Abstract
One of the ironies in modern technology for arthroplasty is the stress shielding in cementless stems. The aim of the development of cementless stems had been reduction of stress shielding which cement stems are not free from. In healthy femur, trabecula start form the femoral head and reach at both medial and lateral cortex in rather narrow area around lesser trochanter. So the load from the femoral head is transferred at the level on both medial and lateral side. Cement stems should have binding to the cortical bone from collar to the tip of the stem where the cement interlays, and then the load is transferred gradually from the tip to the collar, which means mild stress shielding. When distal bonding is removed, the load could be transferred as normal femur. This should have been one of the biggest requests for cementless stem. But in realty many cementless stems have difficulty to obtain a load transfer at the level like normal femur.
Since 1990, we have been mainly using lateral flare stems to obtain contact on both medial and lateral side at proximal level. In the present study, different types and length of the designs were compared by 3-Dimensional fill, 3-Dimensional fit and Finite Element Analysis.
Materials and Methods
Stems from DJO: Revelation Standard, Revelation Short, and Linear stems were inserted into patients' canal geometries. Three-D fill and 3-D fit which were reported ISTA2009 and stress transfer were observed by FEA.
Results
The closest fit and fill were observed Revelation Short and Revelation Standard then Linear. The most proximal load transfer was observed Revelation Short, followed by Revelation Standard then Linear.
