Long Term Functional Outcomes after Total Ankle Arthroplasty

Abstract

Category: Ankle; Ankle Arthritis; Hindfoot Introduction/Purpose: In vivo gait analysis is the objective functional measurement compared to subjective patient-reported outcomes. Intermediate-term gait studies showed positive results of Total Ankle Arthroplasty (TAA). To date, there are no published Long-Term functional outcomes of TAA. Methods: Three-dimensional gait analysis with twelve-camera digital-motion capture system and double force plates recorded temporal-spatial (TS), kinematic (KM), and kinetic (KN) measures, in 33 patients who had STAR (28) or Salto Talaris (5) TAA, done pre-operatively and at intervals post-operatively, with last testing at a mean of 7.6 years. Almost half the patients had 8-13 year follow up. Results: Improvements were found in multiple gait parameters, with TS increases in cadence, (+9.5 steps/min; P <0.001), step length (+4.4 cm; P = 0.001) and walking speed (+0.2 m/s; P<0.001), KM increases in total ROM (+2.0 deg; P = 0.026), plantarflexion at initial contact (+2.7 deg; P=0.004), and maximum plantarflexion (+2.0 deg; P=0.049), and KN analysis showed no loss of ankle power, despite patients’ aging. When examining 15 patients with 8 to 13 year follow-up (mean 10.3 years), there were gains in cadence (+9.8 steps/min, p=0.003), step length (3.6 cm, p=0.024), and walking speed (0.17 m/s, p=0.003), and preservation of the increased sagittal ROM of 2.0 deg. The only difference between prostheses was increased dorsiflexion at initial contact in the STARs vs SALTOs (5.9 degrees, p=0.014). Conclusion: This is the first study to report long-term, objective, functional outcomes of TAA, as measured by 3-D digital gait analysis. Even at a decade or more after TAA, patients had sustained improvement in multiple, objective parameters of gait compared to their preoperative function.