Comparison of Head Center Position and Screw Fixation Options Between a Jumbo Cup and an Offset Center of Rotation Cup in Revision Total Hip Arthroplasty: A Computer Simulation Study.

Jumbo acetabular cups are commonly used in revision total hip arthroplasty (THA). A straightforward reaming technique is used which is similar to primary THA. However, jumbo cups may also be associated with hip center elevation, limited screw fixation options, and anterior soft tissue impingement.

Do jumbo cups cause hip center elevation in revision THA? A computer simulation.

Background: Acetabular revision THA with use of a large (jumbo) cup is an effective treatment for many cavitary and segmental peripheral bone defects. However, the jumbo cup may result in elevation of the hip center and protrusion through the anterior acetabular wall as a result of the oversized geometry of the jumbo cup compared with the physiologic acetabulum.

Questions/purposes: The purpose of this computer simulation was to determine how much elevation of the hip center and anterior wall protrusion occurs in revision THA with use of a jumbo cup technique in which the inferior edge of the jumbo cup is placed at the inferior acetabular rim and the superior edge of the jumbo cup is placed against host bone at the superior margin of a posterosuperior bone defect.

The addition of a hydroxyapatite coating changes the immediate postoperative stability of a plasma-sprayed femoral stem.

Nonbiologic and mechanical effects of hydroxyapatite coatings have received little evaluation. Hydroxyapatite coatings give porous metal the appearance of decreased roughness. We hypothesized that this apparent decrease in surface roughness would result in diminished initial implant stability.