Table 1.

Knee retrieval series

Insert type	Number of retrievals			In vivo duration (months)
	Total	Ti tray	CoCr tray	Median	Range
Sigma® RP
Curved (CR)	27		27	37	0.4–109
PS	67		67	34	2–124
Total RPs	94		94	36	0.4–124
Sigma® fixed bearing Ti trays
Posterior lipped (CR)	19	19		72	10–164
Curved (CR)	85	85		90	6–179
PS	77	77		76	2–164
Total Ti tray	181	181		81	2–179
Sigma® fixed bearing CoCr trays
Posterior lipped (CR)	4		4	12	4–24
Curved (CR)	12		12	16	5–25
PS	21		21	24	4–47
Total CoCr tray	37		37	17	4–47
Total fixed bearing	218	181	37	72	2–179

Ti = titanium; CoCr = cobalt-chrome; RP = rotating platform; CR = cruciate retaining; PS = posterior stabilized.