Histologic findings of periprosthetic tissues retrieved during revision of cementless hip arthroplasties

The authors evaluated the histological findings from periprosthetic material retrieved around acetabular and femoral components of 24 revision operations from 24 patients who had previously received cementless total hip arthroplasty or hemiarthroplasty. The indication for revision was aseptic loosening in 20 patients, technical error during implantation in two patients, periprosthetic femoral fracture with subsequent loosening in one patient, and traumatic socket breakage with component loosening in one patient. The histologic picture of the material retrieved in all cases was similar and was not related to the kind of the prosthesis. It was characterized by early appearance of a newly formed synovial-like membrane that appeared 3 months after hip implantation independently from loosening and not of any particular component. Ossification within the newly formed hip capsule was shown in one third of the revised cases. In all hips, metal debris deposition was observed 3 months after hip implantation. The amount of metal deposits in periprosthetic tissue was dependent on the degree of radiological component loosening and the time lapsed from the last implantation. Periprosthetic granulomatous tissue caused by polyethylene fiber debris and ceramic wear particles were observed in patients presenting with advanced loosening. This investigation showed that periprosthetic osteolysis and bone resorption around cementless acetabular and femoral components most likely are related to periprosthetic tissues contaminated with particles from implant materials caused either by wear or corrosion and resulting in a foreign body reaction that begins in the early postoperative period. Based on the findings of this study, the authors believe that the mechanism of aseptic loosening in cementless hip arthroplasties begins soon after implantation independently from the kind of the prosthesis, associated clinical symptoms, and radiological signs of loosening. Additionally, this study showed that the histologic picture and the course of loosening following hip arthroplasty does not depend on the diagnosis for implantation or the type of cementless prosthesis, but solely on the material of which the prosthesis is composed and the time lapsed from implantation.