Knee Extension and Flexion Weakness in People With Knee Osteoarthritis: Is Antagonist Cocontraction a Factor?

Abstract

flexion strength, 6,50 compared with similarly aged controls. There are 3 factors thought to contribute to knee extension and flexion weakness in those with knee OA: muscle atrophy, failure of voluntary muscle activity, and apparent weakness from increased antagonist muscle cocontraction. 5 Decreases in muscle cross-sectional area (CSA) have been established in subjects with early OA degenerative changes 22 and in those with severe knee OA. 10Ikeda et al 22 found that women with early degenerative changes in the knee joint had reductions in quadriceps CSA of up to 12%, compared with age-matched women without radiographic changes. Fink et al 10 found atrophy of type 2 fibers and type 1 fibers of the vastus medialis in patients undergoing total joint arthroplasty. Importantly, a smaller lean-muscle CSA in the diseased limb, compared to the contralateral limb, in subjects with OA contributes to muscle weakness but is not the only factor involved. 40Several investigators have examined failure of voluntary muscle activity as a contributing factor in reduced knee extension strength. 12,29,33,40,48 Failure of voluntary activity is the measure of an individual's ability to fully activate their muscles during maximal voluntary contractions. 20 Reductions in muscle activation are due to either an inability to recruit all motor units or a reduction in the motor unit discharge rate. 25 In healthy adults, simulated failure of voluntary activity by saline injection into the knee joint to cause effusion resulted in decreased isometric extension strength and knee extension torque during strength testing 23,31 and increased muscle cocon- Q uadriceps weakness is one of the most common and disabling impairments seen in individuals with knee osteoarthritis (OA).19 Sufficient quadriceps and hamstrings strength, both isometric and dynamic, is essential for undertaking basic activities of daily living such as standing and walking. 36 Muscle strength testing has revealed that those with knee OA have a 25% to 45% loss of knee extension strength 6,15,39 and a 19% to 25% loss of kneeControlled laboratory study, cross-sectional data.To investigate isometric knee flexion and extension strength, failure of voluntary muscle activation, and antagonist cocontraction of subjects with knee osteoarthritis (OA) compared with age-matched asymptomatic control subjects.Quadriceps weakness is a common impairment in individuals with knee OA. Disuse atrophy, failure of voluntary muscle activation, and antagonist muscle cocontraction are thought to be possible mechanisms underlying this weakness; but antagonist cocontraction has not been examined during testing requiring maximum voluntary isometric contraction.Fifty-four subjects with knee OA (mean SD age, 65.6 7.6 years) and 27 similarly aged control subjects (age, 64.2 5.1 years) were recruited for this study. Isometric knee flexion and extension strength were measured, and electromyographic data were recorded, from 7 muscles crossing the knee and used to calculate cocontraction ratios during maximal ef...

Muscle activation and knee biomechanics during squatting and lunging after lower extremity fatigue in healthy young women

“…This strategy may be an effort to control knee excursion by increasing resistance to angular joint motion. An increase in co-activation of these opposing muscle groups would reduce the total net joint moment experienced by the knee, creating an apparent decrease in torque generating capacity of the muscles surrounding the knee (Bennell et al, 2013;Heiden et al, 2009). The trend toward a post fatigue increase in co-activation between the vastus lateralis and biceps femoris may therefore have contributed to an apparent decrease in knee moments; however, the increase in co-activation in the current study was not significant.…”

Neuromuscular efficiency during sit to stand movement in women with knee osteoarthritis

“…During single-joint maximum strength tests, the primary role of co-activity is to increase joint stiffness and, perhaps, to stabilise the knee joint (Baratta et al, 1988;De Luca and Mambrito, 1987). Antagonist activation during maximum strength tests is higher in the elderly (Izquierdo et al, 1999) but evidence suggests that it does not differ between women with knee OA and controls (Heiden et al, 2009). During multi-articular movements, however, co-activation of quadriceps and hamstring muscles, may serve to achieve a better control of force transfer from the hip to the knee via the bi-articular components of these muscle groups (Roebroeck et al, 1994).…”

Mid Term Outcome of Home-Based Exercises vs. Sophisticated Physiotherapy Protocol After Total Knee Arthroplasty

“…Latest global statistics declares that 110 million people are suffering from osteoarthritis, which is one of the main causes of total knee arthroplasty (TKA) (1,2). The number of primary total knee arthroplasty has boosted significantly in recent years and amounted to 1.5 million in 2015 (3).…”