Running-specific prosthesis model, stiffness and height affect biomechanics and asymmetry of athletes with unilateral leg amputations across speeds

Athletes with transtibial amputation (TTA) use running-specific prostheses (RSPs) to run. RSP configuration likely affects the biomechanics of such athletes across speeds. We determined how the use of three RSP models (Catapult, Sprinter and Xtend) with three stiffness categories (recommended, ±1), and three heights (recommended, ±2 cm) affected contact length (L(c)), stance average vertical ground reaction force (F(avg)), step frequency (f(step)) and asymmetry between legs for 10 athletes with unilateral TTA at 3–7 m s(−1). The use of the Xtend versus Catapult RSP decreased L(c) (p = 2.69 × 10(−7)) and F(avg) asymmetry (p = 0.032); the effect on L(c) asymmetry diminished with faster speeds (p = 0.0020). The use of the Sprinter versus Catapult RSP decreased F(avg) asymmetry (p = 7.00 × 10(−5)); this effect was independent of speed (p = 0.90). The use of a stiffer RSP decreased L(c) asymmetry (p ≤ 0.00033); this effect was independent of speed (p ≥ 0.071). The use of a shorter RSP decreased L(c) (p = 5.86 × 10(−6)), F(avg) (p = 8.58 × 10(−6)) and f(step) asymmetry (p = 0.0011); each effect was independent of speed (p ≥ 0.15). To minimize asymmetry, athletes with unilateral TTA should use an Xtend or Sprinter RSP with 2 cm shorter than recommended height and stiffness based on intended speed.