Altered gait characteristics in individuals with knee osteoarthritis and self-reported knee instability.

STUDY DESIGN: Experimental laboratory study. OBJECTIVE: To characterize the differences in lower extremity gait biomechanics in individuals who have knee osteoarthritis (OA) with and without self-reported knee instability. BACKGROUND: Individuals with knee OA who experience episodes of knee instability often report gait difficulties that interfere with their daily lives. A better understanding of the alterations in gait biomechanics may help to mitigate symptomatic knee instability in this patient population. METHODS: Seventeen participants with knee OA and self-reported knee instability and 36 participants with knee OA and no self-reported knee instability underwent instrumented gait analysis on level ground. Knee-specific symptoms and functional limitations were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index. RESULTS: Knee instability was associated with greater odds of reporting moderate to severe gait-related pain (odds ratio = 6.0; 95% confidence interval: 1.2, 28.9) and moderate to severe difficulty when walking on flat surfaces (odds ratio = 10.7; 95% confidence interval: 1.7, 69.2). During early stance, the group with self-reported knee instability walked with a greater knee flexion excursion (P = .02) and a smaller lower extremity support moment (P<.01), due to reduced contributions from the hip extensors (P<.01) and ankle plantar flexors (P = .04). The group with self-reported knee instability also walked with a greater knee extensor contribution to the lower extremity support moment (P = .04) during the initial knee extension phase of gait compared to their counterparts with good knee stability. CONCLUSION: These findings suggest that self-reported knee instability is associated with significant alterations in hip, knee, and ankle joint function during the stance phase of gait in individuals with knee OA.

A biomechanical perspective on physical therapy management of knee osteoarthritis.

SYNOPSIS: Altered knee joint biomechanics and excessive joint loading have long been considered as important contributors to the development and progression of knee osteoarthritis. Therefore, a better understanding of how various treatment options influence the loading environment of the knee joint could have practical implications for devising more effective physical therapy management strategies. The aim of this clinical commentary was to review the pertinent biomechanical evidence supporting the use of treatment options intended to provide protection against excessive joint loading while offering symptomatic relief and functional improvements for better long-term management of patients with knee osteoarthritis. The biomechanical and clinical evidence regarding the effectiveness of knee joint offloading strategies, including contralateral cane use, laterally wedged shoe insoles, variable-stiffness shoes, valgus knee bracing, and gait-modification strategies, within the context of effective disease management is discussed. In addition, the potential role of therapeutic exercise and neuromuscular training to improve the mechanical environment of the knee joint is considered. Management strategies for treatment of joint instability and patellofemoral compartment disease are also mentioned. Based on the evidence presented as part of this clinical commentary, it is argued that special considerations for the role of knee joint biomechanics and excessive joint loading are necessary in designing effective short- and long-term management strategies for treatment of patients with knee osteoarthritis. LEVEL OF EVIDENCE: Therapy, level 5.

Association between Disability and Psychological Factors and Dose of Neuromuscular Electrical Stimulation in Subjects with Rheumatoid Arthritis.

BACKGROUND: The therapeutic effect of neuromuscular electrical stimulation (NMES) on muscle strengthening and hypertrophy depends on its dose. Patients must tolerate high doses of NMES to maximize gains in muscle function. It is unknown why some patients are able to achieve high NMES dose while others are not. Disability and psychological attributes may play a role in a patient's tolerance of NMES dose. PURPOSE: To explore if disability and psychological attributes associate with the ability to achieve high doses of NMES in patients with rheumatoid arthritis (RA). METHODS: Cross-sectional study. Forty subjects with RA participated in 2 sessions of NMES intervention to the quadriceps muscles. The highest NMES dose achieved by each subject was recorded. Dose was defined as the torque produced by the NMES as a percentage of the torque produced during a maximum voluntary isometric contraction. Subjects were then grouped in high or low NMES dose. Variables investigated in this study included disability, pain coping strategies, pain acceptance, sense of mastery or control, anxiety, and depression. Correlations were sought between these factors and NMES dose. MAIN RESULTS: In unadjusted models, disability, coping self-statements, catastrophizing, and anxiety were predictors of NMES dose. In adjusted models only disability (OR = 0.17 [95% CI: 0.04, 0.77]) and catastrophizing (OR = 0.85 [95% CI: 0.72, 0.99]) predicted NMES dose. CONCLUSION: Patients with RA with lower disability and lower catastrophising achieve higher doses of NMES. Identifying factors associated with achieving high NMES dose may guide strategies to improve effectiveness of this intervention.

Six-month survival benefits associated with clinical guideline recommendations in acute coronary syndromes

AIMS: The authors sought to define which guideline-advocated therapies are associated with the greatest benefit with respect to 6-month survival in patients hospitalised with an acute coronary syndrome (ACS).METHODS AND RESULTS: The authors conducted a nested case-control study of ACS patients within the Global Registry of Acute Coronary Events cohort between April 1999 and December 2007. The cases were ACS patients who survived to discharge but died within 6 months. The controls were patients who survived to 6 months, matched for ACS diagnosis, age and the Global Registry of Acute Coronary Events risk score. Rates of use of evidence-based medications and coronary interventions (angiography, percutaneous coronary intervention and coronary artery bypass graft surgery) were compared. Logistic regression including matched variables was used, and the attributable mortality from incomplete application of each therapy was calculated. A total of 1716 cases and 3432 controls were identified. Coronary artery bypass graft surgery and percutaneous coronary intervention were associated with the greatest 6-month survival benefit (OR for death 0.60 (95% CI 0.39 to 0.90) and 0.57 (0.48 to 0.72), respectively). Statins and clopidogrel provided the greatest independent pharmacologic benefit (ORs for death 0.85 (0.73 to 0.99) and 0.84 (0.72 to 0.99)) with lesser effects seen with other pharmacotherapies.CONCLUSIONS: A diminishing benefit associated with each additional ACS therapy is evident. These data may provide a rational basis for selecting between therapeutic options when compliance or cost is an issue.

Systemic production of prostacyclin and thromboxane A2 does not correlate with patency of the ductus arteriosus in very low birth weight infants.

Urinary excretion of prostacyclin and thromboxane metabolites (2,3-dinor-6-ketoprostaglandin F1 alpha, thromboxane B2, and 2,3-dinor-thromboxane B2) as indices of systemic biosynthesis was prospectively determined in nine premature infants during the first 10 days of life, by gas chromatography-mass spectrometry. The patients ranged in gestational age from 27 to 29 weeks and in birth weight from 720 to 980 gm. Four infants developed symptomatic patent ductus arteriosus (PDA). Excretion of all metabolites exceeded adult values on the basis of body surface area at birth, reached a maximum on the fourth day of life, was related to urine output, and did not distinguish patients with and without symptomatic PDA. We conclude that neither circulating prostacyclin nor thromboxane A2 contribute significantly to the pathophysiology of symptomatic PDA in very low birth weight infants.