The successful biological fixation of uncemented implants depends on friction between the porous structure and bone. If used, screws can provide the short-term minimization of stress and micromotion to allow for long-term fixation via biological f ixation. Screws have been shown to provide adjunctive fixation to uncemented acetabular components, and constructs consisting of screws and acetabular shells have demonstrated clinical success. However, traditional screw fixation relies on compression to provide fixation of the shell within the acetabular cavity.
For these challenging acetabular revision cases, Smith+Nephew has developed the REDAPT™ Revision Acetabular System with a variable angle locking feature incorporated in the screw holes. This locking feature can be used with traditional non-locking screws to provide compression to the acetabular shell within the cavity, and in conjunction with newly designed REDAPT™ Locking Screws which interface with the tabs in the locking feature and lock the shell in place. The REDAPT™ Locking Screw does not rely solely on compression into bone for fixation as is the case with traditional screws. Instead, it provides a rigid construct when interfaced with the locking feature of the acetabular shell.