Patent ID: 8512339

Claim:
In a fixation system adapted for securing bone members together having: a bearing for securing a first bone fastener in an adjusted angular position in a spherical hole in a plate in which the bone fastener can be respectively secured to a first bone member, said plate being adapted for being respectively secured by a second bone fastener to a second bone member, and thereby secure the bone members together by their respective first and second bone fasteners, said bearing having an outer spherical surface adapted to rotate in the hole in said plate, said bearing having a bore in which the first bone fastener is inserted and can be angularly adjusted by rotation of the bearing in the hole in the plate, the improvement according to which said bearing has upper and lower ends and a surface extending from said upper to said lower end which includes a spherical surface and is provided with a plurality of circumferentially spaced slots therein, each said slot extending from one end of the bearing partially along the length of the bearing towards the other end of the bearing, said slot extending from its one end along the length of the bearing past an equator of the bearing towards its other end for enabling radial expansion of the bearing when the first bone fastener is advanced in the bore in the bearing to produce non-uniform contact between the bearing and the hole in the plate and wherein the slots are so constructed and arranged in the bearing to secure the bearing in the plate and develop non-colinear reactive forces between the surface of the bearing and the surface of the hole in the plate, said first bone fastener having a threaded enlarged portion in threaded engagement with a threaded portion of the bore in the respective bearing when the enlarged portion is threadably advanced in the bore of the bearing to produce expansion of the bearing and engagement of the first bone member with the respective bone, said fixation system comprising a key arrangement between said bearing and the hole in the plate to oppose relative latitudinal rotation therebetween while permitting relative longitudinal rotation therebetween.