Knee Confidence Trajectories Over Eight Years and Factors Associated With Poor Trajectories in Individuals With or at Risk for Knee Osteoarthritis.

OBJECTIVE: To identify distinct trajectories of lack of knee confidence over an 8-year follow-up period and to examine baseline factors associated with poor trajectories in individuals with or at risk for knee osteoarthritis (OA). METHODS: The Osteoarthritis Initiative is a prospective cohort study of individuals with or at high risk for knee OA. Confidence in the knees was assessed within the Knee Injury and Osteoarthritis Outcome Score instrument querying how much the individual is troubled by lack of confidence in his/her knee(s), rated as not-at-all (score = 0), mildly (score = 1), moderately (score = 2), severely (score = 3), and extremely (score = 4) troubled, reported annually from baseline to 96 months. Lack of knee confidence was defined as a score of ≥2. We used latent class models to identify subgroups that share similar underlying knee confidence trajectories over an 8-year period and multivariable multinomial logistic regression models to examine baseline factors associated with poor trajectories. RESULTS: Among 4,515 participants (mean ± SD age 61.2 ± 9.2 years, mean ± SD BMI 28.6 ± 4.8 kg/m2 ; 2,640 [58.5%] women), 4 distinct knee confidence trajectories were identified: persistently good (65.6%); declining (9.1%); poor, improving (13.9%); and persistently poor (11.4%). Baseline predictors associated with persistently poor confidence (reference: persistently good) were younger age, male sex, higher body mass index (BMI), depressive symptoms, more advanced radiographic disease, worse knee pain, weaker knee extensors, history of knee injury and surgery, and reported hip and/or ankle pain. CONCLUSION: Findings suggest the dynamic nature of self-reported knee confidence and that addressing modifiable factors (e.g., BMI, knee strength, depressive symptoms, and lower extremity pain) may improve its long-term course.

Knee Instability and Basic and Advanced Function Decline in Knee Osteoarthritis.

OBJECTIVE: Manifestations of instability in knee osteoarthritis (OA) include low overall knee confidence, low confidence that the knees will not buckle, buckling, and excessive motion during gait. Confidence and buckling may particularly influence activity choices, contributing to events leading to disability. Buckling is more likely to affect advanced than basic functional tasks. In this prospective longitudinal study, we tested the hypothesis that overall knee confidence, buckling confidence, buckling, and frontal plane motion during gait are associated with advanced 2-year function outcomes in persons with knee OA. METHODS: Persons with knee OA were queried about overall knee confidence (higher score = worse confidence), buckling confidence, and knee buckling, and underwent quantitative gait analysis to quantify varus-valgus excursion and angular velocity. Physical function was assessed using the Late-Life Function and Disability Instrument Basic and Advanced Lower Extremity Domain scores. Logistic regression was used to evaluate the relationship between baseline instability measures and baseline-to-2-year function outcome, adjusting for potential confounders. RESULTS: The sample was comprised of 212 persons (mean age 64.6 years, 76.9% women). Buckling was significantly associated with poor advanced function outcome (adjusted odds ratio [OR] 2.08, 95% confidence interval [95% CI] 1.03-4.20) but not basic function outcome. Overall knee confidence was significantly associated with advanced outcome (adjusted OR 1.65, 95% CI 1.01-2.70), while associations between buckling confidence and both outcomes approached significance. Neither varus-valgus excursion nor angular velocity during gait was associated with either outcome. CONCLUSION: Knee buckling and low knee confidence were each associated with poor 2-year advanced function outcomes. Current treatment does not address these modifiable factors; interventions to address them may improve outcome in knee OA.

Factors associated with pain experience outcome in knee osteoarthritis.

OBJECTIVE: Few strategies to improve pain outcome in knee osteoarthritis (OA) exist in part because how best to evaluate pain over the long term is unclear. Our objectives were to determine the frequency of a good pain experience outcome based on previously formulated OA pain stages and test the hypothesis that less depression and pain catastrophizing and greater self-efficacy and social support are each associated with greater likelihood of a good outcome. METHODS: Study participants, all with knee OA, reported pain stage at baseline and 2 years. Baseline assessments utilized the Geriatric Depression Scale, Pain Catastrophizing Scale, Arthritis Self-Efficacy Scale, and Medical Outcomes Study social support survey. Using pain experience stages, good outcome was defined as persistence in or movement to no pain or stage 1 (predictable pain, known trigger) at 2 years. A multivariable logistic regression model was developed to identify independent predictors of a good outcome. RESULTS: Of 212 participants, 136 (64%) had a good pain outcome and 76 (36%) a poor pain outcome. In multivariable analysis, higher self-efficacy was associated with a significantly higher likelihood of good outcome (adjusted odds ratio [OR] 1.14 [95% confidence interval (95% CI) 1.04-1.24]); higher pain catastrophizing was associated with a significantly lower likelihood of good outcome (adjusted OR 0.88 [95% CI 0.83-0.94]). CONCLUSION: This stage-based measure provides a meaningful and interpretable means to assess pain outcome in knee OA. The odds of a good 2-year outcome in knee OA were lower in persons with greater pain catastrophizing and higher in persons with greater self-efficacy. Targeting these factors may help to improve pain outcome in knee OA.

Excess body weight and four-year function outcomes: comparison of African Americans and whites in a prospective study of osteoarthritis.

OBJECTIVE: We evaluated whether African Americans in the Osteoarthritis Initiative (OAI) have a greater risk (versus whites) of poor 4-year function outcome within strata defined by sex, body mass index (BMI), and waist circumference. METHODS: Using Western Ontario and McMaster Universities Osteoarthritis Index function, 20-meter walk, and chair stand performance, poor outcome was defined as moving into a worse function group or remaining in the 2 worst groups over 4 years. Logistic regression was used to evaluate the relationship between racial group and outcome within each stratum, adjusting for age, education, and income, and then further adjusting for BMI, comorbidity, depressive symptoms, physical activity, knee pain, and osteoarthritis (OA) severity. RESULTS: In 3,695 persons with or at higher risk for knee OA, higher BMI and large waist circumference were each associated with poor outcome. Among women with high BMI and among women with large waist circumference, African Americans were at greater risk for poor outcome by every measure, adjusting for age, education, and income. From fully adjusted models, potential explanatory factors included income, comorbidity, depressive symptoms, pain, and disease severity. Findings were less consistent for men, emerging only for the 20-meter walk or chair stand outcomes, and potentially explained by age and knee pain. CONCLUSION: Among OAI women with excess body weight, African Americans are at greater risk than whites for poor 4-year outcome. Modifiable factors that may help to explain these findings in the OAI include comorbidity, depressive symptoms, and knee pain. Targeting such factors, while supporting weight loss, may help to lessen the outcome disparity between African American and white women.

Knee confidence as it relates to physical function outcome in persons with or at high risk of knee osteoarthritis in the osteoarthritis initiative.

OBJECTIVE: To evaluate whether low knee confidence at baseline is associated with poor baseline-to-3-year physical function outcome in the Osteoarthritis Initiative. METHODS: Knee confidence was assessed using an item from the Knee Injury and Osteoarthritis Outcome Score instrument. Physical function was assessed using self-report measures (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] function score and Short Form 12 physical component scale) and performance-based measures (20-meter walk and chair stand test). Poor function outcome was defined as moving into a worse function group or remaining in the 2 worst function groups between baseline and 3 years. Logistic regression was used to evaluate the relationship between baseline knee confidence level and poor baseline-to-3-year function outcome, adjusting for potential confounders. RESULTS: The sample included 3,975 men and women with or at high risk of developing osteoarthritis of the knee, of whom 37-53% had poor baseline-to-3-year function outcome. For both self-report measures, increasingly worse knee confidence was associated with a greater risk of poor function outcome, and trend tests supported a graded response (e.g., the adjusted odds ratios [95% confidence intervals] for the WOMAC function score for worsening confidence categories were 1.26 [1.07-1.49], 1.43 [1.16-1.77], and 2.05 [1.49-2.82], P for trend <0.0001). Similar associations between confidence and performance-based function outcome were observed, but statistical significance did not persist in adjusted analyses. Factors independently associated with poor function outcome for all 4 outcome measures were depressive symptoms, comorbidity, body mass index, and joint space narrowing. CONCLUSION: These findings indicate that worse knee confidence at baseline is independently associated with greater risk of poor function outcome by self-report measures, with evidence of a graded response; the relationship with performance measures is not significant in fully adjusted models.

Factors that affect decisions about physical activity and exercise in survivors of breast cancer: a qualitative study.

BACKGROUND: Exercise has many benefits for survivors of breast cancer, yet only half of this population regularly exercise. Fear has been identified as a barrier to exercise for people with neuromusculoskeletal conditions but has been minimally explored in women with breast cancer. OBJECTIVES: The purposes of this study were: (1) to investigate factors that affected decisions about physical activity and exercise in survivors of breast cancer and (2) to determine whether fear was a factor. DESIGN: This investigation was a grounded-theory qualitative study. Qualitative data were triangulated with data from 2 quantitative scales that measured participants' beliefs about exercise and their activity levels. METHODS: Thirty-four survivors of breast cancer in 8 focus groups participated in semistructured interviews that were recorded, transcribed, and coded. Concept maps created for each group were merged to develop themes. Beliefs about physical activity and exercise were assessed with the Decisional Balance Scale. The Rapid Assessment of Physical Activity was used to assess behaviors regarding physical activity and exercise before and after the breast cancer diagnosis. RESULTS: Participants generally believed that exercise was beneficial (Decisional Balance Scale score: X=28.1 [of a maximum score of 44], SD=7.6, range=10-43). Participants decreased the amount of physical activity or exercise during treatment but increased the amount of exercise beyond prediagnosis levels after treatment (Rapid Assessment of Physical Activity score: median=6, range=2-7). Three prominent themes described participants' behaviors regarding physical activity or exercise: values and beliefs about exercise, facilitators and barriers that were both similar to those affecting the general population and cancer specific, and lack of or inaccurate information about safe exercise. CONCLUSIONS: Survivors who were active were not afraid to exercise. However, concern about lymphedema and knowledge about safe and effective exercise programs influenced choices regarding physical activity and exercise.

Reliability of classifications derived from Cyriax's resisted testing in subjects with painful shoulders and knees.

STUDY DESIGN: Intrarater and interrater reliability. OBJECTIVES: Examine intrarater and interrater reliability of the resisted-testing component of Cyriax's selective tension testing for patients with painful shoulders and knees. BACKGROUND: Clinicians make diagnostic and intervention decisions about lesions in contractile tissues based on resisted testing. Diagnostic and intervention decisions require reliable data gathering, especially when more than 1 physical therapist manages a patient. No studies have examined agreement of the results of the resisted tests used in selective tension testing, either within or between physical therapists, in subjects having pathology. METHODS AND MEASURES: Subjects with pain in 1 knee (18 male, 22 female; mean age +/- SD = 31.8 +/- 9.5 years) or shoulder (21 male, 25 female; mean age +/- SD = 34.3 +/- 12.9 years) were examined twice. Referring diagnoses included ligament injuries, overuse syndromes, joint instability, and postsurgical symptoms, with some subjects seeking initial diagnosis. Two physical therapists used standardized positions to evaluate 2 knee motions or 6 shoulder and elbow motions. Evaluators applied maximal isometric manual resistance and rated the contraction as strong or weak while subjects identified the presence or absence of pain during the contraction. Evaluators did not interview the subjects and were masked to previous test results. Analyses included percentage of agreement, kappa coefficients, confidence intervals, and maximum kappa coefficients. RESULTS: Intrarater kappa coefficients ranged from 0.44 to 0.82 and interrater coefficients ranged from 0.00 to 0.46. The small number of subjects who were classified as weak affected the kappa coefficients. In the intrarater condition, evaluators averaged 91% of maximum kappa for the knee and 66.5% for the shoulder. In the interrater condition, they averaged 60.4% of the maximum kappa for both the knee and the shoulder. CONCLUSIONS: Based on 2 physical therapist evaluators with previous education in the selective tension system and an additional 6 hours of formal training on the methods, intrarater reliability of resisted tests was generally acceptable for the knee but not for the shoulder. Interrater reliability of these tests, however, was generally not acceptable. Results were limited by subjects who were younger and had mostly chronic conditions that were mildly to moderately severe and by the small subject samples in the analyses. Reliability might be improved by more intensive training of the evaluators and by standardizing the magnitude of the applied resistance and stabilization of the subjects.

Quadriceps strength and osteoarthritis progression in malaligned and lax knees.

BACKGROUND: Quadriceps muscle strengthening is a common goal in the management of knee osteoarthritis. In healthy knees, strength protects against new osteoarthritis. In arthritic knees, greater strength may protect joints and thereby delay osteoarthritis progression. Alternatively, in certain joint environments, such as malalignment or laxity, greater strength may translate into damaging joint reaction forces. The relationship between quadriceps strength and progression of knee osteoarthritis may differ according to these factors. OBJECTIVE: To determine whether greater quadriceps strength is associated with greater probability of tibiofemoral osteoarthritis progression in malaligned knees and in high-laxity knees. DESIGN: Prospective, longitudinal cohort study. SETTING: Academic medical center. PARTICIPANTS: 237 persons with primary knee osteoarthritis, definite tibiofemoral osteophytes, and at least some difficulty with knee-requiring activity. Two hundred thirty completed the 18-month evaluation. The current study primarily involved those without advanced osteoarthritis in either knee (n = 171). MEASUREMENTS: Quadriceps strength, knee laxity and alignment, and osteoarthritis progression. RESULTS: The predicted probability of tibiofemoral progression was 0.153 (95% CI, 0.100 to 0.228) in high-strength knees and 0.098 (CI, 0.061 to 0.155) in low-strength knees. In malaligned knees, high strength was associated with a significant increase (P = 0.03) in the likelihood of progression (predicted probability, 0.406 [CI, 0.226 to 0.615] vs. 0.187 [CI, 0.081 to 0.375] in high-strength vs. low-strength knees). Strength was also associated with increased likelihood of progression in high-laxity knees (P = 0.003 when high laxity was defined as > or =6.75 degrees). The probability of patellofemoral progression did not differ between high- and low-strength knees in the full sample or within subsets. CONCLUSIONS: Greater quadriceps strength at baseline was associated with increased likelihood of tibiofemoral osteoarthritis progression in malaligned knees and lax knees. Subset-specific approaches beyond strengthening exercises should be developed to enhance joint-protective muscle activity.