Ceramic Insert Design
Alumina (Al2O3) was selected as the material for the liner based on the history of its clinical use and its excellent wear characteristics when paired with an alumina femoral head. It has been used by the orthopaedic device industry since 1969 and has exhibited excellent biocompatibility.11,12 Most importantly, alumina on alumina articulation couples have demonstrated significantly less wear than THAs involving a polyethylene socket.13
The ceramic LINEAGE® insert and shell are assembled at the time of surgery by impacting the insert into the shell. A self-locating, eighteen degree taper provides a secure method of assembly between the shell and insert. The strength of this shell/insert construct is confirmed by the experimental results.
Shell/Insert Group Sizing Scheme
In order to minimize hospital inventory requirements, LINEAGE® shells and inserts have been designed with a group sizing scheme. Each shell within a grouping uses the same insert. Femoral heads and inserts are available in 28, 32, and 36 mm diameters. Acetabular shells are available with outside diameters in even increments from 46 mm to 68 mm. This information is shown in TABLE 1. Femoral heads are available in three neck lengths.
(OD in mm)
|Group||Femoral Head Sizes
(OD in mm)
|Ceramic Insert Sizes
(ID in mm)
TABLE 1 | LINEAGE® Articulation System Implant Sizing and Grouping Information