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Background: Anterior cruciate ligaments (ACL) injuries represent a major risk factor for early osteoarthritis (OA)., Purpose: To evaluate the prevalence and 4-year progression of knee OA measured with 3T MR-imaging in individuals with ruptured, reconstructed or normal ACL and to assess the impact of thigh muscle characteristics., Methods: A total of 54 knees (23/54 male, 31/54 female) were recruited from the Osteoarthritis Initiative (OAI). At baseline, 15/54 subjects had prevalent ACL ruptures and 15/54 subjects had prevalent ACL reconstruction (24/54 normal ACL). Western Ontario and McMasters Universities Arthritis Index (WOMAC) scores, Physical Activity Scores of the Elderly (PASE) and thigh muscle characteristics including strength, fat infiltration (Goutallier score) and thigh muscle cross-sectional area (CSA) MR measurements were obtained at baseline. Whole-organ MR-imaging Scores (WORMS) were obtained at baseline and at a 4-year follow-up time-point. Multivariate regression models, adjusting for covariates (age, gender, body mass index), were used for statistical analysis., Results: At baseline, subjects with prevalent ACL ruptures had worse WORMS total scores (mean±SEM, 44.1±3.5) than subjects with ACL reconstruction (30.8±4.0; P = 0.015) and worse than subjects with normal ACL (21.3±3.0; P<0.001). Cartilage scores were worse in both femorotibial compartments in ACL injured knees than in knees with normal ACL (P<0.05). Knees with ACL reconstruction showed an increased degeneration of the medial meniscus (P = 0.036), cartilage degeneration at the medial femoral condyle (P = 0.011). In a multivariate regression model, including both ACL groups and total muscle characteristics as influence parameters, high thigh muscle CSA, high muscle/ fat ratio and low Goutallier scores were associated with less degenerative changes at the knee, independent of ACL status. Knees with ACL reconstruction showed an increased progression of cartilage degeneration at the medial tibia compared to the normal ACL group (P = 0.027)., Conclusions: High thigh muscle CSA is associated with less degenerative changes at the knee, independent of the ACL status and may potentially be advantageous in the prevention of early OA., Competing Interests: The funding does not alter our adherence to PLOS ONE policies on sharing data and materials.

Purpose: The purpose of this nested case-control study was to identify baseline, incident, and progressive MRI findings visible on standard MRI clinical sequences that were associated with development of incident knee pain in subjects at risk for OA over a period of 48 months., Methods: We analyzed 60 case knees developing incident pain (WOMAC(pain) = 0 at baseline and WOMAC(pain) ≥ 5 at 48 months) and 60 control knees (WOMAC(pain) = 0 at baseline and WOMAC(pain) = 0 at 48 months) from the Osteoarthritis Initiative. 3 T knee MRIs were analyzed using a modified WORMS score (cartilage, meniscus, bone marrow) at baseline and after 48 months. Baseline and longitudinal findings were grouped into logistic regression models and compared using likelihood-ratio tests. For each model that was significant, a stepwise elimination was used to isolate significant MRI findings., Results: One baseline MRI finding and three findings that changed from baseline to 48 months were associated with the development of pain: at baseline, the severity of a cartilage lesion in the medial tibia was associated with incident pain--(odds ratio (OR) for incident pain = 3.05; P = 0.030). Longitudinally, an incident effusion (OR = 9.78; P = 0.005), a progressive cartilage lesion of the patella (OR = 4.59; P = 0.009), and an incident medial meniscus tear (OR = 4.91; P = 0.028) were associated with the development of pain., Conclusions: Our results demonstrate that baseline abnormalities of the medial tibia cartilage as well as an incident joint effusion, progressive patella cartilage defects, and an incident medial meniscus tear over 48 months may be associated with incident knee pain. Clinically, this study helps identify MRI findings that are associated with the development of knee pain.

Objective: To evaluate differences in meniscal T1ρ and T2 quantification in patients with acute anterior cruciate ligament (ACL) injuries and to determine correlations of these differences with MR morphological grading and patient-reported outcomes., Design: Bilateral knees of 52 patients with acute ACL injury and 20 healthy controls were scanned using 3 T magnetic resonance imaging (MRI) T1ρ and T2 mapping in this prospective study. Quantitative analysis of the meniscus was performed in anterior and posterior horns of the lateral and medial menisci. Morphological meniscal damage was assessed using modified whole-organ MRI scores (WORMS). Measurements were compared between injured, uninjured contralateral, and control knees using a mixed-effects regression model. Correlations between meniscal T1ρ/T2, WORMS and Knee Injury and Osteoarthritis Outcome Scores (KOOS) were examined using partial correlation analysis., Results: Mean meniscal T1ρ and T2 values were significantly higher in ACL-injured knees compared to control and contralateral knees. Menisci of ACL-injured knees without tears, including those limited to modified meniscal WORMS grade 0, also had significantly higher T1ρ and T2 values compared to menisci of uninjured knees. Within ACL-injured knees, T1ρ and T2 values showed significant positive associations with meniscal WORMS and significant negative associations with KOOS., Conclusion: Acute ACL injuries are associated with significantly increased meniscal T1ρ and T2 values in both patients with and without meniscal lesions or tears, suggesting quantitative MRI provides more sensitive measures of meniscal differences compared to traditional morphological MRI sequences. Correlation between meniscal T1ρ/T2 and KOOS suggest that quantitative MRI is reflective of the extent of patients' clinical symptoms., (Copyright © 2015 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Background: Women are at a greater risk for knee osteoarthritis (OA), but reasons for this greater risk in women are not well understood. It may be possible that differences in cartilage composition and walking mechanics are related to greater OA risk in women., Questions/purposes: (1) Do women have higher knee cartilage and meniscus T1ρ than men in young healthy, middle-aged non-OA and OA populations? (2) Do women exhibit greater static and dynamic (during walking) knee loading than men in young healthy, middle-aged non-OA and OA populations?, Methods: Data were collected from three cohorts: (1) young active (<35 years) (20 men, 13 women); (2) middle-aged (≥35 years) without OA (Kellgren-Lawrence [KL] grade < 2) (43 men, 65 women); and (3) middle-aged with OA (KL>1) (18 men, 25 women). T1ρ and T2 relaxation times for cartilage in the medial knee, lateral knee, and patellofemoral compartments and medial and lateral menisci were quantified with 3.0-T MRI. A subset of the participants underwent three-dimensional motion capture during walking for calculation of peak knee flexion and adduction moments, flexion and adduction impulses, and peak adduction angle. Differences in MR, radiograph, and gait parameters between men and women were compared in the three groups separately using multivariate analysis of variance., Results: Women had higher lateral articular cartilage T1ρ (men=40.5 [95% confidence interval {CI}, 38.8-42.3] ms; women=43.3 [95% CI, 41.9-44.7] ms; p=0.017) and patellofemoral T1ρ (men=44.4 [95% CI, 42.6-46.3] ms; women=48.4 [95% CI, 46.9-50.0] ms; p=0.002) in the OA group; and higher lateral meniscus T1ρ in the young group (men=15.3 [95% CI, 14.7-16.0] ms; women=16.4 [95% CI, 15.6-17.2] ms; p=0.045). The peak adduction moment in the second half of stance was lower in women in the middle-aged (men=2.05 [95% CI, 1.76-2.34] %BW*Ht; women=1.66 [95% CI, 1.44-1.89] %BW*Ht; p=0.037) and OA (men=2.34 [95% CI, 1.76-2.91] %BW*Ht; women=1.42 [95% CI, 0.89-1.94] %BW*Ht; p=0.022) groups. Static varus from radiographs was lower in women in the middle-aged (men=178° [95% CI, 177°-179°]; women=180° [95% CI, 179°-181°]; p=0.002) and OA (men=176° [95% CI, 175°-178°]; women=180° [95% CI, 179°-181°]; p<0.001) groups. Women had lower varus during walking in all three groups (young: men=4° [95% CI, 3°-6°]; women=2° [95% CI, 0°-3°]; p=0.013; middle-aged: men=2° [95% CI, 1°-3°]; women=0° [95% CI, -1° to 1°]; p=0.015; OA: men=4° [95% CI, 2°-6°]; women=0° [95% CI, -2° to 2°]; p=0.011). Women had a higher knee flexion moment (men=4.24 [95% CI, 3.58-4.91] %BW*Ht; women 5.40 [95% CI, 4.58-6.21] %BW*Ht; p=0.032) in the young group., Conclusions: These data demonstrate differences in cartilage composition and gait mechanics between men and women in young healthy, middle-aged healthy, and OA cohorts. Considering the cross-sectional nature of the study, longitudinal research is needed to investigate if these differences in cartilage composition and walking mechanics are associated with a greater risk of lateral tibiofemoral or patellofemoral OA in women. Future studies should also investigate the relative risk of lateral versus medial patellofemoral cartilage degeneration risk in women compared with men., Level of Evidence: Level III, retrospective study.

Objective: 1) To establish a gender- and BMI-specific reference database of cartilage T2 values, and 2) to assess the associations between cartilage T2 values and gender, age, and BMI in knees without radiographic osteoarthritis or MRI-based (WORMS 0/1) evidence of cartilage degeneration., Design: 481 subjects aged 45-65 years with Kellgren-Lawrence Scores 0/1 in the study knee were selected. Baseline morphologic cartilage 3T MRI readings (WORMS scoring) and T2 measurements (resolution = 0.313 mm × 0.446 mm) were performed in the medial and lateral femurs, medial and lateral tibias, and patella compartments. To create a reference database, a logarithmic transformation was applied to the data to obtain the 5th-95th percentile values for T2., Results: Significant differences in mean cartilage T2 values were observed between joint compartments. Although females had slightly higher T2 values than males in a majority of compartments, the differences were only significant in the medial femur (P < 0.0001). A weak positive association was seen between age and T2 in all compartments, most pronounced in the patella (3.27% increase in median T2/10 years, P = 0.009). Significant associations between BMI and T2 were observed, most pronounced in the lateral tibia (5.33% increase in median T2/5 kg/m(2) increase in BMI, P < 0.0001), and medial tibia (4.81% increase in median T2 /5 kg/m(2) increase in BMI, P < 0.0001)., Conclusions: This study established the first reference database of T2 values in a large sample of morphologically normal cartilage plates in knees without radiographic knee osteoarthritis (OA). While cartilage T2 values were weakly associated with age and gender, they had the highest correlations with BMI., (Copyright © 2015 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Purpose: To assess lesion detection and artifact size reduction of a multiacquisition variable-resonance image combination, slice encoding for metal artifact correction (MAVRIC-SEMAC) hybrid sequence (MAVRIC-SL) compared to standard sequences at 1.5T and 3T in porcine knee specimens with metal hardware., Materials and Methods: Artificial cartilage and bone lesions of defined size were created in the proximity of titanium and steel screws with 2.5 mm diameter in 12 porcine knee specimens and were imaged at 1.5T and 3T magnetic resonance imaging (MRI) with MAVRIC-SL PD and short T1 inversion recovery (STIR), standard fast spin echo (FSE) T2 PD, and STIR and fat-saturated T2 FSE sequences. Three radiologists blinded to the lesion locations assessed lesion detection rates on randomized images for each sequence using receiver operating characteristic (ROC). Artifact length and width were measured., Results: Metal artifact sizes were largest in the presence of steel screws at 3T (FSE T2 FS: 28.7 cm(2) ) and 1.5T (16.03 cm(2) ). MAVRIC-SL PD and STIR reduced artifact sizes at both 3T (1.43 cm(2) ; 2.46 cm(2) ) and 1.5T (1.16 cm(2) ; 1.59 cm(2) ) compared to FS T2 FSE sequences (27.57 cm(2) ; 13.20 cm(2) ). At 3T, ROC-derived AUC values using MAVRIC-SL sequences were significantly higher compared to standard sequences (MAVRIC-PD: 0.87, versus FSE-T2 -FS: 0.73 [P = 0.025]; MAVRIC-STIR: 0.9 vs. T2 -STIR: 0.78 [P = 0.001] and vs. FSE-T2 -FS: 0.73 [P = 0.026]). Similar values were observed at 1.5T. Comparison of 3T and 1.5T showed no significant differences (MAVRIC-SL PD: P = 0.382; MAVRIC-SL STIR: P = 0.071)., Conclusion: MAVRIC-SL sequences provided superior lesion detection and reduced metal artifact size at both 1.5T and 3T compared to conventionally used FSE sequences. No significant disadvantage was found comparing MAVRIC-SL at 3T and 1.5T, although metal artifacts at 3T were larger. J. Magn. Reson. Imaging 2015;41:1291-1299. © 2014 Wiley Periodicals, Inc., (© 2014 Wiley Periodicals, Inc.)

Study Design: Cross-sectional., Objectives: To investigate the association between knee loading- related osteoarthritis (OA) risk factors (obesity, malalignment, and physical activity) and medial knee laminar (superficial and deep) T1rho and T2 relaxation times., Background: The interaction of various modifiable loading-related knee risk factors and cartilage health in knee OA is currently not well known., Methods: Participants with and without knee OA (n = 151) underwent magnetic resonance imaging at 3 T for superficial and deep cartilage T1rho and T2 magnetic resonance relaxation times in the medial femur (MF) and medial tibia (MT). Other variables included radiographic Kellgren-Lawrence (KL) grade, alignment, pain and symptoms using the Knee injury and Osteoarthritis Outcome Score, and physical activity using the International Physical Activity Questionnaire (IPAQ). Individuals with a KL grade of 4 were excluded. Group differences were calculated using 1-way analysis of variance, adjusting for age and body mass index. Linear regression models were created with age, sex, body mass index, alignment, KL grade, and the IPAQ scores to predict the laminar T1rho and T2 times., Results: Total IPAQ scores were the only significant predictors among the loading-related variables for superficial MF T1rho (P = .005), deep MT T1rho (P = .026), and superficial MF T2 (P = .049). Additionally, the KL grade predicted the superficial MF T1rho (P = .023) and deep MT T1rho (P = .022)., Conclusion: Higher physical activity levels and worse radiographic severity of knee OA, but not obesity or alignment, were associated with worse cartilage composition.

Objective: To investigate longitudinal changes in laminar and spatial distribution of knee articular cartilage magnetic resonance imaging (MRI) T1ρ and T2 relaxation times, in individuals with and without medial compartment cartilage defects., Design: All subjects (at baseline n = 88, >18 years old) underwent 3-Tesla knee MRI at baseline and annually thereafter for 3 years. The MR studies were evaluated for presence of cartilage defects (modified Whole-Organ Magnetic Resonance Imaging Scoring - mWORMS), and quantitative T1ρ and T2 relaxation time maps. Subjects were segregated into those with (mWORMS ≥2) and without (mWORMS ≤1) cartilage lesions at the medial tibia (MT) or medial femur (MF) at each time point. Laminar (bone and articular layer) and spatial (gray level co-occurrence matrix - GLCM) distribution of the T1ρ and T2 relaxation time maps were calculated. Linear regression models (cross-sectional) and Generalized Estimating Equations (GEEs) (longitudinal) were used., Results: Global T1ρ, global T2 and articular layer T2 relaxation times at the MF, and global and articular layer T2 relaxation times at the MT, were higher in subjects with cartilage lesions compared to those without lesions. At the MT global T1ρ relaxation times were higher at each time point in subjects with lesions. MT T1ρ and T2 became progressively more heterogeneous than control compartments over the course of the study., Conclusion: Spatial distribution of T1ρ and T2 relaxation time maps in medial knee OA using GLCM technique may be a sensitive indicator of cartilage deterioration, in addition to whole-compartment relaxation time data., (Copyright © 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Objectives: To evaluate bone marrow changes on knee magnetic resonance imaging (MRI) in patients with 3- to 6-week-long period of unloading., Methods: MRI knee examinations were performed in 30 patients (14 men, 16 women; aged 20-53 years) at baseline and 5-10 weeks after immobilisation of the ipsilateral lower extremity; subsets of patients were examined at additional time-points. Ten volunteers (4 men, 6 women; aged 20-50 years) were studied as control cohort at two time-points. Bone marrow signal abnormalities were analysed according to: (1) severity, (2) signal alteration relative to hyaline cartilage, (3) morphology, (4) increased vascularity in the knee joint and (5) T1-signal alteration. Spearman's rank correlation test (SRC) and Kendall's tau (KT) were used to compare individual scores., Results: All 30 patients presented abnormal bone marrow findings after unloading, which reached a peak at 10-25 weeks (P <0.001). These findings decreased within 1 year (P < 0.001). High scores of severity were associated with confluent and patchy patterns of bone marrow (SCR = 0.923, P < 0.001 and KT = 0.877, P <0.001)., Conclusions: Signal abnormalities of the bone marrow related to unloading are consistent findings and most prominent 10-25 weeks following immobilisation when both confluent and patchy hyperintense patterns are present.

Objective: To evaluate the association of baseline frequent knee bending activities with the prevalence and progression of cartilage and meniscal abnormalities over 3 years and to assess the effect of frequent knee bending on the different knee compartments with 3T magnetic resonance imaging (MRI)., Methods: We studied 115 subjects without radiographic knee osteoarthritis (OA) but with risk factors for OA from the Osteoarthritis Initiative database. The inclusion criteria at baseline were age 45-55 years, body mass index of 19-27 kg/m(2) , Western Ontario and McMaster Universities Osteoarthritis Index pain score of 0, and Kellgren/Lawrence grade <2. Knee bending activities (kneeling, squatting, stair climbing, and weight lifting) were assessed by questionnaire at the baseline clinic visit. Cartilage and meniscal abnormalities were graded using the Whole-Organ MRI Score. Logistic regression was used to determine the association of frequent knee bending with cartilage and meniscal abnormalities., Results: Frequent knee bending activities were associated with an increased risk of prevalent cartilage lesions (odds ratio [OR] 3.63, 95% confidence interval [95% CI] 1.39-9.52), in particular in the patellofemoral compartment (OR 3.09, 95% CI 1.22-7.79). The increase in risk was higher in subjects involved in ≥2 knee bending activities. At 3-year followup, individuals reporting frequent knee bending were more likely to show progression of cartilage damage (OR 4.12, 95% CI 1.27-13.36) and meniscal abnormalities (OR 4.34, 95% CI 1.16-16.32)., Conclusion: Frequent knee bending activities were associated with a higher prevalence of knee cartilage lesions (particularly in the patellofemoral compartment) and with an increased risk of progression of cartilage and meniscal lesions in asymptomatic middle-aged subjects., (Copyright © 2013 by the American College of Rheumatology.)

Objective: To better understand the relationship between knee pain and bilateral knee lesions, we compared focal knee lesions in knee pairs of subjects with no, unilateral, and bilateral knee pain, and risk factors for knee osteoarthritis (OA), but no radiographic knee OA., Materials and Methods: We examined both knees of 120 subjects from the Osteoarthritis Initiative database. We randomly selected 60 subjects aged 45-55 years with OA risk factors, no knee pain (WOMAC pain score=0) and no radiographic OA (KL-score ≤1) in both knees. We also selected two comparison groups with OA risk factors and no radiographic OA in both knees, but with knee pain (WOMAC pain score ≥5): 30 subjects with right only knee pain and 30 subjects with bilateral knee pain. All subjects underwent 3T MRI of both knees and focal knee lesions were assessed., Results: Statistically significant associations between prevalence of focal lesions in the right and left knee with odds ratios up to 13.5 were found in all three subject groups. Focal knee lesions were generally not associated with pain in analyses comparing knee pairs of subjects with unilateral knee pain (p>0.05). The prevalence and severity of focal knee lesions were not significantly different in knee pairs of subjects with no knee pain and those with bilateral knee pain (p>0.05)., Conclusion: Focal knee lesions in the right and left knee of subjects with OA risk factors were positively associated with each other independent of knee pain status, and were not statistically significant different between knees in subjects with unilateral knee pain., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Objective: To evaluate whether T(2) and T(1ρ) relaxation times of knee cartilage determined with 3T magnetic resonance imaging (MRI) at baseline predict longitudinal progression of cartilage degenerative changes., Methods: Quantitative analysis of cartilage was performed using 3T MRI with both T(2) and T(1ρ) mapping techniques in 55 subjects without evidence of severe osteoarthritis (OA) [Kellgren-Lawrence (KL) score of 0-3] at baseline. Morphological abnormalities of cartilage, menisci, ligaments and bone marrow were analyzed on sagittal fat-saturated intermediate-weighted fast spin echo (FSE) sequences. Progression of degenerative changes was analyzed over a period of 2 years. Progression was detected in 27 subjects while in 28 subjects no changes were found. Differences between T(2) and T(1ρ) relaxation times in these two cohorts were compared using one-way analysis of variance (ANOVA) and t tests., Results: Baseline T(2) and T(1ρ) values were significantly higher in the progression cohort in all compartments (P < 0.05) except the lateral tibia (LT) for T(2) and the medial tibia (MT) for T(1ρ). Progression of cartilage degenerative disease was most pronounced at the medial femoral condyles and at the femoro-patellar joint; differences between the two cohorts for T(2) and T(1ρ) were also most significant in these compartments., Conclusions: T(2) and T(1ρ) measurements were significantly higher at baseline in individuals that showed progression of cartilage abnormalities over a period of 2 years and may therefore serve as potential predictors for progression of degenerative cartilage abnormalities in knee OA., (Copyright © 2012 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Objective: To analyze knee trabecular bone structure and spatial cartilage T(1ρ) and T(2) relaxation times using 3-T magnetic resonance imaging (MRI) in subjects with and without tears of posterior horn of the medial meniscus (PHMM)., Design: 3-T MRI from 59 subjects (>18 years), were used to evaluate PHMM tears based on modified Whole-Organ Magnetic Resonance Imaging Score (WORMS) scoring; and to calculate apparent trabecular bone-volume over total bone volume fraction (app. BV/TV), apparent trabecular number (app. Tb.N), apparent trabecular separation (app. Tb.Sp) and apparent trabecular thickness (app. Tb.Th) for overall femur/tibia and medial/lateral femur/tibia; and relaxation times for deep and superficial layers of articular cartilage. A repeated measures analysis using Generalized Estimating Equation (GEE) was performed to compare trabecular bone and cartilage relaxation time parameters between people with (n = 35) and without (n = 24) PHMM tears, while adjusting for age and knee OA presence., Results: Subjects with PHMM tears had lower app. BV/TV and app. Tb.N, and greater app. Tb.Th, and app. Tb.Sp. They also had higher T(1ρ) times in the deep cartilage layer for lateral tibia and medial femur and higher T(2) relaxation times for the deep cartilage layer across all compartments., Conclusions: PHMM tears are associated with differences in underlying trabecular bone and deep layer of cartilage. Over-load of subchondral bone can lead to its sclerosis and stress shielding of trabecular bone leading to the resorptive changes observed in this study. The results underline the importance of interactions of trabecular bone and cartilage in the pathogenesis of knee OA in people with PHMM tears., (Copyright © 2012 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Objective: To evaluate the association of magnetic resonance imaging (MRI)-based knee cartilage T2 measurements and focal knee lesions with knee pain in knees without radiographic osteoarthritis (OA) among subjects with OA risk factors., Methods: We studied the right knees of 126 subjects from the Osteoarthritis Initiative database. We randomly selected 42 subjects ages 45-55 years with OA risk factors, right knee pain (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] pain score ≥5), no left knee pain (WOMAC pain score 0), and no radiographic OA (Kellgren/Lawrence [K/L] score ≤1) in the right knee. We also selected 2 comparison groups: 42 subjects without knee pain in either knee and 42 with bilateral knee pain. Both groups were frequency matched to subjects with right knee pain only by sex, age, body mass index, and K/L score. All of the subjects underwent 3T MRI of the right knee. Focal knee lesions were assessed and cartilage T2 measurements were performed., Results: Prevalences of meniscal, bone marrow, and ligamentous lesions and joint effusion were not significantly different between the groups (P > 0.05), while cartilage lesions were more frequent in subjects with right knee pain only compared to subjects without knee pain (P < 0.05). T2 values averaged over all of the compartments were similar in subjects with right knee pain only (mean ± SD 34.4 ± 1.8 msec) and in subjects with bilateral knee pain (mean ± SD 34.7 ± 4.7 msec), but were significantly higher compared to subjects without knee pain (mean ± SD 32.4 ± 1.8 msec; P < 0.05)., Conclusion: These results suggest that elevated cartilage T2 values are associated with findings of pain in the early phase of OA, whereas among morphologic knee abnormalities only knee cartilage lesions are significantly associated with knee pain status., (Copyright © 2012 by the American College of Rheumatology.)

ObjectiveThis study aimed to investigate the associations between patellofemoral cartilage T1ρ and T2 relaxation times and knee flexion moment (KFM) and KFM impulse during gait.MethodKnee magnetic resonance (MR) images were obtained from 99 subjects with and without patellofemoral joint (PFJ) osteoarthritis (OA), using fast spin-echo, T1ρ and T2 relaxation time sequences. Patellar and trochlear cartilage relaxation times were computed for the whole cartilage, and superficial and deep layers (laminar analysis). Subjects also underwent three-dimensional (3D) gait analysis. Peak KFM and KFM impulse were calculated during the stance phase. Linear regressions were used to examine whether cartilage relaxation times were associated with knee kinetics during walking while adjusting age, sex, body mass index (BMI) and walking speed.ResultsHigher peak KFM and KFM impulse were significantly related to higher T1ρ and T2 relaxation times of the trochlear and patellar cartilage, with standardized regression coefficients ranging from 0.21 to 0.28. Laminar analysis showed that overall the superficial layer of patellofemoral cartilage showed stronger associations with knee kinetics. Subgroup analysis revealed that in subjects with PFJ OA, every standard deviation change in knee kinetics was related to greater increases in PFJ cartilage T1ρ and T2 (standardized coefficients: 0.29 to 0.41). Conversely, in subjects without OA, weaker relationships were observed between knee kinetics and PFJ cartilage T1ρ and T2.ConclusionsOur findings suggest that increased peak KFM and KFM impulse were related to worse cartilage health at the PFJ. This association is more prominent in superficial layer cartilage and cartilage with morphological lesions.

ObjectiveTo evaluate the association of prevalent unilateral total hip arthroplasty (THA) with worsening of degenerative knee abnormalities and clinical outcomes in the ipsilateral and contralateral knee.MethodsBoth knees of 30 individuals in the Osteoarthritis Initiative (OAI) with unilateral THA (n = 14 left, n = 16 right) at baseline were assessed at baseline and at 4-year follow-up for Whole-organ MR Imaging Scores (WORMS), cartilage T2 relaxation times (only available for right knees), Western Ontario and McMasters Universities Arthritis Index (WOMAC) scores and upper leg isometric strength. Right knees of 30 individuals without THA were analyzed as controls. Contralateral knees were compared to ipsilateral knees with paired t-tests and to control knees with multivariate regression analysis adjusting for covariates.ResultsIn paired analyses, compared to ipsilateral knees, contralateral knees had higher WORMS total (P = 0.008) and cartilage scores (P = 0.007) at baseline. Over 4 years contralateral knees worsened more on WORMS total score (P = 0.008). Cartilage T2 values were higher in knees contralateral to the THA (baseline, P = 0.02; follow-up, P

ObjectiveTo determine the effect of weight gain on progression of early knee morphologic abnormalities using magnetic resonance imaging (MRI) in a longitudinal study over 48 months.DesignWe studied the right knee of 100 subjects from the Osteoarthritis Initiative (OAI), selecting subjects aged ≥ 45 with osteoarthritis (OA) risk factors who demonstrated weight gain (minimum 5% increase in body mass index, BMI, n = 50) or no change in weight (BMI change < 2%, n = 50), frequency matched for age, gender, and baseline BMI. Baseline and 48 month knee MRI studies were scored for lesions using a modified whole organ MRI score (WORMS). Logistic regression models were used to compare the differences between the two groups.ResultsThe odds of worsening maximum cartilage (11.3, 95%, CI 3.5-51.4) and meniscal WORMS (4.5, 95% CI 1.4-17.3) were significantly greater in the weight gain group compared to the no change group, in addition to the odds of worsening cartilage defects at the patella and average meniscal WORMS (P < 0.05). Odds of worsening average bone marrow edema pattern (BMEP) were significantly greater for the weight gain group compared to the no change cohort (P < 0.05).ConclusionOur study demonstrated that weight gain is strongly associated with increased progression of cartilage degeneration in middle-aged individuals with risk factors for OA.