Table 2b.

Cumulative reoperation rate with 95% confidence intervals presented by age classification and fracture type

Age group Fracture type Time, years	No. at risk	Cumulative events	CRR (95% CI)
< 50 years
Undisplaced femoral neck fracture (n = 133)
1	133	0	0 (0–0)
2	113	1	0.8 (0.0–2.4)
3	77	1	0.8 (0.0–2.4)
4	52	3	3.6 (0.0–7.7)
5	32	3	3.6 (0.0–7.7)
Displaced femoral neck fracture (n = 159)
1	153	6	3.8 (0.8–6.7)
2	97	19	13 (7.3–18)
3	67	25	19 (12–26)
4	42	28	23 (15–31)
5	20	28	23 (15–31)
50–59 years
Undisplaced femoral neck fracture (n = 274)
1	250	12	4.5 (2.0–6.9)
2	189	20	7.7 (4.4–11)
3	120	24	10 (6.1–14)
4	82	24	10 (6.1–14)
5	41	24	10 (6.1–14)
Displaced femoral neck fracture (n = 230)
1	192	29	13 (8.5–17)
2	132	44	21 (15–26)
3	94	48	23 (17–29)
4	69	50	25 (19–31)
5	44	51	26 (20–33)

CRR: cumulative reoperation rate.