OBJECTIVE:To determine the effect of physical activity on knee osteoarthritis (OA) development in persons without knee injury and according to knee alignment.DESIGN:We combined data from Multicenter Osteoarthritis (MOST) and Osteoarthritis Initiative (OAI), studies of persons with or at high risk of OA. Subjects had long limb and repeated posteroanterior knee radiographs and completed the physical activity survey for the elderly (PASE). We studied persons without radiographic OA and excluded knees with major injury and without long limb films. We followed subjects 30 months (in MOST) and 48 months (in OAI) for one of two incident outcomes: (1) symptomatic tibiofemoral OA (radiographic OA and knee pain), or (2) tibiofemoral narrowing. 'Active' persons were those with PASE score in the highest quartile by gender. We examined risk of OA in active group using logistic regression adjusting for age, gender, body mass index (BMI), Western Ontario and McMaster Arthritis Index (WOMAC) pain score, Kellgren and Lawrence (KL) grade (0 or 1), and study of origin. We also analyzed knees from malaligned and neutrally aligned limbs.RESULTS:The combined sample comprised 2,073 subjects (3,542 knees) with mean age 61 years. The cumulative incidence of symptomatic tibiofemoral OA was 1.12% in the active group vs 1.82% in the others (odds ratio (OR) among active group 0.6, 95% confidence interval (CI) 0.3, 1.3). Joint space narrowing occurred in 3.41% of knees in the active group vs 4.04% in the others (OR among active group 0.9 (95% CI 0.5, 1.5)). Results did not differ by alignment status.CONCLUSIONS:Physical activity in the highest quartile did not affect the risk of developing OA.

OBJECTIVE:To determine whether intra- and periarticular cyst-like lesions of the knee are associated with incident knee pain and incident radiographic knee osteoarthritis (OA).DESIGN:The Multicenter Osteoarthritis (MOST) Study is a cohort of individuals who have or are at high risk for knee OA. Using a nested case-control study design, we investigated the associations of cyst-like lesions (Baker's, meniscal and proximal tibiofibular joint (PTFJ) cysts, and prepatellar and anserine bursitides) with (1) incident pain at 15- or 30-month follow-up and (2) incident radiographic OA at 30-month follow-up. Baseline cyst-like lesions were scored semiquantitatively using the Whole Organ Magnetic Resonance Imaging Score (WORMS). Conditional logistic regression models were used to assess the relation between these lesions and the outcomes, adjusting for potential confounding factors (i.e., cartilage loss, meniscal damage, bone marrow lesions, synovitis and joint effusion, which were also scored using WORMS).RESULTS:Incident knee pain study included 157 cases and 336 controls. Prevalence of meniscal and PTFJ cysts in the case group was twice that in the control group [9 (6%) vs 9 (3%) and 9 (6%) vs 10 (3%), respectively]. Incident radiographic OA study included 149 cases and 298 controls. Prevalence of grade 2 Baker's cysts and PTFJ cysts in the case group was approximately four times that in the control group [16(11%) vs 9 (3%) and 6 (4%) vs 3 (1%), respectively]. However, none of the cyst-like lesions was associated with incident pain or radiographic OA after fully adjusted logistic regression analyses and correction of P-values for multiple comparisons.CONCLUSION:None of the analyzed lesions was an independent predictor of incident knee pain or radiographic OA. Intra- and periarticular cyst-like lesions are likely to be a secondary phenomenon seen in painful or OA-affected knees, rather than a primary trigger for incident knee pain or radiographic OA.

Objective: Homocysteine has been implicated in multiple diseases that involve changes in structural tissue. In vitro studies have found that it alters the structure of collagen cross-linking thus affecting stability and mineralization such as that occurring in bone tissue. In the present study we considered the possible relationship between plasma homocysteine levels and the development and progression of knee osteoarthritis (OA).Methods: The study question was posed in 691 men and 966 women from the original and offspring cohorts of the Framingham Osteoarthritis Study. We divided individuals into three groups according to plasma homocysteine levels and compared their risk for the development of new and progression of existing OA. We adjusted for potential confounders including age, body mass index, weight change, and physical activity.Results: In the crude analysis, men in the middle homocysteine tertile were found to be at a greater risk than men in the lowest tertile for incident OA [odds ratios of 1.9 (1.1-3.5)). This result persisted after adjusting for covariates [odds: 2.0, (1.1-3.8)]. No significant correlation was seen in women for the development of OA. In the evaluation of progression no significant trends were seen for both men and women.Conclusions: Although cellular and molecular studies of homocysteine-related pathophysiology suggest a possible correlation between plasma homocysteine levels and OA, the present clinical study did not conclusively demonstrate such an association. However, further research is needed to explore the role of homocysteine in specific aspects of CA etiopathogenesis. (C) 2008 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

pected with the development of PTOA, cartilage thickness tended to decrease over time (Figure 2), although with modest numbers, no firm statistical conclusions could be drawn. Conclusions: Although double-contrast MDCT scans have been shown to be better than MRI at quantifying cartilage thickness in intact ankles, our clinical experience indicates that after highenergy articular fractures, ankle cartilage cannot consistently be imaged for reliable quantification. Images could not be quantitatively interpreted in up to 50% of cases. Reasons were both inherent joint pathology (arthrofibrosis) and technical (failed injection, metal artifact). Moreover, some patients would not consent for a second study due to discomfort during the first. We are currently pursuing MRI with metal artifact suppression techniques for this purpose. The early arthrofibrosis that was observed after these high-energy articular fractures merits further study. Supported by grants from the NIH/NIAMS (AR048939 and AR055533). 430

OBJECTIVE:To examine whether obesity increases the risk of progression of knee osteoarthritis (OA). METHODS:We used data from the Multicenter Osteoarthritis Study, a longitudinal study of persons with or at high risk of knee OA. OA was characterized at baseline and 30 months using posteroanterior fixed-flexion radiographs and Kellgren/Lawrence (K/L) grading, with alignment assessed on full-extremity films. In knees with OA at baseline (K/L grade 2 or 3), progression was defined as tibiofemoral joint space narrowing on the 30-month radiograph. In knees without OA at baseline (K/L grade 0 or 1), incident OA was defined as the development of radiographic OA at 30 months. Body mass index (BMI) at baseline was classified as normal (<25 kg/m(2)), overweight (25-<30 kg/m(2)), obese (30-<35 kg/m(2)), and very obese (>or=35 kg/m(2)). The risk of progression was tested in all knees and in subgroups categorized according to alignment. Analyses were adjusted for age, sex, knee injury, and bone density. RESULTS:Among the 2,623 subjects (5,159 knees), 60% were women, and the mean +/- SD age was 62.4 +/- 8.0 years. More than 80% of subjects were overweight or obese. At baseline, 36.4% of knees had tibiofemoral OA, and of those, only one-third were neutrally aligned. Compared with subjects with a normal BMI, those who were obese or very obese were at an increased risk of incident OA (relative risk 2.4 and 3.2, respectively [P for trend < 0.001]); this risk extended to knees from all alignment groups. Among knees with OA at baseline, there was no overall association between a high BMI and the risk of OA progression; however, an increased risk of progression was observed among knees with neutral but not varus alignment. The effect of obesity was intermediate in those with valgus alignment. CONCLUSION:Although obesity was a risk factor for incident knee OA, we observed no overall relationship between obesity and the progression of knee OA. Obesity was not associated with OA progression in knees with varus alignment; however, it did increase the risk of progression in knees with neutral or valgus alignment. Therefore, weight loss may not be effective in preventing progression of structural damage in OA knees with varus alignment.

A proposed model suggests that the experience of pain is influenced by psychological and genetic factors. Our previous study reported that pain catastrophizing and catechol-O-methyltransferase (COMT) genotype influenced clinical pain ratings for patients seeking operative treatment of shoulder pain. The current study investigated whether these same psychological and genetic factors predicted responses to induced shoulder pain. Our a priori hypothesis was that subjects with high pain catastrophizing and COMT genotype indicative of low COMT enzyme activity would have the highest induced shoulder pain ratings. Subjects (n = 63) completed the Pain Catastrophizing Scale (PCS) and had COMT genotype determined by PCR-based strategies. Subjects then completed a standardized fatigue protocol to induce delayed onset muscle soreness and underwent post-fatigue assessments at 24, 48, and 72 hours. The post-fatigue assessments included pain intensity (visual analog scale), evoked pressure pain (visual analog scale), muscle force production (maximum voluntary isometric contraction), and upper-extremity disability (Disability of Arm, Shoulder, and Hand Questionnaire). Hierarchical regression investigated the contributions of pain catastrophizing and previously described COMT diplotypes for shoulder pain intensity at 72 hours. A statistically significant interaction between pain catastrophizing and COMT diplotype was detected, and this interaction was the strongest unique predictor of 72 hour pain intensity ratings. This same interaction was statistically significant for prediction of evoked pressure pain at 72 hours, but not for muscle force production or upper-extremity disability. In conclusion, these findings converge with those from the surgical cohort and provide additional evidence that pain catastrophizing and COMT diplotype have the potential to increase the risk of developing chronic pain syndromes. This study was supported by a grant from the University of Florida.

Purpose: As a common treatment of chondral defects on the knee joint, cartilage repair procedures such as microfracture (MFX) and matrixassociated autologous cartilage transplantation (MACT) need to be assessed in the post-operative follow-up.On both patient groups, areas of cartilage repair as well as areas of intact hyaline cartilage can be observed post-operatively since both methods are used in the treatment of single full thickness cartilage lesions.Therefore, detailed assessment of these patients may help highlighting the potential benefits of novel imaging techniques in visualization of articular cartilage and its ultrastructure, in healthy as well as in affected articular cartilage.The purpose of this initial study was to show the potential of magnetization transfer contrast (MTC) imaging in the assessment of articular cartilage and compare it to the more common T2 mapping technique and furthermore, to evaluate deep and superficial cartilage aspects in order to elucidate possible zonal differences.Methods: Thirty-four patients (17 after MFX and 17 after MACT) were examined with 3T MRI.The magnetization transfer ratio (MTR) was calculated from measurements with and without MT contrast.T2 values were evaluated using a multi-echo, spin-echo approach.Global (full thickness of cartilage) and zonal (deep and superficial aspect) region-ofinterest (ROI) assessment of cartilage repair tissue and normal-appearing cartilage was performed by an experienced senior musculoskeletal radiologist in consensus with an orthopedic surgeon with special interest in musculoskeletal MR imaging.An area of cartilage repair and an area of healthy-appearing control cartilage were identified using the morphological images as well as the surgical reports.Initially, the ROIs covered the full thickness of the cartilage layer.For further evaluation of zonal variations, the ROIs were divided into two equal-sized deep and superficial regions.Results: In patients after MFX and MACT, the global MTR of cartilage repair tissue was significantly lower compared to healthy cartilage.Regarding zonal variation, a significant increase could be observed from deep to superficial aspects of healthy control cartilage.Concerning global MTR of cartilage repair tissue, all assessed mean values where significantly decreased in both patient groups.A zonal variation could not be observed within the cartilage repair tissue.The further evaluation of T2 relaxation times showed a clear zonal variation for healthy control cartilage.Concerning cartilage repair tissue mean T2 values showed no decrease in patients after MACT; however a clear decrease in patients after MFX.Zonal variation could be assessed after MACT, but not after MFX.Conclusions: MTC evaluation showed to be capable in the differentiation between healthy control cartilage and cartilage repair tissue after different cartilage repair procedures.Furthermore, it was possible to assess a deep and superficial aspect of articular cartilage and to describe an increase in MTR from deep to superficial in healthy cartilage sites.Compared to T2 mapping, MTC showed to be more sensitive in the discrimination between healthy cartilage sites and cartilage repair tissue after MACT; however, the differentiation between both cartilage repair tissues was better visible using T2 relaxation.

We have measured the total normalized cross section R for the process e+e− → hadrons at centre-of-mass energies between 14.0 and 46.8 GeV based on an integrated luminosity of 60.3 pb−1. The data are well described by the standard SU(3)c⊗SU(2)L⊗U(1) model with the production of the five known quarks. No open production of a sixth quark with charge 2/3 or 1/3 occurs below a centre-of-mass energy of 46.6 or 46.3 GeV, respectively. A fitting procedure which takes the correlations between measurements into account was used to determine the electroweak mixing angle sin2θw and the strong coupling constant αs(S) in second-order QCD. We applied this procedure to the CELLO data and in addition included the data from other experiments at PETRA and PEP. Both fits give consistent results. The fit to the combined data yields αs(342 GeV2) = 0.165±0.030, and sin2θw = 0.236±0.020. Fixing sin2θw at the world average value of 0.23 yields αs(342GeV2) = 0.169±0.025.

A search for single photons, produced in e+e− collisions together with particles interacting only weakly with matter, has been performed using the CELLO detector operating at the PETRA storage ring. From the absence of any signal, an upper limit is set at 15 (90% CL) on the number of light neutrino species, and lower limits on various supersymmetric particle masses are derived. For massless photinos, mass degenerate scalar partners of the left- and right-handed electrons are excluded below 37.7 GeV/c2 (90% CL).

The production of excited quarks has been looked for in e+e− interactions at PETRA at center of mass energies up to 46.8 GeV using the CELLO detector. The different final state topologies considered are four-jets, two-jets and two-photons, three-jets, two-jets and one-photon. No deviation from standard QCD predictions is observed, thus yielding limits on the coupling constants and the masses of these possible quark states.

Using the CELLO detector at PETRA a search has been made for excited leptons by studying e+e− interactions which yield l+l− γγ, l+l− γ and γγ final states, where l=e,μorτ. Good agreement with QED is observed and new limits are set on e∗, μ∗, and τ∗ production.

A search for light leptoquarks decaying into a lepton and a quark has been performed using the CELLO detector at the storage ring PETRA. Decay modes have been looked for where the lepton is either a muon or a neutrino, the latter being detected by a high missing transverse momentum. Except for one event previously reported no further two-jet events with two isolated muons were observed. No evidence for pair production of these particles has been found in other final states configurations. Our results are interpreted within a model where leptoquarks appear as a coloured Goldsone multiplet of charges 2/3.A 95% CL upper limit of 0.30 pb is set on the pair production cross section of such leptoquarks, thus excluding masses between 7 and 20.5 GeV.