Quadriceps weakness is a common clinical sign in persons with moderate-to-severe osteoarthritis and results in physical disability; however, minimal data exist to establish whether quadriceps weakness is present in early stages of the disease. Therefore, our purpose was to determine whether quadriceps weakness was present in persons with early radiographic and cartilaginous evidence of osteoarthritis. Further, we sought to determine whether quadriceps strength decreases as osteoarthritis severity increases.
Three hundred forty-eight women completed radiologic and magnetic resonance imaging evaluation, in addition to strength testing. Anterior-posterior radiographs were graded for tibiofemoral osteoarthritis severity using the Kellgren-Lawrence scale. Scans from magnetic resonance imaging were used to assess medial tibiofemoral and patellar cartilage based on a modification of the Noyes scale. The peak knee extension torque recorded was used to represent strength.
Quadriceps strength (Nm/kg) was 22% greater in women without radiographic osteoarthritis than in women with osteoarthritis (P < 0.05). Quadriceps strength was also greater in women with Noyes' medial tibial and femoral cartilage scores of 0 when compared in women with Noyes' grades 2 and 3-5 (P < or = 0.05).
Women with early evidence of osteoarthritis had less quadriceps strength than women without osteoarthritis as defined by imaging.
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"This suggests that the RF and VM are the principal muscles used to accomplish buttocks-off. However, it has been reported that knee OA patients have decreased quadriceps muscle forceand decreased joint proprioception, preventing them from effectively using their knee extensors. In this study, RMS%MVCs of VM for 30–35% and 35–40% were significantly larger in the knee OA group than in the control group. "
[Show abstract][Hide abstract] ABSTRACT: Objective:
Muscle activities during the sit-to-stand motion (STS) are characterized by coordinated movements between hip extensors and knee extensors. However, previous reports regarding the STS and lower extremity muscle activities have focused on some quantitative assessment, but little qualitative research. This study aimed to examine the muscle activities of the lower extremity both quantitatively and qualitatively.
Study participants included 13 patients with knee osteoarthritis (knee OA) and 11 age-matched asymptomatic controls. The task was STS from a chair with a height-adjustable seat. EMG activities were acquired using surface electromyogram. The root mean square signals normalized as a percentage of maximum voluntary isometric contraction values (RMS%MVC) and the mean power frequency (MPF) were calculated.
During STS, knee OA patients had increased RMS%MVC of the vastus medialis and raised MPF of the rectus femoris before buttocks-off.
These findings suggest that STS of knee OA patients not only increased relative muscle activity of the vastus medialis, but also enlisted the rectus femoris in knee extension to improve muscle contraction force by activating more type II fibers to accomplish buttocks-off.
"Cross-sectional studies suggest that weakness of the knee extensor muscles may precede the development of knee OA [18,19]. However, results from prospective cohort studies that assessed whether quadriceps strength predicts incident knee OA are equivocal. "
[Show abstract][Hide abstract] ABSTRACT: The occurrence of knee osteoarthritis (OA) increases with age and is more common in women compared with men, especially after the age of 50 years. Recent work suggests that contact stress in the knee cartilage is a significant predictor of the risk for developing knee OA. Significant gaps in knowledge remain, however, as to how changes in musculoskeletal traits disturb the normal mechanical environment of the knee and contribute to sex differences in the initiation and progression of idiopathic knee OA. To illustrate this knowledge deficit, we summarize what is known about the influence of limb alignment, muscle function, and obesity on sex differences in knee OA. Observational data suggest that limb alignment can predict the development of radiographic signs of knee OA, potentially due to increased stresses and strains within the joint. However, these data do not indicate how limb alignment could contribute to sex differences in either the development or worsening of knee OA. Similarly, the strength of the knee extensor muscles is compromised in women who develop radiographic and symptomatic signs of knee OA, but the extent to which the decline in muscle function precedes the development of the disease is uncertain. Even less is known about how changes in muscle function might contribute to the worsening of knee OA. Conversely, obesity is a stronger predictor of developing knee OA symptoms in women than in men. The influence of obesity on developing knee OA symptoms is not associated with deviation in limb alignment, but BMI predicts the worsening of the symptoms only in individuals with neutral and valgus (knock-kneed) knees. It is more likely, however, that obesity modulates OA through a combination of systemic effects, particularly an increase in inflammatory cytokines, and mechanical factors within the joint. The absence of strong associations of these surrogate measures of the mechanical environment in the knee joint with sex differences in the development and progression of knee OA suggests that a more multifactorial and integrative approach in the study of this disease is needed. We identify gaps in knowledge related to mechanical influences on the sex differences in knee OA.
Full-text · Article · Dec 2012 · Biology of Sex Differences
"Muscle strength significantly contributes to knee joint loading during walking (Pandy and Andriacchi, 2010) with recent attention being focused on lower limb muscle strength among knee OA patients. While quadriceps muscle weakness is well documented among knee OA patients (Lewek et al., 2004b; Palmieri-Smith et al., 2010; Tan et al., 1995), hamstring muscle strength is less studied and the results are contradictory (Slemenda et al., 1998; Tan et al., 1995). New evidence suggests hip muscles to be weaker in knee OA patients than in controls (Costa et al., 2010; Hinman et al., 2010). "
[Show abstract][Hide abstract] ABSTRACT: Background:
Based on novel classification criteria using magnetic resonance imaging, a subpopulation of "early knee osteoarthritis patients" was clearly defined recently. This study assessed whether these early osteoarthritis patients already exhibit gait adaptations (knee joint loading in particular) and changes in muscle strength compared to control subjects and established knee osteoarthritis patients.
Fourteen female patients with early knee joint degeneration, defined by magnetic resonance imaging (early osteoarthritis), 12 female patients with established osteoarthritis and 14 female control subjects participated. Specific gait parameters and lower limb muscle strength were analyzed and compared between groups. Within the osteoarthritis groups, association between muscle strength and dynamic knee joint loading was also evaluated.
Early osteoarthritis patients presented no altered gait pattern, no significant increase in knee joint loading and no significant decrease in hamstring muscle strength compared to controls, while established osteoarthritis patients did. In contrast, early osteoarthritis patients experienced significant quadriceps weakness, comparable to established osteoarthritis patients. Within the osteoarthritis groups, muscle strength was not correlated with knee joint loading during gait.
The results suggest that gait changes reflect mechanical overload and are most likely the consequence of structural degeneration in knee osteoarthritis. Quadriceps weakness might however contribute to the onset and progression of the disease. This study supports the relevance of classification of early osteoarthritis patients and assists in identifying their functional characteristics. This helps to understand the trajectory of disease onset and progression and further develop more targeted strategies for prevention and treatment of knee osteoarthritis.