Knee contact forces are not altered in early knee osteoarthritis.

OBJECTIVE: This study calculated knee contact forces (KCF) and its relations with knee external knee adduction moments (KAM) and/or flexion moments (KFM) during the stance phase of gait in patients with early osteoarthritis (OA), classified based on early joint degeneration on Magnetic Resonance Imaging (MRI). We aimed at assessing if altered KCF are already present in early structural degeneration. DESIGN: Three-dimensional motion and ground reaction force data in 59 subjects with medial compartment knee OA (N=23 established OA, N=16 early OA, N=20 controls) were used as input for a musculoskeletal model. KAM and KFM, and KCF were estimated using OpenSim software. RESULTS: No significant differences were found between controls and subjects with early OA. In early OA patients, KAM significantly explained 69% of the variance associated with the first peaks KCF but only KFM contributed to the second peaks KCF. The multiple correlation, combining KAM and KFM, showed to be higher. However, only 20% of the variance of second peak KCF was explained by both moments in established OA. CONCLUSION: KCF are not increased in patients with early OA, suggesting that knee joint overload is more a consequence of further joint degeneration in more advanced stages of OA. Additionally, our results clearly show that KAM is not sufficient to predict joint loading at the end of the stance, where KFM contributes substantially to the loading, especially in early OA

Toward a clinical definition of early osteoarthritis: onset of patient-reported knee pain begins on stairs. Data from the osteoarthritis initiative.

OBJECTIVE: Early detection of osteoarthritis (OA) would increase the chances of effective intervention. We aimed to investigate which patient-reported activity is first associated with knee pain. We hypothesized that pain would occur first during activities requiring weight bearing and knee bending. METHODS: Data were obtained from the Osteoarthritis Initiative (OAI), a multicenter, longitudinal prospective observational cohort of people who have or are at high risk of OA. Participants completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC; Likert scale) annually for up to 7 years. Rasch analysis was used to rank the WOMAC pain questions (activities) in order of affirmation as the pain score increased from 0. For each total WOMAC score category (0-20) we selected 25 individuals at random based on their maximum score across all visits. Fit to the Rasch model was assessed in this subset; stability of question ranking over successive visits was confirmed in the full OAI. RESULTS: WOMAC data on 4,673 people were included, with 491 selected for subset analysis. The subset data showed good fit to the Rasch model (χ(2) = 43.31, P = 0.332). In the full OAI, the "using stairs" question was the first to score points as the total pain score increased from 0 (baseline logit score ± 95% confidence interval -4.74 ± 0.07), then "walking" (-2.94 ± 0.07), "standing" (-2.65 ± 0.07), "lying/sitting" (-2.00 ± 0.08), and finally "in bed" (-1.32 ± 0.09). This ordering was consistent over successive visits. CONCLUSION: Knee pain is most likely to first appear during weight-bearing activities involving bending of the knee, such as using stairs. First appearance of this symptom may identify a group suitable for early intervention strategies

MRI-based inverse finite element approach for the mechanical assessment of patellar articular cartilage from static compression test

The mechanical property of articular cartilage determines to a great extent the functionality of diarthrodial joints. Consequently, the early detection of mechanical and, thus, functional changes of cartilage is crucial for preventive measures to maintain the mobility and the quality of life of individuals. An alternative to conventional mechanical testing is the inverse finite element approach, enabling non-destructive testing of the tissue. We evaluated a method for the assessment of the equilibrium material properties of the patellar cartilage based on magnetic resonance imaging during patellofemoral compression. We performed ex vivo testing of two equine patellas with healthy cartilage, one with superficial defects, and one with synthetically degenerated cartilage to simulate a pre-osteoarthritic stage. Static compression with 400 N for 2 h resulted in morphological changes comparable to physiological in vivo deformations in humans. We observed a decrease of the equilibrium Young’s modulus of the degenerated cartilage by -59%, which was in the range of the results from indentation (-74%) and confined compression tests (-58%). With the reported accuracy of magnetic resonance imaging and its reproducibility, the results indicate the potential to measure differences in Young’s modulus with regard to cartilage degeneration and consequently to distinguish between healthy and pre-osteoarthritic cartilage

Illness versus substance use effects on the frontal white matter in early phase schizophrenia: A 4 Tesla \u3csup\u3e1\u3c/sup\u3eH-MRS study

Objective Young adults with early phase schizophrenia often report a past or current pattern of illicit substance use and/or alcohol misuse. Still, little is known about the cumulative and separate effects of each stressor on white matter tissue, at this vulnerable period of brain development. Methods Participants involved 24 healthy controls with a past or current history of sustained illicit drug use and/or alcohol misuse (users), 23 healthy controls without such history (normative data), and 27 users with early phase schizophrenia. 1H-MRS data were acquired from a large frontal volume encompassing 95% of white matter, using a 4 Tesla scanner (LASER sequence, TR/TE 3200/46 ms). Results Reduced levels of choline-containing compounds (Cho) were specific to the effect of illness (Cohen\u27s d = 0.68), with 22% of the variance in Cho levels accounted for by duration of illness. Reduced levels of myoInositol (d = 1.10) and creatine plus phosphocreatine (d = 1.07) were specific to the effects of illness plus substance use. Effect of substance use on its own was revealed by reductions in levels of glutamate plus glutamine (d = 0.83) in control users relative to normative data. Conclusions The specific effect of illness on white matter might indicate a decreased synthesis of membrane phospholipids or alternatively, reduced membrane cellular density. In terms of limitations, this study did not include patients without a lifetime history of substance use (non-users), and the specific effect of each substance used could not be studied separately

Illness Versus Substance Use Effects on The Frontal White Matter in Early Schizophrenia: A 4Tesla 1H-MRS Study

Illness versus substance use effects on the frontal white matter in earlyphase schizophrenia: A 4 Tesla1H-MRS studyDenise Berniera,RobertBarthab, David McAllindona,c, Christopher C. Hanstockd, Yannick Marchande,Kim N.H. Dillena, Michelle Gallanta, Kimberly P. Gooda,PhilipG.Tibboa,⁎aDepartment of Psychiatry, Dalhousie University, Nova Scotia, CanadabRobarts Research Institute, University of Western Ontario, Ontario, CanadacBiomedical Translational Imaging Centre, Halifax, Nova Scotia, CanadadDepartment of Biomedical Engineering, University of Alberta, Alberta, CanadaeFaculty of Computer Science, Department of Psychology and Neuroscience, Dalhousie University, Nova Scotia, Canadaabstractarticle infoArticle history:Received 4 September 2015Received in revised form 13 April 2016Accepted 15 April 2016Available online 6 May 2016Objective:Young adults with early phase schizophrenia often report a past or current pattern of illicit substanceuse and/or alcohol misuse. Still, little is known about the cumulative and separate effects of each stressor onwhite matter tissue, at this vulnerable period of brain development.Methods:Participants involved 24 healthy controls with a past or current history of sustained illicit drug use and/or alcohol misuse (users), 23 healthy controls without such history (normative data), and 27 users with earlyphase schizophrenia.1H-MRSdata were acquired from a large frontal volumeencompassing95% of white matter,using a 4 Tesla scanner (LASER sequence, TR/TE 3200/46 ms).Results:Reduced levels of choline-containing compounds (Cho) were specific to the effect of illness (Cohen\u27sd=0.68), with 22% of the variance in Cho levels accounted for by duration of illness. Reduced levels of myoInositol(d= 1.10) and creatine plus phosphocreatine (d= 1.07) were specific to the effects of illness plus substanceuse. Effect of substance use on its own was revealed by reductions in levels of glutamate plus glutamine (d=0.83) in control users relative to normative data.Conclusions:The specific effect of illness on white matter might indicate a decreased synthesis of membranephospholipids or alternatively, reduced membrane cellular density. In terms of limitations, this study did notinclude patients without a lifetime history of substance use (non-users), and the specific effect of each substanceused could not be studied separately