Outcome and serum ion determination up to 11 years after implantation of a cemented metal-on-metal hip prosthesis.
OBJECTIVE
Little is known about the long-term outcome of cemented metal-on-metal hip arthroplasties. We evaluated a consecutive series of metal-on-metal polyethylene-backed cemented hip arthroplasties implanted in patients under 60 years of age.


METHODS
109 patients (134 joint replacements) were followed prospectively for mean 9 (7-11) years. The evaluation included clinical score, radiographic assessment, and blood sampling for ion level determination.


RESULTS
At the final review, 12 hips had been revised, mainly because of aseptic loosening of the socket. Using revision for aseptic loosening as the endpoint, the survival rate at 9 years was 91% for the cup and 99% for the stem. In addition, 35 hips showed radiolucent lines at the bone-cement interface of the acetabulum and some were associated with osteolysis. The median serum cobalt and chromium levels were relatively constant over time, and were much higher than the detection level throughout the study period. The cobalt level was 1.5 microg/L 1 year after implantation, and 1.44 microg/L 9 years after implantation.


CONCLUSIONS
Revisions for aseptic loosening and radiographic findings in the sockets led us to halt metal-on-metal-backed polyethylene cemented hip arthroplasty procedures. If the rigidity of the cemented socket is a reason for loosening, excessive release of metal ions and particles may be involved. Further investigations are required to confirm this hypothesis and to determine whether subluxation, microseparation, and hypersensitivity also play a role.
Lazennec
Jean-Yves
JY
Department of Orthopaedic Surgery, Pitie-Salpetriere Hospital, Paris, France.
Boyer
Patrick
P
Poupon
Joel
J
Rousseau
Marc-Antoine
MA
Roy
Carine
C
Ravaud
Philippe
P
Catonné
Yves
Y
D000328:Adult; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods; D002484:Cementation; D002857:Chromium / Q000097:blood; D003035:Cobalt / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008670:Metals / Q000097:blood*; D008875:Middle Aged; D020959:Polyethylene; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012086:Reoperation; D013997:Time Factors; D014025:Titanium / Q000097:blood; D016896:Treatment Outcome
D008670:Metals; D002857:Chromium; D003035:Cobalt; D020959:Polyethylene; D014025:Titanium