First consideration of how to prevent stress shielding. The cup is snap-fitted onto the stem, and held by a detachable ring to prevent displacement during cementing. Preparation of the acetabulum and the femur. Cementing of stem. Introduction of cement into the acetabulum, followed by reduction of the femoral component complete with snap-on cup into the acetabulum.
Ring prevents tilting of cup during cementing.
After curing of the cement, the ring is removed. Long-stem THR, designed to cope with the frequent migration into varus of the stems previously used. The Tory-Bloc prosthesis. Unlike the others in this collection, this is a trunnion-type prosthesis, with an additional joint between the head and the neck. Early failures due to wear and trunnion breakage.