Article

Knee joint arthritis causes pain, decreased range of motion, and
mobility limitation. Knee replacement reduces pain effectively. However, people
with knee replacement have decreases in muscle strength ("force-generating
capacity") of the involved leg and difficulties with walking and other physical
activities. OBJECTIVE AND DESIGN: The aim of this cross-sectional study was to
determine the extent of deficits in knee extensor and flexor muscle torque and
power (ability to perform work over time) and in the extensor muscle
cross-sectional area (CSA) after knee joint replacement. In addition, the
association of lower-leg muscle deficits with mobility limitations was
investigated. METHODS: Participants were 29 women and 19 men who were 55 to 75
years old and had undergone unilateral knee replacement surgery an average of 10
months earlier. The maximal torque and power of the knee extensor and flexor
muscles were measured with an isokinetic dynamometer. The knee extensor muscle
CSA was measured with computed tomography. The symmetry deficit between the knee
that underwent replacement surgery ("operated knee") and the knee that did not
undergo replacement surgery ("nonoperated knee") was calculated. Maximal walking
speed and stair-ascending and stair-descending times were assessed. RESULTS: The
mean deficits in knee extensor and flexor muscle torque and power were between
13% and 27%, and the mean deficit in the extensor muscle CSA was 14%. A larger
deficit in knee extension power predicted slower stair-ascending and
stair-descending times. This relationship remained unchanged when the power of
the nonoperated side and the potential confounding factors were taken into
account. LIMITATIONS: The study sample consisted of people who were relatively
healthy and mobile. Some participants had osteoarthritis in the nonoperated knee.
CONCLUSIONS: Deficits in muscle torque and power and in the extensor muscle CSA
were present 10 months after knee replacement, potentially causing limitations in
negotiating stairs. To prevent mobility limitations and disability, deficits in
lower-limb power should be considered during rehabilitation after knee
replacement.

Langue : ANGLAIS