Abstract
Revision THA is guaranteed to throw some light on the question of longevity of implants. This study takes a fresh look at the materials that we have used in 30 years of joint replacement.
We studied four consecutive revision arthroplasties performed in one week. Patient 1 was a 55-year-old woman who in 1994 received a titanium-backed acetabular cup with virgin HDP insert and an alumina femoral head on a titanium stem. Polyethylene osteolysis was obvious and histological assessment confirmed the presence of polyethylene granulomata. Patient 2 was a 28-year-old man who had bilateral ceramic-on-ceramic hip replacements 18 and 19 years previously. The prosthesis on the left became loose and showed a typical alumina-ceramic problem. Patient 3 was a 51-year-old woman with stage-III polyethylene disease after 19 years. Substantial granulomata were seen on histological sections. Patient 4, a 52-year-old woman, had received a gamma cross-linked cup and stainless steel head 22 years previously. She presented with dislocation but no tribological problems. There was no wear and interfaces were perfect.
These four cases highlight the importance of proper selection of tribological materials. Polyethylene disease was an important cause of medium-term or late failure and acrylic debris was only a secondary problem. Literature reports on titanium metallosis seem over-rated, but titanium performance is questionable with cement. Finally, cross-linking of ultra-high molecular weight polyethylene is a simple, cheap and effective way of enhancing long-term performance in joint replacement surgery.
Secretary: Dr H.J.S. Colyn, Editor: Professor M.B.E. Sweet. Correspondence should be addressed to SAOA, Box 47363, Parklands, Johannesburg, 2121, South Africa.
