It will, of course, be apparent to those of ordinary skill in the art that the devices, materials and techniques disclosed herein may be useful for other types of implants and orthopedic surgeries. [0026] As shown in FIGS. 3-5, a first exemplary embodiment of the present invention is a constraining ring 24 adapted to be mounted on a distal end of the acetabular shell 10 (see FIG. 5) for maintainin