Twenty-two cases of scoliosis with Harrington-rods broken after operation were treated by rod-sleevemethod. The results of follow-up from 1 year and 3 months to 9 years and 3 months showed that all of thepatients

but one patient occurred Harrington-rod rebroken and one’s fixation being removed because ofback pain in 6 months and 5 years and 11 months after rod-sleeve prpcedure

respectively

had no com-plaints. The author also found that the rod underwent a decrease in cross-sectional area of approximately43. 7 % at the ratchet-shaft junction in experimental study on Harrington-rods

and stress unfairly distribu-tion

stress concentration and cyclic loading producing fatigue in metals were proved to be the main cause ofbroken by mechanical analysis of Harrington-rod loaded in the body. In concluson

the rod-sleeve proce-dure was the effective method to keep from

Ha rrington - reds broken.