To assess the alterations in cell-specific DNA methylation associated with chondroitin sulphate response using peripheral blood collected from Kashin-Beck disease (KBD) patients before initiation of chondroitin sulphate treatment. Peripheral blood samples were collected from KBD patients at baseline of chondroitin sulphate treatment. Methylation profiles were generated using reduced representation bisulphite sequencing (RRBS) from peripheral blood. Differentially methylated regions (DMRs) were identified using MethylKit, while DMR-related genes were defined as those annotated to the gene body or 2.2-kilobase upstream regions of DMRs. Selected DMR-related genes were further validated by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) to assess expression levels. Tensor composition analysis was performed to identify cell-specific differential DNA methylation from bulk tissue.Aims
Methods
Osteoarthritis, the most common degenerative joint disease, significantly impairs life quality and labor capability of patients. Synovial inflammation, initiated by HMGB1 (High mobility group box 1)-induced activation of macrophage, precedes other pathological changes. As an upstream regulator of NF-κB (nuclear factor-kappa B) and MAPK (mitogen-activated protein kinase) signaling pathway, TAK1 (TGF-β activated kinase 1) participates in macrophage activation, while its function in osteoarthritis remains unveiled. This study aims to investigate the role of TAK1 in the pathogenesis of osteoarthritis via both in vitro and in vivo approaches. We performed immunohistochemical staining for TAK1 in synovial tissue, both in osteoarthritis patients and healthy control. Besides, immunofluorescence staining for F4/80 as macrophage marker and TAK1 were conducted as well. TAK1 expression was examined in RAW264.7 macrophages stimulated by HMGB1 via qPCR (Quantitative polymerase chain reaction) and Western blotting, and the effect of TAK1 inhibitor (5z-7 oxozeaenol) on TNF-α production was evaluated by immunofluorescence staining. Further, we explored the influence of intra-articular shRNA (short hairpin RNA) targeting TAK1 on collagenase-induced osteoarthritis in mice. Immunohistochemical staining confirmed significant elevation of TAK1 in osteoarthritic synovium, and immunofluorescence staining suggested macrophages as predominant residence of TAK1. In HMGB1-stimulated RAW264.7 macrophages, TAK1 expression was up-regulated both in mRNA and protein level. Besides, TAK1 inhibitor significantly impairs the production of TNF-α by macrophages upon HMGB1 stimulation. Moreover, intra-articular injection of lentivirus loaded with shRNA targeting TAK1 (sh-TAK1) reduced peri-articular osteophyte formation in collagenase-induced osteoarthritis in mice. TAK1 exerts a potent role in the pathogenesis of osteoarthritis by mediating the activation of macrophages.
Intervertebral disc degeneration can lead to physical disability and significant pain, while the present therapeutics still fail to biochemically and biomechanically restore the tissue. Stem cell-based therapy in treating intervertebral disc (IVD) degeneration is promising while transplanting cells alone might not be adequate for effective regeneration. Recently, gene modification and 3D-printing strategies represent promising strategies to enhanced therapeutic efficacy of MSC therapy. In this regard, we hypothesized that the combination of thermosensitive chitosan hydrogel and adipose derived stem cells (ADSCs) engineered with modRNA encoding Interleukin − 4 (IL-4) can inhibit inflammation and promote the regeneration of the degenerative IVD. Rat ADSCs were acquired from adipose tissue and transfected with modRNAs. First, the kinetics and efficacy of modRNA-mediated gene transfer in mouse ADSCs were analyzed in vitro. Next, we applied an indirect co-culture system to analyze the pro-anabolic potential of IL-4 modRNA engineered ADSCs (named as IL-4-ADSCs) on nucleus pulposus cells. ModRNA transfected mouse ADSCs with high efficiency and the IL-4 modRNA-transfected ADSCs facilitated burst-like production of bio-functional IL-4 protein. In vitro, IL-4-ADSCs induced increased anabolic markers expression of nucleus pulposus cells in inflammation environment compared to untreated ADSCs. These findings collectively supported the therapeutic potential of the combination of thermosensitive chitosan hydrogel and IL-4-ADSCs for intervertebral disc degeneration management. Histological and in vivo validation are now being conducted.
Quantitative ultrasound (QUS) is a promising tool to estimate bone structure characteristics and predict fragile fracture. The aim of this pilot cross-sectional study was to evaluate the performance of a multi-channel residual network (MResNet) based on ultrasonic radiofrequency (RF) signal to discriminate fragile fractures retrospectively in postmenopausal women. RF signal and speed of sound (SOS) were obtained using an axial transmission QUS at one‐third distal radius for 246 postmenopausal women. Based on the involved RF signal, we conducted a MResNet, which combines multi-channel training with original ResNet, to classify the high risk of fragility fractures patients from all subjects. The bone mineral density (BMD) at lumber, hip and femoral neck acquired with DXA was recorded on the same day. The fracture history of all subjects in adulthood were collected. To assess the ability of the different methods in the discrimination of fragile fracture, the odds ratios (OR) calculated using binomial logistic regression analysis and the area under the receiver operator characteristic curves (AUC) were analyzed. Among the 246 postmenopausal women, 170 belonged to the non-fracture group, 50 to the vertebral group, and 26 to the non-vertebral fracture group. MResNet was discriminant for all fragile fractures (OR = 2.64; AUC = 0.74), for Vertebral fracture (OR = 3.02; AUC = 0.77), for non-vertebral fracture (OR = 2.01; AUC = 0.69). MResNet showed comparable performance to that of BMD of hip and lumbar with all types of fractures, and significantly better performance than SOS all types of fractures.Methods
Results
Total joint replacement (TJR) was one of the most revolutionary breakthroughs in joint surgery. The majority studies had shown that most implants could last about 25 years, anyway, there is still variation in the longevity of implants. In US, for all the hip revisions from 2012 to 2017 in the United States, 12.0% of the patients were diagnosed as aseptic loosening. Variable studies have showed that any factor that could cause a systemic or partial bone loss, might be the risk of periprosthetic osteolysis and aseptic loosening. Breast cancer is the most frequent malignancy in women, more than 2.1 million women were newly diagnosed with breast cancer, 626,679 women with breast cancer died in 2018. It's been reported that the mean incidence of THA was 0.29% for medicare population with breast cancer in USA, of which the incidence was 3.46% in Norwegian. However, the effects of breast cancer chemotherapy and hormonotherapy, such as aromatase inhibitors (AI), significantly increased the risk of osteoporosis, and had been proved to become a great threat to hip implants survival. In this case, a 46-year-old female undertook chemotherapy and hormonotherapy of breast cancer 3 years after her primary THA, was diagnosed with aseptic loosening of the hip prosthesis. Her treatment was summarized and analyzed. Breast cancer chemotherapy and hormonotherapy might be a threat to the stability of THA prosthesis. More attention should be paid when a THA paitent occurred with breast cancer. More studies about the effect of breast cancer treatments on skeleton are required.
As peri-prosthetic aseptic loosening is one of the main causes of implant failure, inhibiting wear particles induced macrophages inflammation is considered as a promising therapy for AL to expand the lifespan of implant. Here, we aim at exploring the role of p110δ, a member of class IA PI3K family, and Krüppel-like factor 4 (KLF4) in titanium particles (TiPs) induced macrophages-inflammation and osteolysis. Firstly, IC87114, the inhibitor of p110δ and siRNA targeting p110δ were applied and experiments including ELISA and immunofluorescence assay were conducted to explore the role of p110δ. Sequentially, KLF4 was predicted as the transcription factor of p110δ and the relation was confirmed by dual luciferase reporter assay. Next, assays including RT-PCR, western blotting and flow cytometry were performed to ensure the specific role of KLF4. Finally, TiPs-induced mice cranial osteolysis model was established, and micro-CT scanning and immunohistochemistry assay were performed to reveal the role of p110δ and KLF4 in vivo. Here, we found that p110δ was upregulated in TiPs-stimulated macrophages. The inhibition of p110δ or knockdown of p110δ could significantly dampen the TiPs-induced secretion of TNFα and IL-6. Further mechanistic studies confirmed that p110δ was responsible for TNFα and IL-6 trafficking out of Golgi complex without affecting their expression in TiPs-treated macrophages. Additionally, we explored the upstream regulators and confirmed that Krüppel-like factor 4 (KLF4) was the transcription repressor of p110δ. Apart from that, KLF4, targeted by miR-92a, could also attenuate TiPs-induced inflammation by mediating NF-κB pathway and M1/M2 polarization. By the establishment of TiPs-induced mice cranial osteolysis model, we found that KLF4 knockdown exacerbated TiPs-induced osteolysis which was strikingly ameliorated by knockdown of p110δ. In summary, our study suggests the key role of miR-92a/KLF4/p110δ signal in TiPs-induced macrophages inflammation and osteolysis.
Circular RNA (circRNA) is involved in the regulation of articular cartilage degeneration induced by inflammatory factors or oxidative stress. In a previous study, we found that the expression of Minus RNA sequencing, fluorescence in situ hybridization, and quantitative real-time polymerase chain reaction (qRT-PCR) were used to detect the expression of Aims
Methods
Developmental dysplasia of the hip (DDH) is a complex musculoskeletal disease that occurs mostly in children. This study aimed to investigate the molecular changes in the hip joint capsule of patients with DDH. High-throughput sequencing was used to identify genes that were differentially expressed in hip joint capsules between healthy controls and DDH patients. Biological assays including cell cycle, viability, apoptosis, immunofluorescence, reverse transcription polymerase chain reaction (RT-PCR), and western blotting were performed to determine the roles of the differentially expressed genes in DDH pathology.Aims
Methods
The aim of this meta-analysis was to assess the prognosis after early functional rehabilitation or traditional immobilization in patients who underwent operative or nonoperative treatment for rupture of the Achilles tendon. PubMed, Embase, Web of Science, and Cochrane Library were searched for randomized controlled trials (RCTs) from their inception to 3 June 2020, using keywords related to rupture of the Achilles tendon and rehabilitation. Data extraction was undertaken by independent reviewers and subgroup analyses were performed based on the form of treatment. Risk ratios (RRs) and weighted mean differences (WMDs) (with 95% confidence intervals (CIs)) were used as summary association measures.Aims
Methods
To explore a novel machine learning model to evaluate the vertebral fracture risk using Decision Tree model and train the model by Bone Mineral Density (BMD) of different compartments of vertebral body. We collected a Computed Tomography image dataset, including 10 patients with osteoporotic fracture and 10 patients without osteoporotic fracture. 40 non-fracture Vertebral bodies from T11 to L5 were segmented from 10 patients with osteoporotic fracture in the CT database and 53 non-fracture Vertebral bodies from T11 to L5 were segmented from 10 patients without osteoporotic fracture in the CT database. Based on the biomechanical properties, 93 vertebral bodies were further segmented into 11 compartments: eight trabecular bone, cortical shell, top and bottom endplate. BMD of these 11 compartments was calculated based on the HU value in CT images. Decision tree model was used to build fracture prediction model, and Support Vector Machine was built as a compared model. All BMD data was shuffled to a random order. 70% of data was used as training data, and 30% left was used as test data. Then, training prediction accuracy and testing prediction accuracy were calculated separately in the two models. The training accuracy of Decision Tree model is 100% and testing accuracy is 92.14% after trained by BMD data of 11 compartments of the vertebral body. The type I error is 7.14% and type II error is 0%. The training accuracy of Support Vector Machine model is 100% and the testing accuracy is 78.57%. The type I error is 17.86% and type II error is 3.57%. The performance of vertebral body fracture prediction using Decision Tree is significantly higher than using Support Vector Machine. The Decision Tree model is a potential risk assessment method for clinical application. The pilot evidence showed that Decision Tree prediction model overcomes the overfitting drawback of Support Vector Machine Model. However, larger dataset and cohort study should be conducted for further evidence.
Whether to perform hybrid surgery (HS) in contrast to anterior cervical discectomy and fusion (ACDF) when treating patients with multilevel cervical disc degeneration remains a controversial subject. To resolve this we have undertaken a meta-analysis comparing the outcomes from HS with ACDF in this condition. Seven databases were searched for studies of HS and ACDF from inception of the study to 1 September 2019. Both random-effects and fixed-effects models were used to evaluate the overall effect of the C2-C7 range of motion (ROM), ROM of superior/inferior adjacent levels, adjacent segment degeneration (ASD), heterotopic ossification (HO), complications, neck disability index (NDI) score, visual analogue scale (VAS) score, Japanese Orthopaedic Association (JOA) score, Odom’s criteria, blood loss, and operating and hospitalization time. To obtain more credible results contour-enhanced funnel plots, Egger’s and Begg’s tests, meta-regression, and sensitivity analyses were performed.Aims
Methods
The objective of this study was to investigate the association of four single-nucleotide polymorphisms (SNPs) of the cannabinoid receptor 2 ( Chinese patients with OP were recruited between March 2011 and December 2015 from our hospital. In this study, a total of 1267 post-menopausal female patients (631 OP patients and 636 control patients) were selected. The mean age of all subjects was 69.2 years (sd 15.8). A generalized multifactor dimensionality reduction (GMDR) model and logistic regression model were used to examine the interaction between SNP and obesity on OP. For OP patient-control haplotype analyses, the SHEsis online haplotype analysis software (Objectives
Methods
Irrigation is the cornerstone of treating skeletal infection by eliminating pathogens in wounds. A previous study shows that irrigation with normal saline (0.9%) and ethylenediaminetetraacetic acid (EDTA) could improve the removal of We established three wound infection models (skin defect, bone-exposed, implant-exposed) by inoculating the wounds with a variety of representative drug-resistant bacteria including methicillin-resistant Objectives
Methods
Radiologic signs such as radiolucent lines around the implant, hardware fracture or displacement and periosteal reaction have been considered suggestive of implant-associated infection. The goal of this study is to assess the correlation of these signs with confirmed internal fixation-associated infection evaluated in a prospective cohort. We evaluated the radiologic appearance of preoperative standard x-ray images in 421 surgeries performed in 380 patients with internal fixation device in place (56.8% male, mean age 53 ± 17 years). This prospective study was performed in a large single center for musculoskeletal surgery from 2013–2017. Infection was suspected preoperatively in only 23.8% of the surgeries. The most common indications for surgeries in which infection was not suspected were nonunion (84 cases) and symptomatic hardware (57 cases). All removed implants were sent to sonication for biofilm removal and detection. In addition, several peri-implant tissue samples were collected. Radiographs were analyzed in a blinded fashion for signs of radiolucent lines around the implant before removal, hardware fracture or displacement, and soft periosteal reactions suggestive of infection. Diagnosis was established according to the IDSA criteria for PJI. Contingency tables were constructed to determine sensitivity and specificity, and to perform Chi-square tests to compare the presence of infection with radiological signs of infection.Aim
Method
Unexpected positive infections are distinct entity in prosthetic revision surgery. The prevalence and characteristics of unexpected positive cultures in internal fixation are however less established. The aim of this study was to describe the prevalence and characteristics of unexpected diagnosis of infection in a prospective cohort of revision surgeries following internal fixation. We reviewed the microbiological results following 356 surgeries that included partial or complete removal of internal fixation, performed in 328 patients (54% male, mean age 53 ± 17 years), in which infection was not initially suspected. This prospective study was performed in a large single center for musculoskeletal surgery from 2013–2017. The implants most commonly removed were plate and/or screws (281 cases, 78,9%), followed by intramedullary nails (64 cases, 18,0%). The main indications for surgery were nonunion (89 cases, 25%) and symptomatic hardware (70 cases, 19,7%). All removed implants were sonicated, and tissue cultures were obtained depending on the surgeon's criteria. Diagnosis of infection was established by the presence of 2 or more positive tissue cultures (1 with a highly virulent microorganism), or ≥ 50 colony-forming units found in the sonication fluid.Aim
Method
Although single-stage revision has attracted a lot of attention due to less socioeconomic cost, this technique is not widely used throughout the world due to strict indications. In this situation, we report our outcome on single-stage revision combined with selective direct intra-articular antibiotic infusion for chronic infected THA, especially for patients with culture-negative hip, fungal infections and multidrug-resistant organism. We retrospectively reviewed 131 patients with chronic infected THA between January 2010 and February 2017 who underwent single-stage revision, including soakage of surgical area with 0.5% aqueous betadine, pouring powdered vancomycin or imipenem into the medullary cavity. For patients with culture-negative hip, fungal infections and multidrug-resistant organism, a direct intra-articular infusion of pathogens-sensitive antibiotics via three-branch catheter were performed postoperatively. Recurrence of infection and clinical outcomes were evaluated. One hundred and fifteen patients were followed-up for an average of 4.5 years (range, 1.2–8 years). Of the 115 patients, 103 patients (89.6%) required no additional surgical or medical treatment for recurrence of infection. A recurrent infection was observed in 4 of the 23 patients (17.4%) with culture-negative infected hip. One of 4 fungal infections was relapse and the success rate in patients with multidrug-resistant organism was 84.2% (16/19). The mean postoperative Harris hip score was 81 points (63 to 92; p < 0.05) at the most recent assessment. Treatment of chronic infected THA by single-stage revision combined with selective direct intra-articular antibiotic infusion can be fairly effective, even for patients with relative “contraindication” of this approach.
Infection is a potentially disastrous complication of total knee arthroplasty (TKA). Although advances in surgical technique and antibiotic prophylaxis have reduced the incidence of infection to approximately 1% in primary TKA, there is still a substantial number of patients. Treatment options include antibiotic suppression, irrigation and debridement with component retention (with or without polyethylene exchange), one-stage or two-stage revision, resection arthroplasty and rarely arthrodesis or amputation. Salvage of prostheses has always been associated with low rates of success. It was reported a success rate of 27% for open debridement. It is suitable for selective cases where infection occurs within the first 4–6 weeks of primary TKA or in the setting of acute hematogenous gram positive infection with stable implants. With the advances in arthroscopic technique, arthroscopy after TKA has become an accepted method to assess and manage the complications of TKA. Arthroscopic treatment for infected TKA was reported and the successful rate was similar or better than open debridement in selected situations. We used arthroscopic debridement combined with continuous antibiotic irrigation and suction to treat acute presentation of infected TKA with acceptable result. From 2010∼2013, we has performed arthroscopic debridement and continuous antibiotic irrigation system for seven patients with infected TKA. All of the seven patients had no open wounds nor sinuses and no radiological evidence of prosthetic instability or evidence of osteomyelitis. Most of the surgical intervention was performed within two weeks from the onset of symptoms. Arthroscopic debridement was performed with a shaver using a multiportal technique (anterolateral, anteromedial, superolateral, superomedial, posterolateral, posteromedial) and a continuous antibiotic irrigation system was used to dilutes concentration of the causative microorganism and keep high local bactericidal concentration of antibiotics. We evaluated the efficacy by using follow up of the C-reactve protein (CRP) test, erythrocyte sedimentation rate (ESR) test and physical examination. Successful treatment was defined as prosthesis retention without recurrent infection by the final follow-up. Six of seven infected TKA were cured without recurrence at a mean follow-up of 23 months (range, 6–41 months). One case with rheumatoid arthritis under long-term steroid therapy had recurred after episode of upper respiratory tract infection for 3 times. However, the infection was controlled by arthroscopic debridement and retention of the prosthesis was achieved. We emphasize the importance of posterior portal to ensure adequate arthroscopic debridement. It is imperative to make early diagnosis and treatment for infected TKA. We should make more effort to preserve the prosthesis in acute infection(within 2 weeks). With the advantage of minimal morbidity, arthroscopic treatement shoulder be an alternative to open debridement.
Implant-related infection (IRI) is closely related to the local immunity of peri-implant tissues. The generation of reactive oxygen species (ROS) in activated macrophages plays a prominent role in the innate immune response. In previous studies, we indicated that implant wear particles promote endotoxin tolerance by decreasing the release of proinflammatory cytokines. However, it is unclear whether ROS are involved in the damage of the local immunity of peri-implant tissues. In the present study, we assessed the mechanism of local immunosuppression using titanium (Ti) particles and/or lipopolysaccharide (LPS) to stimulate RAW 264.7 cells. The results indicate that the Ti particles induced the generation of a moderate amount of ROS through nicotinamide adenine dinucleotide phosphate oxidase-1 (NOX-1), but not through catalase. Pre-exposure to Ti particles inhibited ROS generation and extracellular regulated protein kinase (ERK) activation in LPS-stimulated macrophages. These findings indicate that chronic stimulation by Ti particles may lead to a state of oxidative stress and persistent inflammation, which may result in the attenuation of the immune response of macrophages to bacterial components such as LPS. Eventually, immunosuppression develops in peri-implant tissues, which may be a risk factor for IRI.
This study demonstrated that Sclerostin monoclonal antibody (Scl-Ab) enhanced bone healing in the rat osteotomy model. Scl-Ab increased callus size, callus bone volume fraction, rate of callus bone formation and fracture callus strength. Sclerostin is a protein secreted by osteocytes and is characterized as a key inhibitor of osteoblast-mediated bone formation. Previous studies demonstrated that treatment with a sclerostin monoclonal antibody (Scl-Ab) results in significantly increased bone formation, bone mass and strength in rat closed fracture model (1–2). However, the effects of Scl-Ab on healing of open fracture model have not yet been reported in rats. Previously in ORS and ASBMR Annual Meeting, we have reported that Scl-Ab promoted the open fracture healing at week 3 and week 6 post-fracture. Here we extended our investigation for up to week 9 with additional histological assessments and dynamic histomorphometric analysis to investigate the effects of systemic administration of Scl-Ab on a later phase of fracture repair.Summary Statement
Introduction
The use of tapered junctions in primary hip arthroplasty has excellent results. Large heads are being used to mitigate dislocation and optimize range of motion. The prevalence of larger heads, coupled with recent findings regarding corrosion artifacts at tapered surfaces, has spurred growing interest when considering revision rates. The purpose of this study was to determine if correlations exist between severity of corrosion artifacts and head size, head offset, time Retrieved hip arthroplasty devices with CoCrMo or oxidized zirconium (OxZr) heads were investigated for corrosion artifacts in this study. Female tapered surfaces were scored independently by a panel according to the Goldberg system for assessment of corrosion. Exclusion criteria included less than 1 week INTRODUCTION:
METHODS:
One of the recent advances in the hard-on-hard hip arthroplasty is the development of a new material of diffusion hardened oxidised zirconium (DHOxZr). The DHOxZr material consists of a ceramic layer on the top surface which is supported by a thick oxygen diffusion hardened (DH) zone underneath. With the desired properties of metal substrate, ceramic surface and a gradient structure of the oxygen diffusion zone, the DHOxZr-on-DHOxZr bearing combination is expected to produce low wear and minimal metal ions. This can possibly address the concerns associated with metal hypersensitivity associated with metal on metal bearings and fracture risk associated with ceramics. The aim of this study was to evaluate the wear of DHOxZr-on-DHOxZr as a possible hard on hard bearing combination in hips. Three pairs of 50 mm DHOxZr prototype hip joint devices, each consisting of a DHOxZr modular head and a DHOxZr liner were wear tested in a ProSim hip joint simulator under standard testing conditions used by the Implant Development Centre (IDC), Smith & Nephew, Leamington Spa for 5 million cycles (Mc). The flexion/extension was 30° and 15°. The internal/external rotation was ± 10°. The force was Paul-type stance phase loading, with a maximum load of 3 kN and a standard ISO swing phase load of 0.3 kN. The test frequency was 1 Hz. Gravimetric analysis was carried out at 0, 0.5, 1, 2, 3, 4 & 5 million cycles. The lubricant was new born calf serum with 2 g/l sodium azide concentration diluted with de-ionised water to achieve average protein concentration of 20 g/l. Lubricant was changed every 0.25Mc during the first million cycles of the test and at every 0.33 Mc from 1 to 5Mc.INTRODUCTION
METHODS
Hip wear simulator test results could be affected by many non-bearing related factors such as fixation surface conditions, equipment calibration and component set-up. In an effort to improve the accuracy, reliability and repeatability of hip simulator test, a quality management system has been established at the IDC hip tribology laboratory, which has been accredited by UKAS (United Kingdom Accreditation Service) in accordance with the recognised international standard ISO17025. This study demonstrates that under well-controlled laboratory and testing conditions, satisfactory repeatability can be achieved during hip simulator studies. Between 2008 to 2010, ten 50 mm Birmingham Hip Resurfacing (BHR) devices were tested by the IDC tribology laboratory using two ProSim hip wear simulators in three different tests (T1, T2 and T3). All tests were performed following the same IDC testing protocols at 1 Hz frequency for 5 million cycles (Mc) or until after a steady state was reached. Paul type stance phase loadings with a maximum load of 3 kN and a swing phase load of 0.3 kN was used. The flexion and extension angles were 30 and 15 degree. The internal/external rotation angel was ±10 degree. Wear was measured gravimetrically using an analytical balance (Mettler, Toledo xp504) with an accuracy of 0.1 mg.INTRODUCTION
METHODS
Angiogenesis and osteogenesis are essential for bone growth, fracture repair, and bone remodeling. VEGF has an important role in bone repair by promoting angiogenesis and osteogenesis. In our previous study, endothelial progenitor cells (EPCs) promoted bone healing in a rat segmental bone defect as confirmed by radiological, histological and microCT evaluations (Atesok, Li, Schemitsch 2010); EPC treatment of fractures resulted in a significantly higher strength by biomechanical examination (Li, Schemitsch 2010). In addition, cell-based VEGF gene transfer has been effective in the treatment of segmental bone defects in a rabbit model (Li, Schemitsch et al 2009); Purpose of this study: Evaluation of VEGF gene expression after EPC local therapy for a rat segmental bone defect. Rat bone marrow-derived EPCs were isolated from the rat bone marrow by the Ficoll-paque gradient centrifuge technique. The EPCs were cultured for 7 to 10 days in endothelial cell growth medium with supplements (EGM-2-MV-SingleQuots, Clonetics). and collected for treatment of the rat segmental bone defect. EPCs were identified by immunocytochemistry staining with primary antibodies for CD34, CD133, FLK-1, and vWF. A total of fifty six rats were studied. A five millimeter segmental bone defect was created in the middle 1/3 of each femur followed by mini plate fixation. The treatment group received 1×106 EPCs locally at the bone defect and control animals received saline only. Seven control and seven EPC treated rats were included in each group at 1, 2, 3 and 10 weeks. Animals were sacrificed at the end of the treatment period, and specimens from the fracture gap area were collected and immediately frozen. Rat VEGF mRNA was measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and quantified by VisionWorksLS. All measurements were performed in triplicate.Purpose
Method
Whilst there is a great deal of research on hip implants, few studies have looked at implant orientation and the subsequent effect upon the wear performance of a hip resurfacing. This study aimed to measure implantation angles through radiographic analysis and linear wear for retrieved acetabular cups in order to investigate possible causal links between wear and implant orientation. Seventy Birmingham Hip Resurfacing (Smith & Nephew, UK) cups with known time in vivo were analysed. Linear wear of retrieved cups were assessed using a Talyrond 290 roundness machine. Deviations from the characteristic manufactured profile, was identified as a region of wear. Polar measurements across the wear region were taken to determine wear. The linear wear rate (LWR) of a component was defined as the linear wear (μm) divided by the duration of the implant life in vivo (years). Cups which showed the wear crossing over the edge of the cup were classified as edge loaded (EL). For all non-edge loaded (NEL) cups, the wear area was within the bearing surface. Cup orientation angles were conducted for 31 cups. This was determined by superimposing BHR models of appropriate size, generated by CAD ProEngineer Wildfire 4, onto anterior-posterior x-rays. Anatomical landmarks and specific features of the BHR were used as points of reference to determine cup version and inclination angles.INTRODUCTION
MATERIALS & METHODS
Ion analysis has been used as one of the key indicators to assess the performance of MoM devices in patients. Modular devices, in particular having larger overall surface area (the stem and sleeve), and locking interfaces (head – bore, sleeve- taper and sleeve-bore, stem-taper surfaces) than other MoM devices are expected to release greater number of ions. Concerns have been expressed that the ion release at the taper junction might be a potential cause leading to the failure of the implant [Garbuz The aim of this study was to look into the wear and the associated ion release from the taper junction and the articulating surface of modular devices. For the first time a novel design has been used to isolate the taper junction on modular devices on the hip simulators in order to compare the wear at the taper junction and articulating surface. The taper junction has been isolated in a small gaiter, while the head and cup were contained in a large gaiter. CoCrMo sleeves having an offset of +8 mm have been used on 50 mm modular heads along with Ti6Al4V stems. The acetabular components were standard BHR cups. Three devices (Smith & Nephew, UK) have been tested with newborn calf serum as a lubricant (in the large gaiter) and also as the medium containing the taper junction (in the small gaiter). The serum samples from the articulating surface and taper junction were analysed using HR-ICPMS. The locking interfaces at the taper junction have been left intact throughout the duration of the test. Both the head and the cup have been tested under anatomical conditions using the standard implant development centre's (IDC) profile for 2 million cycles (Mc). The lubricant was newborn calf serum with 0.2% sodium azide diluted with de-ionised water to achieve protein concentration of 20 mg/ml. The flexion/extension was 30°/15° and the internal/external rotation was ±10°. The force was Paul-type stance phase loading with a maximum load of 3 kN and a standard ISO swing phase load of 0.3 kN. The frequency was 1 Hz, with an 8 hour stop after every 16 hours of testing.Introduction
Method
Analysis of retrieved ceramic components have shown areas of localized ‘stripe wear’, which have been attributed to joint laxity and/or impingement resulting in subluxation of the head, causing wear on the edge of the cup. Studies have been conducted into the effects of mild subluxation, however few in vitro tests have looked at severe subluxation. The aim of this study was to develop a more clinically relevant subluxation protocol. Seven (Subluxation n=4; standard test n=3) of 36mm Biolox Forte (R3, Smith & Nephew) ceramic devices were tested for 0.5m cycles (mc). Two of the subluxed joints were further tested to 1 Mc. The devices were subjected to subluxation under standard testing conditions. The flex/ext was 30° and 15° respectively, with internal/external rotation of ±10°. The force was Paul type stance phase loading with a maximum load of 3 kN, and a standard ISO swing phase load of 0.3 kN at 1 Hz. The test was conducted on a ProSim hip joint wear simulator (SimSol, UK). The simulator is equipped with a novel mechanism to achieve translation of the head, to achieve subluxation. During the ISO swing phase load of 0.3kN, a controlled lateral force required for the translation of the head is applied by a cam mechanism, head retraction then occurs during heel strike. The lubricant used was new born calf serum diluted with de-ionised water to achieve average protein concentration of 20 g/l, with 0.2 wt % concentration NaN3, and changed every 250k cycles. Measurements have been taken at 0.5 & 1 mc stages.INTRODUCTION
MATERIALS & METHODS
Metal-on-Metal devices generate significantly lower volumetric wear than conventional total hip replacements. However, clinically some patients may suffer some form of laxity in their joints leading to subluxation of the joint, which in turn may cause edge loading of an implant thereby increasing the chances of failure due to higher than expected wear. In this study, the effect of subluxation on MoM implant wear was investigated on a hip joint simulator. Two groups of 44 mm MoM devices were tested, n=3 in each group. The devices were subjected to 1 and 2 mm of subluxation. The flexion/extension was 30° and 15° respectively, internal/external rotation was ±10°, and cup inclination was 35°. The force was Paul type stance phase loading with a maximum load of 3 kN, with ISO swing phase load of 0.3 kN, run at 1 Hz. The test was carried out on a ProSim deep flexion & subluxation hip wear simulator (SimSol, UK). Rather than separating the head and the cup (microseparation), or reducing the swing phase load, this simulator is equipped with a novel mechanism to achieve translation of the head, while subjecting the devices to subluxation. During the swing phase, a controlled lateral force necessary for the translation of the head is applied by a cam mechanism, head retraction will then take place on heel strike. The lubricant used was new born calf serum with 0.2 wt. % sodium azide concentration diluted with de-ionised water to achieve average protein concentration of 20 g/l. Lubricant was changed every 250k cycles. Gravimetric wear measurements have been taken at 0.25 & 0.5 Mc stages. Tests conducted with 1mm (Group 1) and 2mm (Group 2) subluxation significantly increased volumetric wear compared to standard hip simulator tests [1]. At 0.5 million cycles, group 1 and 2 produced an average volume loss of 4.38±0.98 mm3 (95% CL) and 7.07±1.64 mm3 (95% CL) respectively.Materials & Methods
Results
All hip replacements depend upon good orientation and positioning to ensure that implants function well To investigate the correlation between edge loading and wear on retrieved implants through linear wear analysis and radiographic examination of implants Introduction
Aim
Hip implant research has been carried out for decades using hip simulators to reflect situations Three pairs of 50mm as cast (AC) and four pairs of 50mm double heat treated (DHT) CoCr MoM devices were tested in a ProSim hip simulator. In order to determine the frequency for testing, Patients' activities have been monitored using a Step Activity Monitor (SAM) device. The data showed a relatively slower walking pace (frequency) than that used in the hip simulator studies. The new frequency, along with stop/start motion and various kinetics and kinematics profiles have been used in putting together a more physiologically relevant hip simulator test protocol. The lubricant used in this study was new born calf serum with 0.2 % (w/v) sodium azide concentration diluted with de-ionised water to achieve an average protein concentration of 20 g/l. Gravimetric measurements have been taken at 0.5, 1, 1.5 & 2 million cycle (Mc) stages and ion analysis has been carried out on the serum samples.Introduction
Materials & Methods
osteoblast-hVEGF, fibroblast-hVEGF, Osteoblasts alone, and Fibroblasts only. The cultured cells were harvested at 1, 3 and 7 days after the transfection. The total mRNA was extracted (TRIZOL); both hVEGF and rat VEGF mRNA were measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and quantified by VisionWorksLS.
The in vivo abduction angle and version angle of the cup were determined by superimposing the BHR models onto the radiographs (ProEngineer Wildfire 4 with ISDX II extension software) using anatomical references and specific features of the BHR.
Cup orientation: The abduction angles of the two non-edge loaded cups were 31° and 39°, and their version angles were 12 and 16° respectively. These angles were within recommended orientation for the BHR. In contrast, the adduction angles and/or version angles of all edge loaded devices were outside the recommended orientation. Their abduction angle varied from 40° to 66° and version angle from 5° to 46°. The edge loaded devices with higher inclination angles and/or higher version angels generally had higher linear wear. There is strong correlation between the cup orientation and the linear wear of the implant.
One R3 joint and one BHR device were friction tested in a ProSim hip friction simulator at 0, 3 and 5 million cycles of wear testing. The test was conducted in new born calf serum with added carboxy methyl cellulose (CMC) to generate viscosities of 1 to 100 cP. The loading cycle was set at maximum loads of 2 kN and minimum load of 0.1 kN. The flexion/extension was 30° and 15°, and the frequency was 1 Hz.
Friction: The coefficient of friction (COF) of the R3 joint varied from 0.08 to 0.14 depending on the viscosity of the serum and cycles of wear simulation test. Under physiologically relevant lubricant conditions (1, 3 and 10 cP), the COF for the R3 device tested was comparable to that of the standard BHR device. Wear: The R3 devices generated typical characteristics of wear to the BHR devices, with a higher wear rate during the initial running in period (0 – 0.5 Mc) followed by a low steady state wear rate after 0.5 Mc. The average wear rate at 0.5 Mc was 1.86 mm3/Mc for the R3 and 1.80 mm3/Mc for the BHR devices. The wear rate during the steady state for the R3 and the BHR devices was reduced to 0.09 mm3/Mc and 0.12 mm3/Mc respectively. The difference in average wear rates between the BHR and R3 devices during the running in and steady states were not statistically significant (p >
0.05).
Ion analysis: Serum was collected from test station and allowed to settle for 12 hours. An aliquot of 20 ml from lubricant was collected. Each sample was centrifuged at 2500 g-force for 10 minutes. A 10 ml aliquot was collected from each sample and was further centrifuged at 2500 g-force for 10 minutes. 1.5 ml aliquot was collected and stored at −20 °C. A high resolution inductively-coupled plasma mass spectrometry instrument (ELEMENT, ThermoFinnigan MAT, Bremen/Germany) was then used for the analysis of metal ions.
Hip simulators have been used for ten years to determine the tribological performance of large-head metal-on-metal devices using traditional test conditions. However, the hip simulator protocols were originally developed to test metal-on-polyethylene devices. We have used patient activity data to develop a more physiologically relevant test protocol for metal-on-metal devices. This includes stop/start motion, a more appropriate walking frequency, and alternating kinetic and kinematic profiles. There has been considerable discussion about the effect of heat treatments on the wear of metal-on-metal cobalt chromium molybdenum (CoCrMo) devices. Clinical studies have shown a higher rate of wear, levels of metal ions and rates of failure for the heat-treated metal compared to the as-cast metal CoCrMo devices. However, hip simulator studies in vitro under traditional testing conditions have thus far not been able to demonstrate a difference between the wear performance of these implants. Using a physiologically relevant test protocol, we have shown that heat treatment of metal-on-metal CoCrMo devices adversely affects their wear performance and generates significantly higher wear rates and levels of metal ions than in as-cast metal implants.
The total plasma alkaline phosphatase level has long been recognised as an indicator of osteoblastic activity, but lack of specificity makes it an insensitive index of the progress of disease and the response to treatment. Selective precipitation by wheatgerm lectin allows measurement of the plasma bone-specific alkaline phosphatase. We measured the plasma levels of this isoenzyme in 170 normal Chinese adolescents and adults, in 49 adults with fractures of a long bone, in 15 patients with osteosarcoma and in 38 patients with osteolytic metastases. The enzyme activity was also determined in 39 patients with liver disease. Of the patients with fractures, 94% had increased plasma activity during the healing process. The level was also increased in those with osteosarcoma but not in those with osteolytic bone metastases. There was no significant increase in activity in the patients with liver disease. We conclude that the plasma bone-specific alkaline phosphatase activity is a sensitive and reliable measure of osteoblastic activity.