Surgeons from the New York University Hospital for Joint Diseases report on the results of an uncemented stem hip replacement. A customized lateral flare cementless femoral stem was used in 35 young patients. Patients were followed for at least five years. Some were reexamined up to 12 years later.
The authors report excellent results with this type of hip replacement in a younger age group. All patients were younger than 55 years old. Other studies report high rates of mechanical failure with cemented implants. Loosening and reaction to the cement were major problems.
As a result, changes were made in the shape and design of the femoral stem to eliminate the use of cement. A grit-blasted and coated upper surface of the implant gives a surface that bone can adhere to and grow around. The lower part of the stem down inside the femur (thigh bone) is smooth with large grooves. The design of this part of the stem helps limit contact with bone.
There was a low rate of infection and loosening of the lateral flare stem used in this study. This was a positive finding in favor of uncemented stems for younger, active patients. It is proposed that the lateral flare (wider at the top along the outside edge) helps reduce the load on the bone when standing on the leg.