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Many persons with knee pain have joint pain outside the knee, but despite the impact and high frequency of this pain, its distribution and causes have not been studied. We undertook this study to test the hypothesis of those studying gait abnormalities who have suggested that knee pain causes pain in adjacent joints but that pain adaptation strategies are highly individualized.We studied persons ages 50-79 years with or at high risk of knee osteoarthritis who were recruited from 2 community-based cohorts, the Multicenter Osteoarthritis Study and the Osteoarthritis Initiative, and we followed them up for 5-7 years. We excluded those with knee pain at baseline and compared those who had developed knee pain at the first follow-up examination (the index visit) with those who had not. We examined pain on most days at joint regions outside the knee in examinations after the index visit. Logistic regression analyses examined the risk of joint-specific pain adjusted for age, sex, body mass index, and symptoms of depression, and we performed sensitivity analyses excluding those with widespread pain.In the combined cohorts, 693 persons had knee pain at the index visit and 2,793 did not. A total of 79.6% of those with bilateral knee pain and 63.8% of those with unilateral knee pain had pain during follow-up in a joint region outside the knee, compared with 49.9% of those without knee pain. There was an increased risk of pain at most extremity joint sites, without a predilection for specific sites. Results were unchanged when those with widespread pain were excluded.Persons with chronic knee pain are at increased risk of pain in multiple joints in no specific pattern.

Investigate the relationship between sedentary behavior and physical function in adults with knee osteoarthritis (OA), controlling for moderate-vigorous physical activity (MVPA) levels.Sedentary behavior was objectively measured by accelerometer on 1,168 participants ages 49-83 years in the Osteoarthritis Initiative with radiographic knee OA at the 48-month clinic visit. Physical function was assessed using 20-meter walk and chair stand testing. Sedentary behavior was identified by accelerometer activity counts/minute100. The cross-sectional association between sedentary quartiles and physical function was examined by multiple linear regression, adjusting for demographic factors (age, sex, race/ethnicity, education level), health factors (comorbidity, body mass index, knee pain, knee OA severity, presence of knee symptoms), and average daily MVPA minutes.Adults with knee OA spent two-thirds of their daily time in sedentary behavior. The average gait speed among the most sedentary quartile was 3.88 feet/second, which was significantly slower than the speed of the less sedentary groups (4.23, 4.33, and 4.33 feet/second, respectively). The average chair stand rate among the most sedentary group was significantly lower (25.9 stands/minute) than the rates of the less sedentary behavior groups (28.9, 29.1, and 31.1 stands/minute, respectively). These trends remained significant in multivariable analyses adjusted for demographic factors, health factors, and average daily MVPA minutes.Being less sedentary was related to better physical function in adults with knee OA independent of MVPA time. These findings support guidelines to encourage adults with knee OA to decrease time spent in sedentary behavior in order to improve physical function.

To determine whether thigh muscle strength differs between symptomatic and asymptomatic knees, and/or different radiographic strata of knee osteoarthritis (KOA).Isometric extensor and flexor strength were analyzed in 3,809 Osteoarthritis Initiative participants (2,201 women and 1,608 men) with central radiographic Kellgren/Lawrence (K/L) grade readings. Isometric strength measurements were stratified by radiographic disease status (K/L grades 0, 1, 2, and 3/4) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scores. Age-adjusted, separate-slopes analysis of covariance models was used to compare strength between "symptomatic" (WOMAC score range 5-20) and "asymptomatic" (WOMAC score = 0) legs within and across K/L grade strata. Exploratory analyses focused on strength normalized to body weight and symptom frequency.Isometric strength was significantly lower in symptomatic than in asymptomatic legs: -11 to -13% for extensor strength and -7 to -16% for flexor strength (P0.0001 for both) in men, and -9 to -17% (P = 0.029) for extensor strength, and -10 to -21% (P = 0.049) for flexor strength in women. Similar observations were made for pain frequency strata. Extensor and flexor strength were not significantly different across K/L grade strata in asymptomatic legs in either sex (P ≥ 0.12). However, strength normalized to body weight was lower at higher K/L grades in both sexes (P ≤ 0.02) because the body mass index was greater in participants with more advanced radiographic disease.Knee symptoms (i.e., pain) appear to be the relevant determinant of isometric knee extensor and flexor strength in KOA, whereas no direct association between strength and radiographic severity was observed. These findings suggest that the reduction in thigh muscle strength in KOA is related to pain but not to the structural (radiographic) disease status.

Objective: To test the hypothesis that cartilage displays significant longitudinal thickening in the external subregions of the central medial (ecMF) and lateral (ecLF) femur in knees with early radiographic osteoarthritis (ROA) compared with contralateral knees without ROA, and to explore differences in change in other subregions and in radiographic joint space width (JSW). Methods: 50 participants (50% women; age 61.1±9.7y; BMI 27.7±4.7kg/m2 ) were identified from the Osteoarthritis Initiative cohort with definite femorotibial osteophytes but no JSN in one knee (early ROA), and no osteophytes or JSN in the contralateral knee (non-ROA). A longitudinal within-person, between-knee comparison was performed using measures of subregional cartilage thickness based on analyses of sagittal DESSwe MR images obtained at baseline and 1-year. Medial JSW was evaluated from fixed flexion radiographs. Results: The change between baseline and 1-year was -6±94µm in ecMF and +18±91µm in ecLF in early ROA (p=0.78) vs. -1±68µm and +4±76µm in non-ROA knees (p=0.38). The variability of cartilage thickness change tended to be greater in early ROA than in non-ROA knees. Greater cartilage thickness loss in the lateral tibia and a greater reduction in minimum medial JSW was observed in early ROA vs. non-ROA knees. Conclusion: There was no direct evidence of longitudinal cartilage thickening in external subregions of the central femur in knees with early ROA compared with contralateral non-ROA knees. The observed greater variability in longitudinal thickness change in early ROA knees (but not in non-ROA knees) might be due to cartilage thickening and thinning occurring simultaneously in these knees.

Introduction The aim was to investigate the relationship of cartilage loss (change in medial femorotibial cartilage thickness measured with magnetic resonance imaging (MRI)) with compartment-specific baseline radiographic findings and MRI cartilage morphometry features, and to identify which baseline features can be used for stratification of fast progressors. Methods An age and gender stratified subsample of the osteoarthritis (OA) initiative progression subcohort (79 women; 77 men; age 60.9 ± 9.9 years; body mass index (BMI) 30.3 ± 4.7) with symptomatic, radiographic OA in at least one knee was studied. Baseline fixed flexion radiographs were read centrally and adjudicated, and cartilage morphometry was performed at baseline and at one year follow-up from coronal FLASH 3 Tesla MR images of the right knee. Results Osteophyte status at baseline was not associated with medial cartilage loss. Knees with medial joint space narrowing tended to show higher rates of change than those without, but the relationship was not statistically significant. Knees with medial femoral subchondral bone sclerosis (radiography), medial denuded subchondral bone areas (MRI), and low cartilage thickness (MRI) at baseline displayed significantly higher cartilage loss than those without, both with and without adjusting for age, sex, and BMI. Participants with denuded subchondral bone showed a standardized response mean of up to -0.64 versus -0.33 for the entire subcohort. Conclusions The results indicate that radiographic and MRI cartilage morphometry features suggestive of advanced disease appear to be associated with greater cartilage loss. These features may be suited for selecting patients with a higher likelihood of fast progression in studies that attempt to demonstrate the cartilage-preserving effect of disease-modifying osteoarthritis drugs.