An in vitro simulation method for the tribological assessment of complete natural hip joints.

Dawn Groves,Sophie Williams,John Fisher,Alejandro A Espinoza Orías

doi:10.1371/journal.pone.0184226

Abstract

The use of hip joint simulators to evaluate the tribological performance of total hip replacements is widely reported in the literature, however, in vitro simulation studies investigating the tribology of the natural hip joint are limited with heterogeneous methodologies reported. An in vitro simulation system for the complete natural hip joint, enabling the acetabulum and femoral head to be positioned with different orientations whilst maintaining the correct joint centre of rotation, was successfully developed for this study. The efficacy of the simulation system was assessed by testing complete, matched natural porcine hip joints and porcine hip hemiarthroplasty joints in a pendulum friction simulator. The results showed evidence of biphasic lubrication, with a non-linear increase in friction being observed in both groups. Lower overall mean friction factor values in the complete natural joint group that increased at a lower rate over time, suggest that the exudation of fluid and transition to solid phase lubrication occurred more slowly in the complete natural hip joint compared to the hip hemiarthroplasty joint. It is envisaged that this methodology will be used to investigate morphological risk factors for developing hip osteoarthritis, as well as the effectiveness of early interventional treatments for degenerative hip disease.

Highlights

Osteoarthritis (OA) causes pathological degenerative changes that affect the whole joint [1] leading to pain and loss of function [2, 3]
It is hypothesised that tribological studies of complete natural hip joints using in vitro simulations would be of benefit for investigating relationships between hip geometry and degenerative joint disease such as OA, as well as investigating the efficacy of early interventional treatment, which may delay the onset of OA [5,6,7,8]
Complete natural porcine hip joints (n = 5) and porcine hip hemiarthroplasties (n = 5) with a diametral range of 35–37 mm were successfully positioned with the required anatomical orientation and joint centre height, enabling in vitro tribological testing to be conducted in the pendulum friction simulator

Summary

Introduction

Osteoarthritis (OA) causes pathological degenerative changes that affect the whole joint [1] leading to pain and loss of function [2, 3]. Primary total hip replacement (THR) is often used to alleviate the pain and disability caused by advanced OA of the hip, many younger patients require revision surgery after 15–20 years, and outcomes following this procedure are not always as favourable in terms of patient satisfaction and function [2, 4]. It is hypothesised that tribological studies of complete natural hip joints using in vitro simulations would be of benefit for investigating relationships between hip geometry and degenerative joint disease such as OA, as well as investigating the efficacy of early interventional treatment, which may delay the onset of OA [5,6,7,8]. In-vitro simulation of natural hip joints to this study. The specific roles of these authors are articulated in the ‘author contributions’ section

Objectives

Methods

Results

Conclusion