Etiopathogenesis of osteolytic cysts associated with total ankle arthroplasty, a histological study.

BACKGROUND

Osteolytic cyst formation after total ankle arthroplasty has been identified in recent years and is probably an important problem with longer follow-up. The aim of this study is to describe the outcome of a histological analysis of samples from periprosthetic intra-osseous cysts and joint capsules, retrieved during revision surgery after primary total ankle arthroplasty.

METHODS

All samples (n=22) were analyzed and scored using a semi-quantitative grading system. The main items of interest were polyethylene (PE) particles, metal particles, histiocytes, and giant cells.

RESULTS

All cyst samples contained PE particles. A similar number of PE particles were found in talar and tibial cysts. No significant correlation between the number of PE particles and time to reoperation was found. Metal particles were found in 16 cysts.

CONCLUSIONS

We suggest that PE particles are not the primary cause of osteolytic cyst formation but a secondary contributing factor probably accelerating the process of osteolysis. It is likely that implant design, biomechanical factors and local anatomic-physiological factors play an important role.