Impacted corticocancellous allografts: recoil and strength

Bone allografts were morcellized using 2 different milling machines (Tracer milling machine and Howex milling machine) producing bone chips with different ranges of sizes. In an in vitro model, each type of bone-graft was impacted with 2 different impaction forces. As the impaction force was released, there was a substantial and rapid recoil of the graft bed. More recoil was seen with the smaller chips and with the harder impacted graft beds. Most of the recoil occurred within the first 10 seconds. Using another similar in vitro model, the same 2 kinds of chips were impacted with 2 different impaction forces, and the subsidence of the 4 different graft beds was measured. There was less subsidence with the bigger type of bone chips and less with the harder impacted graft beds.