A retrospective comparative study of mortality and causes of death among patients with metal-on-metal and metal-on-polyethylene total hip prostheses in primary osteoarthritis after a long-term follow-up

Table 1 Number of patients (n) with metal-on-metal or metal-on-polyethylene prostheses stratified by age at operation and number of person-years at risk up to the end of 2005 by age at follow-up.

Age (years)	Metal-on-metal prosthesis		Metal-on-polyethylene prosthesis
	n	Person-years	n	Person-years
20 to 29	2	15.5	4	7.1
30 to 39	6	28.7	16	107.0
40 to 49	25	176.2	55	354.7
50 to 59	145	855.6	291	1800.0
60 to 69	278	2836.3	779	6694.5
70 to 79	113	3898.4	419	10848.2
≥ 80	10	2374.3	21	6595.5
Total	579	10185.1	1585	26406.9

ISSN: 1471-2474