Shoulder replacement generally consists of humeral and glenoid components. The humeral component is made of metal. Various metals including stainless steel, tantalum, titanium, vanadium, cobalt, chromium, tungsten, nickel, and molybdenum have all been tested and now are used mainly as alloys developed to resist corrosion and fatigue. All metals and alloys appear the same on radiographs.
Most glenoid components are now made of polyethylene or metal with a polyethylene surface. Polyethylene is an ultrahigh molecular weight polymer and is the same material used for ski bottoms, runners on snow mobiles, and cutting boards.
Polymers may also be used in the form of polymethylmethacrylate cement for fixation.
Total shoulder arthroplasty with polyethylene glenoid component (below left) and press-fit humeral stem (below right).
Close-up shows roughened surface coating below head to promote bone in-growth.