Table 3.

The prevalence of metal allergy in 327 patients who underwent primary TKA and/or revision surgery. Values are n (%) and (95% CI)

	Operated once once	Reviseda (n = 32)	Revised once (n = 24)	Revised 2 or more times (n = 8)	ORa	p-value
Metal allergy b	46 (16) (12–20)	4 (13) (5–28)	2 (8) (2–26)	2 (25) (7–59)	0.8 (0.3–2)	1
Nickel allergy	37 (13) (9–17)	2 (6) (2–20)	2 (8) (2–26)	0 (0)	0.5 (0.1–2)	0.05
Cobalt allergy	8 (3) (1–6)	1 (3) (1–16)	0	1 (13) (2–47)	1.2 (0.1–9.6)	1
Chromium allergy	12 (4) (2–7)	2 (6) (2–20)	0	2 (25) (7–59)	1.5 (0.3–7)	0.06

^aFor comparison of cases without revision and those with any revisions (chi-square test). Fisher’s exact test was used when the expected frequency in one of the cells was lower than 5.

^bMetal allergy was defined as a positive patch test reaction to nickel, cobalt, or chromium.

OR: odds ratio.