Article

Quadriceps muscle weakness is common in knee osteoarthritis (OA).
Reasons for weakness may include atrophy, reduction in the muscle fibers number,
and changes in the muscle activation. It is uncertain when these muscular changes
begin to appear. Therefore, the purpose of this study was to determine whether
men with early stages of knee OA already had functional and quadriceps muscle
morphologic alterations. DESIGN: Forty men were divided into two groups: control
group (healthy subjects) and OA group (subjects with knee OA). A biopsy of the
vastus lateralis muscle was performed for morphometric analysis. Isokinetic
evaluation of knee extensor torque, concentric and eccentric (90 and 180
degrees/sec), was performed simultaneously with vastus lateralis
electromyographic activity evaluation. RESULTS: Significant differences were
found in knee extensor torque (P < 0.05) and in normalized root mean square (P <
0.01) during the eccentric contractions (both velocities), with higher values for
the control group. No differences were found during concentric contractions. The
OA group presented greater values of the minimum diameter of type 1 fibers and
greater proportion and relative cross-sectional area of type 2b fibers (P <
0.05). CONCLUSIONS: Men with early stages of knee OA do not present alterations
of concentric strength but had decreased eccentric strength and morphologic
quadriceps muscle changes, indicating neuromuscular adaptations.

Langue : ANGLAIS