Summary

In biomehcnaical set-up focal metallic implants lead to defects of the contralateral cartilage already after 6 hours of exploration time

Abstract

Introduction

In patients older then 45 with focal cartilage defects biological repairs are inappropriate with low reported functional outcome measurements. For this special group of patients, a new focal metallic implant was designed (FMI) (Hemi-CAP Arthrosurface Inc., Franklin, MA, USA). Aim of the present study was to evaluate macroscopic and histological effects of a focal metallic implants (FMI) in regard to the contralateral cartilage.

Methods

A novel designed abrasion test machine, which could simulate cyclic axial load on porcine osteochondral cylinders were used. Two different tribological pairs were tested: Cartilage on cartilage (n=9) for 24, 48 and 72 hours and cartilage on FMI (Hemi-CAP Arthrosurface Inc., Franklin, MA, USA) (n= 12) for 1 and 6 hours in two different test mediums. After the tests the cartilage of each cylinder was macroscopically analysed by ink method. Afterwards specimens were fixed in methyl methacrylate, stained with Giemsa-Eosin and evaluated for cartilage damages. Cartilage defects were classified by affected zone.

Results

In control group tibial cartilage on femoral cartilage were tested without any signs of cartilage damage. Tibial cartilage on FMI for 1 hour loading time showed neither cartilage defect in macroscopical analysis, nor histological. Although 2 out of 3 cartilage cylinders on focal metallic implant in saline were without damage after 6 hours, one cylinder had a defect of the tangential zone. In hyaluronic acid 2 cylinders had a defect of the tangential zone after 6 hours, too. The defect of the third cylinder of this group affected the upper part of the transitional and radial zone.

Conclusion

FMIs could lead to superficial damages to the contralateral cartilage even after 6 hours of exploration time. In present set-up hyaluronic acid had no beneficial effect, with tendency to increased rate of cartilage defects. The novel developed abrasion test machine is suitable to simulate cyclic axial load on cartilage specimen.