A COMPARISON OF THE DISASSOCIATION STRENGTH OF MODULAR ACETABULAR COMPONENTS

Five short-term in vivo disassembly of two-piece acetabular cup design s have been reported. This study evaluates the liner retention strengt hs of eight contemporary cup systems. Both push-out (663 +/- 65.5 poun ds force to 29 +/- 1.4 pounds force) and lever-out (684 +/- 114 inch-p ounds to 43 +/- 1.5 inch-pounds) test modes show a wide variation in r etention strength. Repeat liner separation testing demonstrates a 26% and 32% respective decrease in locking mechanism integrity. These find ings indicate that reseating modular liners at the time of surgery or reassembling a previously separated liner should be avoided.