Complete 180° rotatory dislocation in a mobile-bearing knee prothesis.

Dislocation of the rotator platform in mobile-bearing total knee arthroplasty is a well-documented, albeit uncommon, phenomenon. A review of the literature has revealed multiple case reports describing spin out to 90° or complete extrusion of the polyethylene component. Closed reduction may be attempted in the acute presentation followed by revision if instability persists.

Three- to six-year results with the Ultima metal-on-metal hip articulation for primary total hip arthroplasty.

One hundred seventy-one primary total hip arthroplasties were evaluated in a prospective, randomized study. Ninety-five involved a metal-backed cup with an all-metal liner and 76 involved a metal-backed polyethylene cup that was used as the control. All were implanted with an S-ROM cementless femoral component with a 28 mm head.