10-year survival of total ankle arthroplasties

Figures & data

Table 1. Numbers of ankle prostheses implanted in Sweden annually

Year	STAR	BP	AES	Hintegra	Mobility	CCI	Total
1993	6						6
1994	13						13
1995	11						11
1996	8						8
1997	24						24
1998	34						34
1999	25						25
2000	45	1					46
2001	48						48
2002	40	21	3	10			74
2003	25	23	17	14			79
2004	17	29	16	4			66
2005	18	13	23	2	9		65
2006	7	11	21	6	21		66
2007	1	7	18		20		46
2008		4	17		32	16	69
2009					31	40	71
2010 ^a					19	10	29
Total	322	109	115	36	136	66	780

^a up to June 15

Table 2. Demographic data

	n	% females	Mean age (range)
RA	282	78	56 (18–86)
OA	185	48	62 (30–84)
PtA ^a	266	54	58 (25–86)
Other	47	47	56 (28–74)
All diagnoses	780	61	58 (18–86)

^a posttrauma arthritis.

Table 3. Reasons for revision

	Single-coated	Double-coated
	STAR	STAR	BP	AES	Hintegra	Mobility	CCI	Total
Numbers	117	205	109	115	36	132	66	780
Aseptic loosening	33	16	4	5	3	2	4	67
Technical error	8	8		1	2			19
Instability	1	2	5	8	1	3	1	21
Infection	3	10	1	2	1	2		19
Intractable pain	4	6				1		11
PE breakdown/fracture	7	4	3	1		2		17
Painful varus		2	1	4	1		1	9
Fracture		1	3	1				5
Total	56	49	17	22	8	10	6	168

Figure 1. Estimated cumulative survival and 95% CI for all 780 arthroplasties.

Table 4. Life table

Interval (years)	No. entering the interval	No. of events	Cumulative proportion surviving at the end of the interval	95% CI
0–1	780	46	0.94	0.93–0.95
1–2	674	33	0.89	0.88–0.90
2–3	568	17	0.86	0.85–0.87
3–4	496	15	0.83	0.82–0.84
4–5	434	14	0.81	0.79–0.83
5–6	355	13	0.77	0.75–0.79
6–7	288	8	0.75	0.73–0.77
7–8	219	5	0.73	0.71–0.75
8–9	165	5	0.70	0.68–0.72
9–10	114	2	0.69	0.67–0.71

Figure 2. Estimated cumulative survival for ankles replaced due to rheumatoid arthritis (purple), osteoarthritis (red), and posttraumatic osteoarthritis (green).

Figure 3. Estimated survival for the different designs implanted. The blue curve represents the BP-type designs, the green curve the Hintegra, the purple curve the double-coated STAR, and the red curve the single-coated STAR prostheses.

Table 5. Hazard ratio (HR) of survival rates for different prostheses

Prosthesis	HR	95% CI
BP-type	1	Reference
Hintegra	1.2	0.57–2.5
STAR I (single-coated)	1.7	1.1–2.5
STAR II (double-coated)	1.1	0.75–1.6

Table 6. Time (years) and 95% CI from index surgery to revision

Reason for revision	Mean	95% CI
Valgus malalignment	1.0	0.2–1.8
Infection	1.2	0.6–1.8
Technical error	1.3	0.6–2.0
Fracture	1.4	0.3–3.0
Instability	1.8	0.9–2.7
Loosening tibia	2.5	1.7–3.3
Intractable pain	2.5	1.6–3.4
Varus malalignment	2.9	1.3–4.4
Loosening talus and tibia	5.3	4.0–6.5
PE breakdown/fracture	5.6	3.8–7.5
Loosening talus	7.8	6.3–9.2