Biologic response to hydroxylapatite-coated titanium hips. A preliminary study in dogs

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Veterinary Medicine

Background:

• Ti-6A1-4V alloy is a common material for femoral endoprostheses.
• Bone ingrowth and implant stability are critical for successful joint replacement.
• Hydroxylapatite (HA) coating is investigated to improve osseointegration.

Purpose of the Study:

• To evaluate the effect of HA coating on Ti-6A1-4V femoral endoprostheses in a canine model.
• To compare bone apposition and implant stability between HA-coated and uncoated implants with porous or grooved surfaces.

Main Methods:

• Adult dogs (n=12) received unilateral hemiarthroplasties with HA-coated or uncoated Ti-6A1-4V femoral stems.
• Implants featured porous titanium or grooved macrotexture with or without HA coating.
• Histological analysis was performed at intervals up to 52 weeks.

Main Results:

• HA-coated grooved implants showed extensive direct bone apposition by 5 weeks; uncoated grooved implants showed none by 10 weeks.
• Bone ingrowth in uncoated porous implants was similar to HA-coated porous implants by 6-10 weeks.
• All HA-coated implants exhibited consistent bone apposition without fibrous tissue, and no coating deterioration or separation was observed.

Conclusions:

• Hydroxylapatite coating significantly enhances early bone apposition and integration of Ti-6A1-4V femoral implants.
• HA coating promotes a stable, well-integrated implant interface without compromising coating integrity.
• These findings support the use of HA coatings to improve outcomes in femoral endoprostheses.