Modified cementless total coxofemoral prosthesis: development, implantation and clinical evaluation

S.A Arias,H.P Oliveira,J.R.T Blanco,C.M.F Rezende,J.V Doretto,G.L.T Vieira

doi:10.1590/s0102-09352013000600012

Abstract

The aim of this study was to modify canine coxofemoral prostheses and the clinical evaluation of the implantation. Fifteen canine hips and femora of cadavers were used in order to study the surface points of modification in prostheses and develop a perforation guide. Femoral stems and acetabular components were perforated and coated with biphasic calcium phosphate layer. Twelve young adult male mongrel dogs were implanted with coxofemoral prostheses. Six were operated upon and implanted with cemented canine modular hip prostheses, establishing the control group. The remaining six were implanted with a novel design of cementless porous tricalcic phosphate-hydroxyapatite coated hip prostheses. Clinical and orthopedic performance, complications, and thigh muscular hypotrophy were assessed up to the 120th post-operatory day. After 120 days, animals with cementless prostheses had similar clinical and orthopedic performance compared to the cemented group despite the increased pain thigh hypotrophy. Animals that underwent cementless hip prosthesis evidenced more pain, compared to animals with cemented hip prosthesis that required longer recuperation time. No luxations, two fractures and two isquiatic neurapraxies were identified in the course of the study. Using both the cemented and the bioactive coated cementless model were suitable to dogs, showing clinical satisfactory results. Osseointegration and biological fixation were observed in the animals with the modified cementless hip prosthesis.

Highlights

The development of bone-implant permanent fixation mechanisms is a constant challenge in total coxofemoral prosthesis implantation in the dog and human
The implantation of biphasic calcium phosphate coated acetabular component was relatively easier than cemented components and orifices distribution in the cementless components yield good results regarding acetabular cup orientation and fixation
Our study was carried out in dogs and we found that surgery time is, shorter for cementless prosthesis and pain seems to be more severe for cementless than cemented prosthesis

Summary

Introduction

The development of bone-implant permanent fixation mechanisms is a constant challenge in total coxofemoral prosthesis implantation in the dog and human. Prosthesis fixation can be mechanical, biologic or by chemical ligation between the implant and bone. Mechanical fixation can be obtained with either the use of cement or screws (Hanson et al, 2006; Hummel et al, 2010). In biologic fixation the implant is coated with porous material leading to osseous growth inside the pore. A bioactive material (hydroxyapatite, bioglass) is deposited onto prosthesis surface inducing osseous formation (Jasty et al, 1997; Fenollosa et al, 2000; Goyenvalle et al, 2006). Fixation with polymethylmethacrylate (PMMA) cement is the most used in canine hip prostheses and it offers immediate stability to the implant (Massat, 1995; Schulz, 2000)

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