Contralateral shoe-lift: effect on oxygen cost of walking with an immobilized knee.

OBJECTIVE Evaluate the effect of a contralateral shoe-lift on the oxygen cost of walking with an artificially immobilized knee. DESIGN A prospective quantitative evaluation of oxygen cost of walking under varying conditions. Subjects walked (1) normally (N), (2) with one knee immobilized (1), (3) with one knee immobilized and with a one-half-inch shoe-lift applied to the contralateral shoe (I1/2"L), and (4) with one knee immobilized and with a one-inch shoe-lift (I1"L). SETTING Exercise physiology laboratory. SUBJECTS Ten able-bodied subjects without known cardiopolmonary or musculoskeletal problems. MAIN OUTCOME MEASURE Breath-by-breath oxygen consumption measurements in mL/kg/m. RESULTS Oxygen cost on average was 20% more with the knee immobilized (I) compared to normal (N) (mean difference = .0298 +/- .0245mL/kg/m, p = .002). Oxygen cost was significantly less (11% versus 20% above that of normal walking) with the half-inch shoe-lift (mean difference between I1/2" and I = .0167 +/- .0138mL/kg/m, p = .002). Similarly, oxygen cost was significantly less (12% versus 20% above that of normal walking) with the one-inch shoe-lift (mean difference between I1"L and I = .0142 +/- .0116, p = .002). CONCLUSION This study demonstrates that a subject with an immobilized knee requires less energy to walk with a contralateral shoe-lift and provides scientific evidence for prescribing a shoe-lift in patients with an immobilized knee as a result of knee joint fusion, knee immobilization as a result of casting or orthotics, or spastic paretic stiff-legged gait associated with upper motor neuron disease.