Our previous research has demonstrated that minor adjustments to in vitro cellular aggregation parameters, i.e. alterations to aggregate size, can influence temporal and spatial mineral depositions within maturing bone cell nodules. What remains unclear, however, is how aggregate size might affect mineralisation within said nodules over long-term in vivo culture. In this study, we used an osteoblast cell line, MLO-A5, and a primary cell culture, mesenchymal stem cells (MSC), to compare small (approximately 80 µm) with large (approximately 220 µm) cellular aggregates for potential bone nodule development after 8 weeks of culturing in a mouse model (n = 4 each group). In total, 30 chambers were implanted into the intra-peritoneal cavity of 20 male, immunocompromised mice (MF1-Nu/Nu, 4 – 5 weeks old). Nine small or three large aggregates were used per chamber. Neoveil mesh was seeded directly with 2 × 103 cells for monolayer control. At 8 weeks, the animals were euthanised and chambers fixed with formalin. Aggregate integrity and extracellular material growth were assessed via light microscopy and the potential mineralisation was assessed via micro-CT. Many large aggregates appeared to disintegrate, whilst the small aggregates maintained their form and produced additional extracellular material with increased sizes. Both MLO-A5 cells and MSC cells saw similar results. Interestingly, however, the MSCs were also seen to produce a significantly higher volume of dense material compared to the MLO-A5 cells from micro-CT analysis. Overall, a critical cell aggregate size appeared to exist balancing optimal tissue growth with oxygen diffusion, and cell source may influence differentiation pathway despite similar experimental parameters. The MSCs, for example, were likely producing bone via the endochondral ossification pathway, whilst the matured bone cells, MLO-A5 cells, were likely producing bone via the intramembranous ossification pathway.
We aimed to evaluate the utility of 68Ga-citrate positron emission tomography (PET)/CT in the differentiation of periprosthetic joint infection (PJI) and aseptic loosening (AL), and compare it with 99mTc-methylene bisphosphonates (99mTc-MDP) bone scan. We studied 39 patients with suspected PJI or AL. These patients underwent 68Ga-citrate PET/CT, 99mTc-MDP three-phase bone scan and single-photon emission CT (SPECT)/CT. PET/CT was performed at ten minutes and 60 minutes after injection, respectively. Images were evaluated by three nuclear medicine doctors based on: 1) visual analysis of the three methods based on tracer uptake model, and PET images attenuation-corrected with CT and those not attenuation-corrected with CT were analyzed, respectively; and 2) semi-quantitative analysis of PET/CT: maximum standardized uptake value (SUVmax) of lesions, SUVmax of the lesion/SUVmean of the normal bone, and SUVmax of the lesion/SUVmean of the normal muscle. The final diagnosis was based on the clinical and intraoperative findings, and histopathological and microbiological examinations.Aims
Methods
To develop an early implant instability murine model and explore the use of intermittent parathyroid hormone (iPTH) treatment for initially unstable implants. 3D-printed titanium implants were inserted into an oversized drill-hole in the tibiae of C57Bl/6 mice (n = 54). After implantation, the mice were randomly divided into three treatment groups (phosphate buffered saline (PBS)-control, iPTH, and delayed iPTH). Radiological analysis, micro-CT (µCT), and biomechanical pull-out testing were performed to assess implant loosening, bone formation, and osseointegration. Peri-implant tissue formation and cellular composition were evaluated by histology.Aims
Methods
There is conflicting evidence on the safety of intra-articular injections of hyaluronic acid (HA) or corticosteroids (CSs) before total knee arthroplasty (TKA). We performed a meta-analysis of the relationship between intra-articular injections and subsequent infection rates after TKA. We searched PubMed, EMBASE, and the Cochrane Library for cohort studies that assessed the effect of preoperative injection of drugs into the joint cavity on the infection rate after TKA. The outcomes analyzed included the total infection rate, as well as those for different preoperative injection time periods and different drugs.Aims
Methods
To explore the effect of different durations of antibiotics after stage II reimplantation on the prognosis of two-stage revision for chronic periprosthetic joint infection (PJI). This study involved a retrospective collection of patients who underwent two-stage revision for chronic PJI and continued to use extended antibiotic prophylaxis in two regional medical centres from January 2010 to June 2018. The patients were divided into a short (≤ one month) or a long (> one month) course of treatment based on the duration of antibiotics following stage II reimplantation. The difference in the infection control rate between the two groups was compared, and prognostic factors for recurrence were analyzed.Aims
Methods
Despite the interest in the association of gut microbiota with bone health, limited population-based studies of gut microbiota and bone mineral density (BMD) have been made. Our aim is to explore the possible association between gut microbiota and BMD. A total of 3,321 independent loci of gut microbiota were used to calculate the individual polygenic risk score (PRS) for 114 gut microbiota-related traits. The individual genotype data were obtained from UK Biobank cohort. Linear regressions were then conducted to evaluate the possible association of gut microbiota with L1-L4 BMD (n = 4,070), total BMD (n = 4,056), and femur total BMD (n = 4,054), respectively. PLINK 2.0 was used to detect the single-nucleotide polymorphism (SNP) × gut microbiota interaction effect on the risks of L1-L4 BMD, total BMD, and femur total BMD, respectively.Aims
Methods
MicroRNA-183 ( Clinical samples were collected from patients with OA, and a mouse model of OA pain was constructed by surgically induced destabilization of the medial meniscus (DMM). Reverse transcription quantitative polymerase chain reaction was employed to measure the expression of miR-183, transforming growth factor α (TGFα), C-C motif chemokine ligand 2 (Aims
Methods
Assess and characterise the suitability of a novel silk reinforced biphasic 3D printed scaffold for osteochondral tissue regeneration. Biphasic hybrid scaffolds consisted of 3D printed poly(ethylene glycol)-terephthalate-poly(butylene terephthalate)(PEGT/PBT) scaffold frame work (pore size 0.75mm), which has been infilled with a cast and freeze dried porous silk scaffold (5×5×2mm3), in addition to a seamless silk top layer (1mm). Silk scaffolds alone were used as controls. Both the biphasic and control scaffolds were characterised via uniaxial compression testing (strain rate 0.1mm/min), and the potential biocompatibility of the scaffolds was tested via in vitro culture of seeded bone marrow stromal cells post fabrication.Abstract
Objectives
Methods
Initial post-operative implant instability leads to impaired osseointegration, one of the most common reasons for aseptic loosening and revision surgery. In this study, we developed a novel murine model of implant instability and demonstrated the anabolic effect of immediate and delayed intermittent Parathyroid Hormone (iPTH) treatment in the setting of instability-induced osseointegration failure. 3D-printed titanium implants were inserted in an oversized drill-hole in the tibia of C57Bl/6 mice (n=54). After implantation, the mice were randomly divided in 3 treatment groups (control: PBS-vehicle; iPTH; delayed iPTH). Radiographic analysis was performed to confirm signs of implant loosening. Peri-implant tissue formation was assessed through histology. Osseointegration was assessed through µCT and biomechanical pullout testing.Introduction
Methods
Surgical failure, mainly caused by loosening implants, causes great mental and physical trauma to patients. Improving the physicochemical properties of implants to achieve favourable osseointegration will continue to be the focus of future research. Strontium (Sr), a trace element, is often incorporated into hydroxyapatite (HA) to improve its osteogenic activity. Our previous studies have shown that miR-21 can promote the osteogenic differentiation of mesenchymal stem cells by the PI3K/β-catenin pathway. The aim of this study is to fabricate a SrHA and miR-21 composite coating and it is expected to have a favorable bone healing capability. Ti discs (20 mm diameter and one mm thickness for the in vitro section) and rods (four mm diameter and seven mm length for the in vivo section) were prepared by machining pure Ti. The Ti cylinders were placed in a Teflon-lined stainless-steel autoclave for treating at 150°C for 24 h to form SrHA layer. The miR-21 was encapsulated in nanocapsules. The miR-21 nanocapsules were mixed with CMCS powder to form a gel-like sample and uniformly coated on the SrHA modifed Ti. Osteoblast-like MG63 cells were cultured on SrHA and miR-21 modified Ti, Cell proliferation activity and osteogenesis-related gene expression were evaluated. A bone defect model was established with mature New Zealand to evaluate the osseointegration. Cylindrical holes (four mm in diameter) were created at the distal femur and tibial plateau. Each rabbit was implanted with four of the aforementioned rods (distal femur and tibial plateau of the hind legs). After implantation for one, two and three months, the rabbits were observed by X-ray and scanned using u-CT. Histological and Immunohistochemical analysis were performed to examine the osteogenic markers. A biomechanical push-in test was used to assess the bone-implant bonding strength. Both SrHA nanoparticles with good superhydrophilicity and miR-21 nanocapsules with uniform sizes were distributed evenly on the surface of the Ti. In vitro experiments revealed that the composite coating was beneficial to osteoblast proliferation, differentiation and mineralization. In vivo evaluations demonstrated that this coating could not only promote the expression of angiogenic factor CD31 but also enhance the expression of osteoblastic genes to facilitate angio-osteogenesis. In addition, the composite coating also showed a decreased RANKL expression compared with the miR-21 coating. As a result, the SrHA/miR-21 composite coating promoted new bone formation and mineralization and thus enhanced osseointegration and bone-implant bonding strength. A homogeneous SrHA and miR-21 composite coating was fabricated by generating pure Ti through a hydrothermal process, followed by adhering miR-21 nanocapsules. This coating combined the favorable physicochemical properties of SrHA and miR-21 that synergistically promoted angiogenesis, osteogenesis, osseointegration, bone mineralization and thus bone-implant bonding strength. This study provided a new strategy for surface modification of biomedical implants.
PJI is a devastating complication following total joint arthroplasty. In this study, we explore the efficacy of a bacteriophage-derived lysin, PlySs2, against
Introduction
Methods
Poor osseointegration of cementless implants is the leading clinical cause of implant loosening, subsidence, and replacement failure, which require costly and technically challenging revision surgery. The mechanism of osseointegration requires further elucidation. We have recently developed a novel titanium implant for the mouse tibia that maintains in vivo knee joint function and allows us to study osseointegration in an intra-articular, load-bearing environment. Vascular endothelial growth factor (VEGF) is one of the most important growth factors for regulation of vascular development and angiogenesis. It also plays critical roles in skeletal development and bone repair and regeneration. A specialized subset of vascular endothelium, CD31hiEMCNhi cells displaying high cell surface expression of CD31 and Endomucin, has been reported to promote osteoblast maturation and may be responsible for bone formation during development and fracture healing. Because of their potential role in osseointegration, the aim of this study was to use our mouse implant model to investigate the role of VEGF and CD31hiEMCNhi endothelium in osseointegration. Under an IACUC-approved protocol, the implant was inserted into the right tibia of 16-week-old female C57BL/6 mice (N = 38). The mice were then randomized into 2 groups: Control group (N=19) and Anti-VEGFR group (N=19). A cocktail of VEGFR-1 antibody (25mg/kg) and VEGFR-2 antibody (25mg/kg) was given to the mice in the Anti-VEGFR group by intraperitoneal injection every third day starting immediately after surgery until euthanasia. An equivalent amount of an isotype control antibody was given to the control group. Flow cytometric (N = 4/group) and immunofluorescencent (N = 3/group) analyses were performed at 2 weeks post-implantation to detect the distribution and density of CD31hiEMCNhi endothelium in the peri-implant bone. Pull-out testing was used at 4 weeks post-implantation to determine the strength of the bone-implant interface.Introduction
Methods
The incidence of acute Achilles tendon rupture appears to be increasing. The aim of this study was to summarize various therapies for acute Achilles tendon rupture and discuss their relative merits. A PubMed search about the management of acute Achilles tendon rupture was performed. The search was open for original manuscripts and review papers limited to publication from January 2006 to July 2017. A total of 489 papers were identified initially and finally 323 articles were suitable for this review.Objectives
Methods
Poly-lactic acid (PLA) scaffolds are widely used in bone tissue engineering. The introduction of 3D printing has greatly increased the ability for tailoring different geometrical designs of these scaffolds for improved cellular attachment, growth and differentiation. This study aimed to investigate the effect of PLA fibre angle in 3D printed PLA scaffolds on hDPSC attachment and growth Two types of PLA scaffolds were prepared via 3D printing containing fibres angled at either 45° or 90°. hDPSCs (P4, 2*105 cells per scaffold) were statically seeded for 4 hours on to the scaffolds (7×3.5×3 mm3, n=3). Cellular attachment was checked using fluorescence microscopy and the number of unattached cells was counted using a haemocytometer (HCM). The cell-scaffold constructs were then cultured in osteogenic medium for up to 5 weeks. ALP staining and SEM were performed for one construct from each group at week 3. Cellular viability was determined using CMFDA/EHD1 live/dead labelling at week 4. After 5 weeks, constructs were processed for histology. Fluorescence micrographs showed high numbers of hDPSCs attached to scaffold surfaces in both groups after seeding irrespective of fibre angle. However, HCM cell count revealed that the 45° angled PLA scaffolds had significantly greater cell attachment compared to the 90° angled PLA group ( This study showed that 45° angled PLA 3D printed scaffolds enhanced hDPSC attachment and cellular bridging, which may help to rapidly close the macro-pores within the scaffold compared to the 90° angled group. This illustrates the potential of 45° angled 3D printed PLA scaffolds as good candidates for bone tissue engineering.
To investigate the biomechanical mechanism and report preliminary clinical efficacy of eccentric rotational acetabular osteotomy (ERAO) when conduct treatment for developmental dysplasia of the hip (DDH). Biomechanical model of the hip joint was established on six female cadaveric hips embalmed by formalin and stimulate ERAO was then performed on the model. Vertical force was loaded on the cadaveric spine from 0 N to 500 N and strain value on femoral head was measured preoperatively and postoperatively when loading force on spine reached the point of 100, 200, 300, 400 and 500 N. Stress value were then calculated base on the measurements. Besides, we reported postoperative follow up cases which were underwent ERAO to treat DDH in our hospital from July 2007 to October 2014. A total of 25 patients (26 hips) were reported, including 6 males and 19 females. Age varies from 11 to 57 years old, and the average age was 31 years old. Postoperative hip function was evaluated by Harris hip score and anteroposterior X⁃ray of pelvic was taken preoperatively and postoperatively to measure the Acetabular⁃head index (AHI), CE angle and Sharp angle.Objective
Methods
To investigate the biomechanical basis and report preliminary clinical efficacy of eccentric rotational acetabular osteotomy (ERAO) when treating developmental dysplasia of the hip (DDH). Biomechanical model of the hip joint was established on cadaveric hips. After performed ERAO on the biomechanical model, we explored the impact of this surgery on biomechanics of the hip joint. Meanwhile, we reported postoperative follow-up cases who underwent ERAO in our hospital between November 2007 to July 2012. A total of 14 patients (15 hips) were reported, including 4 males and 10 females, mean age was 30 years old. Harris hip score was defined as clinical evaluation standard and radiographic assessment was based on the measurement and further comparison of pre- and post-operative AHI (Acetabular-head index), CE angle (Center-edge angle) and Sharp angle.Objective
Methods
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.
To test the hypothesis that: CERAMENT[™]|G (C-G) would improve new bone growth and decrease infection rate after debridement as compared with 1) CERAMENT|BONE VOID FILLER (CBVF) and 2) no void filler in a rat osteomyelitis model. 72 Sprague Dawley rats were injected with 1.5 × 10∧6 CFU of S. aureus into a drill hole in the right tibia. After 3 weeks, the osteomyelitic defect was debrided, and filled with either: 1) C-G (n=32), 2) CBVF (n=20), or 3) nothing (n=20). 6 weeks after the second surgery, 20 rats from each group were sacrificed and the right tibias were harvested. A long-term group (n=12) of C-G treated rats were also sacrificed at 6 months after the second surgery. The tissues were sonicated and the colony forming units in the sonicate were quantified by serial dilutions and culture. MicroCT was used to quantify the new bone growth (BV/TV) in the debrided osteomyelitic void. Histological samples were analyzed for the presence of a neutrophil response by a blinded pathologist. (*: p<0.05) Positive cultures in:
○ 30% of animals treated with CBVF ○ 25% of animals treated with no void filler ○ 0% of animals treated with C-G (*) Neutrophil reaction in:
○ 35% of animals treated with CBVF ○ 50% of animals treated with no void filler ○ 0% of animals treated with C-G (*) The BV/TV in:
○ C-G treated rats was 24% greater than CBVF treated rats (*) ○ C-G treated rats was 94% greater than rats treated with no void filler (*) ○ CBVF treated rats was 56% greater than rats treated with no void filler (*) Animals sacrificed at 6 months which were treated with C-G did not have any evidence of infection by culture or histology. The bone mass of the implanted limb was higher than the contralateral (non-operated) side. CERAMENT|G decreased the rate of infection and increased new bone growth as compared with both CBVF and no void filler in a debrided osteomyelitic environment. Animals treated with C-G at 6 months showed no evidence of infection and retained a higher bone mass relative to the contralateral (non-operated) side. This study supports the use of CERAMENT|G as a readily available void filler which could be used in osteomyelitic environments after debridement.
The modulation of both quantity and quality of peri-implant bone with either PTH or loading may be viable options to improve implant fixation and patient outcomes. A strong bone-implant interface is essential for successful joint replacement surgery. This study investigated the differences in bone surrounding and within a porous titanium implant after single or combined treatment with two anabolic bone therapies: intermittent parathyroid hormone (teriparatide) and mechanical loading. Porous titanium implants were inserted bilaterally on the distal lateral femurs of rabbits. The right implant was loaded daily (1 MPa, 50 cycles/day) while the left implant was not. Rabbits received daily PTH injections (20 ug/kg) or saline vehicle. Periprosthetic cancellous bone 0.5, 1.0, and 2.0 mm below the implant surface, bone at the 0.25 mm bone-implant interface and total bone within each implant were examined using tissue-level analyses (quantitative backscattered electron microscopy), cellular analyses (immunohistochemistry staining of osteoblasts with procollagen-1 and TRAP staining of osteoclasts), and shear testing (implant-bone interface). Statistical significance was determined using GEE models (p<0.05). For tissue located 0.5 mm below the implant, significant increases in bone area per total area (BA/TA) were observed with PTH treatment (56%) and with loading (27%). Further, an 18% increase in mineralization density with PTH treatment and a 20% increase in mineralization density with loading was found. Loading effects were not present beyond the 0.5 mm periprosthetic region, but PTH significantly increased BA/TA 2.0 mm below and mineralization density 1.0 mm below the implant. Tissue-level changes were supported by increases in osteoblast activity 0.5 mm below the implant with PTH (79%) and loading (34%), as well as by minimal osteoclast changes. At the 0.25 mm implant-bone interface PTH and loading increased BA/TA (16% and 23%, respectively), but only loading increased mineralization density (7%). Further, total integrated bone area was increased 35% with PTH. Both PTH and loading enhanced the mechanical integrity of the implant-bone; shear strength increased 34% and 60%, respectively. Although combined treatment was not synergistic, both PTH and loading individually enhanced the amount and mineralization density of bone at the implant interface and immediately below the interface, thereby increasing the mechanical strength of the metal-bone interface. This research suggests that modulation of both quantity and quality of peri-implant bone may be viable options to improve implant fixation and patient outcomes.Summary Statement
