We studied the function of twenty-two patients who had had a malignant
skeletal tumor adjacent to the knee. An above-the-knee amputation was done
in seven; a resection arthrodesis, in nine; and a replacement arthroplasty,
in six. The patients all walked at a similar speed (sixty-one to sixty-six
meters per minute), which is slower than normal (eighty meters per minute).
They all walked with comparable efficiency at three velocities: the mean
consumption of oxygen was 0.210 milliliter per kilogram of body weight per
meter at free velocity, 0.215 milliliter per kilogram of body weight per
meter when they walked 25 per cent faster, and 0.211 to 0.240 milliliter
per kilogram of body weight per meter when they walked 50 per cent faster.
The three groups of patients and a normal control group consumed oxygen at
similar rates. The patients who had had an amputation were very active, and
they were the least worried about damaging the affected limb, but they had
difficulty walking on steep, rough, or slippery surfaces. The patients who
had had an arthrodesis had a more stable limb and performed the most
demanding physical work and recreational activities, but they had
difficulty sitting. The patients who had had an arthroplasty led sedentary
lives and were the most protective of the limb, but they were the least
self-conscious about the limb.