Quadriceps weakness in knee osteoarthritis: the effect on pain and disability

Abstract

Objectives-(1) To determine the importance of quadriceps strength, structural change, and psychological status in terms of knee pain in the community. (2) To determine the relative importance of quadriceps function, structural change, and psychological status with respect to disability in subjects with knee pain. Methods-300 men and women with pain and 300 controls without pain (aged 40-79) were seen. Isometric quadriceps strength (MVC) was measured and muscle activation was assessed by twitch superimposition. Disability (Western Ontario McMasterOsteoarthritis Index (WOMAC)) and anxiety and depression were assessed (Hospital Anxiety and Depression Index (HAD)). Radiographs were obtained of the tibiofemoral and patellofemoral joints and total score for osteophyte, narrowing, and sclerosis calculated for each knee. Results-Subjects with knee pain had lower voluntary quadriceps strength than those without pain (p<0.005). Quadriceps activation was also lower (p<0.005), but did not fully explain the reduction in strength. When analysed by multiple logistic regression: quadriceps strength (odds ratio 18.8, CI 4.8, 74.1 for MVC <10 kgF); depression (odds ratio 2.4, CI 1.0, 5.5 for HAD score>8); and radiographic change (odds ratio 4.1, CI 1.9, 8.6 for radiographic score >4) were independently associated with pain. In those with knee pain, disability was independently associated with quadriceps strength (odds ratio 8.2, CI 1.5, 44.4 for MVC <10 kgF) and depression (odds ratio 6.2, CI 2.1, 18.0 for HAD score>8); but not with radiographic score. Conclusions-Quadriceps strength is strongly associated with knee pain and disability in the community, even when activation and psychological factors are taken into account. This has important therapeutic implications.

Physical functioning over three years in knee osteoarthritis: Role of psychosocial, local mechanical, and neuromuscular factors

“…A relationship between depressive symptoms and physical function has been described in longitudinal studies not limited to individuals with arthritis, as summarized by Ormel et al (46), and in cross-sectional studies of knee OA (31,34,47,48). The demonstration in the current study that the status of mental health predicts subsequent physical function is important, given how function assessment might be biased by depressive symptoms.…”

“…A downward spiral of pain, weakness, and reduced self-efficacy may lead to substantial reduction in activity. In support of this paradigm, subjects with knee OA and pain were weaker than those without pain (34), and in OASIS, there was evidence of an interaction between strength and pain (38) as well as strength and self-efficacy (7), in evaluating the effects on physical function.…”

“…Given the muscle specificity of this task, and the abundant evidence of a cross-sectional relationship between strength and function (6,11,(31)(32)(33)(34)(35), it is surprising that the protective effect of strength was not greater and that there was attenuation after adjustment. However, these results are consistent with the relatively modest effect of strengthening exercise on physical function in the long term (36), and with the finding, in both of the studies that have considered this question, that strength does not protect against knee OA disease progression (14,37).…”

Association of Thigh Muscle Strength With Knee Symptoms and Radiographic Disease Stage of Osteoarthritis: Data From the Osteoarthritis Initiative

“…O'Reilly et al observed lower quadriceps strength in symptomatic versus asymptomatic legs, but did not match case and control knees for radiographic disease stage (38). Berger et al reported significant differences in knee extensor strength between WOMAC total score tertiles, but not across different K/L grade strata (K/L grades Ͻ2 versus 2 versus Ն2) (7).…”

Isometric muscle force measurement for clinicians treating patients with osteoarthritis of the knee

“…Reduced lower limb muscle strength is particularly marked in people with symptomatic knee OA (10,11). More importantly, several cross-sectional studies have established that reduced knee extensor strength in people with knee OA is strongly associated with increased pain and poor physical function (10 -12).…”