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We studied whether contact stress estimates from knee magnetic resonance images (MRI) predict the development of incident symptomatic tibiofemoral osteoarthritis (OA) 15 months later in an at-risk cohort. This nested case-control study was conducted within a cohort of 3,026 adults, age 50 to 79 years. Thirty cases with incident symptomatic tibiofemoral OA by their 15 month follow-up visit were randomly selected and matched with 30 control subjects. Symptomatic tibiofemoral OA was defined as daily knee pain/stiffness and Kellgren-Lawrence Grade > or =2 on weight bearing, fixed-flexion radiographs. Tibiofemoral geometry was segmented on baseline knee MRI, and contact stresses were estimated using discrete element analysis. Linear mixed models for repeated measures were used to examine the association between articular contact stress and case/control status. No significant intergroup differences were found for age, sex, BMI, weight, height, or limb alignment. However, the maximum articular contact stress was 0.54 +/- 0.77 MPa (mean +/- SD) higher in incident OA cases compared to that in control knees (p = 0.0007). The interaction between case-control status and contact stress was significant above 3.20 MPa (p < 0.0001). The presence of differences in estimated contact stress 15 months prior to incidence suggests a biomechanical mechanism for symptomatic tibiofemoral OA and supports the ability to identify risk by subject-specific biomechanical modeling.

ObjectiveThe lack of strong association between knee osteoarthritis (OA) structural features and pain continues to perplex researchers and clinicians. Evaluating the patellofemoral joint in addition to the tibiofemoral joint alone has contributed to explaining this structure-pain discordance, hence justifying a more comprehensive evaluation of whole-knee OA and pain. The present study, therefore, was undertaken to evaluate the association between patellofemoral and tibiofemoral OA features with localized anterior knee pain (AKP) using 2 study designs.MethodsUsing cross-sectional data from the Multicenter Osteoarthritis Study, our first approach was a within-person, knee-matched design in which we identified participants with unilateral AKP. We then assessed magnetic resonance imaging (MRI)-derived OA features (cartilage damage, bone marrow lesions [BMLs], osteophytes, and inflammation) in both knees and evaluated the association of patellofemoral and tibiofemoral OA features to unilateral AKP. In our second approach, MRIs from 1 knee per person were scored, and we evaluated the association of OA features to AKP in participants with AKP and participants with no frequent knee pain.ResultsUsing the first approach (n = 71, 66% women, mean ± SD age 69 ± 8 years), lateral patellofemoral osteophytes (odds ratio [OR] 5.0 [95% confidence interval (95% CI) 1.7-14.6]), whole-knee joint effusion-synovitis (OR 4.7 [95% CI 1.3-16.2]), and infrapatellar synovitis (OR 2.8 [95% CI 1.0-7.8]) were associated with AKP. Using the second approach (n = 882, 59% women, mean ± SD age 69 ± 7 years), lateral and medial patellofemoral cartilage damage (prevalence ratio [PR] 2.3 [95% CI 1.3-4.0] and PR 1.9 [95% CI 1.1-3.3], respectively) and lateral patellofemoral BMLs (PR 2.6 [95% CI 1.5-4.7]) were associated with AKP.ConclusionPatellofemoral but not tibiofemoral joint OA features and inflammation were associated with AKP.

ObjectiveDetermine the relation of symptomatic and structural features of patellofemoral osteoarthritis (PFOA) to psychological characteristics and measures of pain sensitization, in older adults with or at risk of knee osteoarthritis (OA).MethodsThis study included 1112 participants from the Multicenter Osteoarthritis Study (713 females, mean age 66.8 ± SD 7.6 yrs, body mass index 29.5 ± 4.8 kg/m2). Participants were grouped based on the presence of PFOA symptoms (anterior knee pain and pain on stairs) and magnetic resonance imaging (MRI) PFOA (full-thickness cartilage lesion with bone marrow lesion): (1) patellofemoral (PF) symptoms with MRI PFOA; (2) PF symptoms without MRI PFOA; (3) MRI PFOA without PF symptoms; and (4) no PF symptoms or MRI PFOA (no PFOA). Relation of PFOA classification to depressive symptoms, catastrophizing, temporal summation (TS) and pressure pain thresholds (PPT) was evaluated using logistic (categorical variables) and linear regression (continuous variables).ResultsCompared with no PFOA, those with PF symptoms with or without MRI PFOA had significantly greater odds of depressive symptoms, catastrophizing, and patellar TS (OR range 1.5-2.01), and those with PF symptoms without MRI PFOA had significantly greater odds of wrist TS (OR 1.66). Males with PF symptoms without MRI PFOA had significantly lower pressure PPT at the patella compared with no PFOA and those with MRI PFOA only (no symptoms). There were no significant differences at the wrist for males, or the patella or wrist for females.ConclusionPersons with PFOA symptoms, regardless of MRI PFOA status, are more likely to demonstrate depressive symptoms, catastrophizing, and TS. Males with PFOA symptoms without MRI PFOA demonstrate local hyperalgesia.

AimThe aim of the study was to identify sociodemographic, disease-related, physical and mental health-related determinants of fatigue at 2-year follow-up in individuals with symptomatic knee osteoarthritis (OA).MethodsA longitudinal analysis of participants with symptomatic knee OA from the Multicenter Osteoarthritis Study (MOST) was conducted to identify predictors of fatigue at 2-year follow-up. Participants self-reported fatigue at baseline for the first time in the MOST cohort and at follow-up using a 0-10 visual analog scale. At baseline, questionnaires on sociodemographics, disease-related symptoms, physical and mental health factors were completed. Data were analyzed using linear regressions with a backwards elimination approach.ResultsOf the 2330 individuals in the MOST cohort at baseline, 576 had symptomatic knee OA and of these, 449 with complete fatigue values at baseline and follow-up were included in this analysis. Minimally important fatigue change (ie, worsening [≥1.13], no change [

Purpose To determine the relationship of patellofemoral joint alignment and trochlear morphology to superolateral Hoffa fat pad (SHFP) edema on magnetic resonance (MR) images in older adults with or at risk for osteoarthritis of the knee. Materials and Methods Institutional review board approval and written informed consent were obtained from all subjects. The Multicenter Osteoarthritis Study is a prospective cohort study of older adults with or at risk for osteoarthritis of the knee. Subjects were recruited from Birmingham, Alabama, and Iowa City, Iowa. In this cross-sectional study, patellofemoral joint alignment (bisect offset, patellar tilt angle, and Insall-Salvati ratio), trochlear morphology (sulcus angle, lateral and medial trochlear inclination, and trochlear angle) and SHFP edema were assessed on MR images of the knee. Measures of alignment and morphology were divided into quartiles, and SHFP was determined to be present or absent. Separate logistic regression models were used to determine the relationship of each measure of alignment and morphology to the presence of SHFP edema, with adjustments for age, sex, and body mass index. Results SHFP edema was present in 152 (13.4%) of the 1134 knees that were included. When compared with knees with measurements in the lowest quartile, knees with measurements in the highest quartile for trochlear angle, bisect offset, and Insall-Salvati ratios were 1.6 (95% confidence interval [CI]: 1.0, 2.6), 2.3 (95% CI: 1.3, 4.0), and 8.9 (95% CI: 4.7, 16.9) times more likely to show SHFP edema, respectively. No relationship was found between other measures and SHFP edema. Conclusion A more anterior trochlear facet, a more laterally displaced patella, and knees with patella alta were significantly associated with SHFP edema on MR images in subjects with or at risk for osteoarthritis of the knee. © RSNA, 2017.

The objective of this project was to determine the relationship between medial tibiofemoral joint space width measured on fixed-flexion radiographs and the three-dimensional joint space width distribution on low-dose, standing CT (SCT) imaging. At the 84-month visit of the Multicenter Osteoarthritis Study, 20 participants were recruited. A commercial SCT scanner for the foot and ankle was modified to image knees while standing. Medial tibiofemoral joint space width was assessed on radiographs at fixed locations from 15% to 30% of compartment width using validated software and on SCT by mapping the distances between three-dimensional subchondral bone surfaces. Individual joint space width values from radiographs were compared with three-dimensional joint space width values from corresponding sagittal plane locations using paired t-tests and correlation coefficients. For the four medial-most tibiofemoral locations, radiographic joint space width values exceeded the minimal joint space width on SCT by a mean of 2.0 mm and were approximately equal to the 61st percentile value of the joint space width distribution at each respective sagittal-plane location. Correlation coefficients at these locations were 0.91-0.97 and the offsets between joint space width values from radiographs and SCT measurements were consistent. There were greater offsets and variability in the offsets between modalities closer to the tibial spine. Joint space width measurements on fixed-flexion radiographs are highly correlated with three-dimensional joint space width from SCT. In addition to avoiding bony overlap obscuring the joint, a limitation of radiographs, the current study supports a role for SCT in the evaluation of tibiofemoral OA. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1388-1395, 2017.

ObjectiveTo determine the diagnostic performance of standing computerized tomography (SCT) of the knee for osteophytes and subchondral cysts compared with fixed-flexion radiography, using MRI as the reference standard.MethodsTwenty participants were recruited from the Multicenter Osteoarthritis Study. Participants' knees were imaged with SCT while standing in a knee-positioning frame, and with postero-anterior fixed-flexion radiography and 1T MRI. Medial and lateral marginal osteophytes and subchondral cysts were scored on bilateral radiographs and coronal SCT images using the OARSI grading system and on coronal MRI using Whole Organ MRI Scoring. Imaging modalities were read separately with images in random order. Sensitivity, specificity and accuracy for the detection of lesions were calculated and differences between modalities were tested using McNemar's test.ResultsParticipants' mean age was 66.8 years, body mass index was 29.6 kg/m(2) and 50% were women. Of the 160 surfaces (medial and lateral femur and tibia for 40 knees), MRI revealed 84 osteophytes and 10 subchondral cysts. In comparison with osteophytes and subchondral cysts detected by MRI, SCT was significantly more sensitive (93 and 100%; p < 0.004) and accurate (95 and 99%; p < 0.001 for osteophytes) than plain radiographs (sensitivity 60 and 10% and accuracy 79 and 94%, respectively). For osteophytes, differences in sensitivity and accuracy were greatest at the medial femur (p = 0.002).ConclusionsIn comparison with MRI, SCT imaging was more sensitive and accurate for detection of osteophytes and subchondral cysts than conventional fixed-flexion radiography. Additional study is warranted to assess diagnostic performance of SCT measures of joint space width, progression of OA features and the patellofemoral joint.

PurposeTo assess the association of meniscal root tear with the development or worsening of tibiofemoral cartilage damage.Materials and methodsInstitutional review board approval and written informed consent from all subjects were obtained. A total of 596 knees with radiographically depicted osteoarthritis were randomly selected from the Multicenter Osteoarthritis study cohort. Cartilage damage was semiquantitatively assessed by using the Whole-Organ Magnetic Resonance Imaging Score (WORMS) system (grades 0-6). Subjects were separated into three groups: root tear only, meniscal tear without root tear, and neither meniscal nor root tear. A log-binomial regression model was used to calculate the relative risks for knees to develop incident or progressing cartilage damage in the root tear group and the meniscal tear group, with the no tear group serving as a reference.ResultsIn the medial tibiofemoral joint, there were 37 knees with isolated medial posterior root tear, 294 with meniscal tear without root tear, and 264 without meniscal or root tear. There were only two lateral posterior root tears, and no anterior root tears were found. Thus, the focus was on the medial posterior root tear. The frequency of severe cartilage damage (WORMS ≥ 5) was higher in the group with root tear than in the group without root or meniscal tear (76.7% vs 19.7%, P < .0001) but not in the group with meniscal but no root tear (76.7% vs 65.2%, P = .055). Longitudinal analyses included 33 knees with isolated medial posterior root tear, 270 with meniscal tear, and 245 with no tear. Adjusted relative risk of cartilage loss was 2.03 (95% confidence interval [CI]: 1.18, 3.48) for the root tear group and 1.84 (95% CI: 1.32, 2.58) for the meniscal tear group.ConclusionIsolated medial posterior meniscal root tear is associated with incident and progressive medial tibiofemoral cartilage loss.

The Multicenter Osteoarthritis Study (MOST) is a longitudinal observational study of the effects of biomechanical, bone and joint structural, and nutritional factors on the incidence and progression of knee symptoms and radiographic and symptomatic knee osteoarthritis (OA). It is the first large-scale epidemiologic study to focus on symptomatic knee OA in a community-based sample of adultswith or at high risk for knee OA, based on thepresence of knee symptoms, history of knee injury or surgery or being overweight. Beginning in 2003, 3026 individuals (60.1% women) age 50-79 years were enrolled. Examinations at baseline, and 15, 30, 60, 72 and 84 months later included assessment of risk factors, disease characteristics, body functions and structure, and measures of physical activity and participation. The wealth of data from this longitudinal cohort of community-dwelling older adults affords valuable opportunities for rehabilitation researchers.

PurposeTo assess the associations of meniscal tears, knee mal-alignment, cartilage damage, knee effusion, and body mass index with meniscal extrusion.Materials and methodsThe Multicenter Osteoarthritis study is an observational study of individuals who have or are at risk for knee osteoarthritis (OA). The HIPAA-compliant protocol was approved by the institutional review boards of all participating centers, and written informed consent was obtained from all patients. All subjects with available baseline knee radiographs and magnetic resonance (MR) images were included. MR imaging assessment of meniscal morphologic characteristics, meniscal position, and cartilage morphologic characteristics with use of the Whole-Organ Magnetic Resonance Imaging Score system was performed by two musculoskeletal radiologists. Cross-sectional associations of severity of meniscal tears, knee malalignment, tibiofemoral cartilage damage, knee effusion, and body mass index with meniscal extrusion were assessed by using logistic regression, with multiadjustments when testing each predictor.ResultsA total of 1527 subjects (2131 knees; 2116 medial and 2106 lateral menisci) were included. Medially, meniscal tears, varus malalignment, and cartilage damage were associated with meniscal extrusion, with odds ratios (ORs) of 6.3 (95% confidence interval [CI]: 5.0, 8.0), 1.3 (95% CI: 1.1, 1.7), and 1.8 (95% CI: 1.4, 2.2), respectively. Laterally, meniscal tears, valgus malalignment, and cartilage damage were associated with meniscal extrusion, with ORs of 10.3 (95% CI: 7.1, 14.9), 2.2 (95% CI: 1.5, 3.2), and 2.0 (95% CI: 1.3, 2.9), respectively.ConclusionMeniscal tears are not the only factors associated with meniscal extrusion; other factors include knee malalignment and cartilage damage. Meniscal extrusion is probably an effect of the complex interactions among joint tissues and mechanical stresses involved in the OA process.

Abstract: Objective: To determine which lower limb strength and joint kinetic and kinematic parameters distinguish sit-to-stand (STS) performance of older adults with symptomatic knee osteoarthritis (OA) with higher and lower chair stand time. Design: Cross-sectional. Setting: Motion analysis laboratory. Participants: Individuals (N=49; 26 men, 23 women) aged 50 to 79 years (mean ± SD age, 64.7±8.1y) with radiographic knee OA and daily symptoms, stratified by chair stand times. Interventions: Not applicable. Main Outcome Measures: Lower limb strength and STS strategy. Results: The chair stand times (mean ± SD) in the high-, moderate-, and low-functioning groups in men were 6.5±0.7, 8.6±0.7, and 11.5±1.3 seconds, respectively, and in women were 7.6±1.2, 10.0±0.5, and 12.8±1.8 seconds, respectively. Chair stand time (P=.0391) and all measures of lower limb strength (all P<.0001) differed by sex. In men, no strength measure differed between groups, whereas in women hip abductor strength on the more affected side differed between groups. In men, sagittal hip range of motion (ROM) (P=.0122) differed between groups, and there was a trend toward a difference in sagittal knee power (P=.0501) during STS, while in women only sagittal knee ROM (P=.0392) differed between groups. Conclusions: Higher- and lower-functioning adults with symptomatic knee OA appear to use different strategies when standing from a chair. Higher-functioning men flexed more at the hip and produced greater knee power than lower-functioning men. Higher-functioning women used less knee flexion than lower-functioning women. Since STS is an important mobility task, these parameters may serve as foci for rehabilitation aimed at reducing mobility limitations. [Copyright &y& Elsevier]

Abstract: Segal NA, Yack HJ, Brubaker M, Torner JC, Wallace R. Association of dynamic joint power with functional limitations in older adults with symptomatic knee osteoarthritis. Objectives: To determine which lower-limb joint moments and powers characterize the level of gait performance of older adults with symptomatic knee osteoarthritis (OA). Design: Cross-sectional observational study. Setting: University motion analysis laboratory. Participants: Community-dwelling adults (N=60; 27 men, 33 women; age 50–79y) with symptomatic knee OA. Interventions: Not applicable. Main Outcome Measures: Physical function was measured using the long-distance corridor walk, the Short Physical Performance Battery, and the Late Life Function and Disability Instrument (LLFDI Function). Joint moments and power were estimated using an inverse dynamics solution after 3-dimensional computerized motion analysis. Results: Subjects aged 64.2±7.4 years were recruited. Ranges (mean ± SD) for the 400-m walk time and the LLFDI Advanced Lower-Limb Function score were 215.3 to 536.8 (304.1±62.3) seconds and 31.5 to 100 (57.0±14.9) points, respectively. In women, hip abductor moment (loading response), hip abductor power (midstance), eccentric hamstring moment (terminal stance), and power (terminal swing) accounted for 41%, 31%, 14%, and 48% of the variance in the 400-m walk time, respectively (model R 2=.61, P<.003). In men, plantar flexor and hip flexor power (preswing) accounted for 19% and 24% of the variance in the 400-m walk time, respectively (model R 2=.32, P=.025). Conclusions: There is evidence that men and women with higher mobility function tend to rely more on an ankle strategy rather than a hip strategy for gait. In higher functioning men, higher knee extensor and flexor strength may contribute to an ankle strategy, whereas hip abductor weakness may bias women with lower mobility function to minimize loading across the knee via use of a hip strategy. These parameters may serve as foci for rehabilitation interventions aimed at reducing mobility limitations. [Copyright &y& Elsevier]

Objective: Knee extensor weakness has not been associated consistently with the risk for incident knee pain. Additionally, the balance of hamstring-to-quadriceps strength (H:Q ratio) may affect risk and has not been studied. The authors determined whether knee extensor weakness or muscle imbalance is a risk factor for development of frequent knee pain or stiffness and whether the effect is modified by lower limb alignment.Design: Observational study.Setting: Community.Participants: Community-dwelling adults ages 50-79 years with or at risk of knee osteoarthritis based on obesity, knee injury, or surgery. A total of 1269 knees from women and 1006 knees from men without frequent knee symptoms at baseline and with 15- or 30- month follow-up outcome data were included.Assessment Of Risk Factors: Isokinetic knee extensor and flexor strength as well as radiographic hip-knee-ankle alignment were measured at baseline. H:Q ratio was dichotomized, with normal being considered to be >/=0.6.Main Outcome Measurements: Frequent knee symptoms at 15- or 30-month follow-up (frequent knee pain, aching, or stiffness on most days of the past month reported at both telephone contact just before and at visit).Results: Mean +/- SD age was 62.2 +/- 8.0 years and mean body mass index (BMI) was 30.1 +/- 5.4 kg/m(2). Mean peak knee extensor strength (KES) was 132.6 +/- 42.4 and 76.9 +/- 25.3 N.m in men and women, respectively. Approximately 50% of knees in men and 59% of knees in women had an H:Q ratio <0.6. A total of 307 of 2275 eligible knees developed frequent knee symptoms at follow-up. Logistic regression controlling for age, BMI, femoral neck bone mineral density, activity score, and baseline Kellgren Lawrence grade revealed that neither KES nor H:Q ratio predicted the development of knee symptoms in gender-stratified or combined analyses. These results were unaffected by adjusting for lower limb alignment.Conclusions: Neither concentric quadriceps strength nor H:Q ratios predicted the development of frequent knee symptoms at 15- or 30-month follow-up in this cohort. [ABSTRACT FROM AUTHOR]