RIMODELLAMENTO PERIPROTESICO NEGLI STELI NON CEMENTATI AD ANCORAGGIO DIAFISARIO NELL PROTESI DA RESEZIONE

From 1983 to 1992, at the 'Rizzoli' Institute, 311 resection megaprostheses for lower limb tumoral resections were implanted. During the first five years the prostheses were of the KMFTR type and thereafter of the HMRS type. To obtain a homogeneous population we selected 93 patients with distal femur megaprostheses of the KMFTR type (constrained and uncemented). There were 53 males and 40 females, with ages ranging from 11 to 69 years (mean 23) that underwent resection for a malignant (80 cases) or a beingn tumor (13 cases). The cortical remodelling observed around the stem was classified after 3 and 5 years of follow-up according to 5 types: A) no change; B) reactive sclerosis; C) local osteoporosis; D) bifasic reaction: apical sclerosis and osteoporosis at the base of the stem; F) bone atrophy. We found no correlation between diaphyseal bone remodelling and age of patients, chemotherapy, lenght of resection and stem diameter. We observed correlation between number of screws used for anchorage and quality of remodelling: the stems fixed with 4-6 screws showed more C, D, E types of remodelling than those with 3 or less screws, in which there was more type A remodelling. Finally there was no correlation between radiographic findings and functional results evaluated according to Enneking's classification.