Abnormal lipid metabolism is involved in the development of osteoarthritis (OA). Growth differentiation factor 11 (GDF11) is crucial in inhibiting the differentiation of bone marrow mesenchymal stem cells into adipocytes. However, whether GDF11 participates in the abnormal adipogenesis of chondrocytes in OA cartilage is still unclear. Six-week-old female mice were subjected to unilateral anterior crossbite (UAC) to induce OA in the temporomandibular joint (TMJ). Histochemical staining, immunohistochemical staining (IHC), and quantitative real-time polymerase chain reaction (qRT-PCR) were performed. Primary condylar chondrocytes of rats were stimulated with fluid flow shear stress (FFSS) and collected for oil red staining, immunofluorescence staining, qRT-PCR, and immunoprecipitation analysis.Aims
Methods
The COVID-19 pandemic presents an unprecedented burden on global healthcare systems, and existing infrastructures must adapt and evolve to meet the challenge. With health systems reliant on the health of their workforce, the importance of protection against disease transmission in healthcare workers (HCWs) is clear. This study collated responses from several countries, provided by clinicians familiar with practice in each location, to identify areas of best practice and policy so as to build consensus of those measures that might reduce the risk of transmission of COVID-19 to HCWs at work. A cross-sectional descriptive survey was designed with ten open and closed questions and sent to a representative sample. The sample was selected on a convenience basis of 27 senior surgeons, members of an international surgical society, who were all frontline workers in the COVID-19 pandemic. This study was reported according to the Standards for Reporting Qualitative Research (SRQR) checklist.Aims
Methods
Intraosseous administration of low dose vancomycin has been proven to produce 6 to 20 times higher tissue concentrations compared to intravenous administration in both primary and revision knee replacement. However, these superior levels are achieved when the antibiotic given intraosseously is administered distal to a tourniquet that is inflated for the majority of the case. With increasing interest in limited, or no, tourniquet use during TKA we sought to study the tissue concentrations achieved with limited tourniquet use and intraosseously administered vancomycin compared to weight-based, time optimized intravenous administration. Twenty-four patients undergoing primary TKA were randomized to two groups. The Intravenous (IV) Group received weight based (15mg/kg) vancomycin timed to finish before incision. The Intraosseous (IO) Group received 500 mg of vancomycin injected as a bolus through a needle into the proximal tibia distal to an inflated tourniquet prior to skin incision. In the IO group, the tourniquet was deflated 10 minutes following the injection and re-inflated only for cementation. In the IV group, the tourniquet was only inflated for cementation. During the procedure, fat and bone samples were taken at regular intervals. Tissue antibiotic concentrations were measured using a validated technique involving high performance liquid chromatography.Introduction
Methods
Effectiveness of computer-assisted joint replacement (CA-TJR) compared to conventional TJR has been evaluated by a large body of literature. Systematic reviews provide a powerful, widely accepted, evidence-based approach to synthesize the evidence and derive conclusions, yet the strength of these conclusions is dependent on the quality of the review. Multiple systematic reviews compared CA-TJR and conventional TJR with conflicting results. We aimed to assess the quality of these reviews. We searched MEDLINE, EMBASE, the Cochrane, and Epistemonikos to identify SRs published through May 2017. Full-text articles that met inclusion criteria were retrieved and assessed independently by two reviewers. Evidence was qualitatively synthesized and summarized. Outcome measures were categorized into functional, radiological, and patient safety related. The corrected covered area (CCA) was calculated to assess the degree of overlap between SRs in analyzing the same primary studies. The AMSTAR 2, a valid and reliable tool, was applied to rate the confidence in the results of the SRs (Shea et al., 2017). AMSTAR-2 has 16 domains, of which 7 are critical (e.g., justification for excluding individual studies) and 9 are non-critical (e.g., not reporting conflict of interest for individual studies). Reviews are rated as high (no critical or non-critical flaws), moderate (only non-critical flaws), low (1 critical flaw) and critically low (more than one critical flaw). Disagreement between the 2 reviewers was resolved by discussion with the senior author to achieve consensus. We reported the quality ratings of these studies and the frequency of critical and non-critical flaws.Background
Methods
Adult mice lacking the transcription factor NFAT1 exhibit osteoarthritis (OA). The precise molecular mechanism for NFAT1 deficiency-induced osteoarthritic cartilage degradation remains to be clarified. This study aimed to investigate if NFAT1 protects articular cartilage (AC) against OA by directly regulating the transcription of specific catabolic and anabolic genes in articular chondrocytes. Through a combined approach of gene expression analysis and web-based searching of NFAT1 binding sequences, 25 candidate target genes that displayed aberrant expression in Objectives
Methods
Previous work in a rabbit model of post-traumatic joint contractures shows that the mast cell stabilizer ketotifen decreases contracture severity. We show here that ketotifen decreases collagen gel contraction mediated by rabbit joint capsule fibroblasts when mast cells are present. Ketotifen was shown to decrease contracture severity and associated joint capsule fibrosis in an animal model of post-traumatic joint contractures. Ketotifen prevents the release of profibrotic growth factors from mast cells (MC). An Summary
Introduction
Recent work has shown that joint contracture severity can be decreased with the mast cell stabilizer ketotifen in association with decreased numbers of myofibroblasts and mast cells in the joint capsule of a rabbit model of post-traumatic contractures. Neuropeptides such as Substance P (SP) can induce mast cells to release growth factors. Using a gel contraction assay, we test the hypothesis that joint capsule cell-mediated contraction of a collagen gel can be enhanced with SP, but the effect is magnified in the presence of mast cells. Anterior elbow joint capsules were obtained at the time of surgical release from 2 men (age 34 and 54) and 1 woman (age 40) with chronic (> 1 year) post-traumatic joint contractures. The human mast cell line HMC-1 (Mayo Clinic, Rochester), SP and the NK1 receptor antagonist RP67580 (Sigma, Oakville, ON) were used. NK1 is the SP receptor. Neutralized Collagen solution composed with 58% Vitrogen 100 purified collagen mixed with HMC-1 cells only (7.5 105), human capsule cells (2.5 105), or human capsule cells (2.5 105) and 7.5 105 mast cells (1:3) were cast into 24- well tissue culture plates. In some experiments, SP (1 × 10−5 M) +/− RP67580 (0.5 mM) were added. The gels were maintained with 0.5 ml DMEM composed with 2% BSA and incubated at 37C for 12 h for gelation to occur. The gels were then detached from the wall and the bottom of culture plate wells, and photographed at regular intervals up to 72 hours. Gel contraction studies were carried out on passage 4 and done in triplicate for each patient. The average value of each patients triplicate was combined to give a mean contraction at each time point. Statistical analysis involved an ANOVA with posthoc Bonferroni correction. P < 0.001 was significant.Purpose
Method
The hypothesis is that cells isolated from capsules of joints with contractures will contract collagen gels at a faster rate when compared to cells obtained from capsules of joints free of contractures. Post-traumatic joint contractures were produced by removing cortical bone windows from the femoral condyles of three skeletally mature rabbits and immobilizing the knees for four weeks with a K-wire. The contralateral knees served as an unoperated control. At sacrifice, the posterior capsules were immediately placed in medium and the tissue was minced. Upon confluence, cells were trypsinised and gel contraction studies were carried out on passage four cells. Five x 105 cells/ml were mixed with 58% neutralised bovine collagen solution and five hundred microlitres of collagen gel/cells solution were then cast into wells of a tissue culture plate. Gelation occurred overnight at 37C in a humidified incubator containing 5% CO2. At cultured day zero, day one, day three, the gels were released from the well walls. The areas of the gel were measured using an image analyzer immediately after release (zero hour), and one hour, two hour, three hour and four hour post-release. The amount the collagen gels were contracted depended on the time of preincubation of cells and collagen before release and the source of the joint capsule cells. In general, increasing the time of preincubation heightened the contractile response of the cells. The collagen gel contraction was small for the day zero groups over the first four hours, but for the day three groups the rate of contraction was markedly increased. In all cases the collagen gel contraction was larger for the contracture capsule cells when compared to the control capsule cells. The patterns of the contraction over the four hours post release were similar for contracture and control groups. Cells from capsules of joints with post-traumatic contractures have intrinsically heightened in vitro contractile properties when compared to normal cells. Future work will determine whether the response is exaggerated to fibrotic stimuli such as TGF-beta1 in these capsule cells from post-traumatic joint contractures.
The hypothesis is that mast cell numbers and neuropeptide containing nerve fibres are increased in the elbow joint anterior capsule of patients with post-traumatic contractures when compared to normal capsules. Capsules were obtained from two patients with chronic contractures following radial head fractures and two organ donor elbows free of contractures. Four sections from each capsule were double-labelled with specific antibodies to the mast cell marker chymase and the neuropeptide calcitonin gene-related peptide (CGRP). Species specific secondary fluorescent antibodies were used to detect the marker antibodies and cells were identified with a fluorescent nuclear marker (DAPI). Images were captured using a microscope (200x magnification) and five randomly selected areas were sampled for each section obtained from all joint capsules. Chymase positive cell numbers and numbers of nerve fibers (minimum length fifty micrometres) were gathered. The number of chymase positive mast cells was 6x greater in the contracture capsules when compared to normal capsules. In the contracture capsule, chymase positive mast cells represented 39% of total cells while in control capsules they represented 7% of total cells. Total cell numbers were similar in the capsules of both groups. The number of CGRP positive nerve fibres was increased 3x in the contracture capsule when compared to normal capsule. Mast cell numbers and neuropeptide positive fibre numbers are increased in the elbow joint anterior capsule of patients with post-traumatic contractures when compared to normal tissues. Neuropeptides such as CGRP can induce mast cell degranulation. Mast cells release profibrotic molecules such as transforming growth factor beta1 (TGF-b1), a myofibroblast upregulator. It has been described that TGF-b1 and myofibroblast numbers are elevated in human elbow joint capsules in post-traumatic contractures. While these trends are encouraging, more subjects are needed to determine whether the mast cell and neuropeptide nerve fibre findings can be generalised to larger numbers. If future work supports a myofibroblast - mast cell - neuropeptide - fibrosis axis in the joint capsule in post-traumatic contractures, then methods to modulate this axis, such as mast cell stabilisers, may be evaluated in animal models.
Ligaments, menisci and joint capsules were obtained from experimental knees with post-traumatic joint contractures and their unoperated contralateral controls in 6 rabbits. Relative mRNA expression was altered for six of seven matrix molecules, growth factors and _-SMA (myofibroblast marker) in the joint capsule, four of seven molecules in the ACL, and two of seven molecules in the MCL and medial meniscus. The joint capsule had the most molecules with altered expression corresponding to it’s acknowledged key role in joint contracture development. Changes in molecular expression of several joint structures in post-traumatic contractures is similar to changes seen following ligament injury. To evaluate alteration of mRNA expression in ligaments, meniscus and joint capsules in post-traumatic contractures. mRNA expression was altered most frequently in the joint capsule. The mRNA expression alterations in the joint capsule reflect it’s significant contribution to contractures. The right knee had a stable intraarticular fracture coupled with Kirschner wire immobilization while the left knee was not surgically manipulated. The rabbits (n=6) were sacrificed two weeks later, and the ACL, MCL, posterior joint capsule and medial meniscus were obtained from both knees. Semiquantitative RT-PCR was used to evaluate relative mRNA expression of selected matrix molecules, growth factors and _-smooth muscle actin (_-SMA), a myofibroblast marker. Glyc-eraldehyde-3-phosphate dehydrogenase, a housekeeping gene, served as a normalization. Optical density measures of the gels were used for analysis. Statistical comparisons were made with a paired t-test. Statistical significance was p<
0.05. Relative mRNA expression was altered for six of seven molecules in the joint capsule, four of seven molecules in the ACL, and two of seven molecules for the MCL and meniscus. For the joint capsule, relative mRNA expression in the contracture capsule was 2-4x greater than the expression in the control capsules, except for TIMP one where the expression in the contracture capsule was 1/3 of the control capsules. As has been noted with other joint injuries (ligament instability), several structures in the joint display altered molecular expression as was found in this model of joint injury, post-traumatic joint contractures. Please contact author for tables and/or graphs.
The objective of this report was to evaluate myofibroblast numbers in human elbow anterior joint capsules. Joint capsules were obtained from six patients with post-traumatic contractures and from six elbow joints of age-matched organ donors. Frozen sections were labeled with α-smooth muscle actin (α-SMA), a marker of myofibroblasts. Myofibroblasts were identified in both experimental and control tissues. Myofibroblast numbers and percentage of total cells were significantly elevated in the capsules of patients (919 ± 187; 36 ± 0.04%) when compared to organ donor control tissue (485 ± 335; 9 ± 0.04%). Future work will look at the expression of myofibroblast modulators in human elbow joint contractures. The purpose of this study was to determine whether myofibroblasts are associated with human elbow joint contractures. Myofibroblast numbers and percentage of myofibroblasts to total cells were significantly increased in anterior elbow joint capsules of patients with post-traumatic contractures. Methods to alter myofibroblast expression may be strategies to prevent or treat post-traumatic elbow joint contractures. Joint capsules were obtained from six patients (age 33±13 yrs, preoperative flexion-extension arc range of motion 58°±15°) and from six elbow joints of organ donors free of contractures (age 26±15 yrs). Frozen sections were double labeled using monoclonal antibodies to α-smooth muscle actin (α-SMA) with peroxidase conjugated secondary antibodies, and affinity purified antibodies to laminin with Elexa Fluor 488 conjugated secondary antibodies. The laminin antibodies label components of blood vessels, to differentiate between α-SMA expression associated with blood vessels or myofibroblasts. Endogenous peroxidases were quenched and 10% normal goat serum was used as a blocking agent. DAB/peroxide substrate was added for thirteen minutes. DAPI was applied to label nuclei. Cell nuclei associated with α-SMA and not with laminin were counted as myofibroblasts. Myofibroblast numbers and percentage of total cells were significantly increased (t-test, p <
0.05) in the joint capsules of the patients when compared to organ donor control tissue. Total cell numbers were not significantly different in the patient and control tissue. Modulators of α-SMA expression and myofibroblast formation include growth factors and matrix molecule components. Future work will look at the expression of these modulators in human elbow joint contractures.
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