Natural Joint Research Articles

Selection of high-strength dimension stone cutting method, considering natural jointing

The authors prove feasibility and efficiency of high-strength stone wire saw cutting in rock mass with subvertical and low-angle joints as well as drilling-and-wedge cutting of stone into marketable size blocks on the working site. The article presents and substantiates the procedure for rational selection of technology for high-strength stone preparation for cutting, considering geological conditions (shape of mineral body, orientation and spacing of joints), local temperature, as well as physico-mechanical properties and mineralogical composition of rocks.

Modelling and analysis of a synovial joint

Synovial joint is a joint, which is placed between bones and enclosed in a capsule of thick slippery liquid called synovial fluid. These joints are articulated to move freely between bones. These are widely used in medical applications when joints between bones are broken or damaged due to some other reasons. There are structural and functional defects that will distinguish synovial joint and natural joint such as strength, durability and lubricity. Owing to these defects in the knee joint forces like knee contact force, muscle co–contraction and ligament forces are increasing and causing damage to the knee joint. Many people are suffering with joint diseases and other types such as bone fracture and to mitigate it a mechanical component is designed to replace the knee joint. Therefore, the stress distribution on various knee joint designs is performed and discussed on various defects that affect it so that the possible defects can be reduced.

A coupled experimental and numerical simulation of rock slope joints behavior

In this research, a coupled numerical-experimental analysis of crack propagation, crack coalescence, and breaking process of jointed rock slopes is performed by studying the mechanical behavior of pre-cracked brittle substances considering the specially prepared rock-like specimens (rock-like specimens are specially prepared by a proper mixing of Portland Pozzolana Cement (PPC), fine sand, and water in a rock mechanics laboratory) and natural rock slopes, simultaneously. The numerical analyses are accomplished using a numerical code based on the higher-order displacement discontinuity method (HODDM). A cubic displacement discontinuity variation along each boundary element is assumed to evaluate the mode I and mode II stress intensity factors (SIFs). Based on the LEFM theory, the maximum tangential stress criterion is implemented in the proposed code for predicting the crack initiation and its direction of propagation (crack coalescence path). Experimental tests are accomplished to evaluate the crack propagation process, crack coalescence, and final breakage path of rock-like specimens containing three parallel cracks (simulating the natural joint set in a rock slope). There is a good agreement between the numerical and experimental results obtained from the tested specimens demonstrating the accuracy and effectiveness of the proposed approach.

Lamellar slippage of bilayers--a hypothesis on low friction of natural joints.

The cartilage's amphoteric surface behavior is a physical phenomenon in biological lubrication. However, there is a lack of knowledge on amphoteric phospholipids bilayers and in overcoming friction in cartilage joints. In this paper, friction experiments were conducted, and the cartilage's surface was characterized using pH and wettability, while the interfacial energy and coefficients were determined. The lamellar slippage of bilayers and a short-range repulsion between the interfaces of negatively charged (-PO4 (-)) cartilage surfaces resulted in low frictional properties of the joint.

The O-glycomap of Lubricin, a Novel Mucin Responsible for Joint Lubrication, Identified by Site-specific Glycopeptide Analysis

The lubricative, heavily glycosylated mucin-like synovial glycoprotein lubricin has previously been observed to contain glycosylation changes related to rheumatoid and osteoarthritis. Thus, a site-specific investigation of the glycosylation of lubricin was undertaken, in order to further understand the pathological mechanisms involved in these diseases. Lubricin contains an serine/threonine/proline (STP)-rich domain composed of imperfect tandem repeats (EPAPTTPK), the target for O-glycosylation. In this study, using a liquid chromatography–tandem mass spectrometry approach, employing both collision-induced and electron-transfer dissociation fragmentation methods, we identified 185 O-glycopeptides within the STP-rich domain of human synovial lubricin. This showed that adjacent threonine residues within the central STP-rich region could be simultaneously and/or individually glycosylated. In addition to core 1 structures responsible for biolubrication, core 2 O-glycopeptides were also identified, indicating that lubricin glycosylation may have other roles. Investigation of the expression of polypeptide N-acetylgalactosaminyltransferase genes was carried out using cultured primary fibroblast-like synoviocytes, a cell type that expresses lubricin in vivo. This analysis showed high mRNA expression levels of the less understood polypeptide N-acetylgalactosaminyltransferase 15 and 5 in addition to the ubiquitously expressed polypeptide N-acetylgalactosaminyltransferase 1 and 2 genes. This suggests that there is a unique combination of transferase genes important for the O-glycosylation of lubricin. The site-specific glycopeptide analysis covered 82% of the protein sequence and showed that lubricin glycosylation displays both micro- and macroheterogeneity. The density of glycosylation was shown to be high: 168 sites of O-glycosylation, predominately sialylated, were identified. These glycosylation sites were focused in the central STP-rich region, giving the domain a negative charge. The more positively charged lysine and arginine residues in the N and C termini suggest that synovial lubricin exists as an amphoteric molecule. The identification of these unique properties of lubricin may provide insight into the important low-friction lubricating functions of lubricin during natural joint movement.

The Probable Explanation for the Low Friction of Natural Joints.

The surface of an articular cartilage, coated with phospholipid (PL) bilayers, plays an important role in its lubrication and movement. Intact (normal) and depleted surfaces of the joint were modelled and the pH influence on the surface interfacial energy, wettability and friction were investigated. In the experiments, the deterioration of the PL bilayer was controlled by its wettability and the applied friction. The surrounding fluid of an undamaged articular cartilage, the synovial fluid, has a pH value of approximately 7.4. Buffer solutions were formulated to represent the synovial fluid with various pH values. It was found that the surface interfacial energy was stabilised at its lowest values when the pH varied between 6.5 and 9.5. These results suggested that as the PL bilayers deteriorated, the hydration repulsion mechanism became less effective as friction increased. The decreased number of bilayers changed the wettability and lowered PL lubricant properties.

Preservation of the PCL when performing cruciate-retaining TKA: Is the tibial tuberosity a reliable predictor of the PCL footprint location?

Reconstruction of the joint line is crucial in total knee arthroplasty (TKA). A routine height of tibial cut to maintain the natural joint line may compromise the preservation of the PCL. Since the PCL footprint is not accessible prior to tibial osteotomy, it seems beneficial to identify a reliable extraarticular anatomic landmark for predicting the PCL footprint and being visible within standard TKA approach. The fibula head predicts reliably the location of PCL footprint; however, it is not accessible during TKA. The aim of this study now was to analyze whether the tibial tuberosity can serve as a reliable referencing landmark to estimate the PCL footprint height prior to tibial cut. The first consecutive case series included 216 CR TKA. Standing postoperative lateral view radiographs were utilized to measure the vertical distance between tibial tuberosity and tibial osteotomy plane. In the second case series, 223 knee MRIs were consecutively analyzed to measure the vertical distance between tibial tuberosity and PCL footprint. The probability of partial or total PCL removal was calculated for different vertical distances between tibial tuberosity and tibial cutting surface. The vertical distance between the tibial tuberosity and tibial cut averaged 24.7 ± 4 mm. The average vertical distance from tibial tuberosity to proximal and to distal PCL footprint was found to be 22 ± 4.4 and 16 ± 4.4 mm, respectively. Five knees were considered at 50% risk of an entire PCL removal after CR TKA. Current surgical techniques of tibial preparation may result in partial or total PCL damage. Tibial tuberosity is a useful anatomical landmark to locate the PCL footprint and to predict the probability of its detachment pre-, intra-, and postoperatively. This knowledge might be useful to predict and avoid instability, consecutive pain, and dissatisfaction after TKA related to PCL insufficiency. III.

Assessing joint line positions by means of the contralateral knee: a new approach for planning knee revision surgery?

Reconstructing the natural joint line in knee revision surgery improves clinical and functional outcome but may be challenging when both cartilage and bone were removed during previous operations. Assessing joint lines (JLs) by means of bony landmarks is inadvisable because of large variations in human anatomy. Because of the inherent symmetry of the human body, we hypothesised that JLs may be directly assessed by measuring the distances from the bony landmarks to the JL of the contralateral knee by means of radiographic images. Using scaled weight-bearing radiographs in anteroposterior view of both knees, two independent observers measured the distances from the fibular head, the medial and lateral epicondyle, and the adductor tubercle to the JL. A two-sided p value of ≤0.05 was considered statistically significant. Two hundred knees of 100 patients (50 men and 50 women) were examined. For the fibular head, the mean difference between the treated and the control knee was 0.0 mm with narrow confidence limits ranging from -1.1 to 1.1. As a new assessment method, we have suggested to assess the JL by means of radiographs of the contralateral knee. The most precise parameter was found to be the distance between the fibular head and the JL. The level of arthritis, age, gender, visibility of the landmarks, and misalignment did not influence measurement accuracy. This parameter is the first tibia-related landmark for assessing the JL, which advantageously corresponds to the tibia-first technique in revision surgery. Diagnostic Study, Level II.

Underground rockfall stability analysis using the numerical manifold method

The present study applies the numerical manifold method (NMM) as a tool to investigate the rockfall hazard in underground engineering. The crack evolution technique with crack initiation and propagation criterion, which has been successfully applied to handle cracking problems in rocks, is used in this study. A rockbolt element is introduced, which is first validated by a simple case. The mechanism of the rockbolt in reinforcing a layered rock mass is then investigated through a four-layered rock beam example. The developed NMM is then used to investigate the rockfall instability caused by either natural joints or mining induced fractures in an underground power station house or a tunnel. The results illustrate that the developed NMM can not only capture the entire dynamic process of the rockfall but also locate the keyblock successfully. As such, corresponding reinforcement methods can be chosen reasonably.

Study on the Feasibility of SRV in Coal Reservoir

In our country there is plenty of CBM (coalbed methane), but the state of CBM itself, unique output mechanism and low saturation, low permeability, low reservoir pressure and high gas content, et al. determine the low efficiency of it, so in order to improve CBM recovery, combined with the successful experience of north American shale gas reservoir by SRV(stimulated reservoir volume), the writer summarizes the implementation of SRV, deeply analyzes effectiveness and limitations of this new technology in CBM development. The results of practical research and theoretical analysis show that SRV in the coal reservoir can achieve the desired effect on the condition that there are great quantity of natural fractures, joints and bedding, weak structure surface development in the reservoir, the rock brittleness index is greater than 40 and horizontal principal stress difference is relatively smaller. Finally, simulating a well’s condition by the MEYER software, the result shows that SRV is feasible in coal reservoir, which will create important guiding significance and practical value for the exploration of CBM.

Shear strength of rock joints influenced by compacted infill

Discontinuities such as fault planes, joints and bedding planes in a rock mass may be filled with different types of fine-grained material that are either transported or accumulated as gouge due to weathering or joint shearing. Previous laboratory studies have mainly examined the role of saturated infill that exhibits the minimum shear strength. However, in practice, the infill materials are often partially saturated generating matric suction within the joint that can contribute to increased shear strength. To the authors’ knowledge this is the first study to examine the influence of compacted (unsaturated) infill on the joint shear strength. A series of laboratory triaxial tests on idealised model joints and imprinted natural joint profiles was carried out, with constant water contents of the infill being maintained. From the laboratory results, it is observed that the peak shear strength of infilled joints increased with the decrease of degree of saturation from 85% to 35% for both idealised joints and replicated natural joints. Based on the laboratory observations an empirical model for describing the infilled joint shear strength was developed.

SOME GEOMETRICAL DATA FOR THE ELLIPTICAL BEARINGS IN ARTIFICIAL ROBOTS

In this paper are considered analogies between elliptical-slide bearing occurring in artificial robots and elliptical natural human joints as well artificial human femoral prosthesis. The comparisons between elliptical human femoral prosthesis and mechanical spherical bearings indicate the advantages implicated from the use of elliptical slide bearings. To

Comparison of stability and kinematics of the natural knee versus a PS TKA with a ‘third condyle’

The goal of this study was to compare the kinematics of knees before and after total knee arthroplasty (TKA) that relies on an inter-condylar 'third condyle'. The hypothesis was that the 'third condyle' provides sufficient flexion stability and induces a close to normal femoral rollback, thus granting natural joint kinematics. Intra-operative navigation data were collected from 29 consecutive cases that received a cemented TKA (HLS Noetos, Tornier SA, France) designed with an inter-condylar 'third condyle' that engages within the tibial insert beyond 35° flexion. Operations were guided by a non-image-based system (BLU-IGS, Orthokey Italia srl, Italy) that recorded relative femoral and tibial positions in native and implanted knees during: passive range of motion, anterior drawer test at 90° flexion, and varus-valgus stress tests at full extension and at 30° flexion. The total internal tibial rotation during flexion was similar for native (8.2 ± 4.2°) and implanted knees (8.0 ± 5.4°). The lateral femoral condyle was more posterior in implanted knees (1.2 ± 9.4 mm) than in native knees (9.5 ± 3.6 mm) throughout early flexion (p < 0.01), but this difference diminished beyond 100° flexion (n.s.). The implanted knees did not exhibit paradoxical external tibial rotation. Varus-valgus laxity in full extension was lower for implanted knees than for native knees (p = 0.0221), but at 30° flexion was almost identical for both native and implanted knees. Anteroposterior laxity was similar in implanted and native knees. The 'third condyle' TKA provides similar anteroposterior and mediolateral stability to the natural knee. This feature granted an adequate balance between laxity and constraint to reproduce natural joint kinematics, including smooth femoral rollback, without causing paradoxical external tibial rotation.

Modelling and monitoring of passive control structures in human movement

Passive tissues, ligaments and cartilage are vital to human movement. Their contribution to stability, joint function and joint integrity is essential. The articulation of their functions and quantitative assessment of what they do in a healthy or injured state are important in athletics, orthopaedics, medicine and health. In this paper, the role of cartilage and ligaments in stability of natural contacts, connections and joints is articulated by including them in two very simple skeletal systems: one- and three-link rigid body systems. Based on the Newton–Euler equations, a state space presentation of the dynamics is discussed that allows inclusion of ligament and cartilage structures in the model, and allows for Lyapunov stability studies for the original and reduced systems. The connection constraints may be holonomic and non-holonomic depending on the structure of the passive elements. The development is pertinent to the eventual design of a computational framework for the study of human movement that involves computer models of all the relevant skeletal, neural and physiological elements of the central nervous system (CNS). Such a structure also permits testing of different hypotheses about the functional neuroanatomy of the CNS, and the study of the effects and dynamics of disease, deterioration, aging and injuries. The formulation here is applied to one- and three-link systems. Digital computer simulations of a two rigid body system are presented to demonstrate the feasibility and effectiveness of the approach and the methods.

Accuracy of bony landmarks for restoring the natural joint line in revision knee surgery: an MRI study

Restoring the joint line (JL) improves clinical and functional outcome in total knee arthroplasty (TKA). Therefore, anatomical landmarks to approximate the JL have been published. So far, the natural deviation of the JL 90° to the mechanical tibial axis has not been considered. Thus, we designed this study to: (1) determine the natural JL of knees in healthy persons in respect to the mechanical tibial axis, (2) validate and double-check intra-operative bony landmarks already been published in respect to the natural JL and (3) find possible correlations between distances from bony landmarks to the JL and femoral and tibial width. Eighty MRI scans of knees of healthy persons were examined by two independent observers. Distances from the tip of the fibular head (FH), the medial (ME) and lateral (LE) epicondyles and the adductor tubercle (AT) to the JL within the medial and lateral compartment were measured. Further, we determined the orientation of the JL in respect to the mechanical axis of the tibia. Interobserver correlations were calculated. Differences were analyzed using Student's t test. Linear regression models were calculated to analyze correlations. Interobserver correlation was excellent. Mean JL deviation was 4.2° varus. Distance between the FH, ME, LE and AT to the JL within the medial compartment was 12.2, 33.9, 33.4 and 45.4 mm, respectively. Within in the lateral compartment, distances were 15.3, 31.0, 30.6 and 42.3 mm to the JL. Strong correlation was found between femoral width and distances from the AT, ME and LE to the JL. In TKA, the JL is usually altered due to the classic resection technique, which does not respect the natural deviation of the JL. Estimating the natural JL by adding absolute values to bony landmarks, as proposed in the literature, is not recommended. According to our data, the JL can be best estimated by adding the calculated value: 6.40 + (width femur [mm] × 0.49) to the AT.

Non-union fracture neck femur in a young patient

An 18-year-old boy fell 1 year ago from a tree and sustained righthip injury,whichwas treatedby traction.Atpresentation, 15 years ago, hehadpain, deformity and 300 shortening andwas unable tobearweighton right leg.X-rayof the righthip showed non-union with resorption of neck of femur and proximal migration of femur (Fig. 1), but the head seemed viable. A corrective valgus osteotomy with the fixation of fracture was done using a Dynamic Hip Screw (DHS)with a 135 angle 4 hole plate. The patient did very well and both the osteotomy and fracture united without any avascular necrosis of the femoral head (Fig. 2). At 15 years follow up, the patient came for a routine implant removal (Fig. 3), when he was totally asymptomatic and has had only 1 cm of residual shortening of right hip and almost full range of hip movements. The implants were removed without any significant event (Fig. 4). Fracture neck of femur in young is rare and usually occur due to severe injuries like road traffic accident (RTA), fall from height etc. If the displaced fractures are not treated early then it is often associated with complications. Non-union is one of the commonest complications. Treatment of non-union of these fractures in young is quite challenging. An attempt to save the natural femoral head and hip joint is a priority and hence corrective valgus osteotomy with fixation of the fracture with stable implant is a good choice and may achieve union and preserve the natural hip joint, as it was in our case. Joint replacement may be a secondary choice but considering the young age of these patients, an attempt to fix the fracture along with a corrective osteotomymust be considered first, as it may preserve a natural hip joint.

Influence of surface PMPC brushes on tribological and biocompatibility properties of UHMWPE

Extremely efficient lubrication has been observed between natural joint surfaces and the friction coefficients can reach as low as 0.001. However, attaining the ultra-low friction coefficients between articulating cartilage surfaces in any artificial joints remains a challenge for bio-tribologists. In order to obtain the ultra-low friction coefficients as in natural joints, a biomimetic zwitterionic monomer 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted on the ultra high molecular weight polyethylene (UHMWPE) by UV radiation and self-polymerized to form brush-like structure. The results of total reflection (FT-IR/ATR) spectra and X-ray photoelectron spectroscopy (XPS) spectra indicated successful grafting of PMPC on to the UHMWPE surface (Polymerization of 2-methacryloyloxyethyl phosphorylcholine). The water contact angle of UHMWPE decreased from 80° to 15° after grafting PMPC for 45min. Tribological properties were tested under high contact stress for a longer duration of time. The friction coefficient of the sample grafted with PMPC was found to be much lower than that of untreated UHMWPE at initial stage which increased gradually with the increase of the cycle till it attained the same level as that observed for untreated UHMWPE. The wear rate of modified samples was decreased by 37% and 46% in distilled water and saline, respectively. The highly hydrated PMPC layer provided efficient lubrication at the interface between the sliding couple leading to wear reduction of UHMWPE. Furthermore, blood compatibility of modified artificial joint materials was improved significantly, which has been attributed to the properties and structures of PMPC grafted on the UHMWPE surface.

C211 ゴルフスイング時における生体膝および生体股関節の動態解析(C2-2 生物工学,動態解析)

C211 ゴルフスイング時における生体膝および生体股関節の動態解析(C2-2 生物工学,動態解析)

Benefits of hyperbaric oxygen therapy in a patient with multifocal osteonecrosis mimicking septic arthritis.

Osteonecrosis is a progressive disease characterized with bone damage. Glucocorticosteroids, which are used in treatment of many diseases, are believed to be the most important reason for development of non-traumatic osteonecrosis. Osteonecrosis(ON) generally does not affect multiple joints simultaneously and mimic septic arthritis. In this article, we reported a 48-year-old woman with osteonecrosis who received glucocorticosteroids due to autoimmune hepatitis. The onset of the osteonecrosis was mimicking septic arthritis with multiple joint involvements after corticosteroid therapy. Physical examination; there was mild erythema, effusion, warmth, and diffuse tenderness on palpation in bilateral ankles and knees. Significantly intensity changes were compatible with ON in the femur and the tibia, increased fluid in the knee joint and edema in muscle groups and fatty tissue that are around the knee joint were seen on MRI. Other tests were negative for artiritis.Hyperbaric oxygen treatment was used effectively for the treatment of the patient. Patient's complaint of pain was ceased acoording to Visual Analogue Scale and she did no need to much painkiller. The main purpose of the treatment of ON is intended to protect the patient's natural joint structure. HBO and other medical approaches were provided benefit to patients with ON. Because HBO restores tissue oxygenation, reduces oedema, and induces angioneogenesis. By reducing the intraosseous pressure, venous drainage is restored, and the microcirculation is improved.

Equivalence and dynamic analysis for jointed trusses based on improved finite elements

Deployable trusses that are widely applied in space missions utilize many hinged members to adapt to different geometrical shapes and work conditions. This paper presents two improved finite elements for a link and a bending beam to calculate dynamic characteristics of non-jointed and jointed trusses. First, the axial and transverse wave motion equations of a beam are used to get the shape functions of the link and the beading beam in their axial and transverse directions. Second, the dynamic matrices of stiffness and mass for a link and a bending beam are established on the basis of virtual work principle. The dynamic matrix and a theoretical equation are used to calculate the natural frequency of a cantilever bar. The comparison of the two results shows the effectiveness of the dynamic stiffness matrix. These improved elements are proved to be more accurate in calculating the responses of structures at high frequencies than common elements. Equivalent models of non-jointed and jointed structures are obtained on the basis of the displacement and strain energy equivalence of a truss unit. The result of the period truss confirms the accuracy of the equivalent model of the non-jointed truss expressed by dynamic matrices. The dynamic influences of cubic joints on a jointed structure are evaluated by giving the simulations of the equivalent jointed structure based on improved matrices. The results indicate that the natural frequencies of the jointed structure increase with the excitation force and the stiffness of joints. A relational function among the natural frequencies, joint stiffness, and excitation force is also presented.