The Synovial-Like Membrane at the Bone-Cement Interface

ABSTRACT: The membrane present at the bone-cement interface was retrieved from twenty patients with a loose, non-septic failed total hip replacement at a site clearly remote from the pseudocapsule that re-formed postoperatively. The orientation of the mem-brane was carefully marked to identify the surface in contact with cement. The membrane was studied his-tologically, histochemically, by cell culture, by organ culture, and by assessment of its ability to synthesize prostaglandin E3 and collagenase. This membrane, rather than being a nondescript so-called fibrous membrane, has the histological and histochemical characteristics of a synovial-like lining. The synovial-like cells are adjacent to the cement layer. Deep to them macrophages predominate. Infiamma-tory cells are absent. Cell cultures of this membrane contain stellate cells similar to those found in cell cul-tures of normal and rheumatoid synovial tissue. This membrane has the capacity to produce large amounts of prostaglandin E2 and collagenase. CLINICAL RELEVANCE: This transformation of tissue at the bone-cement interface in patients with a non-septic, loose total hip component to a synovial-like tis-sue with the capacity to generate prostaglandin E.2 and collagenase may explain the progressive lysis of bon