This is the first report of surface-active phospholipid as the boundary lubricant in total hip arthroplasty. Aspirate and rinsings from the bearing surfaces of twenty four revisions have been analysed from three weeks to twenty six years postoperatively. All samples contained substantial amounts ranging from 14 to 4186 micrograms. Being a polar molecule, surface active phospholipid organises itself into layers similar to graphite (lamellated-solid lubrication).

These finding indicate that synoviocytes continue to produce the lubricant in significant quantities after arthroplasty surgery independent of the type of joint replacement and its fixation.

Surface-active phospholipid was found on all bearing surfaces analysed including polyethylene, stainless steel, chrome cobalt, Alumina, Zirconia and Titanium.