Effects of Visual Input Absence on Balance Recovery Responses to Lateral Standing Surface Perturbations in Older and Younger Adults.

Although the ability to recover balance in the lateral direction has important implications with regard to fall risk in older adults, the effect of visual input on balance recovery in response to lateral perturbation and the effect of age are not well studied. We investigated the effect of visual input on balance recovery response to unpredictable lateral surface perturbations and its age-related changes. Ten younger and 10 older healthy adults were compared during balance recovery trials performed with the eyes open and eyes closed (EC). Compared with younger adults, older adults showed increased electromyography (EMG) peak amplitude of the soleus and gluteus medius, reduced EMG burst duration of the gluteus maximus and medius, and increased body sway (SD of the body's center of mass acceleration) in EC. In addition, older adults exhibited a smaller % increase (EC-eyes open) of the ankle eversion angle, hip abduction torque, EMG burst duration of the fibularis longus, and a greater % increase of body sway. All kinematics, kinetics, and EMG variables were greater in EC compared with eyes open in both groups. In conclusion, the absence of visual input negatively affects the balance recovery mechanism more in older adults compared with younger adults.

[Hyaluronic acid in the treatment of osteoarthritis of various localization: A review].

The article discusses the treatment of osteoarthritis (OA), the prevalence of which is high, and according to some forecasts it will increase by 50% in the next 20 years. The authors emphasize the high comorbidity among patients suffering from OA and high cardiovascular and gastrointestinal risks with frequent use of NSAIDs, the volume of consumption of which is constantly increasing. Discussing recommendations for the treatment of patients with OA, the article focuses on the use of hyaluronic acid (HA) preparations in the treatment of OA. The mechanisms of anti-inflammatory and chondroprotective actions of HA in the joint, its effect on cartilage and synovial membrane are discussed. Attention is drawn to the fact that, despite more than 30 years of experience in the effective use of HA preparations in the treatment of OA, this procedure is still a subject of controversy among international professional communities. The article presents data from meta-analyses and systematic reviews confirming the effectiveness of the use of intra-articular management of HA preparations in OA of various localization (knee joints, hip joints, hand joints). In conclusion, the recommendations of the technical expert group established at the International Symposium on Intra-Articular Treatment are given to determine the criteria for the successful administration of HA in OA of various localizations, as well as predictors of success and non-success of therapy with HA drugs. The experts identified indications, contraindications for intra-articular administration of HA preparations, as well as conditions associated with an increased risk of therapy failure. In conclusion, the authors draw conclusions about the importance of using HA preparations for intra-articular administration for the treatment of OA, starting from the early stages, following the recommendations of experts.

Development of a technique for MRI gold-standard direct volumetric measurement of complex joint effusion, and validation at the hip.

OBJECTIVE: Accurate joint fluid quantification on MRI cannot simply rely on measuring the maximum fluid depth or using an ellipsoid approximation as this does not fully characterize the complex shape of a fluid-filled joint. As per the Outcome Measurement in Rheumatology (OMERACT) filter, we sought to evaluate the feasibility, reliability, and validity of a semi-automated supervised technique to quantify hip effusion volume. MATERIALS AND METHODS: Ninety-three hip osteoarthritis patients were imaged with coronal short TI inversion recovery (STIR) and sagittal intermediate weighted fat-suppressed (IWFS) sequences at two time points (Fig. 1). Volumetric quantitative measurement (VQM) of joint fluid and measurement of the largest femoral neck fluid thickness (FTM) was performed using the custom MATLAB software. Self-reported Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and clinical measures of pain, stiffness, and function were recorded. RESULTS: Inter-observer reliability was significantly higher for VQM than FTM (ICC = 0.96 vs. 0.85, p < 0.05). VQM and FTM correlated moderately (r = 0.76, p < 0.0001). There was significantly more articular fluid in symptomatic than asymptomatic hips at baseline (mean = 9.8 vs. 5.9 mL). Volumetric quantitative measurement generally displayed more frequent and stronger correlations to clinical parameters than FTM. Volumetric quantitative measurement required 3.9 min/hip vs. < 1 min/hip for femoral neck fluid thickness. CONCLUSION: Volumetric quantitative measurement of joint effusion can serve as an MRI gold-standard, could apply to other joints and collections, and is highly suited to future automation.

Management of intraoperative acetabular fracture in primary total hip arthroplasty.

BACKGROUND: Intraoperative acetabular fracture(IAF) is a rare complication of primary total hip arthroplasty(THA). The previous reports have lacked a sufficiently large number of subjects to allow for an analysis of the causes and appropriate treatment of this problem. METHODS: Between 2015 to 2018, 4888 primary THA were enrolled. We retrospectively reviewed the records in our Total Joint Registry Database and found that 24 patients (24 hips) had sustained intraoperative acetabular fractures. Twenty-four patients(16 females and 8males)were all treated with a posterolateral approach using uncemented components. Twenty patients(83.3%)underwent supplemental screw fixation, of which 2 patients were treated with steel plate fixation. Two patients' femoral heads were used as a graft. In 4 patients(16.7%), the acetabular components were judged to be stable despite the fracture and no additional treatment was performed. All patients were evaluated clinically with Harris Hip Scores (HHS) and radiographically with serial X-rays which follow up for a mean period of 34.0 ± 12.6 months. We evaluated the anatomic locations, causes, treatments, and outcome of the fractures to study the treatment method and effect of intraoperative acetabular fracture during operation. RESULTS: The fracture rate associated with uncemented components was 0.49%. In 17(70.8%) of these patients, the fracture was noted during the impaction of the real acetabular component. Six patients(25%)with Ankylosing Spondylitis had fractures, 4 in the anterior wall, and 1 in the anterior column, because the patient with hip joint fusion needs a to pre-osteotomy before the dislocation. The HHS score increased from 30.8 ± 9.7 preoperatively to 90.2 ± 4.2 postoperatively. All the latest x-ray showed that the fracture did not move, and there is no translucent line formed in the acetabular cup bone interface. CONCLUSION: Intraoperative acetabular fractures are rare complications of THA, and most commonly occur during the implantation of the acetabular components. It is necessary to prevent the occurrence of fractures as much as possible even if the fractures are found during the operation. It should be noted that patients with ankylosing spondylitis involving hip joints during THA surgery must be careful to prevent IAFs during dislocation and pre-osteotomy.

[Osteoarthrosis in the clinic of internal and occupational diseases: differential diagnostic aspects].

Osteoarthritis is a common pathology, which indicates the great medical and social significance of this disease. The article discusses the issues of pathogenesis, risk factors and diagnosis of professional and professionally caused osteoarthritis: the age of onset of the disease, the specifics of work, the localization of joint damage. Differential diagnosis issues are discussed.

Brucellosis-induced bilateral avascular necrosis of the hip joints in a middle-aged Iranian woman with refractory intolerance to medications: A case report.

INTRODUCTION: Brucellosis is a zoonotic illness caused by Brucella bacteria, primarily transmitted through contaminated dairy products or direct contact with infected animals. Brucellosis is highly prevalent in Iran, with Brucella melitensis biovar 1 being the primary causative agent. Musculoskeletal symptoms, including spondylitis, sacroiliitis, and peripheral arthritis, are common in brucellosis patients, but avascular necrosis of the hip joint is extremely rare. CASE PRESENTATION: This case report presents a middle-aged woman from Iran with untreated brucellosis infection, who developed rapidly progressing avascular necrosis affecting both hip joints. The patient's social history did not indicate any use of tobacco or alcohol. Furthermore, there was no indication of any traumatic events affecting the patient's hip joints. The patient's family history did not reveal any rheumatologic disorders, and the patient had not been diagnosed with or reported using immune suppressant medications. Laboratory results confirmed that the patient was not diagnosed with sickle cell anemia. The patient had been intolerant to the prescribed medications, Rifampin and Doxycycline. Initially, she presented with severe bilateral hip pain, anorexia, vomiting, periodic chills and fever, myalgia, and night sweats. Pelvis X-ray confirmed bilateral hip avascular necrosis, and total hip arthroplasty was scheduled but subsequently canceled due to persistent brucellosis infection. Physical examination revealed limited hip motion, pain, and inability to bear weight. Laboratory tests indicated leukocytosis, elevated levels of CRP, and high titers on Wright and 2ME tests. Intravenous Ciprofloxacin was initiated, and further investigations were scheduled. DISCUSSION: Osteoarticular complications are common in individuals with brucellosis. The sacroiliac joints are affected in 80 % of cases, while the spinal joints are affected in 50 %. Brucella-induced arthritis can be found in over 50 % of patients, with the lower limb joints being the most commonly affected. Failure to diagnose and treat hip arthritis caused by brucellosis promptly can lead to severe complications, including dislocation and avascular necrosis of the femoral head. Avascular necrosis is a condition where bone tissue dies due to compromised blood supply. It often remains asymptomatic initially and is usually found incidentally during radiographic imaging. Osteonecrosis of the femoral head can manifest as Legg-Calve-Perthes disease or as a complication of other medical conditions. Various factors can contribute to avascular necrosis, including hip dislocation or fracture, prolonged use of certain medications, excessive alcohol consumption, and certain medical conditions. Magnetic resonance imaging is considered the standard method for diagnosing avascular necrosis. Delay in diagnosing and treating brucellosis can result in permanent bone complications. CONCLUSION: Brucellosis, a disease prevalent in endemic regions, should be considered as a cause of severe hip pain and other vague symptoms. Timely diagnosis and management are important, especially for high-risk patients with other health conditions and poor drug compliance, to prevent complications such as avascular necrosis.

Effect of motion inputs on the wear prediction of artificial hip joints.

Hip joint simulators have been largely used to assess the wear performance of joint implants. Due to the complexity of joint movement, the motion mechanism adopted in simulators varies. The motion condition is particularly important for ultra-high molecular weight polyethylene (UHMWPE) since polyethylene wear can be substantially increased by the bearing cross-shear motion. Computational wear modelling has been improved recently for the conventional UHMWPE used in total hip joint replacements. A new polyethylene wear law is an explicit function of the contact area of the bearing and the sliding distance, and the effect of multidirectional motion on wear has been quantified by a factor, cross-shear ratio. In this study, the full simulated walking cycle condition based on a walking measurement and two simplified motions, including the ISO standard motion and a simplified ProSim hip simulator motion, were considered as the inputs for wear modelling based on the improved wear model. Both the full simulation and simplified motions generated the comparable multidirectional motion required to reproduce the physiological wear of the bearing in vivo. The predicted volumetric wear of the ProSim simulator motion and the ISO motion conditions for the walking cycle were 13% and 4% lower, respectively, than that of the measured walking condition. The maximum linear wear depths were almost the same, and the areas of the wear depth distribution were 13% and 7% lower for the ProSim simulator and the ISO condition, respectively, compared with that of the measured walking cycle motion condition.

Metal-Driven Autoantifriction Function of Artificial Hip Joint.

The service life of an artificial hip joint is limited to 10-15 years, which is not ideal for young patients. To extend the lifespan of these prostheses, the coefficient of friction and wear resistance of metallic femoral heads must be improved. In this study, a Cu-doped titanium nitride (TiNX -Cu) film with "autoantifriction" properties is deposited on a CoCrMo alloy via magnetron sputtering. When delivered in a protein-containing lubricating medium, the Cu in TiNX -Cu quickly and consistently binds to the protein molecules in the microenvironment, resulting in the formation of a stable protein layer. The proteins adsorbed on the TiNX -Cu surface decompose into hydrocarbon fragments owing to the shear stress between the Al2 O3 /TiNX -Cu tribopair. The synergistic effect of the catalysis of Cu and shear stress between the Al2 O3 /TiNX -Cu tribopair transforms these fragments into graphite-like carbon tribofilms with an antifriction property. These tribofilms can simultaneously reduce the friction coefficient of the Al2 O3 /TiNX -Cu tribopair and enhance the wear resistance of the TiNX -Cu film. Based on these findings, it is believed that the autoantifriction film can drive the generation of antifriction tribofilms for lubricating and increasing the wear resistance of prosthetic devices, thereby prolonging their lifespan.

FEM wear prediction of ceramic hip replacement bearings under dynamic edge loading conditions.

Hard-on-Hard hip implants, specifically ceramic tribo-pair, have produced the highest in-vivo wear resistance, biocompatibility, superior corrosion resistance, and high fracture toughness. However, this ceramic tribo-pair suffers from edge loading, sharply increasing wear and accelerating early implant failures due to micro-separation. Even though in-vitro studies have tested the occurrence of wear due to dynamic edge loading, the Finite Element Method (FEM) gives the advantage of accurately estimating the wear, minimizing the experimental time and cost. A new fundamental FEM model is developed to predict wear for ceramic hip replacement bearings under dynamic edge loading conditions for a fixed separation and fixed inclination angle. The model is directly validated with the existing hip simulator data up to 3 million cycles in terms of wear depth, wear scar and volumetric wear rate. The results from the model show that the accuracy in wear prediction was more than 98% for the wear depth and volumetric wear rate for the dynamic edge loading condition. A stripe wear scar is captured, depicting the edge loading conditions. The developed model from this study can predict wear under pure standard and dynamic edge loading conditions.

Posttraumatic Isolated Right Gluteus Minimus Tear: A Case Report.

Greater trochanteric pain syndrome (GTPS) is often diagnosed in patients who present with pain over the lateral aspect of the hip. Trauma with injury to the gluteus minimus and medius muscles results in hip pain, which should be considered when diagnosing chronic pain of the lateral hip. The gluteus minimus tendon insertion is located anterior to the anterior facet of the greater trochanter of the femur anatomically. Hence, gluteus minimus tendon pathology may also manifest as chronic lateral hip pain and is considered as the etiology of GTPS. These conditions do not respond to physiotherapy and analgesia. Both open and keyhole endoscopic methods have produced good results in addressing hip pain and abduction weakness. There is a lack of literature regarding isolated gluteus minimus tendon tear as the cause of chronic lateral hip pain or GTPS. Here, we present a rare case of a middle-aged lady with GTPS due to isolated gluteus minimus injury.

The prevalence and treatment of osteoporosis in patients undergoing total hip arthroplasty and the levels of biochemical markers of bone turnover.

AIMS: Osteoporosis is common in total hip arthroplasty (THA) patients. It plays a substantial factor in the surgery's outcome, and previous studies have revealed that pharmacological treatment for osteoporosis influences implant survival rate. The purpose of this study was to examine the prevalence of and treatment rates for osteoporosis prior to THA, and to explore differences in osteoporosis-related biomarkers between patients treated and untreated for osteoporosis. METHODS: This single-centre retrospective study included 398 hip joints of patients who underwent THA. Using medical records, we examined preoperative bone mineral density measures of the hip and lumbar spine using dual energy X-ray absorptiometry (DXA) scans and the medications used to treat osteoporosis at the time of admission. We also assessed the following osteoporosis-related biomarkers: tartrate-resistant acid phosphatase 5b (TRACP-5b); total procollagen type 1 amino-terminal propeptide (total P1NP); intact parathyroid hormone; and homocysteine. RESULTS: The prevalence of DXA-proven hip osteoporosis (T-score ≤ -2.5) among THA patients was 8.8% (35 of 398). The spinal osteoporosis prevalence rate was 4.5% (18 of 398), and 244 patients (61.3%; 244 of 398) had osteopenia (-2.5 < T-score ≤ -1) or osteoporosis of either the hip or spine. The rate of pharmacological osteoporosis treatment was 22.1% (88 of 398). TRACP-5b was significantly lower in the osteoporosis-treated group than in the untreated group (p < 0.001). CONCLUSION: Osteoporosis is common in patients undergoing THA, but the diagnosis and treatment for osteoporosis were insufficient. The lower TRACP-5b levels in the osteoporosis-treated group - that is, osteoclast suppression - may contribute to the reduction of the postoperative revision rate after THA.Cite this article: Bone Joint Res 2022;11(12):873-880.

Normal variation of infant hip development : patterns revealed by 3D ultrasound.

AIMS: Studies of infant hip development to date have been limited by considering only the changes in appearance of a single ultrasound slice (Graf's standard plane). We used 3D ultrasound (3DUS) to establish maturation curves of normal infant hip development, quantifying variation by age, sex, side, and anteroposterior location in the hip. METHODS: We analyzed 3DUS scans of 519 infants (mean age 64 days (6 to 111 days)) presenting at a tertiary children's hospital for suspicion of developmental dysplasia of the hip (DDH). Hips that did not require ultrasound follow-up or treatment were classified as 'typically developing'. We calculated traditional DDH indices like α angle (αSP), femoral head coverage (FHCSP), and several novel indices from 3DUS like the acetabular contact angle (ACA) and osculating circle radius (OCR) using custom software. RESULTS: α angle, FHC, and ACA indices increased and OCR decreased significantly by age in the first four months, mean αSP rose from 62.2° (SD 5.7°) to 67.3° (SD 5.2°) (p < 0.001) in one- to eight- and nine- to 16-week-old infants, respectively. Mean αSP and mean FHCSP were significantly, but only slightly, lower in females than in males. There was no statistically significant difference in DDH indices observed between left and right hip. All 3DUS indices varied significantly between anterior and posterior section of the hip. Mean 3D indices of α angle and FHC were significantly lower anteriorly than posteriorly: αAnt = 58.2° (SD 6.1°), αPost = 63.8° (SD 6.3°) (p < 0.001), FHCAnt = 43.0 (SD 7.4), and FHCPost = 55.4° (SD 11.2°) (p < 0.001). Acetabular rounding measured byOCR indices was significantly greater in the anterior section of the hip (p < 0.001). CONCLUSION: We used 3DUS to show that hip shape and normal growth pattern vary significantly between anterior and posterior regions, by magnitudes similar to age-related changes. This highlights the need for careful selection of the Graf plane during 2D ultrasound examination. Whole-joint evaluation by obtaining either 3DUS or manual 'sweep' video images provides more comprehensive DDH assessment.Cite this article: Bone Jt Open 2022;3(11):913-923.

The role of the iliofemoral ligament as a stabilizer of the hip joint.

The purpose of this systematic literature review is to analyse the role of the iliofemoral ligament (ILFL) as a hip joint stabilizer in the current literature.A total of 26 articles were included in the review. The ILFL is the largest hip ligament consisting of two distinct arms and is highly variable, both in its location and overall size, and plays a primary role in hip stability; in the case of hip dislocation, the iliofemoral ligament tear does not heal, resulting in a persistent anterior capsule defect. Clinically, the ILFL is felt to limit external rotation in flexion and both internal and external rotation in extension.The abduction-hyperextension-external rotation (AB-HEER) test is overall the most accurate test to detect ILFL lesions. Injuries of the ILFL could be iatrogenic or a consequence of traumatic hip instability, and can be accurately studied with magnetic resonance imaging. Different arthroscopic and open techniques have been described in order to preserve the ILFL during surgery and, in case of lesions, several procedures with good to excellent results have been reported in the existing literature.The current systematic review, focusing only on the ILFL of the hip, summarizes the existing knowledge on anatomy, imaging and function and contributes to the further understanding of the ILFL, confirming its key role in anterior hip stability. Future studies will have to develop clinical tests to evaluate the functionality and stability of the ILFL. Cite this article: EFORT Open Rev 2021;6:545-555. DOI: 10.1302/2058-5241.6.200112.

Mechanical Performance of Artificial Hip Stems Manufactured by Hot Forging and Selective Laser Melting Using Biocompatible Ti-15Zr-4Nb Alloy.

We investigated the microstructures, tensile properties, fatigue strengths, and durability limits of hot-forged Ti-15Zr-4Nb (Ti-15-4) alloy artificial hip stems. These properties were compared with those of Ti-15Zr-4Nb-4Ta (Ti-15-4-4) and Ti-6Al-4V (Ti-6-4) alloy stems annealed after selective laser melting. The tensile and fatigue properties of test specimens cut from Ti-15-4 stems annealed after hot forging were excellent compared with those of the Alloclassic Zweymüller Stepless (SL) stem, which is used globally. The 0.2% proof stress (σ0.2%PS), ultimate tensile strength (σUTS), total elongation (TE) at breaking, and fatigue strength (σFS) after 107 cycles were 919 ± 10, 983 ± 9 MPa, 21 ± 1%, and 855 ± 14 MPa, respectively. The durability limit (PD) after 5 × 106 cycles of Ti-15-4 stems was excellent compared with that of the SL stem. The σUTS values of 90°- and 0°-direction-built Ti-15-4-4 rods were 1032 ± 1 and 1022 ± 2 MPa, and their TE values were 14 ± 1% and 16 ± 1%, respectively. The σFS values of annealed 90°-direction-built Ti-15-4-4 and Ti-6-4 rods were 640 ± 11 and 680 ± 37 MPa, respectively, which were close to that of the wrought Ti-15-4 rod (785 ± 17 MPa). These findings indicate that the hot forging and selective laser melting (SLM) techniques can also be applied to the manufacture of artificial hip prostheses. In particular, it was clarified that selective laser melting using Ti-15-4-4 and Ti-6-4 powders is useful for the low-cost manufacturing of custom-made artificial joint prostheses and other prosthetic implants.

The Influence of Carrying Anterior Load on the Sagittal and Frontal Plane Kinematics of Lower Extremities during Stair Ascending.

BACKGROUND: Anterior load carriage is a one of the commonly performed activities in some industries. Stair climbing while carrying anterior load significantly alters different biomechanical mechanisms that can potentially affect the musculoskeletal function of the lower extremities. OBJECTIVE: The study aims to assess the effect of carrying an anterior load (20% of body weight) on lower extremity kinematics during the kinematical phases of stairs ascent (weight acceptance, pull up, forward continuance, and swing phase). MATERIAL AND METHODS: In this experimental study, data were collected through the use of a custom made wooden staircase and OPtiTrack motion capture system was composed of 12 infrared cameras and a per modeled reflective marker set. Sixteen female college students volunteered to conduct two tasks of ascending stairs with and without an anterior load of approximately 20% of their body weight. The collected frontal and sagittal plane lower extremity joint angles were calculated using MATLAB software (version R2015a). Statistical comparison between the two study tasks was made using IBM SPSS Statistics software (version 25.0; SPSS Inc., Chicago, IL, USA). RESULTS: Based on the results, there is significant difference (p-value < 0.05) between the two study tasks during ascending stair phases in all three sagittal plan lower extremity joint angles. CONCLUSION: Anterior load carried during stair ascent causes participants to depend more on the hip joint (higher flexion angles) compared to stair ascent without loads, which may increase the risk of falls and injuries, and the importance of muscle-strengthening activities and highlight the use of appropriate technique during load carriage.

The in vivo location of edge-wear in hip arthroplasties : combining pre-revision 3D CT imaging with retrieval analysis.

AIMS: Acetabular edge-loading was a cause of increased wear rates in metal-on-metal hip arthroplasties, ultimately contributing to their failure. Although such wear patterns have been regularly reported in retrieval analyses, this study aimed to determine their in vivo location and investigate their relationship with acetabular component positioning. METHODS: 3D CT imaging was combined with a recently validated method of mapping bearing surface wear in retrieved hip implants. The asymmetrical stabilizing fins of Birmingham hip replacements (BHRs) allowed the co-registration of their acetabular wear maps and their computational models, segmented from CT scans. The in vivo location of edge-wear was measured within a standardized coordinate system, defined using the anterior pelvic plane. RESULTS: Edge-wear was found predominantly along the superior acetabular edge in all cases, while its median location was 8° (interquartile range (IQR) -59° to 25°) within the anterosuperior quadrant. The deepest point of these scars had a median location of 16° (IQR -58° to 26°), which was statistically comparable to their centres (p = 0.496). Edge-wear was in closer proximity to the superior apex of the cups with greater angles of acetabular inclination, while a greater degree of anteversion influenced a more anteriorly centred scar. CONCLUSION: The anterosuperior location of edge-wear was comparable to the degradation patterns observed in acetabular cartilage, supporting previous findings that hip joint forces are directed anteriorly during a greater portion of walking gait. The further application of this novel method could improve the current definition of optimal and safe acetabular component positioning. Cite this article: Bone Joint Res 2021;10(10):639-649.

Polyarticular Neurogenic Heterotopic Ossification in a Spinal Cord Injury: A Case Report from Saudi Arabia.

A 33-year-old male victim of a motor vehicle accident, who presented with a T12 (thoracic 12 vertebra) burst fracture (ISNCSCI T11 AIS-A: International Standards for Neurological Classification of Spinal Cord Injury T11 ASIA Impairment Scale), was admitted to a rehabilitation hospital. A stage-II left ischial pressure ulcer was also reported. An X-ray of the pelvis revealed bilateral neurogenic heterotopic ossification (NHO) in both hips and knees, which was further confirmed by TC-99m methylene diphosphonate (MDP) bone scintigraphy. Interventions included indomethacin and conservative management. Surgery was not preferred, as NHO was still immature. Moreover, patient transfer and lower body dressing were unaffected by NHO. It is important to consider an early radiological screen in selected high-risk cases for NHO, to minimize the risk of associated complications.

Enhanced lubricant film formation through micro-dimpled hard-on-hard artificial hip joint: An in-situ observation of dimple shape effects.

This study evaluates the impact of dimple shapes on lubricant film formation in artificial hip joints. Micro-dimples with 20-50 µm lateral size and 1 ±â€¯0.2 µm depths were fabricated on CrCoMo hip joint femoral heads using a picosecond laser. Tribological studies were performed using a pendulum hip joint simulator to apply continuous swing flexion-extension motions. The results revealed a significantly enhanced lubricant film thickness (≥ 500 nm) with micro-dimpled prosthesis heads at equilibrium position after the lubricant film has fully developed. The average lubricant film thickness of dimpled prostheses with square- and triangular-shaped dimple arrays over time is about 3.5 that of the non-dimpled prosthesis (204 nm). Remarkably, the prosthesis with square-shaped dimple arrays showed a very fast lubricant film formation reaching their peak values within 0.5 s of pendulum movement, followed by prosthesis with triangular-shaped dimple arrays with a transition period of 42.4 s. The fully developed lubricant film thicknesses (≥ 700 nm) are significantly higher than the surface roughness (≈ 25 nm) demonstrating a hydrodynamic lubrication. Hardly any scratches appeared on the post-experimental prosthesis with square-shaped dimple array and only a few scratches were found on the post-experimental prosthesis with triangular-shaped dimple arrays. Thus, prostheses with square-shaped dimple arrays could be a potential solution for durable artificial hip joints.

Some aspects of frictional measurements in hip joint simulators.

The measurement of friction in artificial hip joints can lead to the knowledge of the lubrication mechanisms occurring in the joints. However, the measurement of friction, particularly in spherical contacts, is not always straightforward. The important loading and kinematic features must be appropriate and the friction must be measured in the correct plane. Even defining a coefficient of friction is difficult with spherical contacts as friction acts at different moment arms throughout the contact area. Thus, the generated frictional torques depend on the pressure distribution of the contact and the moment arms at which this pressure acts. The pressure distribution depends on the material properties, the surface entraining velocities, the joint diameters, and the clearance between the two surfaces of the ball and socket joint. Equally measuring friction is very taxing for machines which are applying very high loads. Slight misalignments of the application of these loads can produce torques which are very much greater than the frictional torques that we are trying to measure. This article attempts to share the thoughts behind over 40 years of measuring friction in artificial joints using the Durham Friction Simulators. This has led to accrued consistency of measurement and a robust scientific design rationale to understand the nature of friction in these spherical contacts. It also impacts on how to obtain accurate measurements as well as on the understanding of where the difficult issues lie and how to overcome them.

Extraction of well-fixed extended porous-coated cementless stems using a femoral longitudinal split procedure.

We present a technique of posterior femoral longitudinal split (FLS) osteotomy. This technique allows the expansion of the metaphyseal-diaphyseal region of the proximal femur facilitating extraction of well-fixed extended porous-coated stems. The extractions were performed using extended transfemoral osteotomy (ETO) and FLS osteotomy between June 2002 and March 2014. The study group, which comprised patients with well-fixed extended porous-coated stems, consisted of two men and ten women with an average age of 63.2 years. The stem was successfully removed using the FLS procedure in 8 of the 10 hips. Reimplantation surgery was performed in 6 of the 12 hips with ARMD, periprosthetic infection, or metallosis. This FLS technique may allow the easy removal of well-fixed extended porous-coated stems and become an alternative method for the removal of all stems.