Abstract
INTRODUCTION:
One common surgical treatment of even early OA is the implantation of a Total Joint Arthroplasty. In case of younger patients this procedure is questionable. The present study investigates the behaviour of a new silk derived scaffold supplied by Orthox Ltd. (Abingdon, UK) in an in vivo sheep model. This scaffold allows replacing the damaged areas with a resurfacing technique and will avoid the implantation of a total joint in cases of early OA.
METHODS:
The scaffolds where derived from silk fibres by processing into a composite of an open porous matrix in combination with a fibres mash with the same material and covered with a smooth surface. During the process the fluid silk can be casted in any shape. Eight sheep (4 ± 1 years) underwent a surgery where a large defect (2×1 cm) was created in the weight bearing zone of the medial condylus followed by implantation of a scaffold. The unoperated contra lateral stifle joint served as control.
After six months the animals were sacrificed and the joints inspected for inflammation. The Young's modulus of the cartilage and scaffold was determined by indentation or confined compression tests. All tissues were fixed in formaldehyde for histology. The data were analysed by a Wilcoxon and Mann-Whitney-U-test. The roughness of the smooth surface was measured. Synovial fluid was harvested by punction before opening the joint and analysed for particle wear debris and for any signs of inflammation.
RESULTS:
The sheep were free of lameness between the 2nd and latest the 4th days p.o. The macroscopic analysis of the genual region and the synovial membrane showed no signs of inflammation. The findings were confirmed by histological sections of synovial membrane and scaffold. In histology, amorphous material fibroblast-like cell clusters and connective bone tissue formation was visible inside the pores of the scaffold. The scaffols were complety integrated into the underlying bone. Synovial fluid showed no signs of inflammation only the IL6 level was slightly increased. No wear particles were found. No defetcs or mayor damage of the oponend cartilage were present.
The measured roughness was between 13–18 nm.
DISCUSSION & CONCLUSIONS:
The presented silk scaffold withstood the loads occurring during the six months implantation period. It showed very promising properties concerning biocompatibility and cartilage protection Its mechanical properties were simmilar of those of the surrounding cartilage. Since the material can be casted into any shape it offers a wide potential use in any large joint of the human body. The production of real patient specific implants will be easy to achieve.
