INTERRELATIONSHIPS OF CLINICAL OUTCOME, LENGTH OF RESECTION, AND ENERGY-COST OF WALKING AFTER PROSTHETIC KNEE REPLACEMENT FOLLOWING RESECTION OF A MALIGNANT-TUMOR OF THE DISTAL ASPECT OF THE FEMUR
A. Kawai et al., INTERRELATIONSHIPS OF CLINICAL OUTCOME, LENGTH OF RESECTION, AND ENERGY-COST OF WALKING AFTER PROSTHETIC KNEE REPLACEMENT FOLLOWING RESECTION OF A MALIGNANT-TUMOR OF THE DISTAL ASPECT OF THE FEMUR, Journal of bone and joint surgery. American volume, 80A(6), 1998, pp. 822-831
The relationships between the functional scope according to the system
of the International Society of Limb Salvage, the extent of resection
, energy cost of walking, and gait characteristics were studied in thi
rty-six patients who had had segmental knee replacement after resectio
n of a malignant tumor of the distal aspect of the femur. The mean fre
e-walking velocity was 62.3 meters per minute (79 per cent of normal),
which was a result of decreases in both cadence and stride length. Th
e mean nea energy cost during walking was 35 per cent greater than tha
t of normal controls and correlated with the percentage of the femur t
hat had been resected. All patients had decreased single-limb support
time on the affected side compared with the unaffected side. There was
a weak correlation between the asymmetry of the single-limb support t
ime and the percentage of the femur that had been resected. The mean e
xtensor torque of the affected knee was 30 per cent that of the unaffe
cted knee when one head of the quadriceps muscle had been excised, 19
per cent when two heads had been excised, 4 per cent when three heads
had been excised, and 1 per cent wheal four heads had been excised. Th
e patients who had had an extra-articular resection had lower mean ext
ensor and flexor torques at the knee compared with those who had had a
n intra-articular resection. The asymmetry of the single-limb support
time was inversely related to the residual extensor and flexor torques
. The overall score according to the system of the International Socie
ty of Limb Salvage ranged from 17 to 29 points (mean, 24.6 points; 82
per cent of normal). The net energy cost, percentage of maximum aerobi
c capacity, and asymmetry of the single-limb support time had signific
ant negative correlations with the overall functional score. Multivari
ate analysis showed that the overall functional score anal the percent
age of the femur that had been resected were the two most important fa
ctors that predicted the net energy cost, pb our knowledge, this is th
e first objective validation of the functional score according to the
system of the International Society of Limb Salvage. As the wet energy
cost can be predicted from universally available, inexpensive measure
s, investigators can easily use it as a clinical and research tool to
evaluate prosthetic performance and to assess operative outcome.