Spongeous Bone Research Articles

Bone-GAN: Generation of virtual bone microstructure of high resolution peripheral quantitative computed tomography.

Data-driven development of medical biomarkers of bone requires a large amount of image data but physical measurements are generally too restricted in size and quality to perform a robusttraining. This study aims to provide a reliable in silico method for the generation of realistic bone microstructure with defined microarchitectural properties. Synthetic bone samples may improve training of neural networks and serve for the development of new diagnostic parameters of bone architecture andmineralization. One hundred-fifty cadaveric lumbar vertebrae from 48 different male human spines were scanned with a high resolution peripheral quantitative CT. After prepocessing the scans, we extracted 10,795 purely spongeous bone patches, each with a side length of 32 voxels (5 mm) and isotropic voxel size of 164μm. We trained a volumetric generative adversarial network (GAN) in a progressive manner to create synthetic microstructural bone samples. We then added a style transfer technique to allow the generation of synthetic samples with defined microstructure and gestalt by simultaneously optimizing two entangled loss functions. Reliability testing was performed by comparing real and synthetic bone samples on 10 well-understood microstructuralparameters. The method was able to create synthetic bone samples with visual and quantitative properties that effectively matched with the real samples. The GAN contained a well-formed latent space allowing to smoothly morph bone samples by their microstructural parameters, visual appearance or both. Optimum performance has been obtained for bone samples with voxel size 32 × 32 × 32, but also samples of size 64 × 64 × 64 could be synthesized. Our two-step-approach combines a parameter-agnostic GAN with a parameter-specific style transfer technique. It allows to generate an unlimited anonymous database of microstructural bone samples with sufficient realism to be used for the development of new data-driven methods of bone-biomarkers. Particularly, the style transfer technique can generate datasets of bone samples with specific conditions to simulate certain bonepathologies.

Revision hip arthroplasty

From 1990 to 2000 238 revision hip joint replacements were performed at Joint Replacement Department of CITO. Both cement and cementless implants as well as in case of need allografts in the form of bone chips and spongeous bone were used. Technique peculiarities of revision operations for Sivash and Compomed implants replacement are described. The working time for Com- pomed implants was detected to be up to 5 у ears, for Gerchev implants up to 7 years and for Sivash implants 10 years and more. In revision replacement the following complications occurred: lethal outcome 2 cases, acute myocardial infarction in early postoperative period 1 case (recovery), deep suppuration 1 case (implant was removed), thromboembolia of small branches of a. pulmonalis 3 cases (recovery), paresis of fibular portion of n. ischiadicus 5 cases (complete function restoration), dysbacteriosis during antibacterial therapy 2 cases (recovery). Results of treatment were evaluated in 140 patients in the periods from 3 months to 10 years. In 139 cases complete or almost complete restoration of operated limb function was clinically noted. In 37 out of 139 patients signs of bone resorption around the cup and stem of implant were detected roentgeno- logically.

Reliability and accuracy of cone-beam computed tomography voxel density and linear distance measurement at different voxel sizes: A study on sheep head cadaver

Background/purposeThe reliability and accuracy of linear distance and voxel density (VD) measurements are very important in dentistry. The purpose of this study was to assess the accuracy and reliability of linear distances and VD measurements of cone-beam computed tomography (CBCT) at different voxel sizes. Materials and methodsEighteen-millimeter linears of size 40 gutta-percha were prepared in fresh sheep head. The head was scanned using CBCT with 0.25, 0.3, and 0.40 voxel sizes. Standard linear distances of gutta-percha were measured in panoramic CBCT images at 0.25, 0.3, and 0.4 voxel sizes. VD measurements were made separately on spongeous bone of palatal surfaces of the roots of teeth 4, 5, and 6 of maxilla and on cortical bone of teeth 4, 5, and 6 regions of the left and right hemimandibles through cross-sectional imaging. ResultsWe found that linear distance measurements on panoramic image of CBCT were slightly lower than physical measurements. A significant difference was not found for the gutta-percha linear distances and cortical VD measurements at different voxel sizes (P ≥ 0.05). The correlation between measurements of VD at different voxels in cortical bone was greater than 0.85 (P = 0.000). ConclusionLinear distance measurements on the sheep head cadaver of 0.25, 0.3, and 0.4 voxel sizes were similar and reliable when compared with physical measurements. In minimizing radiation exposure, VD measurement of cortical bone at 0.4 voxel-based CBCT could be used to estimate cortical bone density. However, studies should be performed on the human head cadaver.

Correction of quantification errors in pelvic and spinal lesions caused by ignoring higher photon attenuation of bone in [18F]NaF PET/MR.

MR-based attenuation correction (MRAC) in routine clinical whole-body positron emission tomography and magnetic resonance imaging (PET/MRI) is based on tissue type segmentation. Due to lack of MR signal in cortical bone and the varying signal of spongeous bone, standard whole-body segmentation-based MRAC ignores the higher attenuation of bone compared to the one of soft tissue (MRACnobone). The authors aim to quantify and reduce the bias introduced by MRACnobone in the standard uptake value (SUV) of spinal and pelvic lesions in 20 PET/MRI examinations with [18F]NaF. The authors reconstructed 20 PET/MR [18F]NaF patient data sets acquired with a Philips Ingenuity TF PET/MRI. The PET raw data were reconstructed with two different attenuation images. First, the authors used the vendor-provided MRAC algorithm that ignores the higher attenuation of bone to reconstruct PETnobone. Second, the authors used a threshold-based algorithm developed in their group to automatically segment bone structures in the [18F]NaF PET images. Subsequently, an attenuation coefficient of 0.11 cm(-1) was assigned to the segmented bone regions in the MRI-based attenuation image (MRACbone) which was used to reconstruct PETbone. The automatic bone segmentation algorithm was validated in six PET/CT [18F]NaF examinations. Relative SUVmean and SUVmax differences between PETbone and PETnobone of 8 pelvic and 41 spinal lesions, and of other regions such as lung, liver, and bladder, were calculated. By varying the assigned bone attenuation coefficient from 0.11 to 0.13 cm(-1), the authors investigated its influence on the reconstructed SUVs of the lesions. The comparison of [18F]NaF-based and CT-based bone segmentation in the six PET/CT patients showed a Dice similarity of 0.7 with a true positive rate of 0.72 and a false discovery rate of 0.33. The [18F]NaF-based bone segmentation worked well in the pelvis and spine. However, it showed artifacts in the skull and in the extremities. The analysis of the 20 [18F]NaF PET/MRI examinations revealed relative SUVmax differences between PETnobone and PETbone of (-8.8%±2.7%, p=0.01) and (-8.1%±1.9%, p=2.4×10(-8)) in pelvic and spinal lesions, respectively. A maximum SUVmax underestimation of -13.7% was found in lesion in the third cervical spine. The averaged SUVmean differences in volumes of interests in lung, liver, and bladder were below 3%. The average SUVmax differences in pelvic and spinal lesions increased from -9% to -18% and -8% to -17%, respectively, when increasing the assigned bone attenuation coefficient from 0.11 to 0.13 cm(-1). The developed automatic [18F]NaF PET-based bone segmentation allows to include higher bone attenuation in whole-body MRAC and thus improves quantification accuracy for pelvic and spinal lesions in [18F]NaF PET/MRI examinations. In nonbone structures (e.g., lung, liver, and bladder), MRACnobone yields clinically acceptable accuracy.

AGE DYNAMICS PECULIARITIES OF THE LINEAL SIZES OF THE ALVEOLAR PROCESS OF THE UPPER JAW IN ADULTS

Upper jaw alveolar process age alteration concerns not only its height but also its thickness and layer correlation of the compact and spongeous bone. The aim of the investigation: determination of the lineal sizes of the layers of the osseous tissue of the alveolar process of the upper jaw in male and female adults and establishment of their age dynamics peculiarities. The investigation was hold on the spiral 16-row detecting computer tomographic scanner TOSHIBA Activion 16. 42 individuals (22 female and 20 male) without diseases, which could influence on the osseous tissue state, in the age 22-60 years were examined. All of the examined people were divided into two age groups: in male the first group – 22-35 years, the second – 36-60 years; in female – the first group 22-35 years and the second 36-55 years. Analysis of the thickness indices of the osseous tissue layers of the upper jaw on the level of oral (alveolar arch) and basal (basal arch) parts in individuals of different age groups in male and female, testified that general peculiarity of the structure of the alveolar process of all investigated individuals was correlation of thickness of the osseous tissue layers in the investigated area – the biggest thickness has spongeous layer, external compact layer has the same thickness on the basal and oral levels of the upper jaw alveolar process and the thickness of the internal compact layer changes in inverse proportion to the thickness of the spongeous layer of the osseous tissue. Age dynamic of the investigated indices is different and typical for the individuals of each sex.

Effect of rifampin in combination with allogeneic, alloplastic, and heterogenous bone grafts on bone regeneration in rat tibial bone defects

PurposeThe aim of this study was to evaluate the efficacy of rifampin with allogeneic, alloplastic, and heterogeneous bone graft substitutes on osteogenesis of experimentally created bone defects in rat tibias. Materials and methodsTwenty-eight male Wistar albino rats were used in this study. In each animal, two bone defects (10mm length×3mm width×2mm depth) were created in the left and right tibias, respectively. The animals were divided into four groups. In Group 1, the right defects were irrigated with rifampin alone, and the left defects were irrigated with sterile saline alone. In Group 2, the right defects were filled with rifampin and allogeneic bone graft, and the left defects were filled with allogeneic bone graft alone. In Group 3, the right defects were treated with rifampin and alloplastic bone graft, and the left defects were filled with alloplastic bone graft alone. In Group 4, the right defects were filled with rifampin and heterogeneous bone graft, and the left defects were filled with heterogeneous bone graft alone. ResultsThe animals were sacrified on the 21st postoperative day. Histopathological analysis of samples was performed to evaluate the process of bone regeneration and the presence of spongeous bone, cortex bone, and bone marrow. Bone union (p=0.023) and spongeous bone (p=0.030) values were higher in Group 1A (rifampin alone) than those in Group 1B (saline alone). Bone union (p<0.001) and spongeous bone (p<0.001) values in Group 2B (allograft+saline) were higher than those in Group 2A (allograft+rifampin). These differences were statistically significant. ConclusionsTopical rifampin can accelerate the bone repair process, but the combination of rifampin and allogeneic bone grafts can also reduce new bone formation in osseous defects. Further studies involving long-term follow-up with a larger number of cases and different antibiotic agents should be conducted. These will provide additional data regarding new bone formation, especially in contaminated bone defects, resulting from use of antibiotic-supplemented bone grafts.

The effect of errors in segmented attenuation maps on PET quantification

Accurate attenuation correction is important for PET quantification. Often, a segmented attenuation map is used, especially in MRI-based attenuation correction. As deriving the attenuation map from MRI images is difficult, different errors can be present in the segmented attenuation map. The goal of this paper is to determine the effect of these errors on quantification. The authors simulated the digital XCAT phantom using the GATE Monte Carlo simulation framework and a model of the Philips Gemini TF. A whole body scan was simulated, spanning an axial field of view of 70 cm. A total of fifteen lesions were placed in the lung, liver, spine, colon, prostate, and femur. The acquired data were reconstructed with a reference attenuation map and with different attenuation maps that were modified to reflect common segmentation errors. The quantitative difference between reconstructed images was evaluated. Segmentation into five tissue classes, namely cortical bone, spongeous bone, soft tissue, lung, and air yielded errors below 5%. Large errors were caused by ignoring lung tissue (up to 45%) or cortical bone (up to 17%). The interpatient variability of lung attenuation coefficients can lead to errors of 10% and more. Up to 20% tissue misclassification from bone to soft tissue yielded errors below 5%. The same applies for up to 10% misclassification from lung to air. When using a segmented attenuation map, at least five different tissue types should be considered: cortical bone, spongeous bone, soft tissue, lung, and air. Furthermore, the interpatient variability of lung attenuation coefficients should be taken into account. Limited misclassification from bone to soft tissue and from lung to air is acceptable, as these do not lead to relevant errors.

The compression—rotation stem: An experimental study on the primary stability of a new revision hip stem

In revision hip arthroplasty with bone defects of the proximal femur, a well-established treatment method is reconstruction with impacted allograft spongiosa chips and cemented implantation of a polished stem. Building on this principle of impacted bone grafting, a femoral implant, which is suited to uncemented hip arthroplasty as well as for uncemented revisions, was designed. This so-called compression-rotation stem (CR stem) is collarless and has flanks which compress the impacted bone chips during implantation and thereby increase the rotational stability. To evaluate the primary stability of this new shaft after impaction grafting, the micromotion was determined using six motion transducers. Under physiological loading conditions with simulation of the muscle activities at the proximal femur the application was dynamically loaded for 15,000 cycles with 1000 +/- 500 N and afterwards for 5000 cycles with 1300 +/- 1000 N. Uncemented CR stems and the control Exeter stems were implanted in a standardized manner according to the X-Change method. Therefore they were implanted into artificial femora that had been previously resected, hollowed, and filled with impacted human spongeous bone allograft to simulate bone defects. Subsequently, the femora were loaded under identical conditions and the micromotions measured. In the majority of the implantations, no significant differences could be found. In conclusion, similar clinical results for the two stems should be expected.

Brushite–collagen composites for bone regeneration

Brushite-based biomaterials are of special interest in bone regeneration due to their biocompatibility and biodegradability; on the other hand, collagen is a well-known osteoconductive biomaterial. In the present study a new brushite–collagen composite biomaterial is reported. This new biomaterial was prepared by combining citric acid/collagen type I solutions with a brushite cement powder. The obtained biomaterial was a cement paste, with improved handling properties. The effect of collagen on the setting reaction of brushite cement was studied, and was found to speed up the cement setting reaction. The cement paste set into a hard ceramic material within 18.5 ± 2.1 min and had compressive strength similar to that of spongeous bone (48.9 ± 5.9 MPa in dry conditions and 12.7 ± 1.5 MPa in humid conditions). The combination of collagen with citric acid revealed an interesting synergistic effect on the compressive strength of the composite material. Moreover, this new biomaterial had excellent cohesion properties (ninefold better than brushite cement), and high cellular adhesion capacity (threefold higher than brushite cement). The composite biomaterial described in this study combines good handling properties, compressive strength, cohesion and cell adhesion capacity, along with the osteoconductive and biodegradable properties inherent in brushite and in collagen-based biomaterials.

The dimensional accuracy for preparation of the femoral cavity in HIP arthroplasty

The aim of the study was to determine the precision of the preparation of the femoral cavity in cementless hip arthroplasty. We compared the bone-prosthesis interface after manual- and robot-assisted implantation of the stems. After plastination the specimens were cut to slices of 2.5 mm and documented by microradiography. The interface between prosthesis and bone was measured digitally with a specially designed software. The manually implanted prostheses showed an average full-contact area of 60% and an average area of gaps of 40% with an average height of 0.8 mm. The robot-assisted implanted stems had a significantly higher bone-prosthesis interface area of 93% and gap areas of less than 0.2 mm depth. Destructions of the spongeous bone were seen with the manually implanted stems but not after robot-assisted implantations. There was one stem fracture during the manual preparation of a stem. Microradiographic examination showed microfractures in the region of the lesser trochanter in two femora after robot-assisted implantation The robot-assisted technique highly increased the fitting area at the bone-prosthesis interface. The main reason for the fractures might be the absence of a robot done marker for the ideal implantation height with the applied type of prosthesis.

Central odontogenic fibroma, granular cell variant

A case of central odontogenic fibroma (COF) of the epithelium-rich type (granular cell variant) is reported. A 46-year-old female, demonstrated a multilocular, septated radiolucency below and between the roots of the teeth in 44–47 region. On microscopy the lesion revealed an odontogenic fibroma of the epithelium-rich type with areas characterized by lobules of spherical cells of varying size containing fine S-100 negative granules. In addition, scattered foci of cementoid/osteoid calcified material occurred. Based on several studies, the present authors entertain the hypothesis that supports a histiocystic origin the granular cells. Therapy consisted of curettage of the lesion. The defect was filled with spongeous bone. No recurrence occurred after follow-up of two years.

Tibial plateau fracture--biodegradable bonecement-augmentation

Between October 1996 and January 1999,29 patients (f:16,m:13,age: 22-86) with fractures of the lateral tibial plateau were operated on arthroscopic,fluoroscopic control or were treated with open reduction and internal fixation. 15 of them were retrospective and 14 prospective analysed. The metaphyseal defect after elevation of the depressed fragment was augmented in 11 cases with autologous spongeous bone grafting,in 9 cases with biodegradable bone cement (Norian SRS). Augmentation was unnecessary in 9 cases. The results according to the Lysholm score and the radiological results were good or excellent. Concerning the kind of augmentation no difference was noted. In the Norian SRS-group the duration of postoperative treatment was shorter than in the other group. The duration of partial weight bearing was shorter too. The results of the present study suggest that an injectable calcium phosphate cement may be a competent material for augmentation in lateral tibial plateau fractures because of the application form and the initial high mechanical stability.

Onlay grafts in combination with endosseous implants in severe mandibular atrophy: one year results of a prospective, quantitative radiological study.

In taking an overall view of the radiographs made of patients that underwent simultaneous onlay-grafting and implant placement in the anterior mandible, changes are seen in the grafts. The impression arose that a number of stages could be distinguished in this process of remodelling of the graft. The purpose of the present study was to objectivate the existence of those stages in the first year after bone-grafting by densitometric and height measurements of the onlay grafts using standardized extraoral radiographs (OLCR) and densitometric analysis in a group of 8 patients. OLCRs were taken at regular intervals in the first year after surgery. The measurements were performed in three fixed fields, both ventrally and dorsally of each implant. Generally the densitometric measurement fields were located at the (upper) cortex, the upper spongiosa and the lower spongiosa of the onlay graft. The OLCRs were also used for measurements of the height of the complete graft and of the thickness of the cortex of the graft, using a gauged caliper. The results indicate the following remodelling of the structure of the onlay grafts: 1) decrease in the thickness and the radiographic density of the (upper) cortex of the onlay graft predominantly in the first 6-month period; 2) no significant changes in the radiographic density of the upper spongeous part of the graft; 3) a decrease of approximately 25% in the overall height of the graft, particularly during the first 6-month period; 4) an increase in the radiographic density of the lower part of the spongeous bone in the second 6-month period. It is concluded that the remodelling of the graft has a predictable pattern in time: the first half year being dominated by bone resorption, mainly confined to the cortex of the graft, whereas the second half year is characterized by an increase in bone density in the (remaining) cortex as well as the lower spongeous parts of the graft.

Clinical Nurses Forum

Clinical Nurses Forum

Articular and osseous lesions in recent ligament tears: arthroscopic changes compared with magnetic resonance imaging findings

The treatment of ligament injuries of the knee has undergone rapid progress, especially with the improvement of arthroscopic reconstruction of the anterior cruciate ligament (ACL). Since the advent of magnetic resonance imaging (MRI) after knee trauma with ligament injuries, interest has focussed on the clinical significance of concomitant articular and osseous lesions. In 48 of 141 MRIs, different types of these lesions were found; in 38 cases an arthroscopy was performed and 34 times the patients could clinically and radiologically be examined after at least 6 months. Bone bruise was found 26 times, in 16 cases associated with ACL-tears. Eleven patients had subchondral fractures, 7 osteochondral fractures, and in 4 patients, stress fractures were found. They were attributed to various mechanisms of trauma, in different percentages associated with ligament tears and in different dimensions visible or progressive on follow-up MRIs. Obviously some of the different lesions of subchondral and spongeous bone can indicate later degenerative arthritis, so that we find hints for a modification of rehabilitation, e.g., open versus closed kinetic chain or orthosis with relief of single compartments. Arthroscopy 1998 Sep;14(6):597-604

VII Securing of an Osteochondral Joint Surface Bearing Fragment Using Bone Transplants: A clinical review

Restauration of the articular surface and securing of an osteochondral fragment using cortical and spongeous bone transplants has been utilized in the treatment of the following disorders, i. e. osteochondritis dissecans, osteochondral fracture, and osteonecrosis.In the cases reviewed in literature, the fragment united within 2–6 months, and the cortical bone transplants slowly resorbed. The joint surface mainly got smooth, and minor irregularities only were observed in the demarcation line between the osteochondral fragment and the condyle as well as in locations where the bone transplants were inserted. In a few cases, minimal osteoarthritic changes were found after a prolonged observation period.