Fiber type area and metabolic potential of the thigh muscle in man after knee surgery and immobilization.

The muscle atrophy of the quadriceps muscle was investigated in patients after knee operations and immobilization in a long leg plaster cast. Muscle biopsies were taken before operation and after 5 weeks immobilization. The activity of oxidative (SDH) and glycolytic (PFK) enzymes was determined. The fiber area of the different fiber types were measured and enzyme activities in single characterized fibers were analyzed. A selective type 1 atrophy was found with a reduced cross-cut area of the type 1 fiber, and a reduced oxidative enzyme activity occurred in the slow-twitch type 1 fibers. The effect of the muscle tension in the immobilized leg and the inhibiting role of the postoperative pain is discussed.