Human Rib Research Articles

Enzymatic maceration of bone: a gentler technique than boiling.

This proof of concept study investigates the removal of soft tissue from human ribs with the use of two common methods: boiling with a laundry detergent and using enzymes. Six individuals were autopsied, and one rib from each individual was removed for testing. Each rib was cut into pieces and afterwards macerated by one of the two methods. DNA extraction was performed to see the effect of the macerations on DNA preservation. Furthermore, the bone pieces were examined in a stereomicroscope to assess for any bone damage. The results demonstrated that both methods removed all flesh/soft tissue from the bones. The DNA analysis showed that DNA was preserved on all the pieces of bones which were examined. Finally, the investigation suggests that enzyme maceration could be gentler on the bones, as the edges appeared less frayed. The enzyme maceration was also a quicker method; it took three hours compared with the traditional method which took about 24 hours. However, a more standardised study should be performed to confirm this.

HIFU scattering by the ribs: constrained optimisation with a complex surface impedance boundary condition

High intensity focused ultrasound (HIFU) enables highly localised, non-invasive tissue ablation and its efficacy has been demonstrated in the treatment of a range of cancers, including those of the kidney, prostate and breast. HIFU offers the ability to treat deep-seated tumours locally, and potentially bears fewer side effects than more established treatment modalities such as resection, chemotherapy and ionising radiation. There remains however a number of significant challenges which currently hinder its widespread clinical application. One of these challenges is the need to transmit sufficient energy through the ribcage to ablate tissue at the required foci whilst minimising the formation of side lobes and sparing healthy tissue. Ribs both absorb and reflect ultrasound strongly. This sometimes results in overheating of bone and overlying tissue during treatment, leading to skin burns. Successful treatment of a patient with tumours in the upper abdomen therefore requires a thorough understanding of the way acoustic and thermal energy is deposited. Previously, a boundary element (BE) approach based on a Generalised Minimal Residual (GMRES) implementation of the Burton-Miller formulation was developed to predict the field of a multi-element HIFU array scattered by human ribs, the topology of which was obtained from CT scan data [1]. Dissipative mechanisms inside the propagating medium have since been implemented, together with a complex surface impedance condition at the surface of the ribs. A reformulation of the boundary element equations as a constrained optimisation problem was carried out to determine the complex surface velocities of a multi-element HIFU array which generated the acoustic pressure field that best fitted a required acoustic pressure distribution in a least-squares sense. This was done whilst ensuring that an acoustic dose rate parameter at the surface of the ribs was kept below a specified threshold. The methodology was tested at an excitation frequency of 1 MHz on a spherical multi-element array in the presence of anatomical ribs.

Non-destructive assessment of human ribs mechanical properties using quantitative ultrasound

Advanced finite element models of the thorax have been developed to study, for example, the effects of car crashes. While there is a need for material properties to parameterize such models, specific properties are largely missing. Non-destructive techniques applicable in vivo would, therefore, be of interest to support further development of thorax models. The only non-destructive technique available today to derive rib bone properties would be based on quantitative computed tomography that measures bone mineral density. However, this approach is limited by the radiation dose. Bidirectional ultrasound axial transmission was developed on long bones ex vivo and used to assess in vivo health status of the radius. However, it is currently unknown if the ribs are good candidates for such a measurement. Therefore, the goal of this study is to evaluate the relationship between ex vivo ultrasonic measurements (axial transmission) and the mechanical properties of human ribs to determine if the mechanical properties of the ribs can be quantified non-destructively. The results show statistically significant relationships between the ultrasonic measurements and mechanical properties of the ribs. These results are promising with respect to a non-destructive and non-ionizing assessment of rib mechanical properties.This ex vivo study is a first step toward in vivo studies to derive subject-specific rib properties.

Invited Commentary on “Thoraco-pleuro-pneumonectomy (TPP) with Riblike Reconstruction for Recurrent Thoracic Sarcomas” by A. Gronchi et al., (ASO-2013-09-1533.R1)

The authors’ solution for recurrent advanced low-intermediate grade thoracic sarcomas is interesting, promising, and unique. As stated, there are no other reported interventions of this scale. The organic shape and fluid kinetics of the thorax are critical to its function. Previous attempts at lesser resections of the chest wall have been successful when combined with reconstruction. For the reconstruction, surgeons have used muscle, autologous bone, biologic mesh, synthetic mesh, and synthetic sternal shields to try and attain the perfect balance of rigidity and pliability to most accurately reflect normal chest physiology. This paper increases the definition of resectability and expands the methods or reconstruction and hence the boundaries of potential cure for large low-grade chest wall sarcomas. Soft tissue sarcomas are rare malignant tumors whose benign counterparts are 100 times more common. They occur in every anatomic location, but are predominantly found in extremities and the retroperitoneum. Approximately 10 % of these tumors are found in the trunk, making the chest wall one of the least common locations. As shown in the NCCN guidelines, the main decision point in the treatment algorithm for sarcomas is resectable versus nonresectable. The resection of the hemithorax in this paper was extensive and thorough, but the resection would have been in vain if not for the unique reconstruction that followed. Chest wall reconstruction is performed for four reasons: malignancy, radiation injuries, infection, and trauma. Reconstruction should always be functional and has been described in the literature. There are biologic materials and synthetic meshes on the market today of all sizes and pliability, yet these are all less than ideal for such a largescale resection. The authors used riblike reconstruction, which mimics the 3-dimensional attributes of the human rib cage. This may provide more functionality than its mesh predecessors, and it aesthetically looks natural as the authors have demonstrated. As with any large resection with foreign material implantation, there are some concerns: the scope of the resection is extensive, the technology of reconstruction is not common, and a risk of infection is real. In spite of this, there exists no good alternative therapy. The large, lowgrade sarcomas are unlikely to be cured by chemotherapy and/or radiation therapy. The authors have demonstrated that immediate riblike reconstruction is a valid option for this select group of individuals within an experienced center. While this procedure is currently being performed in one center, it would seem reasonable to expand its use to experienced hands in high-volume tertiary thoracic centers. Currently, its effectiveness is only reaching a small fraction of the patient population who may benefit. With any multistep, innovative operation there will be a steep learning curve. With appropriate mentoring and a structured program of education, it is possible to effectively reduce the learning curve of complex thoracic operations. The follow-up by this group does show promising results in terms of short-term survival, infection rate, and graft durability. With further investigation, this operation may become a more common option for the patient with a first time diagnosis of large low-grade chest wall sarcoma. Recurrence is treated with a similar algorithm as the initial tumor as seen again in the NCCN guidelines. It is Society of Surgical Oncology 2014

Two newly identified Mousterian human rib fragments from Combe-Grenal (Domme, France)

This paper presents the discovery and study of two new fossil human remains from the mousterian site of Combe-Grenal located in the commune of Domme in Dordogne. These two fragments are from ribs and they have been found in level 25 (Bordes’ excavation ; Quina type Mousterian). One of them is a fragment of an adult right first rib. The second is a fragment of an adolescent lower mid-thoracic rib (possibly the 8th or 9th). Although none of these fragments have clear Neandertal traits due to their preservation state, they are nevertheless the first elements from the human trunk identified at Combe-Grenal. Therefore, they increase the diversity of the known bony parts found at this site. Nonetheless, the minimum number of individuals (MNI) is unchanged. The adult first rib shows traces of post-mortem anthropic manipulations.

Scattering of high-intensity focused ultrasound by the ribs: Constrained optimization with a complex surface impedance boundary condition

One of the challenges of trans-rib high-intensity focused ultrasound (HIFU) treatment is the need to transmit sufficient energy through the ribcage to ablate tissue whilst minimizing the formation of side lobes, and sparing healthy tissue. Ribs strongly absorb and reflect ultrasound. This may result in overheating of bone and overlying tissue during treatment, leading to skin burns. Successful treatment of a patient with tumors of the liver or the pancreas therefore requires a thorough understanding of the way acoustic and thermal energy is deposited. A boundary element approach was developed to predict the field of a multi-element HIFU array scattered by human ribs in 3D. This forward model has been reformulated as a constrained least squares optimization problem where the velocity of each individual element on the array is an optimization variable. A locally reacting complex surface impedance condition at the surface of the ribs has been implemented. The methodology has been tested at an excitation frequency of 1 MHz on a spherical section multi-element array and a total of six array-rib configurations have been investigated. The results were compared against other focusing and rib-sparing approaches, demonstrating the efficacy and flexibility of the constrained optimization approach.

Human rib response to different restraint systems in frontal impacts: a study using a human body model

Finite-element human body models (FE-HBMs) can be used to evaluate restraint systems by predicting thoracic injury. The biofidelity assessment of an FE-HBM Total HUman Model for Safety (THUMS) 50th percentile male occupant and the characterisation of its rib response to loads from frontal car crashes are the objectives of this study. The rib-cage mesh of THUMS version 3.0 was refined to improve the shoulder-belt interaction, material properties of lungs and skin modified, and the model biofidelity assessed against tests representative of frontal crashes. The modified THUMS response improved with respect to the baseline model. The modified THUMS was used to analyse the rib loading in frontal impacts. The rib response included shear, torsion and bending in belt and airbag-like load cases. This indicates that a criterion based only on rib anteroposterior compression may not be enough to predict fractures and that a criterion should consider compression, torsion and shear.

Characterization of the Centroidal Geometry of Human Ribs

While a number of studies have quantified overall ribcage morphology (breadth, depth, kyphosis/lordosis) and rib cross-sectional geometry in humans, few studies have characterized the centroidal geometry of individual ribs. In this study, a novel model is introduced to describe the centroidal path of a rib (i.e., the sequence of centroids connecting adjacent cross-sections) in terms of several physically-meaningful and intuitive geometric parameters. Surface reconstructions of rib levels 2-10 from 16 adult male cadavers (aged 31-75 years) were first extracted from CT scans, and the centroidal path was calculated in 3D for each rib using a custom numerical method. The projection of the centroidal path onto the plane of best fit (i.e., the "in-plane" centroidal path) was then modeled using two geometric primitives (a circle and a semiellipse) connected to give C1 continuity. Two additional parameters were used to describe the deviation of the centroidal path from this plane; further, the radius of curvature was calculated at various points along the rib length. This model was fit to each of the 144 extracted ribs, and average trends in rib size and shape with rib level were reported. In general, upper ribs (levels 2-5) had centroidal paths which were closer to circular, while lower ribs (levels 6-10) tended to be more elliptical; further the centroidal curvature at the posterior extremity was less pronounced for lower ribs. Lower ribs also tended to exhibit larger deviations from the best-fit plane. The rib dimensions and trends with subject stature were found to be consistent with findings previously reported in the literature. This model addresses a critical need in the biomechanics literature for the accurate characterization of rib geometry, and can be extended to a larger population as a simple and accurate way to represent the centroidal shape of human ribs.

Towards the optimisation of acoustic fields for ablative therapies of tumours in the upper abdomen

The efficacy of high intensity focused ultrasound (HIFU) for the non-invasive treatment of cancer has been demonstrated for a range of different cancers including those of the liver, kidney, prostate and breast. As a non-invasive focused therapy, HIFU offers considerable advantages over other techniques such as chemotherapy and surgical resection, in terms of its non-invasiveness and low risk of harmful side effects. There is, however, a number of significant challenges which currently hinder its widespread clinical application. One of these challenges is the need to transmit sufficient energy through the ribcage to induce tissue necrosis at the required foci whilst minimising the formation of side lobes and sparing healthy tissue. Ribs both absorb and reflect ultrasound strongly. As such, a common side effect of focusing ultrasound in regions located behind the rib cage is the overheating of bone and surrounding tissue, which can lead to skin burns. Successful treatment of a patient with tumours in the upper abdomen therefore requires a thorough understanding of the way acoustic and thermal energy are deposited. This is likely to rely on a treatment planning procedure in which optimal source velocity distributions are obtained so as to maximise a dose quantity at the treatment sites, whilst ensuring that this quantity does not exceed a specified threshold at other field locations, particularly on the surface of the ribs. Previously, a boundary element approach based on a Generalised Minimal Residual (GMRES) implementation of the Burton-Miller formulation was developed to predict the field of a multi-element HIFU array scattered by human ribs, the topology of which was obtained from CT scan data [1]. This work describes the reformulation of the boundary element equations as a least-squares minimisation problem with non-linear constraints. The methodology was subsequently tested at an excitation frequency of 100 kHz on a spherical multi-element array in the presence of a perfectly rigid cylindrical scatterer with hemi-spherical end-caps. Reduction of side lobes in the exterior domain and of acoustic pressure magnitudes on the surface of the cylinder were achieved whilst preserving a local maximum in the focal region.

Computed Tomography Measurement of Rib Cage Morphometry in Emphysema

BackgroundFactors determining the shape of the human rib cage are not completely understood. We aimed to quantify the contribution of anthropometric and COPD-related changes to rib cage variability in adult cigarette smokers.MethodsRib cage diameters and areas (calculated from the inner surface of the rib cage) in 816 smokers with or without COPD, were evaluated at three anatomical levels using computed tomography (CT). CTs were analyzed with software, which allows quantification of total emphysema (emphysema%). The relationship between rib cage measurements and anthropometric factors, lung function indices, and %emphysema were tested using linear regression models.ResultsA model that included gender, age, BMI, emphysema%, forced expiratory volume in one second (FEV1)%, and forced vital capacity (FVC)% fit best with the rib cage measurements (R2 = 64% for the rib cage area variation at the lower anatomical level). Gender had the biggest impact on rib cage diameter and area (105.3 cm2; 95% CI: 111.7 to 98.8 for male lower area). Emphysema% was responsible for an increase in size of upper and middle CT areas (up to 5.4 cm2; 95% CI: 3.0 to 7.8 for an emphysema increase of 5%). Lower rib cage areas decreased as FVC% decreased (5.1 cm2; 95% CI: 2.5 to 7.6 for 10 percentage points of FVC variation).ConclusionsThis study demonstrates that simple CT measurements can predict rib cage morphometric variability and also highlight relationships between rib cage morphometry and emphysema.

Relationship between human rib mechanical properties and cortical bone density measured by high-resolution quantitative computed tomography

Thoracic injuries are among the most serious injuries in vehicle crash accidents. To improve the safety of vehicle occupants, it is essential to have a better knowledge on biomechanical responses of human rib cage (Vezin and Berthet 2009). A better knowledge of the bone mechanical properties should be of great interest to take into account the inter-individual differences in the population. For such purpose, a non-invasive technique is requested. Quantitative computed tomography (QCT) is a clinical modality that can be used to measure bone density. A literature review by Helgason et al. (2008) demonstrated that bone density (measured by QCT) was a good predictor of bone mechanical properties. Kopperdahl et al. (2002) and Duchemin et al. (2008) showed the relationships between bone density assessed by QCT and mechanical properties on vertebral cancellous bone and femoral cortical bone respectively. In this context, the question is: do such relationships exist on human ribs? No study has demonstrated such relationships on this anatomical site. Thus, the goal of this study is to assess the relationship between human rib mechanical properties and the density.

The Effects of Sterilization Methods on Lyophilized Cartilage Grafts in an Experimental Model

Cartilage graft is an effective method for reconstructing the bony framework of the face and covering the bony defect site. As a process method of cartilages, lyophilization has the advantages of long-term storage and easy handling. We hypothesized that the type of procedure used to sterilize lyophilized cartilage may affect outcomes after implantation into the body. We compared the effects of ethylene oxide (EO) gas, γ-irradiation, and autoclaving methods on cartilage grafts. After sterilization, lyophilized human rib cartilage was inserted into subperiosteal pockets created in New Zealand white rabbit skulls. We assessed the weights and ratios of the remaining cartilage and examined histologic changes throughout the implantation period. Over a 5-week period, the γ-irradiated grafts remained more than the other grafts, but after more than 5 weeks, there were no significant differences between γ-irradiated and EO gas-sterilized cartilages. Autoclave-sterilized cartilages were totally resorbed at 10 weeks. Over 10 weeks of follow-up, based on persistence measurements and histologic appearance, there was little difference between γ-irradiated and EO gas-sterilized lyophilized cartilage used in experimental bone grafts.

Scaling of Haversian canal surface area to secondary osteon bone volume in ribs and limb bones

Studies of secondary osteons in ribs have provided a great deal of what is known about remodeling dynamics. Compared with limb bones, ribs are metabolically more active and sensitive to hormonal changes, and receive frequent low-strain loading. Optimization for calcium exchange in rib osteons might be achieved without incurring a significant reduction in safety factor by disproportionally increasing central canal size with increased osteon size (positive allometry). By contrast, greater mechanical loads on limb bones might favor reducing deleterious consequences of intracortical porosity by decreasing osteon canal size with increased osteon size (negative allometry). Evidence of this metabolic/mechanical dichotomy between ribs and limb bones was sought by examining relationships between Haversian canal surface area (BS, osteon Haversian canal perimeter, HC.Pm) and bone volume (BV, osteonal wall area, B.Ar) in a broad size range of mature (quiescent) osteons from adult human limb bones and ribs (modern and medieval) and various adult and subadult non-human limb bones and ribs. Reduced major axis (RMA) and least-squares (LS) regressions of HC.Pm/B.Ar data show that rib and limb osteons cannot be distinguished by dimensional allometry of these parameters. Although four of the five rib groups showed positive allometry in terms of the RMA slopes, nearly 50% of the adult limb bone groups also showed positive allometry when negative allometry was expected. Consequently, our results fail to provide clear evidence that BS/BV scaling reflects a rib versus limb bone dichotomy whereby calcium exchange might be preferentially enhanced in rib osteons.

Paleodietary Analysis of Human Remains from a Hellenistic-Roman Cemetery at Camihöyük, Turkey

The presence of copper, zinc, magnesium, iron, lead, molybdenum, manganese and nickel was discovered on 22 human ribs in a Hellenistic-Roman cemetery located in the ancient city of Camihöyük, Turkey. The levels of each element found in the males were higher than those in females, except iron. Copper, magnesium, iron, molybdenum, and nickel levels were measured to be higher in the soil than in the skeletons, whereas the other elements were higher in the human skeletons. Lead was not traced in the soil, but on the skeletons. These individuals had probably been exposed to this element during their lives due to higher consumption of vegetables than meat.

Dynamic mechanical properties of human ribs

In order to characterise the mechanical behaviour of bones under various loading conditions, it is important to determine the effect of strain rate on the load carrying capacity and fracture behaviour of various members of our skeletal system. This study aims to understand the mechanical behaviour of human thoracic ribs through the application of a variety of strain rates. In this experiment, embalmed ribs were tested in a three-point bending mode under three different rates of deformation ranging from 0.05 to 8 mm/s. Mechanical parameters such as maximum bending moment, maximum deformation, bending stiffness and energy absorption capacity were determined. The maximum bending moment and stiffness showed an increase by 53% and 8%, respectively, at the highest rate of deformation compared to the lowest. The ultimate deformation and energy absorbed also increased by 26% and 66%, respectively, in this range of deformation rate. This data confirm that bone is viscoelastic in nature and exhibits different mechanical properties that are a function of strain rate.

Histological Estimation of Age at Death from the Compact Bone of Burned and Unburned Human Ribs

This study describes the estimation of age at death from the compact bone of burned and unburned human ribs. Bone samples came from individuals of known age, sex, and cause of death. Each bone was divided into four sections; three sections were burned at 700, 800, and 1000°C. Undecalcified, unstained ground cross sections were photographed, and 28 variables were analyzed in the bones using SigmaScan Pro 5. Age-related as well as heat-induced microstructural changes were found. These changes were often very similar and made estimating the age at death difficult in the burned bones. Differences between the sexes were found in some variables, caused by both aging and also by the different behavior of some variables during burning. Regression equations were developed to estimate age at death for unburned bones (r² = 0.579 and 0.707), bones burned at 700°C (r² = 0.453 and 0.501), and 800°C (r² = 0.334 and 0.340).

The optimization of acoustic fields for ablative therapies of tumours in the upper abdomen

High intensity focused ultrasound (HIFU) enables highly localized, non-invasive tissue ablation and its efficacy has been demonstrated in the treatment of a range of cancers, including those of the kidney, prostate and breast. HIFU offers the ability to treat deep-seated tumours locally, and potentially bears fewer side effects than more invasive treatment modalities such as resection, chemotherapy and ionizing radiation. There remains however a number of significant challenges which currently hinder its widespread clinical application. One of these challenges is the need to transmit sufficient energy through the ribcage to ablate tissue at the required foci whilst minimizing the formation of side lobes and sparing healthy tissue. Ribs both absorb and reflect ultrasound strongly. This sometimes results in overheating of bone and overlying tissue during treatment, leading to skin burns. Successful treatment of a patient with tumours in the upper abdomen therefore requires a thorough understanding of the way acoustic and thermal energy is deposited. Previously, a boundary element approach based on a Generalized Minimal Residual (GMRES) implementation of the Burton–Miller formulation was developed to predict the field of a multi-element HIFU array scattered by human ribs, the topology of which was obtained from CT scan data (Gélat et al 2011 Phys. Med. Biol. 56 5553–81). The present paper describes the reformulation of the boundary element equations as a least-squares minimization problem with nonlinear constraints. The methodology has subsequently been tested at an excitation frequency of 1 MHz on a spherical multi-element array in the presence of ribs. A single array–rib geometry was investigated on which a 50% reduction in the maximum acoustic pressure magnitude on the surface of the ribs was achieved with only a 4% reduction in the peak focal pressure compared to the spherical focusing case. This method was then compared with a binarized apodization approach based on ray tracing and against the decomposition of the time-reversal operator (DORT). In both cases, the constrained optimization provided a superior ratio of focal peak pressure to maximum pressure magnitude on the surface of the ribs.

Stress analysis of a centrally fractured rib fixated by an intramedullary screw

The stress on an intramedullary screw rib fixation device holding together a centrally fractured human rib under in vivo force loadings was studied using finite element analysis (FEA). Validation of the FEA modelling using pullout from porcine ribs proved FEA to be suitable for assessing the structural integrity of screw/bone systems such as rib fixated by a screw. In the human rib fixation investigation, it was found that intramedullary bioresorbable Bioretec screws can fixate centrally fractured human ribs under normal breathing conditions. However, under coughing conditions, simulation showed Bioretec fixating screws to bend substantially. High stresses in the screw are mainly the result of flexion induced by the force loading, and are restricted to thin regions on the outside of the screw shaft. Stiffer screws result in less locally intense stress concentrations in bone, indicating that bone failure in the bone/screw contact regions can be averted with improvements in screw stiffness.

The temperature of cremation and its effect on the microstructure of the human rib compact bone

The presented study deals with the effect of the cremation temperature on the microstructure and morphology of the human compact bone. The biological material consisted of samples from ribs of recent Central European origin belonging to individuals of known age, sex and cause of death. Each bone sample was divided into several sections. One section remained unburned and the rest were burned at 700, 800 and 1000 degrees C. A few samples were burned also at the temperature of 600 degrees C. The undecalcified unstained ground cross-sections were made from burned and unburned bones; photographed and analysed using the SigmaScan Pro 5 programme. During burning, both the macroscopic and microscopic dimensions of the bone shrink, including the measures of the individual microstructures. The percentual representation of the area of individual microstructures on the area of the cross-section decreases. The number of individual microstructures per mm2 of the compact bone cross-section increases. Most microstructural variables demonstrated statistically significant differences at the individual temperatures of cremation. The burned bones showed a large scale of the colours, especially at 700 degrees C.

AGE-RELATED CHANGES IN MECHANICAL PROPERTIES OF HUMAN RIBS

Knowledge of thoracic biomechanics is important for complete examination and understanding of chest behaviour under conditions of physiological and pathological work, and under the impact of external forces leading to traumatic loading of the chest [Kent,2005]. The purpose of the study was to analyse the mechanical properties of human ribs obtained from individuals under 22 years of age and their correlation with age and level of the examined rib.