The acetabular cement-bone interface in experimental arthroplasties in dogs

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Histology

Background:

• Clinical loosening of total hip arthroplasty (THA) acetabular components is a concern, particularly in young, active patients and with long follow-up periods.
• Previous evaluations of the cement-bone interface have been limited by small sample sizes and interpretational challenges.

Purpose of the Study:

• To investigate the effects of cement fixation on the acetabular component-bone interface in a canine model of hip surface replacement.

Main Methods:

• Serial observations of 21 dogs undergoing hip surface replacement over 2 to 46 weeks.
• Analysis of acetabular fixation using epoxy-embedded specimens and conventional histologic sections to preserve the cement-bone interface.

Main Results:

• No direct cement-bone contact was observed at two weeks post-surgery.
• A correlation was found between cement fixation adequacy and interface membrane thickness.
• Poor acrylic fixation was associated with thick membranes (up to 2 mm) and horizontal trabeculation, while good cement intrusion resulted in thin membranes (2-3 cells thick).

Conclusions:

• Adequate cement fixation is essential for minimizing interface membrane formation.
• The thickness of the cement-bone interface membrane is a reliable indicator of fixation quality in hip replacements.
• Histological evaluation provides critical insights into the biological response at the acetabular component-bone interface.