Proposal for a histopathological consensus classification of the periprosthetic interface membrane

Area of Science:

• Orthopaedic Surgery
• Histopathology
• Biomaterials Science

Background:

• Periprosthetic membranes are common in total joint arthroplasty revision surgery.
• Standardized evaluation criteria for these membranes are lacking.
• Understanding membrane types is crucial for diagnosing prosthetic device loosening.

Purpose of the Study:

• To introduce clearly defined histopathological criteria for standardized evaluation of periprosthetic membranes.
• To classify periprosthetic membranes into distinct types based on histomorphological features.
• To assess the utility of this classification in understanding prosthetic device loosening.

Main Methods:

• Histomorphological analysis of 370 periprosthetic membranes from revision surgeries.
• Defined four types: wear particle-induced (Type I), infectious (Type II), combined (Type III), and indeterminate (Type IV).
• Correlated histopathological findings with microbiological diagnoses and assessed inter-observer reproducibility.

Main Results:

• Type I (wear particle-induced) was most frequent (54.3%), followed by Type II (infectious, 19.7%).
• Type IV (indeterminate) represented 15.4% of cases, indicating non-infectious, non-particle-induced loosening.
• High correlation (89.7%) between histopathological and microbiological diagnoses and sufficient inter-observer reproducibility (85%).

Conclusions:

• The proposed classification provides a standardized method for typing periprosthetic membranes.
• This classification can serve as a tool for further research into the pathogenesis of total joint replacement loosening.
• The study underscores the clinical significance of Type IV membranes in prosthetic device loosening.