regulated by mechanical force by means of integrin-dependent mechanotransduction pathways.

Percutaneous bone biopsy in the diagnosis of renal osteodystrophy.

Renal failure is associated with many complex bone and mineral complications. The spectrum of diseases is wide, encompassing defects in bone turnover, remodeling, and mineralization. Disease is currently defined in terms of whether a high or low turnover lesion is present. Measurement of serum parathyroid hormone levels (PTH) remains an important aspect in the management of renal bone disease, however, is limited by its lack of sensitivity in many clinical settings. Multiple biochemical markers are also available both commercially and experimentally to assist in assessing the degree of bone formation or resorption. However, when definitive diagnosis is important, when the clinical setting is confusing or complex, or when parathyroidectomy is being considered, the use of percutaneous bone biopsy is an essential tool in the understanding of underlying bone pathology and in directing therapy intervention.

Osteogenesis in Cat Cranioplasty with Composite Hydroxylapatite/Plaster

AbstractComposite hydroxylapatite (HA)/plaster alloplasts were studied for frontal and parietal cranioplasty. The experimental defects were created in 61 anesthetized cats. They were filled with a moist 2:1 mixture of durapatite/plaster or Interpore/plaster containing 0.85% potassium sulfate. After setting, the implant site was sutured. The filled defects were very firm by physical examination and showed little particle scatter by radiography. At the time this report was prepared only 43 of the cat skulls were available for examination. After sacrifice, postmortem visual examination (VE) of the skulls suggested that new bone had formed over some implants. In most implants, however, VE could not determine whether new bone had formed between the HA particles. Probing examination (PE) of the parietal implants with a periodontal explorer gave a better indication; the presence of new bone rather than soft tissue between the HA particles was confirmed by x-ray microanalysis. The ventral surfaces (VS) of the parietal implants showed greater degrees of bone formation by PE; only 12 of 43 parietal implants showed a high degree of bone formation on the dorsal surfaces (DS) by PE whereas 34 of 43 showed this on the VS. The highly significant difference (^3X) in the amount of bone formation on the VS compared with the DS suggests that this osteogenesis, like that observed in cranial trauma, may be stimulated by the dura which acts as a periosteum by supplying blood vessels to the implant.

SKELETAL ALTERATIONS IN HYPERPARATHYROIDISM: DETERMINATION OF BONE FORMATION, RESORPTION AND MORPHOLOGIC CHANGES BY MICRORADIOGRAPHY.

Specimens of posterior iliac crest bone from 26 cases of primary hyperparathyroidism and 21 control cases were studied by microradiography. Surfaces of bone formation and of bone resorption were directly assessed and quantitatively expressed as a percentage of the total surface in the section (Jowsey method). All cases of hyperparathyroidism demonstrated increased bone resorption; 4 cases also had increased bone formation. A significant correlation was found between the preoperative serum calcium concentration and the degree of bone resorption. No correlation was observed between the amount of porosity in the bone and the degree of bone formation or between the dietary intake of calcium and the extent of the disease (except perhaps in 3 cases with unusually low intakes). A spectrum of morphologic changes was seen, ranging from minimal alterations limited to an increase in resorbing surfaces to grossly abnormal metaplastic bone. It is concluded that most, if not all, hyperparathyroid patients have some deg...