A 3D printed porous titanium alloy rod with biogenic lamellar configuration for treatment of the early-stage femoral head osteonecrosis in sheep

There is no ideal implant for mechanical strut on early-stage osteonecrosis of the femoral head (ONFH) after core decompression. In this study, a biogenic trabecular porous titanium rod with lamellar configuration was designed and fabricated using selective laser melting technique. Early-stage ONFH of sheep induced by cryo-insult were dealt with core decompression combined with rod insertion (Rod group) and core decompression alone (CD group) after X-ray evaluation was used to assess the necrotic region one months after cryo-intervention. Bone integration and ingrowth of the two groups were investigated and compared. Early-stage ONFH intervened with the rod gained better bone ingrowth than CD 3 and 6 months after the intervention, as evidenced by radiographic, micro-CT and histological evaluation. X-ray images showed compact integration between rods and peripheral bone, evidenced by no radiolucent lines encircling the rods at 3 and 6 months. Micro-CT and histological images showed that the new bone had grown into the centre of rods along the metal at 3 months, whereas the new bone grew mainly at the periphery of the decompressive channel. Micro-CT analysis show that the ratios of bone volume to total volume (BV/TV) of volume of interest (VOI) in Rod group was 890.0% and 438.1% higher than CD group at 3 (0.198 ± 0.0094 VS 0.020 ± 0.0058, p