AAA Triple A® Component Design Rationale

AAA Triple A® Ankle replacement

"The AAA Triple A® Total Ankle Replacement is based on the principle of separating the multi-axial movements of the human ankle joint by using a three-component design. This prevent increased contact stresses on the interface possibly leading to component loosening and allowing for full range of motion.. (1,2,3)

To cope with one of the major complications in three compartmental TAR designs, instability, (4) the articulation between the polyethylene bearing and the distal surface of the tibial component has been provided a patented oval shaped indentation and the bearing with a spherical dome. This has led to a semi-constrained design . Pre-clincial ankle simulation tests have shown that this does not increase the potential of polyethylene wear of the bearing. To provide sufficient immediate post-operative stability, a condition for bone ingrowth , the stemmed design was selected for the tibial component. The talar implant was designed to allow for milling of the talar bone, rather than cutting the bone into a trapezium shape as done in many other designs. This will reduces the amount of bone removed, leaving all options open in case of revision. Also this allows the AAA Triple A® TAR to be used in many revision cases of current designs.

Design Characteristics

  • Surgical alignment with the full leg length axis

  • Minimal resection by precise, spherical milling of the talus

  • Full stability in extension by congruency between tibia and bearing

  • Unrestricted rotation between tibia and bearing

  • Dorsiflexion and plantarflexion between bearing and talar component with increased lateral stability

The AAA Triple A® Movements

  • Dorsiflexion : 135 degrees

  • Plantarflexion : 20 degrees

  • unlimited axial rotation

Component Sizes and Matching

AAA Triple A® Ankle replacement

TheAAA Triple A ® Total Ankle replacement is available in

  • 5 sizes for the tibial component
  • 4 sizes for the mobile bearing
  • 4 size for the talar component
  • References:

    (1) Buechel FF, Pappas MJ, Iorio LJ: New Jersey low contact stress total ankle replacement: biomechanical rationale and review of 23 cementless cases. Foot Ankle 8(6):279-290, 1988

    (2) Raikin SM, Heim CS, Plaxton NA, Greenwald AS: Mobility Characteristics of Total Ankle Replacements" available at The Orthopaedic Reasearch Laboratories homepage: www.orl-inc.com