12-year survival analysis of 322 Hintegra total ankle arthroplasties from an independent center

Figures & data

Figure 1. The center of the tibial plateau was determined by drawing a circle within the medial and lateral cortex. A second circle fit inside the distal tibia between the medial and lateral cortex and touched the plafond distally. The mechanical axis goes through both the center of the distal tibia and the center of the talus. A line marking the tibial plateau/distal tibial component intersected the mechanical axis for the medial distal tibial (MDTA; small arch) angle. The medial talus (large arch) angle was measured from a transecting line, tracing the superior talus/talar component. An angle above 90° is a valgus angle and below 90° is a varus angle.

Figure 2. Markings to calculate the anterior distal tibial angle tibial plateau/distal tibial component (ADTA; green arch). For tibial axis, see Figure 1.

Figure 3. Flow chart.

Table 1. 322 total ankle arthroplasties (TTAs) distributed among 8 different surgeons and subsequent revision surgeries, 13 unknowns

Surgeon	1	2	3	4	5	6	7	8	Unknown
Years active	2008–2014	2005–2010	2014–2016	2006–2016	2010–2016	2004–2011	2007–2016	2012	2003–2007
Primary TAAs	21	11	14	117	67	38	40	1	13
Revision, n	1	4	0	11	11	23	3	1	6

Figure 4. Kaplan–Meier plot of the survival rates of generation 2 and generation 3.

Table 2. The Cox proportional hazard multivariate analysis of risk for revision

Factor	Hazard ratio (95% CI)
Male sex	1.10 (0.50–2.4)
Age	0.98 (0.95–1.0)
Generation 3	0.56 (0.23–1.3)
Post-trauma	1.23 (0.48–3.2)
Post-infection	1.26 (0.10–22)
Rheumatoid arthritis	1.26 (0.31–5.1)
Angle pre-Hintegra (per 1°)
MDTA	1.05 (0.95–1.2)
Medial talus angle	0.95 (0.90–1.0)
ADTA	1.01 (0.94–1.1)
Angle post-Hintegra (per 1°)
MDTA	0.84 (0.72–0.98)
Medial talus angle	1.02 (0.90–1.2)
ADTA	1.04 (0.93–1.2)

The Cox proportional hazard multivariate analysis shows changes in risk for revision when the variable is increased by 1 unit. When the MDTA and medial talus variable are increased by 1° it means that the ankle goes towards a valgus position. Whether it results in an increase or reduction of the risk depends on the hazard ratio size; if this is less than 1, there is a reduced risk and if it is more than 1, it is an increased risk. MDTA = medial distal tibial angle, ADTA = anterior distal tibial angle.