| abstract |
A provisional prosthesis used during trial fitting of a bipolar or unipolar joint prosthesis such as a hip acetabular component. The provisional prostheses include an outer provisional shell component having an interior part-spherical surface having an open end with at least one recess extending from said open end into said interior surface. An inner component, such as a head for femoral component, is provided which has a part-spherical outer surface for articulation with respect to the part-spherical inner surface. The outer surface has at least one recess aligned with a polar axis of the inner component and the outer component has an inner surface with at least one recess which can be aligned with a recess on the inner component. A locking assembly, including a pin, is provided which can be inserted into the aligned grooves to rotationally lock the inner and outer components together. In order to keep the inner component from disengaging with the outer component, the outer component has an inner part-spherical surface which extends beyond the equator and the inner component has a flat cord formed around the circumference thereof which has a diameter less than or equal to the diameter of the opening in the outer component so that the head component can be placed inside and rotated and be constrained within the outer component throughout the range-of-motion of the implant. |