Cadaveric Bones Research Articles

Low Cost Osseointegrated Implant System for Developing Countries

Objective: Osseointegrated hearing implants have been readily available and extensively used in developed countries for over twenty years. Despite a great need for this technology, use of these implants in developing countries has been limited due to the prohibitive cost of the surgical implant system as well as the implant devices themselves. To address this problem we have developed a drill and implant system that mimics the currently available instrumentation using materials that are readily available at a fraction of the cost. Study Design: Proof of Concept. Methods: The construction of the drill and implant system will be described. Testing of the system so that it adhered to Cochlear’sTM Bone anchored hearing aid system specifications including the drill speed and torque settings were measured. Temperature readings were also recorded during procedures performed on human cadaveric temporal bones. Results: The speed of the drill with the guide drill and countersink drill bits ranged from 1400 revolutions per minute (rpm) to 2300 rpm’s. The temperature change of the room temperature temporal bones varied from 0 degrees to +0.2 degrees Fahrenheit during the drilling process with both drill bits. All five implants were stable in the cadaver bone after being checked for initial stability. Conclusion: This low cost implant system may make the BAHA technology more easily available to developing countries pending future studies with animal models.

Pullout Strength Of Anterior Lumbar Interbody Fusion Plates: Fixed Versus Variable Angle Screw Designs

Abstract Purpose: To compare the pullout loads of variable versus fixed angle screws in anterior lumbar interbody fusion (ALIF) plate/screw constructs in both foam and cadaveric models. Methods: An ALIF plate was secured to a 0.160 g/cm3 polyurethane foam block (N = 10) with fixed or equivalently positioned variable angle screws and pulled out at 1 mm/min to failure. Embalmed human vertebral pairs (N = 10) were similarly utilized to compare fixed versus variable angle plate/screw constructs for pullout strength. Results: There was no statistically significant difference between fixed and variable angle plates for either foam (p = 0.6) or vertebral specimens (p = 0.3) based on maximum load or stiffness. The maximum load for the vertebral specimens was on average 39% of that for the foam (p = 0.001) and the stiffness was about 55% of that for the foam (p = 0.001). Conclusions: In this study, no statistically significant difference in pullout strength or stiffness was found between fixed and variable angle ALIF plate/screw constructs. However, the embalmed cadaveric bone model was shown to be statistically weaker in pullout strength and stiffness when compared to the foam model. This study suggests that the foam model may not always be representative of the cadaveric model in the magnitude of load, but may still provide good comparative results between different designs.

Effect of Screws Placement on Locking Compression Plate for Fixating Medial Transverse Fracture of Tibia

Locking Compression Plates (LCP) are useful fixation devices for tibia and other human long bones. Orthopedists use LCPs with various numbers of holes to fix bone fractures (1) . Not all of holes on plates are often used with Screws so various screw positioning is possible in operations. In this research, a 3D model of tibia is created with the exact geometry of the real bone by using CT scan images of the human right leg .It was materialized by MIMIX and developed in ABAQUS software. This was done considering whole bone material including bone marrow and cancellous bone that have been mostly ignored in previous researches (2) . The model is mechanically validated and verified in comparison with response and behavior of previous cadaveric bone studies (3) . Comparing the stress and stiffness in various positioning of screws on a stainless steel 11 holes LCP used for fixating tibia with a medial transverse fracture in various treatments and finding the optimized screw omission, was the purpose of this paper which can help orthopedists to choose the suitable cases of screws positioning of fixation devices.

Subject-specific bone loading estimation in the human distal radius

High-resolution in vivo bone micro-architecture assessment, as possible now for the distal forearm, in combination with bone remodelling simulation algorithms could, eventually, predict patient-specific bone morphology changes. To simulate load-adaptive bone remodelling, however, physiological loading conditions must be defined. In this paper we test a previously developed algorithm to estimate such physiological loading conditions from the bone micro-architecture. The aims of this study were to investigate if realistic boundary forces and moments are predicted for the scanned distal radius section and how these predicted forces and moments should be distributed to the scanned section in order to obtain a load transfer similar to that in situ. Images at in vivo resolution were generated for the clinically measured section of nine distal radius cadaver bones, converted to micro-finite element models and used for load estimation. Models of the full distal radius were created to analyse tissue loading distributions of the sections in situ. It was found that predicted forces and moments at the boundaries of the scanned region varied considerably but, when translated to equivalent radiocarpal joint forces, agreed well with values reported in the literature. Bone tissue loading distribution was in best agreement with in situ distributions when loading was applied to an extra layer of material at both ends of the clinical scan region. The agreement of the predicted loading to previous studies and the wide range of predicted loading values indicate that subject-specific bone loading estimation is possible and necessary.

Comparative Biomechanical Evaluation of a Pin‐Sleeve Transfixation System in Cadaveric Calf Metacarpal Bones

To compare proximal fragment displacement and the peri-implant strain using a pin-sleeve cast (PSC) system and a transfixation pin cast (TPC) system on a cadaveric calf metacarpal bone fracture model. Experimental. Cadaveric calf metacarpal bones (n= 6 pairs). Paired samples were instrumented with either the TPC or the PSC systems. Strain gauges were applied proximal to the transfixation implants and the bones encased in cast material. The distal part of the construct was removed to mimic an unstable distal comminuted fracture. Constructs were fixed to the material testing machine and initially loaded in axial compression in their elastic range to determine construct stiffness. Constructs were loaded cyclically with a sinusoidal curve that increased until failure. Variables compared statistically between constructs were the initial construct stiffness and, at given load points, the mean metacarpal axial displacement in loading and unloading condition and mean axial strain. Initial construct mean± SD axial stiffness was not significantly different between constructs (PSC: 689± 258; TPC: 879± 306 N/mm). There was no significant difference between either investigated displacements of metacarpal bones transfixed with PSC and those transfixed with TPC at all load points. The PSC constructs had a significant decrease in the recorded mean strain (502± 340 μstrain) compared to the TPC construct (1738± 2218 μstrain). The PSC significantly reduced peri-implant strain with comparable axial displacement to the TPC in cadaveric calf metacarpal bones.

Mechanical and morphological properties of trabecular bone samples obtained from third metacarpal bones of cadavers of horses with a bone fragility syndrome and horses unaffected by that syndrome

To determine morphological and mechanical properties of trabecular bone of horses with a bone fragility syndrome (BFS; including silicate-associated osteoporosis). Cylindrical trabecular bone samples from the distal aspects of cadaveric third metacarpal bones of 39 horses (19 horses with a BFS [BFS bone samples] and 20 horses without a BFS [control bone samples]). Bone samples were imaged via micro-CT for determination of bone volume fraction; apparent and mean mineralized bone densities; and trabecular number, thickness, and separation. Bone samples were compressed to failure for determination of apparent elastic modulus and stresses, strains, and strain energy densities for yield, ultimate, and failure loads. Effects of BFS and age of horses on variables were determined. BFS bone samples had 25% lower bone volume fraction, 28% lower apparent density, 18% lower trabecular number and thickness, and 16% greater trabecular separation versus control bone samples. The BFS bone samples had 22% lower apparent modulus and 32% to 33% lower stresses, 10% to 18% lower strains, and 41 % to 52% lower strain energy densities at yield, ultimate, and failure loads, compared with control bone samples. Differences between groups of bone samples were not detected for mean mineral density and trabecular anisotropy. Results suggested that horses with a BFS had osteopenia and compromised trabecular bone function, consistent with bone deformation and pathological fractures that develop in affected horses. Effects of this BFS may be systemic, and bones other than those that are clinically affected had changes in morphological and mechanical properties.

Is balloon osteoplasty attractive or questionable treatment for Hill-Sachs lesion?

Dear Editor, We have read the article “Balloon osteoplasty—a new technique for minimally invasive reduction and stabilisation of Hill-Sachs lesions of the humeral head: a cadaver study” by Sandmann et al. [1] with great interest. Hill-Sachs lesion treatment is very difficult regarding its widespread approaches. Too many treatment protocols can be found in current literature with different success rates. The balloon-osteoplasty technique may be seen as attractive, but we have many questions to the authors about this technique. We use balloon osteoplasty for fresh spinal compression fracture. If compression healed with fibrosis, balloon strength is not sufficient for restoration. Short tau inversion recovery (STIR) sequence is very sensitive for detecting vertebral oedema following fresh fractures or micro-fractures [2]. This study was performed on cadaveric bone and all fractures created manually and were therefore fresh. This is not the case with old Hill-Sachs fractures, which is why it is not so easy to restore height in Hill-Sachs lesions. Violatin might cause joint fracture and leakage to occur into the joint space. Is this technique effective for all kinds of Hill-Sachs lesions? Other technical complications from the inappropriate placement of instruments during balloon osteoplasty have resulted in a breach of the joint and inadvertent leakage of cement into the spinal canal. Your instruments were modified; thus, is the entrance point the same for all patients? And is one modified instrument sufficient for all kinds of Hill-Sachs lesions? What is the time of exposure to radiation? Is the modified instrument cost high? What is the ideal amount of augmentation necessary to restore a desirable degree of local strength and stiffness?

Distal radius fracture fixation with volar locking plates and additional bone augmentation in osteoporotic bone: a biomechanical study in a cadaveric model

Fractures of the distal radius represent the most common fractures in adults. Volar locked plating has become a popular method for treating these fractures, but has been subject to several shortcomings in osteoporotic bone, such as loss of reduction and screw purchase. In order to overcome these shortcomings, cement augmentation has been proposed. AO-type 23-A3.3 fractures were made in 8 pairs of fresh frozen osteoporotic cadaveric radial bones. All specimens were treated with volar plating, and divided into cement augmentation or non-augmentation groups (n = 8/group). Constructs were tested dynamically and load to failure, construct-stiffness, fracture gap movement and screw cutting distance were measured. Cement augmentation resulted in a significant increase in cycles and load to failure, as well as construct stiffness at loads higher than 325 N. When compared to the non-augmented group, fracture gap movement decreased significantly at this load and higher, as did screw cutting distance at the holes of the ulnar column. The cycles to failure depend on the BMD in the distal region of the radius. Cement augmentation improves biomechanical properties in volar plating of the distal radius.

Characterization of modified Ti6Al4V alloy after fretting–corrosion tests using near-field microscopy

Fretting wear and corrosion of Ti6Al4V alloys at the bone/implant stem interface produce the release of wear particles and corrosive ions from the stem into the surrounding tissue that can induce bone resorption. In this work, oxidation treatments at 500° and 700°C for 1h have been studied for increasing the friction–corrosion resistance at these interfaces. The friction–corrosion process of thermally treated Ti6Al4V disks against pins of cadaver bone was evaluated in bovine serum medium for 1millioncycles of loading at 4Hz with maximum contact pressures of 10MPa. Cyclic displacement of 120μm for pin-on-disk samples in a linear motion was applied. Samples were characterized, before and after the oxidation treatment, by atomic force microscopy (AFM), scanning Kelvin probe (SKP) and scanning electrochemical microscopy (SECM). The characterization of the Ti6Al4V samples showed the growth and the different morphologies of the oxides as a consequence of the temperature. SKP and SECM revealed that the surface of oxidized samples had lower electrochemical activity than as-received surfaces. After the fretting–corrosion test, the thermally treated samples showed low electrochemical reactivity; specifically oxidation treatment at 700°C revealed that the rutile scale formed potentially improves the performance of Ti6Al4V in fretting–corrosion against bone.

Assessment of cortical bone with clinical and ultrashort echo time sequences

We describe the use of ultrashort echo time (UTE) sequences and fast spin echo sequences to assess cortical bone using a clinical 3T scanner. Regular two- and three-dimensional UTE sequences were used to image both bound and free water in cortical bone. Adiabatic inversion recovery prepared UTE sequences were used to image water bound to the organic matrix. Two-dimensional fast spin echo sequences were used to image free water. Regular UTE sequences were used together with bicomponent analysis to measure T*2s and relative fractions of bound and free water components in cortical bone. Inversion recovery prepared UTE sequences were used to measure the T*2 of bound water. Saturation recovery UTE sequences were used to measure the T1 of bone water. Eight cadaveric human cortical bone samples and a lower leg specimen were studied. Preliminary results show two distinct components in UTE detected signal decay, a single component in inversion recovery prepared UTE detected signal decay, and a single component in saturation recovery UTE detected signal recovery. Regular UTE sequences appear to depict both bound and free water in cortical bone. Inversion recovery prepared UTE sequences appear to depict water bound to the organic matrix. Two-dimensional fast spin echo sequences appear to depict bone structure corresponding to free water in large pores.

Embalmed and fresh frozen human bones in orthopedic cadaveric studies: which bone is authentic and feasible?

Background and purpose The most frequently used bones for mechanical testing of orthopedic and trauma devices are fresh frozen cadaveric bones, embalmed cadaveric bones, and artificial composite bones. Even today, the comparability of these different bone types has not been established.Methods We tested fresh frozen and embalmed cadaveric femora that were similar concerning age, sex, bone mineral density, and stiffness. Artificial composite femora were used as a reference group. Testing parameters were pullout forces of cortex and cancellous screws, maximum load until failure, and type of fracture generated.Results Stiffness and type of fracture generated (Pauwels III) were similar for all 3 bone types (fresh frozen: 969 N/mm, 95% confidence interval (CI): 897–1,039; embalmed: 999 N/mm, CI: 875–1,121; composite: 946 N/mm, CI: 852–1,040). Furthermore, no significant differences were found between fresh frozen and embalmed femora concerning pullout forces of cancellous screws (fresh frozen: 654 N, CI: 471–836; embalmed: 595 N, CI: 365–823) and cortex screws (fresh frozen: 1,152 N, CI: 894–1,408; embalmed: 1,461 N, CI: 880–2,042), and axial load until failure (fresh frozen: 3,427 N, CI: 2,564–4290; embalmed: 3,603 N, CI: 2,898–4,306). The reference group showed statistically significantly different results for pullout forces of cancellous screws (2,344 N, CI: 2,068–2,620) and cortex screws (5,536 N, CI: 5,203–5,867) and for the axial load until failure (> 7,952 N).Interpretation Embalmed femur bones and fresh frozen bones had similar characteristics by mechanical testing. Thus, we suggest that embalmed human cadaveric bone is a good and safe option for mechanical testing of orthopedic and trauma devices.

Interfragmentary Compression Profile of 4 Headless Bone Screws: An Analysis of the Compression Lost on Reinsertion

To evaluate the interfragmentary compression force generated by 4 different types of headless compression screws and to examine the effects of removal and reinsertion of the screw. We chose foot bones rather than scaphoids for the model because they were larger and would enable comparison of 2 screw designs in the same bone, thereby controlling for the effect of interspecimen variability. A transverse osteotomy was made in 10 fresh-frozen cadaveric navicular bones and 10 medial cuneiforms. A load cell was used to measure compression between the 2 fragments as a screw was inserted across the fracture. Each bone was tested twice, with an Acutrak Mini (Acumed, Hillsboro, OR; n = 10) and an SBi AutoFIX screw (SBi, Morrisville, PA; n = 10) or an Extremifix (Osteomed, Addison, TX; n = 10) and a Barouk screw (Depuy, Warsaw, IN; n = 10). Compression was recorded at initial insertion and on removal and reinsertion of the screw twice to the same position. Compression was also measured after one additional full turn further than the initial position. The mean interfragmentary compression generated by the Acutrak Mini screw was greater than that of the SBi AutoFIX screw (96 N vs 22 N). There was a trend toward a greater mean compression generated by the Extremifix screw compared to the Barouk screw (85 N vs 22 N). There was a significant loss of compression upon removal and reinsertion of the screws. An additional full turn of the screw was able to re-establish a large proportion of the original compression. The compression forces achieved by headless screw systems appeared to vary according to the screw design, depth of insertion, and the quality of the bone. Substantial compression was lost if the screw was removed and replaced. Some screw designs appeared to require a greater depth of insertion to achieve effective compression, and the number of additional turns required to re-establish compression might vary according to the thread design. Surgeons should be aware of the compression profile of each screw design and the effect of screw removal and reinsertion in the clinical setting of small bone fixation.

Comparison of thoracic wall behavior in large animals and human cadavers submitted to an identical ballistic blunt thoracic trauma

BackgroundSeveral models of ballistic blunt thoracic trauma are available, including human cadavers and large animals. Each model has advantages and disadvantages regarding anatomy and physiology, but they have not been compared with identical ballistic aggression. MethodsTo compare thoracic wall behavior in 40-kg pigs and human cadavers, the thorax of 12 human cadavers and 19 anesthetized pigs were impacted with two different projectiles at different speeds. On the thoracic wall, the peak acceleration, peak velocity, maximal compression, viscous criterion, and injury criteria (e.g. abbreviated injury scale and number of rib fractures) were recorded. The correlations between these motion and injury parameters and the blunt criterion were compared between the two groups. The bone mineral density of each subject was also measured. ResultsThe peak acceleration, the peak velocity and the viscous criterion were significantly higher for the pigs. The AIS and the number of rib fractures were significantly higher for human cadavers. The bone mineral density was significantly higher for cadavers, but was, for the two groups, significantly lower than for 30-year-old human. ConclusionThe motion of the pig's thoracic wall is greater than that of the human cadaver, and the severity of the impact is always greater for human cadavers than for pigs. In addition, pig bone is more elastic and less brittle than older human cadaver bone. Due to the bone mineral density, the thoracic wall of human adults should be more rigid and more resistant than the thoracic wall of human cadavers or pigs.

Scintigraphic and Tomographic Evaluation of Biological Activities of Prefabricated Free and Vascularized Bone Allografts

We performed an experimental study on rabbits to compare the biologic activities of free and vascularized cortical and corticocancellous solvent-dehydrated bone allografts by scintigraphy and three-dimensional computed tomography (CT). Twenty New Zealand white rabbits (2500-3000 g) were divided into 2 groups each consisting 10 animals. In group 1, solvent-dehydrated human cadaveric cranium allografts (corticocancellous bone) were used. The grafts were divided into 20 pieces, approximately 10 × 10 × 5 mm. On the right ears, grafts were placed on dissected vascular bundles. On their left ears, allografts were implanted into subcutaneous pockets without dissecting any vascular bundle. The same procedure was performed in group 2 with solvent-dehydrated human cadaveric fibula bone allografts (cortical bone). No infection or any animal death occurred during 12 months of observation. At the end of the 12th month, implanted bone allografts were evaluated by 3-phase bone scintigraphy to observe the circulation and viability of the grafts and three-dimensional CT scans to measure their dimensions. Radioactive uptake by scintigraphy of grafts placed on vascular bundle was higher than grafts placed in pockets. t-Test was calculated for region of interest of right ear (vascularized) to left ear rate (nonvascularized) according to graft type. Rate for corticocancellous bone graft was 1.187 ± 0.179 (P = 0.038) and cortical bone graft was 1.055 ± 0.052 (P = 0.038). There was correlation between region of interest generated from arm and neck regions and graft regions (P = 0.001). Regarding the dimension measurement made by three-dimensional CT, all the grafts grew whether they were on vascular bundle or not. Mann-Whitney test was used to determine whether differences between preoperative and postoperative volumes of grafts and growth of all grafts were significant (P = 0.007 for vascularized cortical bone and P = 0.005 for others). Kolmogorov-Smirnov test was performed to evaluate the distribution of growth rate. Vascularized medullar-cortical and nonvascularized medullar bone grafts expanded more than nonvascularized cortical bone (P = 0.001, P = 0.005, P = 0.001, respectively). Vascularized bone allograft combines the advantages of autogenous and allogenous grafts. Both scintigraphic and tomographic results overlapped that corticocancellous and cortical bones developed more on vascular bundle. Even though radioactive uptake was statistically higher in vascularized bone allografts, we determined that this small difference did not affect the overall late vascularity of the bone allografts. In conclusion, regardless their types or placement on vascular bundle, prefabricated bone allografts had similar metabolic function after 1 year of integration.

Computationally-Optimized Bone Mechanical Modeling from High-Resolution Structural Images

Image-based mechanical modeling of the complex micro-structure of human bone has shown promise as a non-invasive method for characterizing bone strength and fracture risk in vivo. In particular, elastic moduli obtained from image-derived micro-finite element (μFE) simulations have been shown to correlate well with results obtained by mechanical testing of cadaveric bone. However, most existing large-scale finite-element simulation programs require significant computing resources, which hamper their use in common laboratory and clinical environments. In this work, we theoretically derive and computationally evaluate the resources needed to perform such simulations (in terms of computer memory and computation time), which are dependent on the number of finite elements in the image-derived bone model. A detailed description of our approach is provided, which is specifically optimized for μFE modeling of the complex three-dimensional architecture of trabecular bone. Our implementation includes domain decomposition for parallel computing, a novel stopping criterion, and a system for speeding up convergence by pre-iterating on coarser grids. The performance of the system is demonstrated on a dual quad-core Xeon 3.16 GHz CPUs equipped with 40 GB of RAM. Models of distal tibia derived from 3D in-vivo MR images in a patient comprising 200,000 elements required less than 30 seconds to converge (and 40 MB RAM). To illustrate the system's potential for large-scale μFE simulations, axial stiffness was estimated from high-resolution micro-CT images of a voxel array of 90 million elements comprising the human proximal femur in seven hours CPU time. In conclusion, the system described should enable image-based finite-element bone simulations in practical computation times on high-end desktop computers with applications to laboratory studies and clinical imaging.

Biomechanical assessment of different kinds of fixing of unstable fractures in the acetabular region of the femur in experiment

Unstable (A3) fractures in the acetabular region of the femur in the acetabular region of the femur were experimentally modelled on 18 preparations from cadaver bones of elderly people. The preparations were divided into three groups, by 6 in each. Fragments were fixed with a cemented endoprosthesis stem in group 1, with a DHS plate in group 2, and 130 degree angle plates in group 3. Biomechanical studies of the fragment fixation resistance to axial loads, fractures and maximum dynamic axial loads were conducted. Results of the above studies demonstrated a high rigidness of fracture fixation with angle plates and a low resistance of fragments to maximum compression loads. In osteosynthesis with DHS plates, preparations bore weight up to 140 kg, but turned out to be half resistant to cyclic and fracture loads versus their fixation with angle plates and one-eighth as strong (up to 12 %) as when fixed with endoprostheses. In cases of fixing with wire, screws and endoprosthesis stems with cement, resistance to loads was close to that of an intact bone.

Stem Requirements of Tibial Augmentations in Total Knee Arthroplasty

Various tibial augmentations have been employed to overcome the problem associated with proximal tibial bony deficiencies mainly in revision total knee arthroplasty (TKA). It has generally been recommended that stem extensions should always be applied to the tibial tray in the event that block augments have been used to compensate for bone loss. The rationale for such routine use of stems has not been clearly established and further this adds to implant costs and may contribute to substantial bone loss if a future revision is required. We investigated the stability of three implant configurations (Deltafit Keel tibial tray only (no bone loss), tray with block augment (with bone loss), and tray with block and extended stem) utilizing both cadaveric human bone as well as commercially available composite tibias. The experimental results revealed that comparable stability can be achieved with the configuration of Deltafit Keel tibial tray and a block as compared to the case of Deltafit Keel tray only without bone loss. Addition of a stem provided moderate improvement of stability but with significant stress shielding. For the amount of bone loss evaluated in this study, a Deltafit Keel tibial tray with a block provided adequate stability and avoided obvious stress shielding.

Advanced core decompression, a new treatment option of avascular necrosis of the femoral head - a first follow-up

Aseptic necrosis of the femoral head (AVN) leads to destruction of the affected hip joint, predominantly in younger patients. Advanced core decompression (ACD) is a new technique that may allow better removal of the necrotic tissue by using a new percutaneous expandable reamer. A further modification is the refilling of the drill hole and the defect with an injectable, hard-setting, composite calcium sulphate (CaSO₄)-calcium phosphate (CaPO₄) bone graft substitute. Compression tests were performed on seven pairs of femoral cadaver bones. One femur of each pair was treated with ACD, while the opposite side remained untreated. Clinically, the postoperative outcome of 27 hips in 23 patients was performed by physical examination 6 weeks after ACD and at average follow-up of 9.69 months, and compared with the preoperative results. MRI was used to assess the removal of the necrotic tissue, any possible progression of AVN and evaluation of collapse. In the biomechanical analysis, the applied maximum compression force that caused the fracture did not significantly differ from the untreated opposite side. The overall results of postoperative physical examinations were significantly better than preoperatively. Five hips (18.5%) were converted to a total hip replacement. The follow-up MRIs of the other patients showed no progression of the necrotic area. The first follow-up results of ACD have been encouraging for the early stages of aseptic necrosis of the femoral head. In our opinion, an assured advantage is the high stability of the femoral neck after ACD, which allows quick rehabilitation.

Nursing Coordination of a Life-Saving Cadaveric Tandem Lung and Bone Marrow Transplant in a Pediatric Patient with Congenital Immunodeficiency and Pulmonary Failure

Nursing Coordination of a Life-Saving Cadaveric Tandem Lung and Bone Marrow Transplant in a Pediatric Patient with Congenital Immunodeficiency and Pulmonary Failure

Evaluation of Ultra-Low Dose CT in the Diagnosis of Pediatric-Like Fractures Using an Experimental Animal Study

ObjectiveThe aim of this prospective study was to evaluate the performance of ultra-low dose CT for the diagnosis of pediatric-like fractures and ascertain the lowest dose level sufficient for diagnostics.Materials and MethodsFifty-one bones of young pig cadavers were artificially fractured and subsequently examined by using a 64 multi-detector CT with 36 various dose levels down to a dose comparable with that of X-rays. Two pediatric radiologists analysed the CT scans according to the presence or absence of a fracture, determination of the fracture type and the displacement as well as the diagnostic certainty. For each dose protocol, a success rate for the correct determination of the above-mentioned CT analyses was calculated. A success rate of at least 95% was considered sufficient for diagnostics.ResultsAll but the lowest dose levels were sufficient to identify the fracture. Only the two lowest dose levels were insufficient to detect the fracture type. All dose levels were adequate for the identification of the displacement. The lowest dose level sufficient for diagnostics was 120 kVp, 11 mAs, and pitch 1.5, with a CTDIvol of 10% of a standard dose and an effective dose three times as large as that of X-rays.ConclusionUltra-low dose CT provides the feasibility of a significant dose reduction, still allowing sufficient diagnostics of pediatric-like fractures.