Preserving native distal tibial angles in total ankle replacement does not negatively affect implant survival.

BACKGROUND

In total ankle replacement (TAR), the tibial component is positioned at 90° to the tibial axis, although distal tibia angles (DTAs) of healthy ankle joints vary. This study investigated DTA changes during TAR and their impact on prosthesis survival.

METHODS

In this retrospective case series of 152 consecutive third-generation TARs (142 patients), pre- and postoperative lateral and anterior distal tibia angles (LDTA, ADTA) and changes (ΔLDTA, ΔADTA) were measured. Prosthesis survival (all causes) was compared using Hazard ratios (HRs) between patients with and without alterations of native DTAs. Secondly, associations between postoperative alignment and revision, as well as consistency of LDTA measurements between Mortise and Whole Limb views, were evaluated.

RESULTS

Mean follow-up was 6.7 ± 4.5 (0.01-18.4) years. Twenty (13.2%) TARs were revised after an average of 5.4 ± 4.7 years (5-year survival of 86.8%). No correlation was found between DTA alteration and revision for either LDTA (HRs 1.03-2.29, p=0.18-0.98) or ADTA (HRs 1.06-2.28, p=0.23-0.91). No significant differences were observed among change-in-alignment groups. However, in the sagittal plane, a trend was observed favoring maintenance of non-neutral alignment (>3°) over altering ADTAs >3° to neutral. LDTAs measured on the different views appeared comparable (p=0.16).

CONCLUSION

Non-neutral postoperative alignment appeared to have less direct influence on revision rates than previously described. Although no significant association was found between changes in native tibial anatomy and TAR revision rates, this study highlights that surgeons may want to consider native anatomy more closely, rather than adhering to a rigid, neutral manufacturer's approach.