Increased risk of revision in patients with non-traumatic femoral head necrosis

Figures & data

Table 1. Patient demographics, type of fixation, and causes of revision

	FHN n, (%)	POA n, (%)
Sex
Male	4,868 (42)	168,847 (41)
Female	6,721 (58)	247,370 (59)
Age
< 50	2,082 (18)	12,102 (2.9)
50–59	2,022 (17)	54,750 (13)
60–69	2,498 (22)	134,634 (32)
70–79	2,863 (24)	156,987 (38)
≥ 80	2,124 (18)	57,744 (14)
Type of fixation
Cup
Cemented	7,550 (65)	284,188 (68)
Uncemented	4,039 (35)	132,029 (32)
Stem
Cemented	7,931 (68)	297,673 (72)
Uncemented	3,658 (32)	118,544 (29)
Causes of revision
Any reason, 2 years	346 (3.0)	7,112 (1.7)
Any reason, 16 years years	805 (6.9)	19,632 (4.7)
Specific reasons, 16 years
Loosening/lysis	317 (2.7)	9,603 (2.3)
Dislocation	207 (1.8)	4,015 (1.0)
Deep infection	121 (1.0)	2,627 (0.6)
Periprosthetic fracture	74 (0.6)	1,249 (0.3)
Other reasons	87 (0.8)	2,174 (0.5)
Not revised	10,784 (93)	396,585 (95)

Mean survival ± 95% CI according to Kaplan-Meier based on revision for any reason (panel A), loosening (B), dislocation (C), infection (D), and periprosthetic fracture (E). Light gray: primary osteoarthritis; dark gray: femoral head necrosis.

Table 2. Relative risk of revision for any reason, from 0 to 2 years and after 2 years

Variable	n	RR	95% CI	p-value
0–2 years
Diagnosis unadjusted
FHN ^a	11,589	1.79	1.61–1.99	< 0.001
Primary OA ^b	416,217	1	1
Diagnosis adjusted
FHN ^a	11,589	1.44	1.34–1.54	< 0.001
Primary OA ^b	416,217	1
Age, years
< 50	14,184	0.73	0.64–0.82	< 0.001
50–59	56,772	0.78	0.72–0.84	< 0.001
60–69	137,132	0.82	0.78–0.87	< 0.001
70–79 ^b	159,850	1
≥ 80	59,868	1.08	1.005–1.16	0.04
Sex
Female ^b	254,091	1
Male	173,715	1.24	1.18–1.30	< 0.001
Cup
Cemented ^b	291,738	1
Uncemented	136,068	1.49	1.39–1.59	< 0.001
Stem
Cemented ^b	305,604	1
Uncemented	122,202	1.46	1.36–1.56	< 0.001
2–16 years
Diagnosis unadjusted
FHN ^a	11,589	1.52	1.38–1.67	< 0.001
Primary OA ^b	416,217	1	1
Diagnosis adjusted
FHN ^a	11,589	1.25	1.14–1.38	< 0.001
Primary OA ^b	416,217	1
Age, years
< 50	14,184	2.37	2.19–2.56	< 0.001
50–59	56,772	1.90	1.80–2.00	< 0.001
60–69	137,132	1.53	1.47–1.60	< 0.001
70–79 ^b	159,850	1
≥ 80	59,868	0.60	0.54–0.65	< 0.001
Sex
Female ^b	254,091	1
Male	173,715	1.27	1.22–1.31	< 0.001
Cup
Cemented ^b	291,738	1
Uncemented	136,068	1.28	1.22–1.34	< 0.001
Stem
Cemented ^b	305,604	1
Uncemented	122,202	0.75	0.71–0.80	< 0.001

^a FHN – Femoral head necrosis

^b Reference category

Table 3. Unadjusted and adjusted relative risk of revision in FHN and POA for any reason up to 2 years, separated into age groups. Adjustment for sex and for cup and stem fixation (risk ratios for covariates are not shown)

Age group/diagnosis	n	RR	95% CI	p-value
Unadjusted
< 50 years
FHN ^a	2,082	1.13	0.97–1.31	0.1
Primary OA ^b	12,108	1
50–59 years
FHN ^a	2,022	1.37	1.18–1.60	< 0.001
Primary OA ^b	54,750	1
60–69 years
FHN ^a	2,498	1.79	1.55–2.06	< 0.001
Primary OA ^b	134,634	1
70–79 years
FHN ^a	2,863	1.56	1.33–1.83	< 0.001
Primary OA ^b	156,987	1
≥ 80 years
FHN ^a	2,124	1.48	1.17–1.86	0.001
Primary OA ^b	57,744	1
Adjusted
< 50 years
FHN ^a	2,082	1.14	0.98–1.33	0.09
Primary OA ^b	12,108	1
50–59 years
FHN ^a	2,022	1.36	1.17–1.59	< 0.001
Primary OA ^b	54,750	1
60–69 years
FHN ^a	2,498	1.84	1.60–2.12	< 0.001
Primary OA ^b	134,634	1
70–79 years
FHN ^a	2,863	1.69	1.44–1.98	< 0.001
Primary OA ^b	156,987	1
≥ 80 years
FHN ^a	2,124	1.63	1.29–2.05	< 0.001
Primary OA ^b	57,744	1

^a FHN – Femoral head necrosis

^b Reference category