Abstract
Introduction
Surgeons are often confronted with large amounts of bone loss during the revision of total hip prostheses. Regularly, porous metals are applied to reconstruct the missing bone. Rapid and extensive bone infiltration into the implant's pores is essential to obtain strong and durable biological fixation. Today, specialised layered manufacturing techniques provide the flexibility to produce custom-made metallic implants with a personalized external shape and a well-controlled internal network of interconnected pores. In this study, bone ingrowth in porous titanium structures that were manufactured by selective laser melting (SLM) was evaluated in an in vivo goat model.
Methods
Cylindrical Ti6Al4V constructs (Ø8mm × 14mm, porosity 75%) with or without hydroxyapatite coating were implanted in six Saanen goats. Three holes were drilled in the subchondral bone of each tibia and femur. Constructs were inserted into the holes in a press-fit manner. Resonance frequency analysis was used to measure construct stability. At 3, 6 and 9 weeks after surgery, fluorochrome labels were injected. After 6 and 12 weeks, samples were explanted. Some samples were scanned with micro-CT and subsequently sectioned for histological analysis. The others were used for pull-out tests.
Results
Resonance frequency analysis indicated a noticeable increase in implant stability. Evaluation of micro-CT and histological data showed bone ingrowth for all goats at 6 and 12 weeks. Most bone ingrowth occurred during the first 6 weeks, which was followed by a slight increase between week 6 and 12. Fluorochrome labeling confirmed these results. Pull-out tests showed an increased fixation at the bone-implant interface.
Conclusion
Porous titanium structures manufactured by SLM have good osseointegration characteristics. As custom-made bone augments, they provide a promising approach to the reconstruction of severe bone defects.
