Natural Joint Research Articles

Experimental Investigation of Anisotropic Wear Damage for Natural Joints under Direct Shearing Test

AbstractThe anisotropic morphology of natural joints always affects their shear behavior. This experimental study aimed at exploring the anisotropic wear damage of asperities for natural joints und...

Patient satisfaction related outcome after total hip arthroplasty; does bearing surface play a role?

BackgroundThe aim of this study was to compare the functional outcome, the patient’s perception of the replaced hip joint with different bearing surfaces and to study the effect of femoral head size on joint perception as well. MethodsOne hundred and ten (110) patients, who underwent primary total hip replacement with an average follow-up of 48 months (12–156 months), were assessed for their functional outcome and joint perception. The functional outcome was calculated based on Oxford hip score (OHS) and SF-36. Joint perception was categorized as to whether the replaced joint was perceived like a natural joint or artificial joint with or without restriction of movements. ResultsThere were 50 patients operated for ceramic on ceramic (CoC-hard-on-hard bearing), 60 patients for hard-on-soft bearing (Metal on Polyethelene-MoP 46, Ceramic on Polyethelene-CoP 14). Most of the patients with hard-on-hard bearings perceived their operated hip like a natural joint (p = 0.04) compared to hard-on-soft bearings. There was no significant difference in the functional outcome (OHS, SF-36) between the two bearing surface groups (p > 0.05). There were fifty patients with 28 mm size head while remaining 60 had larger heads (>32 mm). Patients with large heads felt like natural joint compared to small heads (p = 0.007). ConclusionThe hard-on-hard bearing surfaces (CoC) and large femoral heads (32 mm, 36 mm) are perceived more like a natural joint. Different bearing surfaces do not affect the functional outcome after total hip replacement in a medium term follow up.

Acoustic Emission Characteristics and Failure Prediction of the Granite with Orthogonal Cracks under Compressive Loading

Natural joints existing in rock significantly affect the stability of long‐term served subsurface engineering. In this paper, granite specimens with two orthogonal cracks were made for uniaxial compressive tests. The acoustic emission monitoring (AE) and digital image correlation techniques were employed to record the acoustic events and cracking of rock. The stress, ring‐down count, and cumulative ring‐down count of AE during the tests were obtained. The b‐value of AE was calculated based on the magnitude and number of AE events. The relationship between the b‐value and rock cracking for the specimens with orthogonal cracks was discussed. Further, the effects of orthogonal cracks distribution on the b‐value and rock cracking were investigated. Experimental results show that the specimens with orthogonal cracks would undergo multiple cycles of energy accumulation‐release‐reaccumulation‐rerelease under the uniaxial compression. For the specimens with orthogonal cracks, the b‐value of AE was volatile but generally decreased until complete failure. Every cracking event during the loading made the b‐value drop and then the reaccumulation of energy made the b‐value increase or stable. The specimen with orthogonal cracks was more prone to initial cracking than the intact rock. The orientation of cracks had effects on the b‐value evolution and crack patterns. The b‐value reaching about 1.5 can be used as the failure precursor of specimens with orthogonal cracks.

Alternating view in controversial treatment of osteoarthritis of knee (Restoknee vs TKR)

The osteoarthritis of knee is a wide spread condition worldwide and specially in country like India where the routine life is such where knee joint arthritis occurs at an early age. The widely used treatment option for knee arthritis is total knee replacement which have its own complication and once the complication like infection sets in we are left with nothing but to do arthrodesis or revision knee after controlling infection which cause a lot of problem for the patient as well as doctors. And moreover if total knee replacement done at an early age predisposes the patient to revision surgery as the life of the joint used is not more than life expectancy of the patient this puts a surgical toll over patient as well as financial load. Here we have compared our technique of treating osteoarthritis wherein we are preserving the natural joint and no implant are used in our technique which in itself reduced the major complications and even if by any chance complication occurs we are left with many options to give functional knee to the patient rather than going for arthrodesis which is not very well accepted by many patients. In this article we have compared pros and cons of our technique with total knee replacement.

Influencing Factors for Joint Perception After Total Hip Arthroplasty: Asian Cohort Study

BackgroundPerceiving replaced joints as natural is one of the best scenario after total hip arthroplasty (THA). We investigated the distribution of and influencing factors for patient’s joint perception after THA in Asian cohort, which is not well known. MethodsWe mailed a questionnaire to Asian patients who had undergone THA in our institution between 2012 and 2016, and this study included 318 Asian patients. The questionnaire assessed patient’s joint perception, Oxford Hip Score (OHS), Short Form-12 Health Survey (SF-12) physical, mental, and role component summaries, and satisfaction score. Leg length discrepancy and global femoral offset before and after THA were measured using radiographs. The patients were divided into 2 groups with patient’s joint perception: natural and artificial perception groups. OHS, SF-12, satisfaction, leg length discrepancy, and global femoral offset were compared between natural and artificial perception groups, and which factors significantly influenced joint perception were determined. ResultsOf the 318 patients, 165 patients (51.8%) perceived their replaced joint as a natural joint. OHS, SF-12 physical and role component summaries, and satisfaction score in natural perception group were significantly higher than those in artificial perception group, without significant difference in SF-12 mental component summary. Multivariate analysis showed that less of usual pain, easier to get in or out of a car, and osteoarthritis in the contralateral hip were positively associated with natural joint perception after THA. ConclusionThis study indicated to surgeons that pain relief and improvement in getting in or out of a car after THA could lead to even better patient’s joint perception.

An enhanced index for evaluating natural joint roughness considering multiple morphological factors affecting the shear behavior

Accurate description of joint morphology is a key issue for understanding natural joint’s shear behavior and estimating its shear strength. Five sets of joint specimens with different morphological characteristics are shearing tested under different normal loads. These test results reveal that three factors, i.e., inclination angle, asperity height, and morphology of the joint back slope along the shear direction, significantly affect shear behavior. Considering the affecting mechanism of these three factors on joint’s shear behavior, a new index, named shear roughness coefficient (SRC), is proposed to accurately estimate the shear strength of rock joints. With the help of this new index, the classical JRC-JCS shear strength model can be extended from 2D to 3D surface of natural joint, which can improve estimation accuracy and reflect the shearing direction effect on joint’s shear strength.

A method for the assessment of the coefficient of friction of articular cartilage and a replacement biomaterial

Replacement biomaterials for articular cartilage should encourage a coefficient of friction similar to the natural joint. Whilst the literature has assessed the coefficient of friction of articular cartilage against that of a potential biomaterial, it is unknown what the friction of articular cartilage in sliding against a surface defect, repaired with a biomaterial is. This evaluation is crucial to allow for the development of effective biomaterials to closely have the behaviour of articular cartilage. Thus, the aim of this study was to develop a novel technique for the assessment of the coefficient of friction of replacement biomaterials within articular cartilage, with this original testing configuration. For this study, a biomaterial was induced within an artificial defect perforated on the surface of bovine articular cartilage, whilst the material was assessed in sliding against articular cartilage itself. Calcium alginate was selected as the sample biomaterial for evaluation in this study. The tests were performed in sliding on a pin-on-disc tribometer in Ringer's solution. Two further tests were carried out, one as a benchmark comparison of a cartilage pin against a cartilage plate, as well as a cartilage pin against an aluminium plate. A constant induced stress of 0.06 MPa was applied at a frequency of 1 Hz. For the cartilage-cartilage, cartilage/hydrogel-cartilage and cartilage-aluminium test, the overall median coefficient of friction extracted across six repeats was of 0.36, 0.38 and 0.32, respectively. Statistical insignificance was identified across all three groups tested (p > 0.05). Similarity was observed in the coefficient of friction of cartilage-cartilage and cartilage/hydrogel-cartilage tests, however high-speed data identified the greatest wear for the cartilage/hydrogel-cartilage test.

Perception of a Natural Joint After Total Knee Arthroplasty

BackgroundAssessing patients’ functional outcomes following total knee arthroplasty (TKA) with traditional scoring systems is limited by their ceiling effects. Patient’s Joint Perception (PJP) question of the reconstructed joint is also of significant interest. Forgotten Joint Score (FJS) was created as a more discriminating option. The actual score constituting a “forgotten joint” has not yet been defined. The primary objective of this study is to compare the PJP and the FJS in TKA patients to determine the FJS score that corresponds to the patient’s perception of a natural joint. MethodsOne hundred TKAs were assessed at a mean of 40.6 months of follow-up using the PJP question, FJS, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Correlation between the 3 scores and their ceiling effects were analyzed. ResultsWith PJP question, 39% of the patients perceived a natural joint (FJS: 92.9; 95% confidence interval [CI], 89.4-96.4), 12% an artificial joint with no restriction (FJS: 79.5; 95% CI, 65.7-93.3), 36% an artificial joint with minor restrictions (FJS: 70.0; 95% CI, 63.2-76.9), and 13% had major restrictions (FJS: 47.3; 95% CI. 32.8-61.7). PJP has a high correlation with FJS and WOMAC (Spearman’s rho, −0.705 and −0.680, respectively). FJS and WOMAC had a significant ceiling effect with both reaching the best possible score in >15%. ConclusionPatients perceiving their TKA as a natural knee based on PJP have a FJS ≥89. PJP has a good correlation with FJS and may be a shorter, simple, and acceptable alternative.

Finite Element Analysis of Different Hip Implant Designs along with Femur under Static Loading Conditions.

Background: The hip joint is the largest joint after the knee, which gives stability to the whole human structure. The hip joint consists of a femoral head which articulates with the acetabulum. Due to age and wear between the joints, these joints need to be replaced with implants which can function just as a natural joint. Since the early 19th century, the hip joint arthroplasty has evolved, and many advances have been taken in the field which improved the whole procedure. Currently, there is a wide variety of implants available varying in the length of stem, shapes, and sizes. Material and Methods: In this analytical study of femur, circular, oval, ellipse and trapezoidal-shaped stem designs are considered in the present study. The human femur is modeled using Mimics. CATIA V-6 is used to model the implant models. Static structural analysis is carried out using ANSYS R-19 to evaluate the best implant design. Results:All the four hip implants exhibited the von Mises stresses, lesser than its yielded strength. However, circular and trapezoidal-shaped stems have less von Mises stress compared to ellipse and oval. Conclusion:This study shows the behavior of different implant designs when their cross-sections are varied. Further, these implants can be considered for dynamic analysis considering different gait cycles. By optimizing the implant design, life expectancy of the implant can be improved, which will avoid the revision of the hip implant in active adult patients.

Characterizing carbonate reservoir fracturing from borehole data – A case study of the Viséan in northern Belgium

Abstract Fractured carbonate rocks are widely used as hydrocarbon or geothermal reservoirs. To provide a better understanding of the distribution and characteristics of such fractures, a general workflow will be presented for the characterization of fracturing from borehole data, by exploration and statistical analyses of integrated datasets. In a case study of Visean limestones in a Belgian borehole, both cores and geophysical well logs were used to investigate which factors control the characteristics of partially open veins, which contribute to permeability. Relationships between multiple variables were tested statistically. Lithology, geochemistry and geophysical well log values were taken into account, as well as quantified veins, vugs and stylolites from cores. Although natural joint frequencies appeared hard to quantify from the available data, partially open vein characteristics could be well quantified. The results show that differential compaction controlled the development of fractures. Fracturing occurred preferentially in massive reefal buildup boundstones in contrast to layered wacke- to grainstones. Layer-parallel slip along bedding surfaces could also have reduced fracture development in the latter limestones. Frequencies of cemented veins and partially open veins are positively correlated, which suggests that the partially open veins result from either re-opening by dissolution, or (re-)opening due to a later fracturation phase. In summary, this multi-source study provides a workflow for fracture characterization from boreholes, as well as insights into the factors controlling the distribution and characteristics of partially open veins, which enhance reservoir permeability.

A comparison of seismic response to conventional and face destress blasting during deep tunnel development

Abstract A novel design of development face destress blasting was implemented during the construction of an experimental tunnel at great depth. A second tunnel was developed nearby using conventional blasting as a control. The tunnels were developed parallel to one another and perpendicular to a high sub-horizontal stress. High resolution seismic monitoring was used to record and compare the seismic response generated by each excavation. Analysis of the seismic data from the conventionally blasted tunnel indicated that the seismogenic zone of stress-driven instability extended up to 3.6 m ahead of the face. Destress blasting within the corresponding zone of the adjacent tunnel had the effect of reducing the rock mass stiffness, primarily due to weakening of the pre-existing natural discontinuities. The reduction in rock mass stiffness was inferred from the spatial broadening of the seismogenic zone and associated reduction in the measured spatial density of events, radiated energy and seismic potency ahead of the face. High strain gradients around the unsupported portion of the conventionally blasted excavation were implied by the rate at which the spatial density of seismicity changed with respect to the tunnel face position. In contrast, the change in the spatial density of seismicity around the destressed development face was much more gradual. This was indicative of lower strain gradients in the rock there. A reduction in rock mass stiffness following destress blasting was also indicated by the much wider variety of seismic source mechanisms recorded adjacent to the destressed tunnel. Seismic source mechanisms associated with destress blasting were also more clearly characteristic of compressive overstressing with fracture closure. The source mechanism data also indicated that destress blasting induced instability on all natural joint sets. When compared to conventional development blasting, destress blasting typically reduced violent strain energy release from the rock mass and the associated seismicity, but not always.

Numerical Modeling of Discrete Fractures in a Field-Scale FORGE EGS Reservoir

The response of the Fallon FORGE geothermal reservoir to hydraulic stimulation is modeled numerically to aid the conceptual design of the well geometries and completions. The numerical modeling approach is based on (a) a full hydro-mechanical coupling; and (b) explicit representation of a discrete fracture network (DFN). The reservoir-scale model has a core region of 1500 × 1200 × 1200 m3 volume around the positions of conceptual sub-horizontal well designs at the Fallon FORGE site. It contains relevant geological structure and a fracture network constructed and simplified using borehole data. Stimulation was modeled in six stages/zones along the horizontal well using both openhole (low injection rate at 5 kg/s) and cased borehole (combination of high, 80 kg/s, and low injection rates) completions to test the effectiveness of hydraulic fracturing combined with hydro-shearing. The reservoir stimulation in the two models was analyzed and quantitatively assessed. Results indicate that the Fallon FORGE site is well suited for an EGS by multi-staged hydraulic stimulation using sub-horizontal wells. The conclusion is based on the evaluation of potential for fracture slip and aperture increase as functions of induced pressure changes and the orientations of the natural joints relative to the regional principal stresses. Advantages and limitations of explicit representation of the DFN in the numerical models are presented and discussed.

Reconstruction of the Medial Ulnar Collateral Ligament of the Elbow: Biomechanical Comparison of a Novel Anatomic Technique to the Docking Technique.

Background:In recent years, understanding of the anatomy of the ulnar collateral ligament (UCL) has evolved, demonstrating that the insertional footprint of the UCL on the ulna is more elongated and distally tapered than previously described. Current UCL reconstruction configurations do not typically re-create this native anatomy, which may represent a potential area for improvement.Purpose/Hypothesis:The purposes of this study were (1) to describe a novel anatomic UCL reconstruction technique designed to better replicate the native UCL anatomy and (2) to biomechanically compare this with the docking technique. The hypothesis was that the ultimate load to failure for the anatomic technique would not be inferior to the docking technique.Study Design:Controlled laboratory study.Methods:A total of 16 fresh-frozen cadaveric upper extremities (8 matched pairs) were utilized. One elbow in each pair was randomized to receive UCL reconstruction via the docking technique or the novel anatomic UCL reconstruction technique with palmaris tendon autograft. Following reconstruction, biomechanical testing was performed by applying valgus rotational torque at a constant rate of 5 deg/s until ultimate mechanical failure of the construct occurred. Maximal torque (N·m), rotation stiffness (N·m/deg), and mode/location of failure were recorded for each specimen.Results:The mean ultimate load to failure for elbows in the docking technique group was 23.8 ± 6.1 N·m, as compared with 31.9 ± 8.4 N·m in the anatomic technique group (P = .045). Mean rotational stiffness was 1.9 ± 0.7 versus 2.3 ± 0.9 N·m/deg for the docking and anatomic groups, respectively (P = .338). The most common mode of failure was suture pullout from the graft, which occurred in all 8 (100%) docking technique specimens and 7 of 8 (88%) specimens that underwent the anatomic UCL reconstruction technique.Conclusion:Ultimately, the anatomic UCL reconstruction technique demonstrated superior strength and resistance to valgus torque when compared with the docking technique, and this was comparable with that of the native UCL from prior studies. Increased initial strength may allow for earlier initiation of throwing postoperatively and potentially shorten return-to-play times.Clinical Relevance:Current UCL reconstruction techniques do not accurately reproduce the UCL insertional anatomy on the ulna. The novel anatomic technique described may result in more natural joint kinematics. This study demonstrated load-to-failure rates that are significantly higher than with the docking technique and consistent with the native ligament, as reported from previous studies. These findings may serve as a foundation for future clinical study and optimization of this technique.

Simplifying the human lumbar spine (L3/L4) material in order to create an elemental structure for the future modeling

The human lumbar spine incorporates the best joints in nature due to its optimal static and dynamic behavior against the internal and external loads. Developing an elemental structure based on this joint requires simplification in terms of the materials employed by keeping the mechanical and anatomical behaviors of the human lumbar spine. In the present study, the finite element (FE) of two motion segments of the human lumbar spine (L3/L4) was developed based on the CT scan data as the base for vertebrae geometry, verified geometry properties for another part of two motion segments, and combination of materials and loads obtained from the validated resources. Then, simplification occurred in four continuous steps such as omitting the annual fibers of annual matrix, representing the material of the annual matrix to the nucleus, demonstrating the material of annual matrix to the endplates too, and omitting the trabecular part of vertebrae. The present study aimed to propose the method for developing the basic structure of the human lumbar spine by simplifying its materials in the above-mentioned steps, analyzing the biomechanical effects of these four steps in terms of their internal and external responses, and validating the data obtained from the FE method. The validated simplified way introduced in this study can be used for future research by making implants, prosthesis, and modeling based on the human lumbar spine in other fields such as industrial design, building structures, or joints, which results in making the model easier, cheaper, and more effective.

A review of acoustic emission as a biotribological diagnostic tool

ABSTRACTAcoustic emission (AE) testing has been used in the detection of the onset and progression of mechanical flaws. It has also proven advantageous in the tribological assessment of mechanical systems and human joints as well as for implant condition monitoring. Current modes of diagnosing implant failures are becoming less effective and time consuming calling for the development of a more effective and dynamic diagnostic method. This review aims to provide an overview of the current tribological applications of AE and to highlight how this can be instrumental in the development of a more effective failure diagnosis method. It can be concluded that AE has potential capabilities as a tool for monitoring the tribological phenomenon of artificial joints which would not only allow for a more effective way of diagnosing implant failures but also for diagnosing natural joint diseases such as back pain and arthritis.

Incipient karst formation in carbonate rocks: Influence of fracture network topology

Karst features in limestone aquifers often exhibit highly heterogeneous patterns, which are strongly governed by structural complexities such as the spatial distribution and organization of fractures in natural carbonate rocks. However, until now, little is known about the impact of structural complexity on karstification processes. In this paper, we use numerical models to investigate how structural heterogeneity affects the generation of incipient karst in natural fractured systems. We develop a numerical model which couples the processes of fluid flow, mass transport and dissolution kinetics that govern the growth of fracture aperture, based on discrete fracture networks. We apply the model to simulate conduit evolution in a natural joint network that displays a distinctive topological pattern. A wide range of hydraulic gradient and initial fracture aperture is considered. Our results show that the network topology may generate a significant impact on dissolution pattern depending on how flow is organized within the discrete network. If a channelized structure occurs in the flow network, the dissolution pattern depends highly on the initial hydrogeological settings, while if the flow network consists of branched segments, a similar dissolution pattern emerges for a broad range of initial hydrogeological settings. When the flow direction is normal to the persisting fracture orientation, intermittent interruptions to the positive feedback process between flow and dissolution occur. Therefore, the breakthrough is delayed. We discuss the link between our results of dissolution modeling in fracture networks to previous modelling efforts in the context of single rough fractures and fracture network formed by orthogonal fracture sets.

Natural articular cartilage: A smart biointerface

In healthy joints, the cartilage surface coated with phospholipid multi-bilayers is governed by the lamellar-repulsive hydration mechanism. The phospholipid bilayers of biological surface are investigated by friction testing, while surface degradation is controlled by wettability. This paper proposes the presence of cartilage surfaces that are negatively charged results in highly efficient lubrication in natural joints. At pH �7.4, the mechanism of lamellar-repulsion between contacting cartilage surfaces is supported by charged macromolecules of synovial fluid and phospholipid lamellar phases. It was proven experimentally that phospholipid (PLs) bilayers with lamellar structure can act as an effective solid lubricant in friction and wear under biological test conditions

Analytical Prediction of the Shear Behaviour of Rock Joints with Quantified Waviness and Unevenness Through Wavelet Analysis

We present an analytical model for the shear behaviour of a rock joint with waviness and unevenness. The waviness and unevenness of a natural joint profile are quantitatively separated through wavelet analysis. The critical waviness and critical unevenness of a joint profile are subsequently determined. The degradation process of each-order asperity is predicted by considering the role of plastic tangential work in shear, by which the sheared-off asperity area and the dilation angle are quantified. Both the dilation angles of critical waviness and critical unevenness decay, as plastic tangential work accumulates. The analytical predictions are compared with the experimental data from direct shear tests on both regular- and irregular-shaped joints. Good agreement between analytical predictions and laboratory-measured curves demonstrates the capability of the developed model. Therefore, the model is capable of assessing the stability of rock-engineering structures with ubiquitous joints.

Assessing fracturing mechanisms and evolution of excavation damaged zone of tunnels in interlocked rock masses at high stresses using a finite-discrete element approach

Deep underground excavations within hard rocks can result in damage to the surrounding rock mass mostly due to redistribution of stresses. Especially within rock masses with non-persistent joints, the role of the pre-existing joints in the damage evolution around the underground opening is of critical importance as they govern the fracturing mechanisms and influence the brittle responses of these hard rock masses under highly anisotropic in situ stresses. In this study, the main focus is the impact of joint network geometry, joint strength and applied field stresses on the rock mass behaviours and the evolution of excavation induced damage due to the loss of confinement as a tunnel face advances. Analysis of such a phenomenon was conducted using the finite-discrete element method (FDEM). The numerical model is initially calibrated in order to match the behaviour of the fracture-free, massive Lac du Bonnet granite during the excavation of the Underground Research Laboratory (URL) Test Tunnel, Canada. The influence of the pre-existing joints on the rock mass response during excavation is investigated by integrating discrete fracture networks (DFNs) of various characteristics into the numerical models under varying in situ stresses. The numerical results obtained highlight the significance of the pre-existing joints on the reduction of in situ rock mass strength and its capacity for extension with both factors controlling the brittle response of the material. Furthermore, the impact of spatial distribution of natural joints on the stability of an underground excavation is discussed, as well as the potentially minor influence of joint strength on the stress induced damage within joint systems of a non-persistent nature under specific conditions. Additionally, the in situ stress-joint network interaction is examined, revealing the complex fracturing mechanisms that may lead to uncontrolled fracture propagation that compromises the overall stability of an underground excavation.

Roughness Effects on the Shear Strength of Concrete and Rock Joints in Dams Based on Experimental Data

This paper investigates the effects of joint roughness on shear strength based on experimental data obtained from shear tests on 18 specimens presenting an unbonded contact interface, i.e., fully open with no bond, drilled from concrete, concrete–rock, and rock joints in existing dams. Original and practical procedures are developed to numerically process 3D profiles of laser-scanned interfaces of the tested contact specimens, and then evaluate the corresponding roughness parameters for the prediction of joint shear strength. Orientation-dependent joint roughness coefficient (JRC) and joint matching coefficient (JMC) are also proposed to investigate roughness effects as a function of shearing direction. The analysis of the experimental results confirmed that the contribution of roughness to the shear strength of a dam joint has to be considered. Furthermore, the results suggest that only little shear-induced degradation occurs along the contact specimens during the tests. Shear strength values from shear tests conducted on contact specimens are compared to predictions using an analytical equation adapted to include the orientation-dependent JRC and JMC. The results highlight the significant role of roughness and matching properties on the shear strength of unbonded natural joints, although the quality of the predictions was found to be sensitive to the selection of the residual friction angle $$\phi_{\text{r}}$$ and the joint compressive strength JCS. It is also found that joint roughness and matching depends on shear direction which can significantly affect shear strength predictions. These results clearly illustrate the need for sensitivity analyses to evaluate the variation of joint shear strength should a potential dam sliding occur along a direction different from the one adopted during shear tests.