Radiographic Densitometry Research Articles

A Radiological Evaluation of Bone Healing in Postextraction Sockets Following Bone Grafting Using Beta-Tricalcium Phosphate and Calcium Phosphosilicate: A Controlled Comparative Study.

Background:Healing unbinds a well choreographed array of cellular, physiologic, biochemical, and molecular processes directed toward restoring the integrity and functional capacity of the damaged structures. The rate and degree of healing vary among individuals but is greatest during the first few months or years after tooth loss. Evidence suggests that alveolar bone ridge resorption may be prevented, initially by reconstructive surgical techniques using several materials which are employed at the time of extraction. This droves to the development of bone substitutes materials such as hydroxyapatite, beta tricalcium phosphate (β TCP), and bioactive glasses. These regenerative materials not only act as an osteoconductive scaffold but also interact with the surrounding tissues and impart an osseostimulatory effect.Methods:Twenty adult patients who required bilateral removal of homologous tooth, were informed and described regarding post extraction socket grafting using β TCP and CPS followed by covering with Collagen Membrane. Radiographic densitometry evaluation of postoperative visits of immediate; 1st month; 3rd month; and 6th month using orthopantomograph was done.Results:The Karl Pearson's Correlation coefficient was used to determine the degree of bone density with adjacent bone preoperatively and postoperatively. The statistical evaluation, CPS was more superior to β TCP, with a difference of 58.75 and P value showed more significance (<0.0001).Conclusion:This article evaluates radiographically quality and quantity of bone formation in the socket, following extraction and bone grafting using Calcium Phosphosilicate (CPS) and β TCP, it is concluded that the two modalities of treatment were efficient in improving the clinical outcome parameters as well as showed comparable regenerative effects when used in the treatment of “socket grafting” while between them CPS more superior to β TCP biomaterials by Osteogenic properties.

Avaliação da densidade mineral óssea por meio da densitometria óptica radiográfica em 42 fêmures caninos

This study evaluates the bone mineral density of 42 canine femurs using radiographic optical densitometry and validates radiographic optical densitometry as a parameter to standardize bone tissue samples used in biomechanical tests, contributing to the diagnosis of osteoporosis in dogs. The ImageJ 1.46r® program was used for the radiographic optical densitometry. After selecting the aluminum steps and the area of interest in the femur, the data obtained were stored in a table and converted into mm/Al using the MS Excel® trend function. Statistical analysis demonstrated the absence of atypical values (outiliers) in the samples analyzed. The samples evaluated were homogeneous and the densitometric data obtained may contribute to reducing the scarcity of densitometric references in the veterinary literature. Ex vivo biomechanical studies may benefit from the method used in this study to standardize their sample when evaluating bone mineral density, validating their respective projects

Skeletal pathology and bone mineral density changes in wild muskrats (Ondatra zibethicus) and red squirrels (Tamiasciurus hudsonicus) inhabiting arsenic polluted areas of Yellowknife, Northwest Territories (Canada): A radiographic densitometry study

The City of Yellowknife is a known hotspot of arsenic contamination and there is a growing body of evidence suggesting that local wildlife in the vicinity of the abandoned Giant Mine site may be at risk of decreased bone mineralization and various bone disorders. The purpose of this study was to preliminarily measure bone mineral density (BMD) changes and investigate the incidence, pattern, and severity of bone lesions in wild muskrats and red squirrels breeding in three (3) catchment areas at different distances from the Giant Mine Site in Yellowknife, Northwest Territories (Canada): ~2 km (location 1), ~18 km (location 2), and ~40–100 km (location 3). Full femoral bones of 15 muskrats and 15 red squirrels were collected from the three sampling locations (5 from each location) and subjected to radiographic analysis and densitometric measurements. The patterns and severities of bone lesions, including changes in bone mineral density, were evaluated and compared between groups. As levels were significantly higher in the bones of muskrats caught from location 1 and 2, relative to location 3. Further, As and Cd levels were significantly higher in the bones of squirrels caught from locations 1 and 2 relative to squirrels caught from location 3. The preliminary results from bones revealed that radiographic abnormalities such as bone rarefaction, osteopenia, and thinning of the femoral shafts with significant ossific cystic lesions and bowing were the most common skeletal pathologies found in bones of red squirrels from the three locations. Radiographic appearances of massive sclerosis and dysplasia, including severe osteocondensation and osteopathia striata-like abnormalities, were found in the bones of muskrats from all the sampling locations. Densitometric evaluation showed no significant differences between the three locations in the bone parameters measured. However, there was a statistically significant correlation between As content in the bones of muskrats and percent fat content in the femur samples, which suggests that accumulation of As could have been a causal factor for a change in percent fat in femurs of muskrats.

DESENVOLVIMENTO ÓSSEO E DENSITOMETRIA RADIOGRÁFICA EM CODORNA-JAPONESA (Coturnix japonica)

Resumo O desenvolvimento ósseo nas aves é diferenciado e, radiograficamente, não existe uma placa de crescimento visível. A densitometria radiográfica (DR) é utilizada para avaliar e mensurar a densidade óssea. Foram utilizadas cinquenta e quatro codornas-japonesas (Coturnix japonica) de um dia de vida e de ambos os sexos. A cada três dias foram pesados dois animais e, em seguida, identificados, submetidos à eutanásia e radiografados. Foi utilizada uma escada de alumínio de vinte e um degraus para a mensuração densitométrica. Realizaram-se mensurações de comprimento do úmero, rádio, ulna, fêmur, tibiotarso e tarsometatarso; correlação do período de postura com a ocorrência de hiperostose poliostótica (HP) nos ossos longos; bem como avaliação densitométrica ao longo de 80 dias. Houve aumento na densidade óssea conforme crescimento em comprimento dos ossos em úmero, seguido pelo tibiotarso, ulna e fêmur, verificado principalmente no período de sete a 13 dias de vida. No úmero e no fêmur, houve significativo aumento de densidade óssea também entre 70 a 79 dias. A partir do 61º dia, foi identificada a presença de hiperostose poliostótica nos fêmures das fêmeas. A DR é uma técnica aplicável em C. japonica como um método acessível e de baixo custo. Os resultados confirmam um grande aumento mineral ao longo do crescimento e durante a postura, confirmando a presença de HP na espécie.

Detecting demineralization of enamel and cementum after gamma irradiation using radiographic densitometry.

The purpose of this study was to evaluate the ability of radiographic densitometry in detecting the early demineralization of human enamel and cementum in irradiated and non-irradiated teeth. Sixty extracted teeth were divided into two groups: irradiated group and non-irradiated group. After irradiation, the groups were subjected to demineralization-remineralization (PH) cycling. Radiographic densitometric measurements (gray values) of a selected area of interest in the enamel and in the cementum of each tooth were performed at baseline and after PH cycling. After PH cycling, there was a significant reduction in gray values for both groups. The difference between "baseline" and "after PH cycling" values represents the reduction in the mineral content of the hard tissue, i.e., the demineralization. Results show that the demineralization of irradiated tooth enamel and cementum was significantly higher compared to that of non-irradiated tissues as determined by gray-level values. It is concluded that densitometric measurements by means of digital radiographs allow for the detection of demineralization of enamel and cementum, and can be used successfully for diagnosis of the early carious lesions in patients who received head and neck radiotherapy. This will allow implementation of remineralizing therapy and avoid the risk of progression of radiation caries. Furthermore, it is concluded that gamma irradiation with typical therapeutic doses for head and neck carcinoma is a direct cause of demineralization of tooth enamel and cementum.

КЛІНІКО-ФУНКЦІОНАЛЬНІ ТА БІОХІМІЧНІ АСПЕКТИ ЕФЕКТИВНОСТІ ЗАСТОСУВАННЯ КІНЕЗІОТЕЙПУВАННЯ У ВІДНОВНОМУ ЛІКУВАННІ ІДІОПАТИЧНОГО СКОЛІОЗУ

Метою дослідження було порівняти ефективності стандартного відновного лікування і додаткового залучення кінезіотейпування у дітей старшого шкільного віку, хворих на ідіопатичний сколіоз 1–2 ступенів. Проводили зіставлення показників динаміки клінічних, біомеханічних та рентгенологічних досліджень, ультразвукової денситометрії та біохімічного дослідження маркерів стану опорно-рухового апарату. Дослідження встановило, що застосування кінезіотейпування призводить до більш значних зсувів показників дослідження, чим при стандартному відновлювальному лікуванні, на що вказує суттєве переважання позитивної динаміки: рентгенографічних даних – зсувів кута викривлення хребта – (-1,18±0,86)о (при стандартному лікуванні – (-0,61±1,02)о, р&lt;0,0016); оцінки болю за ВАШ – (-1,66±1,25) бала (при стандартному лікуванні – (-0,29±0,58) бала, р&lt;0,0001); біомеханічних – згинання хребта – (-0,91±0,84) см (при стандартному лікуванні – (-0,32±0,50) см, р&lt;0,0001) і розгинання хребта – (-1,41±1,78) (при стандартному лікуванні – (-0,24±1,28)о, р&lt;0,0001). Також при застосуванні кінезіотейпування значно переважають зсуви активності у крові ЛФ, вмісту в крові креатиніну, активності у сечі КФК та вмісту в сечі оксипроліну і кальцію. Отже, застосування кінезіотейпування дозволяє підвищити ефективність відновного лікування ідіопатичного сколіозу 1–2 ступенів, що обґрунтовує подальші дослідження у цьому напрямку.

Early Evidence of Low Bone Density and Decreased Serotonergic Synthesis in the Dorsal Raphe of aTauopathy Model of Alzheimer's Disease.

Reduced bone mineral density (BMD) and its clinical sequelae, osteoporosis, occur at a much greater rate in patients with Alzheimer’s disease (AD), often emerging early in the disease before significant cognitive decline is seen. Reduced BMD translates to increased bone fracture risk, decreased quality of life, and increased mortality for AD patients. However, the mechanism responsible for this observation is unclear. We hypothesize that bone loss is an additional component of an AD prodrome-changes that emerge prior to dementia and are mediated by dysfunction of the central serotonergic pathways. We characterized the skeletal phenotype of htau mice that express human forms of the microtubule-associated protein tau that become pathologically hyperphosphorylated in AD. Using radiographic densitometry, we measured BMD in female and male htau mice from 2–6 months of age–time-points prior to the presence of significant tauopathy in the hippocampal/entorhinal regions characteristic of this model. We found a significantly reduced BMD phenotype in htau mice that was most pronounced in males. Using western blotting and immunofluorescence, we showed overall reduced tryptophan hydroxylase (TPH) protein in htau brainstem and a 70% reduction in TPH-positive cells in the dorsal raphe nucleus (DRN)–a pivotal structure in the regulation of the adult skeleton. Elevations of hyperphosphorylated tau (ptau) proteins were also measured in brainstem, and co-labeled immunofluorescence studies showed presence of ptau in TPH-positive cells of the DRN as early as 4 months of age in htau mice. Together, these findings demonstrate that reduced BMD occurs earlier than overt degeneration in a tau-based AD model and that pathological changes in tau phosphorylation occur in the serotonin-producing neurons of the brainstem raphe in these mice. This illuminates a need to define a mechanistic relationship between bone loss and serotonergic deficits in early AD.

Combinations of cholecalciferol and 25-hydroxycholecalciferol as vitamin D sources in white laying hen feed diets

The effect of cholecalciferol (D3) and 25-hydroxycholecalciferol (25-OHD3) as isolated or associated sources of vitamin D (100%-0%, 75%-25%, 50%-50%, 25%-75%, 0%-100%) on the productive performance, egg quality, and bone characteristics was evaluated in white egg-laying hens fed two levels of calcium (Ca) and phosphorus (P) in the basal diet (BD) (BD1 = 0.38% Ca - 0.36% available P and BD2 = 3.2% Ca - 0.30% available P). Nine hundred and sixty Dekalb White hens (24 weeks old) were distributed into 80 cages, under a completely randomized factorial design for 16 weeks. The use of associated sources of vitamin D reduced the feed intake and feed conversion ratio, as well as BD1, which also increased the egg production and egg mass. The association of vitamin D sources with up to 50% 25-OHD3 increased the eggshell percentage. There was interaction (p&lt;0.05) between the sources of vitamin D and the concentrations of Ca and available P, sources with at least 50% 25-OHD3 increased ash percentage and bone radiographic densitometry (BRD) with BD1; in BD2 the use of 25-OHD3 as isolated vitamin D source increased BRD. The association of D3 and 25-OHD3 improved the productive performance, increased the percentage of eggshell and had different positive effects on the bone characteristics that depend on the concentrations of Ca and available P in the balanced feed of white egg-laying hens.

Radiodensitometric and DXA analyses for the measurement of bone mineral density after systemic alendronate therapy

Precise techniques for the measurement of maxillary bone mineral density (BMD) are useful for the early diagnosis of systemic diseases. The aim of this study was to compare in vivo the efficacy of dual-energy x-ray absorptiometry (DXA) and radiographic densitometry for the measurement of BMD after systemic administration of sodium alendronate. Wistar rats were randomly allocated to a control group (n = 5), which received distilled water, and a sodium alendronate group (n = 8), which received two doses of chemically pure sodium alendronate (1 mg/kg) per week. After 8 weeks, the animals were euthanized, the tibias were removed, and the BMD of the proximal tibial metaphysis was analyzed radiographically and by DXA. The data were subjected to statistical analysis by the Kruskal-Wallis test at a significance level of 5%. Both of the techniques revealed that the alendronate-treated group had a significantly higher BMD (p < 0.05) than the control group after 8 weeks of treatment. Comparing the groups with and without alendronate therapy revealed increases of 14.9% and 29.6% in BMD, as detected radiographically and by DXA, respectively. In conclusion, both of the methods were able to detect an increase in BMD of the proximal tibial metaphysis after alendronate therapy.

The primacy of platelet-rich fibrin on bone regeneration of various grafts in rabbit's calvarial defects

AimsThis study investigated the effect of platelet-rich fibrin (PRF) on bone regeneration of various grafting materials in rabbit calvarial defects. Material and methodsTwo bicortical skull defects were prepared in 20 New Zealand white rabbits; 10 rabbits were treated with PRF and the other 10 were non-PRF. In both groups, autogenous bone was compare to empty defects in 5 rabbits and the composite of autogenous bone and deproteinized bovine bone versus deproteinized bovine bone (DBB) in the other five. The animals were sacrificed at 8 weeks. Bone formation was assessed by radiographic densitometry and histomorphometric analysis. ResultsThe mean optical density (OD) and histomorphometric analysis (HA) of the percentage of new bone showed that the PRF groups were significantly higher than the non-PRF groups in the autogenous bone graft (OD: 0.60 ± 0.19 vs 0.36 ± 0.03; HA: 38.03 ± 4.23 vs 26.21 ± 10.58) and the empty defect (OD: 0.29 ± 0.06 vs 0.11 ± 0.06; HA: 18.81 ± 9.27 vs 6.24 ± 5.01), but not in the DBB group (OD: 1.18 ± 0.17 vs 1.07 ± 0.05; HA: 13.067 ± 3.64 vs 9.63 ± 5.47) and the composite group (OD: 0.81 ± 0.15 vs 0.91 ± 0.05; HA: 22.63 ± 3.61 vs 21.29 ± 3.52). ConclusionsPRF had a positive effect on bone formation when used alone or combined with autogenous bone, but not with deproteinized bovine bone.

Alterações da densidade mineral óssea em vértebras de ratos Wistar submetidos à ausência de carga nos membros pélvicos

The suspension of rats by the tail model is used to investigate the behavior of bone in animals unable to move around. Bone is an adaptative tissue that develops in structure and function, among other factors, in response to mechanical forces applied to it and metabolic demands that it will suffer. The absence of mechanical forces and deformation of bone that occurs causes a decrease in calcium deposition in the absence of stimuli on osteoblasts and osteocytes, favoring the action of osteoclasts, making bones weak and brittle. Therefore, the mechanical action is necessary to stimulate local bone response and thus provide growth and remodeling. The aim of this study was to evaluable by radiographic densitometry, the tail suspension for 15 and 36 days alter the bone mineral density of cervical vertebrae (C3), thoracic (T6) and lumbar (L1 and L3) of Wistar rats. Thirty Rattus norvegicus albinus, adult, male, Wistar strain, average body mass ± 350g, were divided into 3 groups: control (n = 10) - not suspended; S15 (n = 10) - suspended for 15 days and S36 (n = 10) - suspended for 36 days. For densitometric analysis vertebrae were radiographed, scanned, digitized and analyzed by the computer program ImageJ®. There was a statistically significant increase in bone mineral density in group S15, probably by the restlessness of the animals to the suspension, with a decrease in group S36, and this hypothetically is linked to the accommodation of the rats, concluding that the tail suspension altered bone mineral density in first time with a decrease over time.

Alveolar bone healing process in spontaneously hypertensive rats (SHR): A radiographic densitometry study

Hypertension is one of the most important public health problems worldwide. If undiagnosed or untreated, this pathology represents a systemic risk factor and offers unfavorable conditions for dental treatments, especially those requiring bone healing.Objectives The purpose of this study was to demonstrate, by analysis of bone mineral density (BMD), that the alveolar bone healing process is altered in spontaneously hypertensive rats (SHRs). Material and Methods Wistar rats and SHRs were submitted to extraction of the upper right incisor and were euthanized 7, 14, 21, 28 and 42 days after surgery. Right maxillae were collected, radiographed and analyzed using Digora software. BMD was expressed as minimum (min), middle (med) and maximum (max) in the medium (MT) and apical (AT) thirds of the dental alveolus. ResultsThe results were compared across days and groups. Wistar showed difference in med and max BMD in the MT between 7 and 28 and also between 14 and 28 days. The AT exhibited significant difference in med and min BMD between 7 and 28 days, as well as difference in min BMD between 28 and 42 days. SHRs showed lower med BMD in the MT at 28 days when compared to 21 and 42 days. Differences were observed across groups in med and min BMD at day 28 in the MT and AT; and in max BMD at 14, 21 and 42 days in the MT. Conclusions These results suggest that the alveolar bone healing process is delayed in SHRs comparing with Wistar rats.

The evaluation of the effects of hyperbaric oxygen therapy on new bone formation obtained by distraction osteogenesis in terms of consolidation periods

The aim of this study was to evaluate the effect of hyperbaric oxygen therapy on new bone formation obtained by distraction osteogenesis in long- or short-term consolidation periods. Twenty-four rabbits were used. The animals were divided into two groups of 12 animals each, and vertical mandibular distraction osteogenesis was performed. Hyperbaric oxygen therapy was administered in the first group. Each group was subdivided into two subgroups according to the 30- and 60-day consolidation period. The acquired bone amounts were compared according to their radiographic density and histopathology. Histopathologically, in the experimental group, callus formation was increased and the new bone was more mineralized. According to the radiographic densitometry analyses, there were no statistically significant differences between the 30-day consolidated subgroups of the experimental group and the 60-day consolidated subgroup of the control group (p = 0.873). Hyperbaric oxygen therapy can be used to increase the quality and the quantity of bone and to decrease the maturation time which may shorten the consolidation period of vertical distraction osteogenesis. The effect of hyperbaric oxygen therapy on vertical distraction osteogenesis procedure according to consolidation periods has been determined. Hyperbaric oxygen therapy may increase the quality and the quantity of bone and shorten the consolidation period.

Densitometry, radiography, and histological assessment of collagen as methods to evaluate femoral bones in an experimental model of osteoporosis

All methods to detect experimental loss of bone present technique limitations. The sensitivities of image and histological analyses to detect the effects of teriparatide in rats with bone loss after ovariectomy were evaluated. All methods were qualitatively valid. The standardization of methods to assess bone loss after ovariectomy is crucial to establish the degree of experimental osteoporosis. In general, methods per image or histological techniques are used. To validate these two ways to determine the degree of bone loss in ovariectomized rats, we evaluated the sensitivities of bone densitometry, conventional radiography, and histological analysis of the area occupied by collagen, detecting the effects of teriparatide treatment in the femur of ovariectomized rats with bone loss. Wistar rats were divided into three groups: a control group, in which the animals were only subjected to laparotomy; an ovariectomized group, in which bilateral removal of the ovaries was performed; and an ovariectomized + teriparatide group, in which bilateral removal of the ovaries was performed, and the animals were treated with 3 μg/100 g/day of teriparatide. Three months following the ovariectomy, bone densitometry, radiographic densitometry, and histological analysis of the area occupied by collagen fibers were carried out in the femur diaphysis. The bone densitometry revealed 11.2% reduction in femur density; in the conventional radiography, the loss of bone mass was 14.5%, and with the histological analysis, a 40.9% reduction in the area occupied by collagen was detected in the femur diaphysis. In conclusion, histological analysis could not be quantitatively compared with the methods of bone densitometry and conventional radiography; however, all of these methods were qualitatively valid for assessing the loss of bone stemming from ovariectomy and the therapeutic effect of teriparatide in the prevention of osteoporosis.

CT artefact reduction by signal to thickness calibration function shaping

It is frequently a task to calibrate the radiogram intensity in reference to the object thickness/density value. This knowledge is important when the radiographic densitometry, thickness measurements or precise computed tomography are required. Often aluminum is used as calibrating material and processed radiogram of the real object is evaluated as aluminum equivalent. This approach is qualitatively convenient for transmission radiograms; however, certain secondary artefacts remain in CT reconstructions. Fortunately the calibration function can be shaped using only one or two known thickness values of the object investigated. The shaped calibration function obtained produces the right signal to thickness relationship and CT quality is improved when it is applied.

The influence of local administration of simvastatin in calvarial bone healing in rats

Some authors have associated the use of statins, hypolipidemic drugs, and new bone formation. The aim of this work was to evaluate the effect of locally administered simvastatin on bone healing. Bone calvarial defects 5 mm in diameter were made in 64 rats. The animals were divided into four groups according to the graft material: the control group, in which the defects were not treated, the SIM-1 group, which received a sponge of collagen soaked with simvastatin (2.2 mg/50 μl), the SIM-2 group, which received a sponge of collagen soaked with simvastatin (0.5 mg/50 μl), and the carrier (CAR) group, which received a sponge of collagen and water. The animals were sacrificed after 30 or 60 days. The skulls were removed, and radiographic densitometry and histometric analyses of the bone defect area were performed. Local crust formation was clinically verified in SIM-1 and SIM-2 animals. After statistical analysis ( p < 0.05) of bone area data, we observed no significant differences among the groups after 30 days. After 60 days, however, there was less bone formation in the CAR and SIM-2 groups. The SIM-2 group also presented with lower radiographic densities after 60 days. According to the methodology used, we conclude that locally administered simvastatin was detrimental to the repair of defects in the calvaria of rats.

Effect of Intermittent Systemic Administration of Recombinant Parathyroid Hormone (1-34) on Mandibular Fracture Healing in Rats

To establish a rat mandibular fracture model and investigate the short- and long-term effects of recombinant parathyroid hormone (PTH 1-34) on mandibular fracture healing in rats. A controlled unilateral mandibular fracture was created surgically in 29 male Sprague-Dawley rats and then stabilized using an external fixation device. The rats were divided into 2 groups: 1 group received daily subcutaneous injections of 10 microg/kg of PTH(1-34) and 1 group served as the vehicle control. The rats were killed on postoperative days 7 and 21, and radiographic densitometry and histologic evaluation of new bone formation were performed. A novel unilateral mandibular fracture model was established that has significant differences from previously published models, both in the location of the osteotomy site and in the rigid external stabilization device. The PTH(1-34) treated rats showed a statistically significant difference (P < .05) in callous formation compared with the control animals. Radiographic densitometry evaluation of the injury site revealed an increase in bone density, apparent at day 7 in the experimental group. Visual inspection of the histologic sections stained with Masson's trichrome blue showed an apparent increase in new bone formation at 21 days in the PTH-treated group compared with the control group. Intermittent systemic administration of PTH(1-34) might enhance the healing of mandibular fractures in the early phase (7-day period). Long-term administration (21-day period) showed no statistically significant differences between the control and experimental group by radiographic densitometry.

Use of Radiographic Densitometry to Predict the Bone Healing Index in Distraction Osteogenesis

Bone lengthening with distraction osteogenesis involves prolonged application of an external fixator frame. Qualitative and quantitative evaluation of callus has been described using various imaging modalities but there is no simple reliable and readily available method. This study aims to investigate the use of a densitometer to analyze plain radiographic images and correlate them with the rate of new bone formation as represented by the bone healing index. A total of 34 bone lengthening procedures in 29 patients were retrospectively reviewed. We used an X-Rite 301 densitometer to measure densities of new callus on plain radiographs taken at 4 and 8 weeks after surgery. Patients aged below 16y had significantly lower BHIs indicating faster bone healing and shorter duration of treatment. The ratio of radiographic densities between centre and edge of the new bone measured from plain radiographs taken at 8 weeks correlated positively with the eventual BHI of the patient. This method provides a simple and easy way to predict the rate of bone healing at an early stage of treatment and may also allow remedial action to be taken for those with poor progress in bone formation.

Osteoconductive Effects of 3 Heat-Treated Hydroxyapatites in Rabbit Calvarial Defects

This study aimed to detect the osteoconductive ability of 3 bovine hydroxyapatites (HAs) that were sintered at 800 degrees C (HA800), 1,200 degrees C (HA1200), and 1,350 degrees C (HA1350), according to new bone formation. Two bicortical skull defects were prepared in 10 New Zealand white rabbits. Four rabbits were used as controls; in each, 1 defect was filled with autogenous bone chips and the contralateral defect was left empty for the critical size defect (CSD). The other 6 rabbits had a total of 12 defects, 4 each randomly filled with HA 800, HA1200, or HA1350. The animals were sacrificed at 8 weeks. New bone formation was assessed by radiographic densitometry and histomorphometric analysis. The mean optical density (OD) of the CSD group (0.092 +/- 0.006) was less than that of the autogenous bone chip (0.102 +/- 0.002), HA1200 (0.108 +/- 0.005), and HA 1350 (0.102 +/- 0.003) groups. The mean OD of the HA 1200 group was significantly different from that of the HA 800 group (0.094 +/- 0.003). The histomorphometric analysis demonstrated that the autogenous bone chip group (34.89 +/- 4.61) was significantly different from the CSD (12.16+/- 6.97), HA 800 (18.32 +/- 7.33), and HA1350 (13.99 +/- 3.94) groups, but not the HA1200 group (24.83 +/- 12.12). The findings demonstrate that heat-treated bovine HA enhances bone formation, and HA 1200 tends to provide greater bone formation than the other 2 HAs.

A Novel Double-row Rotator Cuff Repair Exceeds Strengths of Conventional Repairs

Double-row rotator cuff repairs are becoming popular because of their ability to improve initial ultimate failure load for full-thickness rotator cuff tears, especially in middle-aged to elderly patients. We hypothesized a quasi-double-row repair using a combination of transosseous sutures, anchors, and double knots (TOAK technique) would exceed the clinically relevant 250-N load threshold and the initial mean ultimate failure loads of anchor-only and transosseous suture-only fixation. In simulated full-thickness supraspinatus tears in cadavers (mean age, 62 years; range, 50-77 years), failure loads of two repair techniques were compared with a TOAK repair using sutures and bioabsorbable anchors. Radiographic densitometry was conducted on all humeral heads. Testing was performed at 6 mm per minute in 18 bones in the following three groups (n = 6 per group): (1) transosseous suture-only with weave-type stitch and single-knot fixation; (2) anchor-only with horizontal mattress stitch and single-knot fixation; and (3) TOAK. The mean ultimate failure load was 238 N for the transosseous suture-only group and 215 N for the anchor-only group. Although the bones had lower density, TOAK specimens failed at 55% to 67% higher loads (mean, 404 N) than the other groups. These data support further evaluation of the TOAK technique for full-thickness supraspinatus tears in middle-aged to elderly patients.