Table 3.

Observed versus expected recurrent hip fractures and standardized incidence ratios (SIR, with 95% confidence interval) among 2434 Olmsted County, Minnesota, residents with a first-ever hip fracture in 1980-2006, by hip fracture type and laterality

Sites of first and second*	Observed	Expected	SIR (95% CI)
Initial femoral neck	122	73.2	1.7 (1.4-2.0)
All ipsilateral recurrences	7	37.5	0.2 (0.1-0.4)
Ipsilateral femoral neck	3	18.9	0.2 (0.03-0.5)
Ipsilateral trochanteric	4	18.6	0.2 (0.1-0.6)
All contralateral recurrences	115	35.7	3.2 (2.7-3.9)
Contralateral femoral neck	79	17.6	4.5 (3.6-5.6)
Contralateral trochanteric	36	18.1	2.0 (1.4-2.8)
Initial trochanteric	94	63.5	1.5 (1.2-1.8)
All ipsilateral recurrences	6	32.4	0.2 (0.1-0.4)
Ipsilateral trochanteric	5	16.3	0.3 (0.1-0.7)
Ipsilateral femoral neck	1	16.1	0.1 (0.01-0.3)
All contralateral recurrences	88	31.1	2.8 (2.3-3.5)
Contralateral trochanteric	64	15.3	4.2 (3.2-5.3)
Contralateral femoral neck	24	15.8	1.5 (0.97-2.3)

^*Excluded from the overall figure for femoral neck fractures are two subsequent hip fractures of unknown site. Also, one initial hip fracture of uncertain site was excluded from this analysis.