Joint Contact Characteristics in Agility Total Ankle Arthroplasty

Misalignment of Total Ankle Components Can Induce High Joint Contact Pressures

“…Specifically, we investigated component version ranging between ±10°from the manufacturer's recommended implant position and rotations of 5°from the recommended position. When the imposed misalignment caused average contact pressures to increase above levels that have recently been associated with delamination of the polyethylene component (10 MPa) 15 , an intermediate misalignment (half of the previous misalignment magnitude) was simulated.…”

“…The reduced kinematic constraint imposed by threecomponent mobile-bearing designs generally allows improved component congruency over a wider range of motion (thus maximizing contact area) and has been hypothesized to lead to more uniform polyethylene contact pressure distributions 7 . However, few published studies have quantitatively investigated the influence of total ankle replacement geometry on the average and peak contact pressures and distributions on the polyethylene component 15,16 . While joint contact characteristics for various two and three-component total ankle replacement designs have been investigated, sensitivity to implant misalignment as a potentially important factor in premature wear has not been studied, to our knowledge, until now 17 .…”

“…The first of these 15 was in a cadaver model to assess contact characteristics (average contact area, average contact pressure, and peak contact pressure) for the Agility total ankle replacement. The mean peak contact pressures exceeded recommended contact pressures (10 MPa) 15 as well as the compressive yield point for polyethylene (18 to 20 MPa) 18 .…”

“…The first of these 15 was in a cadaver model to assess contact characteristics (average contact area, average contact pressure, and peak contact pressure) for the Agility total ankle replacement. The mean peak contact pressures exceeded recommended contact pressures (10 MPa) 15 as well as the compressive yield point for polyethylene (18 to 20 MPa) 18 . A more recent computational study used the finite element method to simulate a three-component mobile-bearing total ankle replacement (BOX; Finsbury Orthopaedics, Surrey, United Kingdom) over a complete gait cycle 16 .…”

Management of Massive Hindfoot Osteolysis Secondary to Failed INBONE I Total Ankle Replacement

“…In brief, this process involves a macrophage-mediated osteolytic destruction of periprosthetic bone secondary to phagocytosable polyethylene wear debris usually as a result of component malposition. [1][2][3][4][5][6][7][8][9][10][11] Tibial and talar aseptic osteolysis either does or does not involve subsidence of the prosthetic components and component loosening may or may not exist. Regardless of the specific total ankle replacement system used, the bone loss associated with aseptic osteolysis can be quite extensive.…”