Investigation of contact behavior on a model of the dual-mobility artificial hip joint for Asians in different inner liner thicknesses

BACKGROUND The four components that make up the current dual-mobility artificial hip joint design are the femoral head,the inner liner,the outer liner as a metal cover to prevent wear,and the acetabular cup.The acetabular cup and the outer liner were constructed of 316L stainless steel.At the same time,the inner liner was made of ultra-high-molecular-weight polyethylene(UHMWPE).As this new dual-mobility artificial hip joint has not been researched extensively,more tribological research is needed to predict wear.The thickness of the inner liner is a significant component to consider when calculating the contact pressure.AIM To make use of finite element analysis to gain a better understanding of the contact behavior in various inner liner thicknesses on a new model of a dual-mobility artificial hip joint,with the ultimate objective of determining the inner liner thickness that was most suitable for this particular type of dual-mobility artificial hip joint.METHODS In this study,the size of the femoral head was compared between two diameters(28 mm and 36 mm)and eight inner liner thicknesses ranging from 5 mm to 12 mm.Using the finite element method,the contact parameters,including the maximum contact pressure and contact area,have been evaluated in light of the Hertzian contact theory.The simulation was performed statically with dissipated energy and asymmetric behavior.The types of interaction were surface-to-surface contact and normal contact behavior.RESULTS The maximum contact pressures in the inner liner(UHMWPE)at a head diameter of 28 mm and 36 mm are between 3.7-13.5 MPa and 2.7-10.4 MPa,respectively.The maximum von Mises of the inner liner,outer liner,and acetabular cup are 2.4–11.4 MPa,15.7–44.3 MPa,and 3.7–12.6 MPa,respectively,for 28 mm head.Then the maximum von Mises stresses of the 36 mm head are 1.9-8.9 MPa for the inner liner,9.9-32.8 MPa for the outer liner,and 2.6-9.9 MPa for the acetabular cup.A head with a diameter of 28 mm should have an inner liner with a thickness of 12 mm.Whereas the head diameter was 36 mm,an inner liner thickness of 8 mm was suitable.CONCLUSION The contact pressures and von Mises stresses generated during this research can potentially be exploited in estimating the wear of dual-mobility artificial hip joints in general.Contact pressure and von Mises stress reduce with an increasing head diameter and inner liner’s thickness.Present findings would become one of the references for orthopedic surgery for choosing suitable bearing geometric parameter of hip implant.

Characterisation of wear particles from biomedical carbon/carbon composites with different preforms in hip joint simulator

A hip joint simulator was employed to predict the clinical wear behaviour of carbon/carbon （C/C） composites with needled carbon cloth preform and carbon felt preform. Wear particles generated from the two kinds of C/C composites were isolated and characterised by the size distribution and morphology. The evolvement of wear particles in the hip joint simulator was proposed. The results show that the wear particles from two kinds of C/C composites have a size ranging from submicron to tens of micrometers. The wear particles have various morphologies including broken fiber, fragment fiber, slice pyrolytic carbon and spherical pyrolytic carbon. C/C composites with needled carbon cloth preforms have larger size range and more broken fiber particles and slice pyrolytic carbon particles in comparison with C/C composites with carbon felt preforms. The evolvement of pyrolytic carbon particles is caused by surface regularization, whereas, the evolvement of carbon fiber particles is related to stress direction in the hip joint simulator.

Jumbo cup in hip joint renovation may cause the center of rotation to increase

BACKGROUND Utilizing the large jumbo cup in revision total hip arthroplasty is an effective approach to cure many lacunar and segmental peripheral bone defects.However,with the use of the jumbo cup,the center of the hip joint may become elevated relative to the primary acetabulum,and the diameter of the large cup is greater.AIM To study the height and the significance of the elevation of the hip joint center.METHODS Eighty-eight patients matched the criteria for this condition and were included in the study.The center height of the hip joint was measured relative to the opposite normal hip joint.The diameter of the jumbo cup was measured and checked according to operation notes,and the diameter of the jumbo cup was measured with a prosthesis label.Then,the horizontal and vertical centers of rotation were measured on the surgical side and opposite side.The average center height of the hip joint on the renovated side and the opposite side and the position of the hip cup relative to the teardrop were compared using a paired t-test.RESULTS Radiometric analysis showed that the average hip joint center was elevated by 7.6 mm.The rotational center height delta of the renovated hip was 7.6±5.6 mm,and there was an obvious difference between the two groups(P=0.00).The difference in horizontal distance was 0.5±5.1 mm(-11.5-14.0 mm),and there was no obvious difference between the two groups(P=0.38).According to the foreign standard,the rotational center height delta of the renovated hip was 7.5±6.2 mm,and there was a significant difference between the two groups(P=0.00).There was no obvious difference between the domestic and foreign standards(P>0.05)between the two groups.CONCLUSION The application of the jumbo cup elevates the rotational center of the hip joint,but it is feasible and effective to use the jumbo cup.

A Biomimetic Hip Joint Simulator and its Application in in vitro Study of the Integrity of Replacement Cemented Hip

A biomimetic hip joint simulator that can be used to evaluate the outcome of the cemented total hip replacement has been designed, manufactured and evaluated. The simulator produces motion in the extension/flexion plane, with a socket to rotate internal/externally. At the same time a dynamic loading cycle is applied. A validation test was performed on a cemented femoral stem within a novel composite femur. The hone quality has a strong effect on the stem migration and on the integrity of the interfaces. The migration of the stem is a combination of 3-D translation and rotation of the stem. Under the same loading conditions, weak bone allows more stem migration than strong bone. There is a great decrease in the strength of the stem-cement interface after the dynamic test, and the weak bone composite exhibited a greater reduction in interfacial strength than the strong bone composite. The decrease of the interfacial strength indicates that the primary bonding between the stem and the cement mantle had deteriorated and the integrity of stem-cement interface was damaged. The study demonstrates the value of using a hip joint simulator to investigate stem migration and interface integrity within the cemented hip replacement, suggesting that method can be used for in vitro evaluation of the biomaterials used in the cemented hip replacements.

Chromium Content in the Human Hip Joint Tissues

Objective Chromium has many important functions in the human body. For the osseous tissue, its role has not been clearly defined. This study was aimed at determining chromium content in hip joint tissues. Methods A total of 91 hip joint samples were taken in this study, including 66 from females and 25 from males. The sample tissues were separated according to their anatomical parts. The chromium content was determined by the AAS method. The statistical analysis was performed with U Mann-Whitney＇s non-parametric test, P〈0.05. Results The overall chromium content in tissues of the hip joint in the study subjects was as follows： 5.73 μg/g in the articular cartilage, 5.33 μ/g in the cortical bone, 27.86 μ/g in the cancellous bone, 5.95 μg/8 in the fragment of the cancellous bone from the intertrochanteric region, and 2.28 μ/g in the joint capsule. The chromium contents were observed in 2 group patients, it was 7.04 μ/g in people with osteoarthritis and 22.59 μ/g in people with fractures. Conclusion The observed chromium content was highest in the cancellous bone and the lowest in the joint capsule. Chromium content was significantly different between the people with hip joint osteoarthritis and the people with femoral neck fractures.

ANALYSIS AND RESEARCH OF COMPUTER-AIDED MODEL OF HIP JOINT BASED ON REVERSE ENGINEERING

Former research work about the modeling of hip joint focus on the uppersegment of femoral, and assumes the acetabulum cup is sphere concave, and the acetabulum prosthesesis semisphere. A method of acquiring the point data on the surface of the hipbone using the reverseengineering technology is presented. After analyzing the acetabulum surface fitting error, arotation ellipsoid CAD model is applied to fit the acetabulum surface, and then optimizationtechnique is used to find the geometric parameters of the model. The fitting error between thesphere and rotation ellipsoid is compared and gets the result that the fitting error of rotationellipsoid is smaller than sphere, and the rotation ellipsoid can describe the shape of theacetabulum better.

The Developmentand Clinical Application of Acoustical Technique in Hip Joint

A non- invasive acoustical system was developed for the measurement of transmission properties of acoustic waves in the hip joints.The instrumentation consisted of three sub- system s. An excitation system employed a vibratory force at the sacrum of the test subjects.A transduction system included a pair of identical microphones installed in the tubes of two stethoscopes,which were placed at the greater trochanters on both sides for picking up the acoustical signals transm it- ted across the hip joints.The data acquisition and analysis system was a portable signal analyzer with a program of dual channel digital filter for m easuring the power of acoustical signal in 1/ 3- oc- tave frequency bands.2 7normal adults,2 0 normal pre- school children and 4 0 norm al neonates were random ly selected for testing.Coherence function (CF) and discrepancy(D) was measured during the testing.Results from the three groups showed that there was a high coherence of the signals (CF>0 .9) and a sm all discrepancy(D<3d B) between bilateral hips in the frequency range of2 0 0— 315 Hz.For normal neonates,there was a wider frequency range of16 0 - 315 Hz in which the acoustical signals m aintained a high coherence (CF>0 .93) and a smaller discrepancy (D <2 d B) was observed.This study showed that the development of the acoustical technique pro- vided a practical m ethod with objective parameters.The results obtained in this study can offer a baseline for further investigation of hip disorders particularly those related to structural abnorm ali- ties of the hip.

3D Finite Element Analysis of a Man Hip Joint Femur under Impact Loads

Objective： The biomechanical characters of the bone fracture of the man femoral hip joint under impact loads are explored. Methods ：A biosystem model of the man femoral hip joint by using the GE （ General Electric） lightspeed multi-lay spiral CT is conducted. A 3D finite element model is established by employing the finite element software ANSYS. The FE analysis mainly concentrates on the effects of the impact directions arising from intense movements and the parenchyma on the femoral hip joint on the stress distributions of the proximal femur. Results：The parenchyma on the hip joint has relatively large relaxation effect on the impact loads. Conclusion：Effects of the angle δ of the impact load to the anterior direction and the angle γ of the impact load to the femur shaft on the bone fracture are given;δ has larger effect on the stress and strain distributions than the angle γ,which mainly represents the fracture of the upper femur including the femoral neck fracture when the posterolateral femur is impacted, consistent with the clinical resuits.

Can periprosthetic hip joint infections be successfully managed by debridement and prosthesis retention?

To evaluate the current literature about how successfully periprosthetic hip joint infections can be managed by debridement and prosthesis retention.A literature search was performed through Pub Med until September 2013.Search terms were"DAIR(debridement,antibiotics,irrigation,and retention)"alone and in combination with"hip"as well as"hip infection+prosthesis retention".A total of 11 studies reporting on 292 cases could be identified.Five different treatment modalities have been described with varying success rates(debridement-21%infection eradication rate;debridement+lavage-75%infection eradication rate;debridement,lavage,with change of modular prosthesis components-70.4%infection eradication rate;debridement,lavage,change of modular prosthesis components+vacuum-assisted closure-92.8%infection eradication rate;acetabular cup removal+spacer head onto retained stem-89.6%infection eradication rate).With regard to the postoperative antibiotic therapy,no general consensus could be drawn from the available data.Debridement,antibiotic therapy,irrigation,and prosthesis retention is an acceptable solution in the management of early and acute hematogenous periprosthetic hip joint infections.The current literature does not allow for generalization of conclusions with regard to thebest treatment modality.A large,multi-center study is required for identification of the optimal treatment of these infections.

Hip joint center localisation: A biomechanical application to hip arthroplasty population

AIM: To determine hip joint center(HJC) location on hip arthroplasty population comparing predictive and functional approaches with radiographic measurements.METHODS: The distance between the HJC and the mid-pelvis was calculated and compared between the three approaches. The localisation error between the predictive and functional approach was compared using the radiographic measurements as the reference. The operated leg was compared to the non-operated leg.RESULTS: A significant difference was found for the distance between the HJC and the mid-pelvis when comparing the predictive and functional method. The functional method leads to fewer errors. A statistical difference was found for the localization error between the predictive and functional method. The functional method is twice more precise.CONCLUSION: Although being more individualized, the functional method improves HJC localization and should be used in three-dimensional gait analysis.

Dynamic knee valgus kinematics and their relationship to pain in women with patellofemoral pain compared to women with chronic hip joint pain

Background:Dynamic knee valgus(DKV)is an abnormal movement pattern visually characterized by excessive medial movement of the lower extremity during weight bearing.Differences in hip and knee kinematic components of DKV may explain the emergence of different pain problems in people who exhibit the same observed movement impairment.Using a secondary analysis of exiting data sets,we sought to determine whether hip and knee frontal and transverse plane angles during a functional task differed between women with patellofemoral pain and women with chronic hip joint pain and the relationship between joint-specific kinematics and pain in these 2 pain populations.Methods:In the original studies,3-dimensional hip and knee kinematics during a single-limb squat were obtained in 20 women with patellofemoral pain and 14 women with chronic hip joint pain who demonstrated visually classified DKV.Pain intensity during the squat was assessed in both groups.For the secondary analysis,kinematic data were compared between pain groups using their respective control groups as a reference.Within each pain group,correlation coefficients were used to determine the relationship between kinematics and pain during the squat.Results:Hip adduction and contralateral pelvic drop were greater in those with chronic hip joint pain compared to those with patellofemoral pain(effect sizes ≥0.40).Greater knee external rotation(r= 0.47,p= 0.04)was correlated with greater knee pain in those with patellofemoral pain,while greater hip adduction(r = 0.53,p = 0.05)and greater hip internal rotation(r = 0.55,p = 0.04)were correlated with greater hip pain in those with chronic hip joint pain.Conclusion:Hip frontal plane motion was greater in those with chronic hip joint pain compared to those with patellofemoral pain.In both groups,greater abnormal movement at the respective joint(e.g.,knee external rotation in the patellofemoral pain group and hip adduction and internal rotation in the chronic hip joint pain group)was associated with greater pain at that joint during a single-limb squat.

Use of Dental Inlay for Treatment of Hip Joint Dysregulation: A Case Report

The purpose of this study was to demonstrate the improvement of hip joint dysregulation, including pain (coxalgia), tension, and restriction of joint mobility, using a dental gold alloy inlay. The subject was a 63-year-old man who was suffering from the abovementioned symptoms for several months. On placement of the gold alloy inlay on his chest, the joint flexibility was observed to increase, and the severity of the abovementioned symptoms decreased. When the inlay was placed in his tooth, the flexibility of the joint further increased, and all other symptoms disappeared. No side effects were observed, and the prognosis was good. We believe that these effects may be explained using the electromagnetic waves emitted by the inlay and by the restoration of biting conditions. Future multidisciplinary research focusing on possible underlying mechanisms regarding the relation between electromagnetic waves and dentistry is necessary.

Hip Joint Osteoarthritis Pain Sources and Control

Hip joint osteoarthritis, a widespread disabling disease with no known cause, produces considerable bouts of intractable pain as a result of multiple disease associated problems. This paper examines some sources of osteoarthritic hip joint pain, a poorly understood topic at best. Presented in three parts are data retrieved from several sources, including animal models. It is concluded that to improve the effectiveness of treatments designed to minimize hip osteoarthritis pain, a better understanding of the diverse origins of hip joint pain, and hip joint neurology, may permit the development of more precise as well as targeted pain strategies.

Leg-length equalization for total hip joint replacement patients

Objective To investigate the methods to maintain leg equalization for patients undergoing primary total hip joint replacement. Methods 40 patients,45 hips with various diseases were treated by total hip joint replacement from Jan 2000 to Sep 2001.Before operation, the perpendicular length from center of femoral head to the summit of great tuberosity and the tip of less tuberosity to the line of bilateral ischial tuberosity were measured; the length from anterior superior iliac spine to medial malleolus were measured at same time.Leg length was decided and corrected according to these lines. Results Before operation, shortening of limbs were presented in 39 hips, 1 to 4 cm, average 2.4 cm.After operation, discrepancy of both legs was 0～0.8 cm.Apparent limps were not observed in all patients. Conclusion This measurement is a useful method to maintain and recover leg length in total hip joint replacement.

A TETRACYCLINE LABELING STUDY OF SUBCHONDRAL BONE TISSUES IN OSTEOARTHRITIC HIP JOINT

Seven female patients (mean age of 56 years) with advanced hip joint osteoarthritis underwent total hip replacement. Four days before operation they were given oral tetracycline for two days. During operation specimens were taken from the white articular cartilage, the yellowish articular cartilage and the ivory bone together with their subchondral bone tissues. The undecalcified specimens were cut into 10 μm sections and observed under the fluorescence microscope. In all the specimens the following findings could be observed. 1. The osteoarthritic articular cartilage became thinner, with uneven surface and fissures. 2. The superficial and deep surfaces and the central part of the subchondral bone plate showed bright golden yellow fluorescence. It reflected extensive new bone formation. 3. The subchondral bone trabeculae also revealed bright golden yellow fluorescence on their peripheral borders, so trabeculae turned thicker obviously. 4. The marrow tissues between the bone trabeculae exhibited particulate or spherical bright golden yellow fluorescence, reflecting new bone formation in the marrow. The particulate and spherical bright golden yellow fluorescent materials might aggregate, enlarge and merge into large piece of new bone and they also fused with the neighbouring bone trabeculae. The aforementioned changes in the structure of the subchondral bone tissues increased greatly the mass in the osteoarthritic femoral head.

Analysis of Proprioception of Hip Joint in Total Hip Arthroplasty

Introduction: The instability of the joint is classified roughly into mechanical and functional. It is reported that the postoperative dislocation often occurs by the posterior approach of the THA and may be caused by functionality instability due to the injury of the periarticular soft tissue. We analyzed the joint position sense of the hip according to an approach of the THA and examined effect to give postoperative dislocation. Materials & Methods: 92 patients (184 hip joints) who received THA in our hospital were selected in the study. Cases in which position sensation measurements were insufficient were excluded. As for the classification, the posterior approach (PL groups) was 39 hips, anterolateral approach (AL groups) was 30 hips, and control group was 37 hips. Results: There was no significant difference between the AL group and PL group in the absolute reproduction angle error score (ARAES). The relative reproduction angle error scores (RRAES) for passive internal and external rotations and active internal rotation were significantly lower in the AL and control groups than the PL group. Discussion: This study was suggested that the hip joint position sense in the AL group was better retained for the preservation of the soft tissue.

Use of Image processing software in Hip Joint surgery

The scope of this project was to investigate the possibility of application of Image Processing Technique in the field of Shaft Alignment process. Misalignment of shaft using image processing software Visionbuilder was calculated. The further purpose of this project was to check whether the image processing technique can be used in bone transplant surgery. The model of the hip was used for the experimentation purpose. Image processing software Visionbuilder was used to match the profiles of the bone before implant and bone after implant.

Desmoid Tumor Causing Hip Joint Contracture: A Case Report

Desmoid tumor (DT) is a relatively uncommon, cytologically bland fibrous neoplasm that is associated with possibility of local recurrence but without the potential to spread to other parts of the body. This disease affects mostly younger adults and is the most common cause of abdominal wall masses in women 20 - 35 years of age. However, it may involve nearly every body part, including the extremities, head and neck, trunk, and abdominal cavity;as such, patients with DT may present to a range of general and subspecialty radiologists. The consensus for treatment has changed over the past decade, with most centers moving away from primary radical surgery towards a front-line “wait-and-see” policy. Here, we present a case of a tumor mass that induced hip joint contracture. DT does not usually cause functional disorder. Oncologists should be aware that a desmoid tumor can cause hip joint contracture if the mass occurs in the gluteal region. Moreover, DT resulting in such a functional disorder should be treated by resection.

Finite element study on the predicted equivalent stresses in the artificial hip joint

The subsurface fatigue that occurs in the Ultra-High Molecular Weight Polyethylene (UHMWPE) hip joint cup has been identified to be correlated with the contact stress at that cup. This cup stress is known to be affected by the implant design, dimensions and materials. In this study, a 3D finite element modeling has been used to investigate the effects on the cup contact stress when using low stiffness Titanium alloy (Ti) as a femur head. Also, the effects on the cup contact stress due to using different sizes of femur heads, and the presence of metal backing shell with different thicknesses are studied. The finite element results show that the use of low stiffness Ti alloy femur head results in a significant decrease in the cup contact stress compared with Stainless Steel (SS) and Cobalt Chromium (Co Cr Mo) femur heads. The presence of metal backing shell up to 1 mm thickness results in a remarkable decrease in the cup contact stresses especially for small femur heads. Finally, the use of larger femur heads, up to 32 mm diameter, results in significant decrease in the overall predicted hip joint contact. The present results indicate that any changes in design and geometrical parameters of the hip joint have significant consequences in the long term behaviour of the artificial hip joint and should be taken into consideration.

Coverage of Femoral Head at Weight-Bearing Interface of the Hip Joint in Children: An MRI Analysis

Objective: To analyze the features of coverage of femoral head at weight-bearing interface of the hip joints in children. Material and Methods: MRI scans of the hips were performed in 95 normal children aged from 1 to 8 years. Radial scans of the hip joints were performed using FFE sequence. Review the morphological features of weight-bearing interface of the acetabulum and the femoral head. Total covering angle (TCA), acetabular covering angle (ACA) and labral covering angle (LCA) were measured, inter-group comparison and correlation analysis were done. Result: The acetabulum and the femoral head had congruent articulating surface at each weight-bearing position. There was no statistical TCA difference at each position. Average ACA increased, while average LCA decreased from anterior to posterior. TCA correlated with LCA, ACA negatively correlated with LCA. Conclusion: TCA is a good index in indicating stability of the hip joint. Cartilage ossifies slower at posterior than anterior positions. Cartilage acetabulum and the labrum serve as complementary structures that contribute in total stabilizing of the hip joint in development.