Introduction

Total hip replacement (THR) is highly effective in reducing pain and improving mobility in dogs with hip osteoarthritis (OA). In humans, THR longevity is often limited implant wear, osteolysis and aseptic loosening, but the significance of these processes in dogs remains controversial.

Objectives

The goal of this case study was to document a detailed retrieval analysis on a THR implant after 9 years of active in vivo service.

Methods

A spayed female Catahoula Mix (6.5 years, 29 kg) with severe hip dysplasia underwent left cemented (CFX, BioMedtrix LLC) total hip replacement. The routine post-operative rehabilitation period was followed by annual radiographic rechecks and the owner recorded the dog’s activity with a pedometer. The dog was euthanised for reasons unrelated to the THR and tissues were submitted for retrieval analysis (histological analysis of periprosthetic tissues and tribological analysis of the acetabular cup and femoral head). Data from the implanted components were compared with age­ matched, non-implanted implants.

Results

After an uneventful recovery, the dog returned to an active lifestyle after surgery, running over 9000 miles on the operated hip. Profilometry revealed excellent congruency between cup and femoral head, although the surfaces of both components were rougher than those of the non-implanted implants. The femoral head exhibited small scratches only. On histology, there was excellent preservation of the stem-cement and cement­bone interfaces.

Conclusions

Cemented THR implants can provide a robust, long-term solution for dogs with hip OA. Retrieval studies produce objective data to support or refute the safety and long­term performance of current and novel implant systems.