Complications with hydroxyapatite particulate separation in total hip arthroplasty

Area of Science:

• Biomaterials science
• Orthopedic surgery
• Histopathology

Background:

• Hydroxyapatite (HA)-coated implants are used in orthopedic surgery.
• Osteolysis, a common complication, can occur around these implants.
• Analysis of retrieved implants and surrounding tissue is crucial for understanding implant performance and complications.

Purpose of the Study:

• To analyze retrieved hydroxyapatite (HA)-coated implants and associated periprosthetic tissue.
• To investigate the presence and nature of particles and inflammation in cases of osteolysis.
• To correlate histological findings with implant material analysis.

Main Methods:

• Clinical retrieval of HA-coated implants from patients diagnosed with osteolysis.
• Semiquantitative histological grading of periprosthetic tissue.
• Back-scattered electron (BSE) imaging and elemental analysis of implant components and tissue.
• Distinguishing HA particles from bone chips using morphology and gray level differences.

Main Results:

• Osteolysis was present in five patients with HA-coated stems.
• Histological analysis revealed Grade 3+ presence of HA, polyethylene, and metal particles in osteolytic regions.
• Inflammatory cells were also present at Grade 3+ in these regions.
• HA particulate was identified within the polyethylene inserts using BSE and elemental analysis.

Conclusions:

• The presence of HA, polyethylene, and metal particles, along with inflammation, is associated with osteolysis in HA-coated implants.
• HA particulate can be found within the polyethylene inserts of retrieved implants.
• Careful follow-up is recommended for patients with HA-coated orthopedic devices.