Abstract
The aim of this study was to analyze the frequency and reveal the most common reasons of the endoprosthetic instability in patients with malignant bone tumors. From 1992 – 2008, 625/515 patients, endoprosthetic replacement of major joints were performed. The median age of the patients was 30.3 years (13 to 72 years).
Aseptic instability was observed after 3/71(4.2%) humeral joint replacement out of total operations at this location, after 4/80 (5%) hip prosthesis, after 19/133 (14%) proximal tibial prostheses, after 44/299 (14.7%) distal femoral prostheses and after 2/37 (5.4%) total femur replacements.
The retrospective analyses has shown that the reasons of instability were the following: aseptic loosening of the stems of endoprosthesis in 26 cases (24.4%), stem break in 31 (36.1%), endoprosthetic unit destruction in 10 (11.6%), untwistment of fixational screws in 10 (11,6%), migration of hip endoprosthesis components in 2 (2.3%) and endoprosthesis dislocation in 12 (14%). The timing of endoprosthetic instability ranged from 7 days to 12.2 years (average 26.2 months). Statistic analyses was performed in a group of patients with aseptic endoprosthesis instability developed after proximal tibia and distal femur resection.
We conclude that the most frequent reason of aseptic instability was endoprosthetic stem break. The instability rate was actually lower among the patients who had underwent 5–10cm distal tibia resection comparing with the group of 10–15cm bone mass resection (p=0.05). Femoral resection enhanced the instability frequency comparing with proximal tibia resection in the group of 5–10cm bone mass resection (p=0.05).
Correspondence should be addressed to Professor Stefan Bielack, Olgahospital, Klinikum Stuttgart, Bismarkstrasse 8, D-70176 Stuttgart, Germany. Email: s.bielack@klinikum_stuttgart.de
