Metabolomic profiles of cartilage and bone reflect tissue type, radiography-confirmed osteoarthritis, and spatial location within the joint.

Osteoarthritis is the most common chronic joint disease, characterized by the abnormal remodeling of joint tissues including articular cartilage and subchondral bone. However, there are currently no therapeutic drug targets to slow the progression of disease because disease pathogenesis is largely unknown. Thus, the goals of this study were to identify metabolic differences between articular cartilage and subchondral bone, compare the metabolic shifts in osteoarthritic grade III and IV tissues, and spatially map metabolic shifts across regions of osteoarthritic hip joints. Articular cartilage and subchondral bone from 9 human femoral heads were obtained after total joint arthroplasty, homogenized and metabolites were extracted for liquid chromatography-mass spectrometry analysis. Metabolomic profiling revealed that distinct metabolic endotypes exist between osteoarthritic tissues, late-stage grades, and regions of the diseased joint. The pathways that contributed the most to these differences between tissues were associated with lipid and amino acid metabolism. Differences between grades were associated with nucleotide, lipid, and sugar metabolism. Specific metabolic pathways such as glycosaminoglycan degradation and amino acid metabolism, were spatially constrained to more superior regions of the femoral head. These results suggest that radiography-confirmed grades III and IV osteoarthritis are associated with distinct global metabolic and that metabolic shifts are not uniform across the joint. The results of this study enhance our understanding of osteoarthritis pathogenesis and may lead to potential drug targets to slow, halt, or reverse tissue damage in late stages of osteoarthritis.

Induced Membrane Technique Is Effective for the Management of Acute Traumatic Bone Loss in Both Diaphyseal and Metaphyseal Lower Extremity Fractures.

OBJECTIVE: To compare outcomes of Masquelet-induced membrane technique (IMT) in metaphyseal and diaphyseal fractures with acute bone loss. DESIGN: Retrospective cohort study. SETTING: Four Level 1 Academic Trauma Centers. PATIENTS/PARTICIPANTS: Patients acutely treated with IMT for traumatic lower extremity bone loss at 4 Level 1 trauma centers between 2010 and 2020. INTERVENTION: Operative treatment with placement of cement spacer within 3 weeks of initial injury followed by staged removal and bone grafting to the defect. MAIN OUTCOME MEASUREMENTS: Fracture union, infection, revision grafting, time to union, and amputation. RESULTS: One hundred twenty fractures met inclusion criteria, including 43 diaphyseal fractures (DIM) and 77 metaphyseal fractures (MIM). Demographic characteristics were not significantly different, except for age (DIM 34 years vs. MIM 43 years, P < 0.001). Union after treatment with IMT was 89.2% overall. After controlling for age, this was not significantly different between DIM (41/43, 95.3%) and MIM (66/77, 85.7%) ( P = 0.13) nor was the rate of infection between groups. There was no difference in any secondary outcomes. CONCLUSIONS: The overall union rate in the current series of acute lower extremity fractures treated with the induced membrane technique was 89%. There was no difference in successful union between patients with diaphyseal bone loss or metaphyseal bone loss treated with IMT. Similarly, there was no difference in patients with tibial or femoral bone loss treated with induced membrane. Defect size after debridement may be more prognostic for secondary operations rather than the limb segment involved or the degree of soft-tissue injury. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Correlations between metabolites in the synovial fluid and serum: A mouse injury study.

Osteoarthritis occurs frequently after joint injury. Currently, osteoarthritis is diagnosed by radiographic changes that are typically found after the disease has progressed to multiple tissues. The primary objective was to compare potential metabolomic biomarkers of joint injury between synovial fluid and serum in a mouse model of posttraumatic osteoarthritis. The secondary objective was to gain insight into the pathophysiology of osteoarthritis by examining metabolomic profiles after joint injury. Twelve-week-old adult female C57BL/6 mice (n = 12) were randomly assigned to control, Day 1, or Day 8 postinjury groups. Randomly selected stifle joints were subjected to a single rapid compression. At Days 1 and 8 postinjury, serum was extracted before mice were euthanized for synovial fluid collection. Metabolomic profiling detected ~2500 metabolites across serum and synovial fluid. Of these, 179 were positively correlated and 51 were negatively correlated between synovial fluid and serum, indicating the potential for the development of metabolomic biomarkers. Synovial fluid captured injury-induced differences in metabolomic profiles at both Days 1 and 8 after injury whereas serum did not. However, synovial fluid and serum were distinct at both time points after injury. In synovial fluid, pathways of interest mapped to amino acid synthesis and degradation, bupropion degradation, and transfer RNA (tRNA) charging. In serum, pathways were amino acid synthesis and degradation, the phospholipase pathway, and nicotine degradation. These results provide a rich picture of the injury response at early time points after joint injury. Furthermore, the correlations between synovial fluid and serum metabolites suggest the potential to gain insight into intra-articular pathophysiology through analysis of serum metabolites.

Global metabolomic profiling of human synovial fluid for rheumatoid arthritis biomarkers.

OBJECTIVES: The objective of this study was to analyse the metabolomic profiles of rheumatoid arthritis synovial fluid to test the use of global metabolomics by liquid chromatography-mass spectrometry for clinical analysis of synovial fluid. METHODS: Metabolites were extracted from rheumatoid arthritis (n=3) and healthy (n=5) synovial fluid samples using 50:50 water: acetonitrile. Metabolite extracts were analysed in positive mode by normal phase liquid chromatography-mass spectrometry for global metabolomics. Statistical analyses included hierarchical clustering analysis, principal component analysis, Student's t-test, and volcano plot analysis. Metabolites were matched with known metabolite identities using METLIN and enriched for relevant pathways using IMPaLA. RESULTS: 1018 metabolites were detected by LC-MS analysis in synovial fluid from rheumatoid arthritis and healthy patients, with 162 metabolites identified as significantly different between diseased and control. Pathways upregulated with disease included ibuprofen metabolism, glucocorticoid and mineralocorticoid metabolism, alpha-linolenic acid metabolism, and steroid hormone biosynthesis. Pathways downregulated with disease included purine and pyrimidine metabolism, biological oxidations, arginine and proline metabolism, the citrulline-nitric oxide cycle, and glutathione metabolism. Receiver operating characteristic analysis identified 30 metabolites as putative rheumatoid arthritis biomarkers including various phospholipids, diol and its derivatives, arsonoacetate, oleananoic acid acetate, docosahexaenoic acid methyl ester, and linolenic acid and eicosatrienoic acid derivatives. CONCLUSIONS: This study supports the use of global metabolomic profiling by liquid chromatography-mass spectrometry for synovial fluid analysis to provide insight into the aetiology of disease.

Bond strength of gold alloys laser welded to cobalt-chromium alloy.

The objective of this study was to investigate the joint properties between cast gold alloys and Co-Cr alloy laser-welded by Nd:YAG laser. Cast plates were fabricated from three types of gold alloys (Type IV, Type II and low-gold) and a Co-Cr alloy. Each gold alloy was laser-welded to Co-Cr using a dental laser-welding machine. Homogeneously-welded and non-welded control specimens were also prepared. Tensile testing was conducted and data were statistically analyzed using ANOVA. The homogeneously-welded groups showed inferior fracture load compared to corresponding control groups, except for Co-Cr. In the specimens welded heterogeneously to Co-Cr, Type IV was the greatest, followed by low-gold and Type II. There was no statistical difference (P<0.05) in fracture load between Type II control and that welded to Co-Cr. Higher elongations were obtained for Type II in all conditions, whereas the lowest elongation occurred for low-gold welded to Co-Cr. This study indicated that, of the three gold alloys tested, the Type IV gold alloy was the most suitable alloy for laser-welding to Co-Cr.

Criminal offending in schizophrenia over a 25-year period marked by deinstitutionalization and increasing prevalence of comorbid substance use disorders.

OBJECTIVE: This study examined the pattern of criminal convictions in persons with schizophrenia over a 25-year period marked by both radical deinstitutionalization and increasing rates of substance abuse problems among persons with schizophrenia in the community. METHOD: The criminal records of 2,861 patients (1,689 of whom were male) who had a first admission for schizophrenia in the Australian state of Victoria in 1975, 1980, 1985, 1990, and 1995 were compared for the period from 1975 to 2000 with those of an equal number of community comparison subjects matched for age, gender, and neighborhood of residence. RESULTS: Relative to the comparison subjects, the patients with schizophrenia accumulated a greater total number of criminal convictions (8,791 versus 1,119) and were significantly more likely to have been convicted of a criminal offense (21.6% versus 7.8%) and of an offense involving violence (8.2% versus 1.8%). The proportion of patients who had a conviction increased from 14.8% of the 1975 cohort to 25.0% of the 1995 cohort, but a proportionately similar increase from 5.1% to 9.6% occurred among the comparison subjects. Rates of known substance abuse problems among the schizophrenia patients increased from 8.3% in 1975 to 26.1% in 1995. Significantly higher rates of criminal conviction were found for patients with substances abuse problems than for those without substance abuse problems (68.1% versus 11.7%). CONCLUSIONS: A significant association was demonstrated between having schizophrenia and a higher rate of criminal convictions, particularly for violent offenses. However, the rate of increase in the frequency of convictions over the 25-year study period was similar among schizophrenia patients and comparison subjects, despite a change from predominantly institutional to community care and a dramatic escalation in the frequency of substance abuse problems among persons with schizophrenia. The results do not support theories that attempt to explain the mediation of offending behaviors in schizophrenia by single factors, such as substance abuse, active symptoms, or characteristics of systems of care, but suggest that offending reflects a range of factors that are operative before, during, and after periods of active illness.