Sixty-six knees (sixty patients) that had had a proximal tibial
osteotomy were evaluated to determine if any alteration of the patellar
height had occurred as a result of the operation. Eighty-nine per cent of
the patellae, as measured by the Insall-Salvati index, and 76.3 per cent,
as measured by the Blackburne-Peel index, were observed to be lowered as
they appeared on the postoperative lateral radiograph. This was probably
due to shortening of the patellar ligament after prolonged immobilization
in a cast, interstitial scarring of the patellar ligament, and new-bone
formation in the area of insertion of the patellar ligament. There was no
correlation between the postoperative height of the patella and the need
for subsequent revision to a total knee replacement.