The increase in energy cost of walking with an immobilized knee or an unstable ankle.

The effect of an immobilized knee joint or of an unstable ankle joint on the walking capacity has been assessed with 50 walking tests in ten healthy subjects. The knee joint was immobilized in extension with a standard splint and an unstable ankle joint was simulated by a modified shoe. A significant decrease in convenient walking speed was found. The energy cost of walking as assessed by oxygen cost at a convenient speed was significantly increased both with an immobilized knee (23%) and with an unstable ankle (10%), compared to normal condition of the subjects. Implications for the management of patients with similar joint disorders are discussed.