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In the operation of mechanisms with lubricated clearances, uncertain parameters such as the temperature of lubricant, driving speed, and clearance value will lead to dynamic variations for oil film thickness of lubricated clearance. The lubrication may fail when the oil film thickness of bearing surfaces is insufficient, thereby significantly affecting the performance of the mechanism. This paper presents a novel method for the dynamic reliability of lubricated clearances by improved response surface method (IRSM). Firstly, the mathematical model of lubricated clearance is established, and the oil film load of lubricated clearance is defined, then the dynamic model of mechanism considering lubricated clearances is built through Lagrange method. Secondly, considering the failure mechanism of the lubricated clearance, the surrogate model is established using the IRSM with minimum oil film thickness as the failure criterion. Finally, taking the 9-link mechanism with multiple lubricated clearances as a numerical example, the dynamic minimum oil film thickness of the lubricated clearance considering uncertain parameters is computed. The reliability of the lubricated clearance is investigated by the surrogate model, and the applicability of the model is verified by the Monte Carlo method (MCM). The results demonstrate that the IRSM has higher accuracy compared to the traditional response surface method (TRSM). This paper provides a theoretical basis for the study of failure mechanism and reliability of lubricated clearances, and also has practical significance for engineering applications. [ABSTRACT FROM AUTHOR]

While total hip arthroplasty (THA) remains effective for improvement of pain and function in patients with osteoarthritis and avascular necrosis, there remain areas of continued pursuit of excellence, including decreasing rates of dislocation, leg length discrepancy, implant loosening, and infection. This review article covers several bearing surfaces and articulations, computer-assisted navigation and robotic technology, and minimally invasive surgical approaches that have sought to improve such outcomes. Perhaps the most significant improvement to THA implant longevity has been the broad adoption of highly cross-linked polyethylene, with low wear rates. Similarly, navigation and robotic technology has proven to more reproducibly achieve intraoperative component positioning, which has demonstrated clinical benefit with decreased risk of dislocation in a number of studies. Given the projected increase in THA over the coming decades, continued investigation of effective incorporation of technology, soft tissue–sparing approaches, and durable implants is imperative to continued pursuit of improved outcomes in THA. [ABSTRACT FROM AUTHOR]

The issue of using vortex generators to improve the take-off and landing characteristics of a transport category aircraft has been considered. Three directions have been analyzed. The first: the installation of vortex generators on the nacelles of the main engines to increase the maximum value of the lift coefficient in landing modes. The second: the installation of vortex generators on the upper surface of the flap to increase the lifting characteristics of the wing by improving the flow around the flap. The third: the installation of vortex generators in the tail unit to increase the efficiency of control surfaces and reducing handling speeds. Examples of the use of vortex generators in each of the directions are given. It is shown that the improvement of the aerodynamic characteristics of the aircraft is possible in the presence of wing separation boundaries on the lifting surfaces in flight operating modes and the elimination of these zones by installing vortex generators. The results of computational studies, experiments in wind tunnels, as well as data from flight tests of an experimental aircraft confirming the effectiveness of using vortex generators are presented. The concept of increasing their stability by installing vortex generators in places with maximum flow velocity is proposed. Considering this concept, new locations for installing vortex generators on the upper surface of the flap, as well as on the fin of an experimental aircraft for repeated flight tests have been selected. The installation of vortex generators on the fin involves increasing the efficiency of the rudder to reduce the handling speeds. The possibilities of optimizing the parameters of the installation of vortex generators are considered. Recommendations are given on the choice of shape, size, and angles of their installation, depending on the tasks solved with the help of vortex generators and considering the possible increase in drag from their installation.

Background: Ceramic-on-ceramic (COC) bearings in total hip arthroplasty (THA) have long been considered the coupling with the lowest overall wear. However, concerns about complications such as ceramic breakage and noise, combined with the improved performance of polyethylene, have limited its use in the United States. This postapproval follow-up reports long-term (10 years) results of Delta COC in THA patients primarily enrolled in an Investigational Device Exemption study. Methods: Patients received Delta COC THA in a prospective multicenter study with either 28-mm (N = 105 hips in 104 patients) or 36-mm (N = 81) articulations. Annual clinical and radiographic evaluations were performed for years 5 to 10, and study patients were asked about hip noises and reproducibility. Results: There have been 4 additional reports of noise in 4 patients (COC 28, n = 3; COC 36, n = 1). The cumulative incidence rate for squeaking or noise at 10 years is 5.9% for COC 28 and 13.5% for COC 36. There have been 2 additional reports of dislocation in 2 patients (COC 28, n = 1; COC 36, n = 1). The cumulative incidence rate for dislocation at 10 years is 3.7% for COC 28 and 3.5% for COC 36. At 10 years, there were greater than 40 hips available for follow-up. At mean 10-year follow-up, there were a total of 3 ceramic liner fractures, but none since the previous report. There were no revisions in the 28-mm cohort, and 2 revisions in the 36-mm cohort (1 for recurrent dislocation and 1 for pain and noise). Overall Kaplan-Meier survivorship was 95.96% at 10.5 years (28 mm: 97.68% at 10.2 years; 36 mm: 94.11% at 10.4 years.) Conclusions: At 10-year follow-up, we report excellent results in regard to survivorship, with one patient revised for pain with associated squeaking.

Introduction: Metallosis, characterized by the collection of metallic debris in periarticular tissues, is primarily associated with metal-on-metal bearings in hip arthroplasty. This report presents a rare case of metallosis after metal-on-polyethylene (MoP) total hip arthroplasty (THA), highlighting diagnostic challenges and management strategies. Metallosis following MoP arthroplasty is extremely rare, with only a limited number of documented cases in the literature., Case Report: A 70-year-old man presented with post-traumatic hip pain and instability 6 years after an uncemented MoP THA. Radiographs revealed a fractured acetabular cup with metal fragments and displacement of the femoral head. A computed tomography scan confirmed liner failure, cup breakage, and radiodense opacities around the joint. Given the post-traumatic presentation and the risk of heterotopic ossification, the patient underwent revision surgery. Revision surgery involved acetabular component exchange, and clinical follow-up indicated satisfactory outcomes., Conclusion: This case highlights the atypical presentation of metallosis following MoP THA, emphasizing the significance of early diagnosis and awareness for optimal patient outcomes., Competing Interests: Conflict of Interest: Nil, (Copyright: © Indian Orthopaedic Research Group.)

Abstract Background The ideal bearing surface for patients of avascular necrosis (AVN) undergoing total hip arthroplasty (THA) remains controversial. The purpose of this study is to evaluate the clinical outcomes, health-related quality of life (HRQL), and wear of the bearing surface between ceramic-on-ceramic (CoC) and ceramic-on-highly cross-linked polyethylene (CoXPE) THA for patients of AVN after midterm follow-up. Methods We performed a retrospective case-control analysis of 93 CoC and 77 CoXPE consecutive THAs for patients of AVN. The cases were followed at a minimum 5 years follow-up (average 7 years). Harris hip score (HHS) score and bearing-related complications were assessed. The health-related quality of life (HRQL) was assessed with the Short Form 36 (SF-36). Plain radiographs and computed tomography (CT) were used for radiographic evaluation. Results Both the CoC group and CoXPE group showed statistically significant improvements in HHS scores with no difference between the two bearing surfaces. There was no significant difference as for SF-36 at the latest follow-up between two groups, except for significant higher scores in the dimensions of general health in the CoC group (75.7 vs 64.7, P = 0.032). No radiographic evidence of osteolysis and loosening was present at the final follow-up. The mean wear rate of the CoC was 0.0096 mm/year and the CoXPE was 0.047 mm/year after evaluation with reconstructed CT. Conclusions CoC THAs acts as well as CoXPE THAs for patients with femoral head avascular necrosis after midterm follow-up. CoC bearing can significantly decrease the wearing rate than CoXPE bearing.

Introduction: The literature around use of Large Diameter Heads (LDH) is abundantly available for revision Total Hip Arthroplasty (THA) but is lacking for primary uncomplicated THA. This systematic review was undertaken to synthesize data around primary THA involving LDH and analyze the associated complications (dislocation, volumetric wear, implant survivorship and functional score) along with reported effects on range of motion (ROM), patient reported outcomes and impingement rate/groin pain. Methods: A PRISMA compliant systematic review was done using extensive search in PubMed database, along with offline search looking for the literature published in English language between 2008 and 2018. The articles providing data on the use of large diameter heads (LDH) (36 mm or larger) on various bearing surfaces were collected. This included robust national joint registries of different countries. Narrative approach to data synthesis was used. Results: A total of 23 papers met our inclusion criteria, including six national joint registries. It was observed that LDH had significantly low dislocation rates, excellent implant survival rate as per Kaplan–Meier survivorship (> 90% at five years). Surgical approaches, except Minimally Invasive Surgery (MIS), did not increase any risk of dislocation as long as it was meticulously repaired. There was no significant improvement in any functional scores or improved ROM. Conclusions: LDH of 32–36 mm are now commonly used in primary THA and is accepted as a popular size. The beneficial effects of a large head size are negated beyond 38 mm. The most favored size for LDH THA, therefore, is 36 mm contrary to the older literature favoring 28 mm. [ABSTRACT FROM AUTHOR]

Although total knee arthroplasty is one of the most successful and consolidated surgical procedure, the infection rate is still elevate. To treat infected knee arthroplasties, in the past years was approached a procedure that involved the implantation of an antibiotic-loaded temporary spacer. This spacer helps maintain an appropriate soft tissue envelope and the patients are able to walk during the interim period. This study investigated the tribological behavior of antibiotic-impregnated knee spacers under dynamic loading. Three temporary spacer specimens were subjected to a cyclic test on a knee wear simulator for 500,000 walking cycles under a modified international guidelines (ISO 14243). During this test we address about the evaluation of the mechanical resistance and to quantify the wear rate of the devices. All the kinematics and the axial load were set to simulate more than six months of patient use. All the femoral and tibial specimens completed the 500,000 cycles without breakage. The wear patterns observed on the contact surfaces were similar over the specimens. On the basis of the present data, the authors believe that the use of temporary antibiotic-impregnated knee spacers could be an effective wear-resistance temporary substitute of a total knee two-stage revision arthroplasty. [ABSTRACT FROM AUTHOR]

Promising results of total hip allowed to perform a hip replacement in younger and active patients. However, the results of arthroplasty in young populations are still not comparable with outcomes in patients of older age groups. The advent of new materials and further improvement of production technology is increasing interest in the use of alternative bearing surfaces, but to assess the effectiveness of each new implants needed long-term clinical studies. Use of any bearing surface has its own potential advantages and disadvantages that must be assessed in each case.

Formation of wear particles within total hip replacement is one of the main causes of its failure. In addition to improving the lubrication and wear resistance of materials used as bearing surfaces, understanding of wear particle distribution patterns within lubricants inside an implant gap could be used to improve design parameters and implants’ lifespan. In this study, the behaviours of biolubricants (with compositions similar to human joint synovial fluid) and suspended particles were investigated by micro-particle image velocimetry in curved mini channels under oscillatory Couette flow conditions. The studied biolubricants had shear-thinning viscoelastic characteristics. The authors found that increasing shear-thinning, elasticity or motion frequency levels did not affect the trend behaviours of biolubricant flows due to the low strain values of the experimental conditions applied. However, suspended particles formed strings along flow directions and exhibited cross-stream migration to channel walls. Motion frequency, fluid shear thinning and elasticity characteristics and channel dimensions strongly affected particle behaviours.

Introduction: We have investigated the revision rates of all bearing surface combinations for primary total hip replacement (THR) registered on the New Zealand Joint Registry (NZJR) to determine which coupling has been the most durable and successful over the last 16 years. Methods: There were 106,139 primary THRs registered, resulting in 4,960 revisions for any cause. We examined all-cause revision rates, reasons for revision and performed survival analyses. Results: Ceramic-on-highly cross-linked polyethylene (CoPx) had the lowest all-cause revision rate of 0.54/100-component-years (cys) (95% confidence interval 0.48 to 0.61). This was superior to all other hard-on-soft bearing combinations in unadjusted analysis. Furthermore, the age of patients receiving CoPx was significantly lower than for metal-on-polyethylene (mean 62.9; standard deviation [SD] 10.1 vs. 69.1; SD 9.6; p<0.001). Acetabular loosening was the reason for revision in 14.5% of CoPx, compared to 33% of MoP THRs (p<0.001). Metal-on-metal bearings had the highest revision rate of 1.43/100 cys and were significantly inferior to CoPx (p<0.001). Kaplan-Meier analysis and Cox regression analyses were performed and we adjusted the analyses to control for age, femoral head size, surgical approach and fixation. Conclusions: CoPx remained the most durable and successful coupling used in primary THR in New Zealand irrespective of age, gender or size of femoral head. [ABSTRACT FROM AUTHOR]

As indications for total hip arthroplasty (THA) have expanded, the incidence of THA has increased among younger patients, who live longer and tend to place more strain on implants via higher activity levels. This demographical shift accentuates the importance of advancing innovation to ensure implant longevity for younger and more active patients. Future innovation, as it pertains to THA components, is likely to focus on modifying implant designs and tribology in conjunction with identification and application of newer biomaterials. By reviewing the literature for development status of various materials and novel design advancements in THA component outside of the standard highly cross-linked polyethylene, this investigation provided an update on the current and future status of design initiatives as they pertain to THA. Though the highlighted alternative bearing surfaces have shown promising in vitro and limited, yet encouraging clinical data, they lack larger and longer-term clinical trial results. Further research and innovation is warranted to identify the optimal bearing surface to most effectively accommodate for the trend of younger and more active patients undergoing THA. Implant longevity is crucial if the clinical success of THA is to be maintained. [ABSTRACT FROM AUTHOR]

Background: Metal wear and corrosion from modular junctions in total hip arthroplasty can lead to further unwanted surgery. Trunnion tribocorrosion is recognized as an important contributor to failure. This study was performed to determine if new metal heads restore mechanical integrity of the original modular junction after impaction on corroded trunnions, and assess which variables affect stability of the new interface created at revision total hip arthroplasty.Methods: Twenty-two trunnions, cobalt-chromium (CoCr) and titanium alloy (TiAIV), (CoCr, n = 12; TiAIV, n = 10) and new metal heads were used, 10 trunnions in pristine condition and 12 with corrosion damage. Test states were performed using an MTS Machine and included the following: 1, Assembly; 2, Disassembly; 3, Assembly; 4, Toggling; and 5, Disassembly. During loading, three-dimensional motion of the head-trunnion junction was measured using a custom jig.Results: There were no statistical differences in the tested mechanical properties between corroded and pristine trunnions implanted with a new metal femoral head. Average micromotion of the head versus trunnion interface was greatest at the start of loading, stabilizing after approximately 50 loading cycles at an average of 30.6 ± 3.2 μm.Conclusion: Corrosion at the trunnion does not disrupt mechanical integrity of the junction when a CoCr head is replaced with a CoCr trunnion. However, increased interface motion of a new metal head on a corroded titanium trunnion requires additional study. The evaluation of ball head size on mechanical integrity of trunnions would also be a potential subject of future investigation, as increasing the ball head size at the time of revision is not uncommon in revisions today. [ABSTRACT FROM AUTHOR]

Background: Dual mobility designs were introduced to increase stability and reduce the risk of dislocation, both being common reasons for surgical revision after total hip arthroplasty. The in vivo behavior of dual mobility constructs remains unclear, and to our knowledge, no data have been published describing in vivo surface damage to the polyethylene bearing surfaces.Methods: We used surface damage assessed on the inner and outer polyethylene bearing surfaces in 33 short-term retrieved dual mobility liners as evidence of relative motion at the 2 bearings. A lever out test was performed to determine the force required for dislocation of the cobalt-chromium femoral head from the polyethylene liner.Results: Both bearings showed damage; however, the inner polyethylene bearings had higher damage scores, lower prevalence of remaining machining marks, and higher incidence of concentric wear, all consistent with more motion at the inner polyethylene bearing. The inner polyethylene bearings also had a higher occurrence of embedded titanium debris. The damage sustained in vivo was insufficient to lead to intraprosthetic dislocation in any of the retrieved components. Lever out tests of 12 retrievals had a mean dislocation load of 261 ± 52 N, which was unrelated to the length of implantation.Conclusion: Our short-term retrieval data of 33 highly cross-linked polyethylene dual mobility components suggest that although motion occurs at both bearing articulations, the motion of the femoral head against the inner polyethylene bearing dominates. Although damage was not severe enough to lead to intraprosthetic dislocation, failure may occur long term and should be assessed in future studies. [ABSTRACT FROM AUTHOR]

This article presents examination of a failed total hip replacement with surface engineered metal-on-metal (MoM) articulation. The implant was coated with a thin TiNbN film (Physical Vapor Deposition), and at retrieval 53 months after implantation the coating was abraded on weight-bearing part of the head and acetabular component. Scanning electron microscopy of bearing surfaces demonstrated multifocal crack formation, delamination of small film fragments, and formation of aggregates containing nanometer sized wear debris. We also observed coating damage in third body mechanism. Complex failure mechanism of TiNbN coating demonstrated in this study suggests insufficient bonding strength between the coating and substrate alloy and raise concerns regarding the use of such coatings in total hip arthroplasty with MoM bearing. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1043-1049, 2016. [ABSTRACT FROM AUTHOR]

Background: Bearing surfaces in total hip arthroplasty (THA) may affect implant longevity and hence patient outcomes. This randomized clinical trial determined how ceramic-on-ceramic (CERAMIC) bearing THA affected joint-specific pain, function, and stiffness and prosthesis fixation/longevity over 10 postoperative years compared with ceramic-on-highly-crosslinked-polyethylene (POLYETHYLENE) bearing THA. This is a follow-up to previously reported 5-year outcomes.Methods: Subjects aged <61 years were randomized to CERAMIC (n = 48) or POLYETHYLENE (n = 44) THA. Subjects were assessed using the Western Ontario McMaster Osteoarthritis Index and the RAND 12-Item Health Survey preoperatively, and at 1, 5, and 10 years postoperatively. Plain radiographs were evaluated at 10 years for fixation, and medical records were reviewed for revisions.Results: Of 92 subjects, 6 (7%) died within 10 years; 68 (79%) survivors provided radiographic and/or clinical follow-up at 10 years postoperatively. Improvements seen at 5 years in both the Western Ontario McMaster Osteoarthritis Index and RAND 12-Item Health Survey were retained at 10 years with no group differences (P > .48). There were no failures or loss of fixation related to bearing surfaces/wear in either group. Over 10 years, 3 subjects in the POLYETHYLENE group had revisions that were related to recurrent dislocation; 2 revisions were performed within 2 years of surgery, and one further subject underwent revision at 7 years postoperatively.Conclusions: This is one of the first randomized clinical trials to examine 10-year outcomes between CERAMIC and POLYETHYLENE bearing THAs. Both bearing surfaces performed well out to 10 years in subjects who were <61 years at time of surgery. [ABSTRACT FROM AUTHOR]

Background: Large-diameter, monoblock acetabular components have been used for both hip resurfacing arthroplasty and metal-on-metal (MoM) total hip arthroplasty (THA). If revision is required, one solution is to retain the shell and use a dual-mobility bearing.Methods: We reviewed the results of 25 revision THAs including 11 hip resurfacing arthroplasty and 14 MoM THAs where a monoblock acetabular component was mated to a dual-mobility bearing.Results: At a mean of 29 months, there was one failure, an intraprosthetic dislocation of the dual-mobility bearing. There was a significant decrease in serum metal ion levels postoperatively.Conclusion: Retention of a well-fixed, monoblock MoM acetabular shell and mating it to a dual-mobility bearing in the setting of revision surgery seems to be a reasonable, low-morbidity option at short-term follow-up in appropriately positioned cups. [ABSTRACT FROM AUTHOR]

We reviewed 27 patients who underwent revision for an adverse local tissue reaction (ALTR) secondary to corrosion at the head-neck junction with MoP bearings. Serum cobalt and chromium levels were elevated in all cases, with a mean cobalt of 11.2 ppb and chromium of 2.2 ppb. Patients underwent modular bearing exchange, including a ceramic head with a titanium sleeve in 23 of 27 cases with only one recurrence of ALTR in one of the four patients not treated with a ceramic head. The diagnosis of ALTR secondary to corrosion is associated with cobalt levels of >1 ppb with cobalt levels elevated above chromium. Retention of a well-fixed stem and modular exchange to a ceramic head leads to resolution of symptoms and decreases in metal levels. [ABSTRACT FROM AUTHOR]

This study reports mid-term results of Delta ceramic on ceramic (COC) in total hip arthroplasty (THA). Subjects received Delta COC THA in a prospective multi-center study with either 28 mm ( n = 177) or 36 mm ( n = 168) articulations. Annual clinical and radiographic evaluations were performed, and patients were asked about hip noises. At mean 5.3-year follow-up there were 3 (0.9%) post-operative liner fractures. Nine revisions were performed (2 liner fracture, 4 stem loosening, 3 deep infection). Kaplan-Meier survivorship at 6 years was 96.9% (94.0–98.4). Twenty-six (7.5%) subjects reported squeaking, of whom none were revised. One (0.3%) subject could reproduce a sound in clinic. More patients reported squeaking with a 36 mm bearing (28 mm: 7/177, 36 mm: 19/168, P = 0.013). [ABSTRACT FROM AUTHOR]

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Background: Most literature in the field of total hip arthroplasty (THA) for fused hips, until date has reported the results of using metal on polyethylene and ceramic on polyethylene bearings. Results of THA using ceramic on ceramic (CoC) bearings in fused hips have not been published in literature. This study reports the results of cementless THA using CoC articulation perfomed in fused hips. Materials and Methods: Twenty-three patients (25 hips) with fused hips underwent conversion to THA using CoC bearings and were followed up for a mean 5.4 years. The conventional posterolateral approach was used in 15 hips, a modified two incision technique in 7 hips and a direct lateral approach with greater trochanteric osteotomy in 3 hips. Postoperatively, range of motion exercises were encouraged after 2-3 days of bed rest and subsequent gradual weight bearing using crutches was begun. Results: Mean Harris hip score improved from 42.4 to 84.2 and mean leg lengthening of 36.6 mm was achieved. In the average 5.4 years (range 2.8-9.1 years) followup there were no cases with osteolysis around acetabular cup and femoral stem. In this study, there was no case of ceramic fracture. There was one case of squeaking. Conclusion: This study suggests that cementless THA performed for fused hips with CoC bearings can provide good early clinical results. [ABSTRACT FROM AUTHOR]

Background: Previous studies have demonstrated equivalent survivorship of modular metal-backed tibial (MBT) and all-polyethylene tibial (APT) components. The purpose of this study is to compare the utilization and outcomes of APT and MBT components in a large US database.Methods: The American Joint Replacement Registry was queried to identify all patients undergoing primary total knee arthroplasty (TKA) during the study period from 2012 to 2019. These patients were divided into cohorts based on tibial component (APT or MBT). Cohort demographics including gender, hospital size, hospital teaching status, region, age, and Charlson Comorbidity Index were reported with descriptive statistics. Overall reoperation rates and revisions for infection, aseptic loosening, periprosthetic fracture, manipulation under anesthesia, and revision for other reasons were identified using International Classification of Diseases, Ninth Revision and Current Procedural Terminology codes and compared across APT and MBT cohorts. Kaplan-Meir survival analysis was performed based on reason for reoperation for APT and MBT.Results: During the study period, 703,007 TKAs were reported with 97.8% utilizing MBT and 2.2% utilizing APT components. Despite the introduction of alternative payment models during the study period, the utilization of APT decreased from 5.8% in 2012 to 1.7% in 2019. The survival of APT and MBT TKAs were similar across the study period: 98.1% vs 98.6% at 8 years. The rate of reoperation for all-causes was higher for APT compared to MBT (1.36% vs 1.00%; odds ratio 1.52).Conclusion: Despite their paucity of use and lower cost APT remained within a 0.4% margin of survivorship when compared to MBT implants for up to 8 years.Level Of Evidence: Level III, retrospective. [ABSTRACT FROM AUTHOR]

While mechanically-assisted crevice corrosion (MACC) at the head/neck junction of modular total hip arthroplasty (THA) femoral components was first described over two decades ago, it is only within the last few years that investigators have observed that adverse local tissue reactions (ALTRs) associated with MACC are an increasingly prevalent mode of failure of contemporary THAs. As yet, the incidence, etiology and pathogenesis of MACC-associated ALTR are not well understood. In this review, possible implant-, patient-, and surgeon-related factors are considered in the context of a small but growing body of evidence from laboratory simulations, implant and tissue retrieval studies and clinical case series. It is likely that MACC-associated ALTR is a multifactorial process and that ongoing research will lead to multiple strategies that will facilitate early diagnosis and ultimately prevention of the adverse clinical sequelae of this phenomenon. [ABSTRACT FROM AUTHOR]

Background: The ideal bearing surface for patients of avascular necrosis (AVN) undergoing total hip arthroplasty (THA) remains controversial. The purpose of this study is to evaluate the clinical outcomes, health-related quality of life (HRQL), and wear of the bearing surface between ceramic-on-ceramic (CoC) and ceramic-on-highly cross-linked polyethylene (CoXPE) THA for patients of AVN after midterm follow-up. Methods: We performed a retrospective case-control analysis of 93 CoC and 77 CoXPE consecutive THAs for patients of AVN. The cases were followed at a minimum 5 years follow-up (average 7 years). Harris hip score (HHS) score and bearing-related complications were assessed. The health-related quality of life (HRQL) was assessed with the Short Form 36 (SF-36). Plain radiographs and computed tomography (CT) were used for radiographic evaluation. Results: Both the CoC group and CoXPE group showed statistically significant improvements in HHS scores with no difference between the two bearing surfaces. There was no significant difference as for SF-36 at the latest follow-up between two groups, except for significant higher scores in the dimensions of general health in the CoC group (75.7 vs 64.7, P = 0.032). No radiographic evidence of osteolysis and loosening was present at the final follow-up. The mean wear rate of the CoC was 0.0096 mm/year and the CoXPE was 0.047 mm/year after evaluation with reconstructed CT. Conclusions: CoC THAs acts as well as CoXPE THAs for patients with femoral head avascular necrosis after midterm follow-up. CoC bearing can significantly decrease the wearing rate than CoXPE bearing. [ABSTRACT FROM AUTHOR]

This article highlights some hot topics and controversies in total hip arthroplasty. It discusses the use of pharmacologic agents, mechanical compression devices, and aspirin for thromboembolic prophylaxis. It also reviews the use of long versus short stems, as well as ceramic-on-ceramic and ceramic-on-highly cross-linked polyethylene bearing surfaces. [ABSTRACT FROM PUBLISHER]

Background: Dual mobility designs were introduced to increase stability and reduce the risk of dislocation, both being common reasons for surgical revision after total hip arthroplasty. The in vivo behavior of dual mobility constructs remains unclear, and to our knowledge, no data have been published describing in vivo surface damage to the polyethylene bearing surfaces., Methods: We used surface damage assessed on the inner and outer polyethylene bearing surfaces in 33 short-term retrieved dual mobility liners as evidence of relative motion at the 2 bearings. A lever out test was performed to determine the force required for dislocation of the cobalt-chromium femoral head from the polyethylene liner., Results: Both bearings showed damage; however, the inner polyethylene bearings had higher damage scores, lower prevalence of remaining machining marks, and higher incidence of concentric wear, all consistent with more motion at the inner polyethylene bearing. The inner polyethylene bearings also had a higher occurrence of embedded titanium debris. The damage sustained in vivo was insufficient to lead to intraprosthetic dislocation in any of the retrieved components. Lever out tests of 12 retrievals had a mean dislocation load of 261 ± 52 N, which was unrelated to the length of implantation., Conclusion: Our short-term retrieval data of 33 highly cross-linked polyethylene dual mobility components suggest that although motion occurs at both bearing articulations, the motion of the femoral head against the inner polyethylene bearing dominates. Although damage was not severe enough to lead to intraprosthetic dislocation, failure may occur long term and should be assessed in future studies., (Copyright © 2016 Elsevier Inc. All rights reserved.)

This article presents examination of a failed total hip replacement with surface engineered metal-on-metal (MoM) articulation. The implant was coated with a thin TiNbN film (Physical Vapor Deposition), and at retrieval 53 months after implantation the coating was abraded on weight-bearing part of the head and acetabular component. Scanning electron microscopy of bearing surfaces demonstrated multifocal crack formation, delamination of small film fragments, and formation of aggregates containing nanometer sized wear debris. We also observed coating damage in third body mechanism. Complex failure mechanism of TiNbN coating demonstrated in this study suggests insufficient bonding strength between the coating and substrate alloy and raise concerns regarding the use of such coatings in total hip arthroplasty with MoM bearing. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1043-1049, 2016., (© 2015 Wiley Periodicals, Inc.)