Survivorship of rough-surfaced threaded acetabular cups. 382 consecutive primary Zweymüller cups followed for 0.2-12 years.

We studied prospectively 382 cementless (Zweymüller stem) and hybrid (cemented stem) primary total hip replacements and used a cementless grit-blasted titanium alloy threaded cup. After a median 5 (0.2-12) year follow-up, 1 cup was exchanged, 2 cups were removed for deep sepsis, and 3 cups showed definite loosening; of these, 2 subsequently required revision. Actuarial calculation methods indicated a 10-year survivorship of 99% with cup retrieval for any cause (clinical failure), definite cup-loosening (radiographic failure), and revision for aseptic cup-loosening as endpoints. These intermediate results exceed those from smooth-surfaced screw rings and compare favorably with those from cemented cups and cementless, press-fit, metal-backed cups.