Hip muscle strength and protection against structural worsening and poor function and disability outcomes in knee osteoarthritis.

OBJECTIVE: Examine associations of hip abductor strength with (1) cartilage damage worsening in the tibiofemoral and patellofemoral compartments 2 years later, and (2) poor function and disability outcomes 5 years later. METHODS: Participants had knee osteoarthritis (K/L ≥ 2) in at least one knee. Hip abductor strength was measured using Biodex Dynamometry. Participants underwent 3.0T MRI of both knees at baseline and 2 years later. Baseline-to-2-year cartilage damage progression, defined as any worsening of WORMS cartilage damage score, was assessed at each tibiofemoral and patellofemoral surface. LLFDI (Late-Life Function and Disability Instrument) and Chair-Stand-Rate were recorded at baseline and 5-year follow-up; outcomes analyzed using quintiles. Poor outcomes were defined as remaining in the same low-function quintiles or being in a worse quintile at 5-year follow-up. We analyzed associations of baseline hip abductor strength with cartilage damage worsening and function and disability outcomes using multivariable log-binomial models. RESULTS: 275 knees from 164 persons [age = 63.7 (SD = 9.8) years, 79.3% women] comprised the structural outcome sample, and 187 persons [age = 64.2 (9.7), 78.6% women] the function and disability outcomes sample. Greater baseline hip abductor strength was associated with reduced risks of baseline-to-2-year medial patellofemoral and lateral tibiofemoral cartilage damage worsening [adjusted relative risks (RRs) range: 0.80-0.83) and with reduced risks of baseline-to-5-year poor outcomes for Chair-Stand-Rate and LLFDI Basic Lower-Extremity Function and Disability Limitation (adjusted RRs range: 0.91-0.94). CONCLUSION: Findings support a beneficial role of hip abductor strength for disease modification and for function and disability outcomes, and as a potential therapeutic target in managing knee osteoarthritis.

Association of baseline knee sagittal dynamic joint stiffness during gait and 2-year patellofemoral cartilage damage worsening in knee osteoarthritis.

OBJECTIVE: Knee sagittal dynamic joint stiffness (DJS) describes the biomechanical interaction between change in external knee flexion moment and flexion angular excursion during gait. In theory, greater DJS may particularly stress the patellofemoral (PF) compartment and thereby contribute to PF osteoarthritis (OA) worsening. We hypothesized that greater baseline knee sagittal DJS is associated with PF cartilage damage worsening 2 years later. METHODS: Participants all had OA in at least one knee. Knee kinematics and kinetics during gait were recorded using motion capture systems and force plates. Knee sagittal DJS was computed as the slope of the linear regression line for knee flexion moments vs angles during the loading response phase. Knee magnetic resonance imaging (MRI) scans were obtained at baseline and 2 years later. We assessed the association between baseline DJS and baseline-to-2-year PF cartilage damage worsening using logistic regression with generalized estimating equations (GEE). RESULTS: Our sample had 391 knees (204 persons): mean age 64.2 years (SD 10.0); body mass index (BMI) 28.4 kg/m2 (5.7); 76.5% women. Baseline knee sagittal DJS was associated with baseline-to-2-year cartilage damage worsening in the lateral (OR = 5.35, 95% CI: 2.37-12.05) and any PF (OR = 2.99, 95% CI: 1.27-7.04) compartment. Individual components of baseline DJS (i.e., change in knee moment or angle) were not associated with subsequent PF disease worsening. CONCLUSION: Capturing the concomitant effect of knee kinetics and kinematics during gait, knee sagittal DJS is a potentially modifiable risk factor for PF disease worsening.

Knee tissue lesions and prediction of incident knee osteoarthritis over 7 years in a cohort of persons at higher risk.

OBJECTIVE: Among high risk individuals, whether knee lesions in tissues involved in osteoarthritis (OA) can improve prediction of knee OA is unclear. We hypothesized that models predicting (1) incident osteophytes and (2) incident osteophytes and joint space narrowing can be improved by including symptoms or function, and further improved by lesion status. DESIGN: In Osteoarthritis Initiative (OAI) participants with normal knee X-rays, we assessed cartilage damage, bone marrow lesions (BMLs), and menisci. Cox proportional hazards models were used to develop risk prediction models for risk of each outcome. Nested models (increasingly larger baseline covariable sets) were compared using likelihood ratio tests and Schwarz Bayesian Information Criterion (SBC). Model discrimination used receiver operating characteristic (ROC) curves and area under the curve (AUC). RESULTS: In 841 participants [age 59.6, body mass index (BMI) 26.7, 55.9% women] over up to 7 years follow-up, each larger set improved prediction (+hand OA, injury, surgery, activities; +symptoms/function). Prediction was further improved by including cartilage damage both compartments, BMLs both compartments, meniscal tear, meniscal extrusion, sum of lesion types, number of subregions with cartilage damage, number of subregions with BMLs, and (concurrently) subregion number with cartilage damage, subregion number with BMLs, and meniscal tear. AUCs were ≥0.80 for both outcomes for number of subregions with cartilage damage and the combined model. CONCLUSIONS: Among persons at higher risk for knee OA with normal X-rays, MRI tissue lesions improved prediction of mild as well as moderate disease. These findings support that disease onset is likely occurring during the "high-risk" period and encourage a reorientation of approach.

External knee adduction and flexion moments during gait and medial tibiofemoral disease progression in knee osteoarthritis.

OBJECTIVE: Test the hypothesis that greater baseline peak external knee adduction moment (KAM), KAM impulse, and peak external knee flexion moment (KFM) during the stance phase of gait are associated with baseline-to-2-year medial tibiofemoral cartilage damage and bone marrow lesion progression, and cartilage thickness loss. METHODS: Participants all had knee OA in at least one knee. Baseline peak KAM, KAM impulse, and peak KFM (normalized to body weight and height) were captured and computed using a motion analysis system and six force plates. Participants underwent MRI of both knees at baseline and 2 years later. To assess the association between baseline moments and baseline-to-2-year semiquantitative cartilage damage and bone marrow lesion progression and quantitative cartilage thickness loss, we used logistic and linear regressions with generalized estimating equations (GEE), adjusting for gait speed, age, gender, disease severity, knee pain severity, and medication use. RESULTS: The sample consisted of 391 knees (204 persons): mean age 64.2 years (SD 10.0); BMI 28.4 kg/m(2) (5.7); 156 (76.5%) women. Greater baseline peak KAM and KAM impulse were each associated with worsening of medial bone marrow lesions, but not cartilage damage. Higher baseline KAM impulse was associated with 2-year medial cartilage thickness loss assessed both as % loss and as a threshold of loss, whereas peak KAM was related only to % loss. There was no relationship between baseline peak KFM and any medial disease progression outcome measures. CONCLUSION: Findings support targeting KAM parameters in an effort to delay medial OA disease progression.

Varus thrust and knee frontal plane dynamic motion in persons with knee osteoarthritis.

OBJECTIVE: Varus thrust visualized during walking is associated with a greater medial knee load and an increased risk of medial knee osteoarthritis (OA) progression. Little is known about how varus thrust presence determined by visual observation relates to quantitative gait kinematic data. We hypothesized that varus thrust presence is associated with greater knee frontal plane dynamic movement during the stance phase of gait. METHODS: Participants had knee OA in at least one knee. Trained examiners assessed participants for varus thrust presence during ambulation. Frontal plane knee motion during ambulation was captured using external passive reflective markers and an 8-camera motion analysis system. To examine the cross-sectional relationship between varus thrust and frontal plane knee motion, we used multivariable regression models with the quantitative motion measures as dependent variables and varus thrust (present/absent) as predictor; models were adjusted for age, gender, body mass index (BMI), gait speed, and knee static alignment. RESULTS: 236 persons [mean BMI: 28.5 kg/m(2) (standard deviation (SD) 5.5), mean age: 64.9 years (SD 10.4), 75.8% women] contributing 440 knees comprised the study sample. 82 knees (18.6%) had definite varus thrust. Knees with varus thrust had greater peak varus angle and greater peak varus angular velocity during stance than knees without varus thrust (mean differences 0.90° and 6.65°/s, respectively). These patterns remained significant after adjusting for age, gender, BMI, gait speed, and knee static alignment. CONCLUSION: Visualized varus thrust during walking was associated with a greater peak knee varus angular velocity and a greater peak knee varus angle during stance phase of gait.

Valuing clinical strategies early in development: a cost analysis of allogeneic peripheral blood stem cell transplantation.

Allogeneic peripheral blood stem cell transplantation (alloPBSCT) is an emerging technology. As this technology develops, transplant centers are concerned with looking for technologic advances that will result in improvements in clinical outcomes and lower costs. We provide comparative estimates of costs and resource use for alloPBSCT in comparison to allogeneic bone marrow transplantation (alloBMT) for persons with hematologic malignancies from the time of harvest to 100 days post transplant. A retrospective, cost-identification analysis was conducted for patients in two consecutive phase II clinical trials at the University of Nebraska Medical Center. Identical preparative regimens, graft-versus-host disease prophylaxis, post-transplant hematopoietic colony-stimulating factor treatment regimens, and discharge criteria were used. Total median costs were $18,304 lower for alloPBSCT, with lower costs during recovery; specifically for hospitalization, platelet products, hematopoietic growth factors, intravenous hyperalimentation, supportive care agents, supplies, and antibacterial agents. This study provides preliminary evidence for short-term cost savings associated with alloPBSCT. However, concerns exist over the potential for higher costs due to preliminary reports of higher rates of chronic graft-versus-host disease, as well as more intensive induction regimens that may result in lower relapse rates. The premature adoption of new technologies based on short-term economic factors, in the absence of adequate clinical trial data, may prove to be ill-advised, particularly for complex medical treatments such as allogeneic transplantation.

Disease damage and low bone mineral density: an analysis of women with systemic lupus erythematosus ever and never receiving corticosteroids.

OBJECTIVES: To evaluate the relationship between disease damage and bone mineral density (BMD) in women with systemic lupus erythematosus (SLE). METHODS: A cross-sectional study was conducted among 307 women with SLE. Patients attended a single clinic visit that included an interview, physical examination, laboratory testing and BMD measurements (hip and/or lumbar spine). Women were stratified by the Systemic Lupus International Collaborating Clinics/American College of Rheumatology cumulative disease damage index (SDI) > or =1 (Damage) vs SDI=0 (No Damage), and prior use of corticosteroids (CS), yielding four groups: (1) Damage/CS(+) (n=138), (2) Damage/CS(-) (n=23), (3) no Damage/CS(-) (n=100), and (4) no Damage/CS(-) (n=46). RESULTS: Mean age at SLE diagnosis was 32.7 +/- 11.8 yr, 24.4% were African American, 65.0% were premenopausal, and mean SDI +/- S.D. was 1.3 +/- 1.8. In the unadjusted and adjusted models controlling for significant univariate risk factors for osteoporosis, the reference group (Group 1) had significantly lower mean BMD T-scores at the hip and lumbar spine than groups having no disease damage (Groups 3 and 4) independent of CS use status. Similar hip and lumbar spine mean BMD T-scores were observed in women with disease damage with and without CS exposure (Groups 1 and 2). CONCLUSIONS: Women with SLE having disease damage and no CS use had BMD T-scores at the hip and lumbar spine similar to those of women with disease damage and prior CS use. These findings suggest an association between disease damage and lower BMD T-scores in women with SLE.

Optically controlled Fabry-Perot interferometer using a liquid crystal light valve.

We report an optically controlled Fabry-Perot interferometer which uses a liquid crystal light valve (LCLV) for one of the mirrors. The light valve rotates the plane of polarization for light incident on its read side through an angle dependent on the intensity of a write beam incident on its other side. The Fabry-Perot interferometer is constructed using a polarizing cube beam-splitter and a second mirror. The finesse of this Fabry-Perot varies sharply with the rotation angle introduced by the LCLV. The dependence of this rotation angle on the incident write beam intensity varies with the frequency of the voltage applied to the LCLV, the bias voltage, and the orientation angle of the LCLV. Experimental performance is examined using a single mode He-Ne laser beam and compares well with theoretical predictions: This device has potential uses in optical computing and optical neural networks.

Understanding costs of home and community based services.

With detailed cost information, home and community-based services (HCBS) providers can make intelligent choices that reduce costs without compromising quality and outcomes. Using cost and utilization data from a large HCBS program, monthly costs are estimated and related to demographic and clinical variables. HCBS costs are positively related to disability and cognitive impairment, but not to available social support. Costs vary significantly across the nursing home-eligible population, indicating that caution is warranted when seeking to capitate HCBS services. Per capita costs are strongly related to program volume and experience, falling from $508 to $423 (16.7 percent) over the course of the program.