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.