The histomorphologic and morphometric study of asymptomatic hip arthroplasty. A postmortem study.

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Histopathology

Background:

• Total hip replacement (THR) success relies on long-term implant stability.
• Understanding the tissue response at the bone-cement interface is crucial for improving THR longevity.
• Previous studies often focused on failed THR cases, leaving gaps in knowledge regarding successful implant interfaces.

Purpose of the Study:

• To investigate the histologic characteristics of the bone-cement interface in asymptomatic, successful total hip replacements (THR) retrieved post-mortem.
• To correlate specific histologic findings with clinical and radiological success criteria.
• To elucidate the tissue response to cemented THR prostheses in a successful cohort.

Main Methods:

• Histomorphometric analysis of retrieved cemented THR specimens from 12 patients (14 hips) with a mean implantation time of 4.7 years.
• Evaluation of the membrane at the bone-cement interface.
• Assessment of histiocyte density, polyethylene particle presence, and membrane thickness.

Main Results:

• A fibrohistiocytic membrane was consistently observed at the bone-cement interface in successful THRs.
• Histiocyte density correlated positively with membrane thickness, polyethylene particle load, and duration of implantation.
• The observed membrane characteristics were similar to those reported in literature for loose THR cases.

Conclusions:

• Even in successful, asymptomatic total hip replacements, a fibrohistiocytic membrane forms at the bone-cement interface.
• The findings suggest that particle-induced inflammation, characterized by histiocyte accumulation, occurs even in the absence of clinical loosening.
• This study provides insights into transcellular particle transportation mechanisms in response to THR endoprostheses.