Side differences of thigh muscle cross-sectional areas and maximal isometric muscle force in bilateral knees with the same radiographic disease stage, but unilateral frequent pain – data from the osteoarthritis initiative

Abstract

Objective To determine whether anatomical thigh muscle cross-sectional areas (MCSAs) and strength differ between osteoarthritis (OA) knees with frequent pain compared with contralateral knees without pain, and to examine the correlation between MCSAs and strength in painful versus painless knees. Methods 48 subjects (31 women; 17 men; age 45–78 years) were drawn from 4796 Osteoarthritis Initiative (OAI) participants, in whom both knees displayed the same radiographic stage (KLG2 or 3), one with frequent pain (most days of the month within the past 12 months) and the contralateral one without pain. Axial MR images were used to determine MCSAs of extensors, flexors and adductors at 35% femoral length (distal to proximal) and in two adjacent 5 mm images. Maximal isometric extensor and flexor forces were used as provided from the OAI data base. Results Painful knees showed 5.2% lower extensor MCSAs (p=0.00003; paired t-test), and 7.8% lower maximal extensor muscle forces (p=0.003) than contra-lateral painless knees. There were no significant differences in flexor forces, or flexor and adductor MCSAs (p>0.39). Correlations between force and MCSAs were similar in painful and painless OA knees (0.44<r<0.66). Conclusions Knees with frequent pain demonstrate lower MCSAs and force of the quadriceps (but not of other thigh muscles) compared with contra-lateral knees without knee pain with the same radiographic stage. Frequent pain does not appear to affect the correlations between MCSAs and strength in OA knees. The findings suggest that quadriceps strengthening exercise may be useful in treating symptomatic knee OA.

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

“…In this study, we did not detect side differences in thigh muscle anatomic cross-sectional areas (MCSAs) and isometric strength (39). In contrast, a com- parison of participants with unilateral frequent knee pain but concordant radiographic (K/L grade) knee status revealed lower thigh MCSAs and isometric strength in the symptomatic knee (6). However, both studies had lower numbers of participants (Յ48) and there was concern that findings in control knees may be confounded by the contralateral case knees due to the between-knee, withinperson study design and lack of independence of observations in bilateral knees of the same person.…”

“…Baseline measurements for maximum isometric extensor and flexor strength were drawn from the OAI database (clinical data set 0.2.2) (32). These measurements were obtained using the Good Strength Chair (Metitur Oy) (6,33,34), with the participant sitting upright with a fixed pelvis and thigh. The knee was placed in 60°of flexion for testing.…”

“…Thigh muscle weakness has been commonly observed in patients with knee osteoarthritis (KOA) (1)(2)(3)(4)(5) or knee pain (6,7), and low muscle strength has been associated with incident symptomatic, but not with incident radiographic KOA (8). Muscle weakness is considered a potentially modifiable (9) risk factor of KOA and quadriceps muscle strengthening is recommended by the current Osteoarthritis Research Society International KOA treatment guidelines (10).…”

Targeting Care

“…Decreased quadriceps strength in knee OA has been attributed to both loss of muscle cross-sectional area (43) and reduced ability to activate the muscles (44). In a cohort of 111 subjects taken from a larger RCT, baseline ability to activate quadriceps was examined as one of 9 possible predictors of changes in strength of the muscle following a 6 week exercise program for subjects with knee OA.…”

Association of Knee Muscle Strength with Lower Extremity Dysfunction in Patients with Osteoarthritis: a Comparison with Rheumatoid Arthritis Patients and Healthy Controls

“…Some studies showed that quadriceps strength was significantly reduced in patients with radiographic knee OA. [37] However, Brandt et al [38] detected reduced muscle strength in patients without radiographic knee OA, and PalmieriSmith et al [39] could not identify any distinction in the quadriceps strength of patients with different radiographic grades according to the KL grading system. In our study, radiological grade was not an influential variable that affected muscle strength in the lower limbs of the OA patients.…”