Abstract
Introduction
The purpose of this study was to investigate whether combining PRP or concentrated bone marrow aspirate (CBMA) with a biphasic collagen/glycosaminoglycan (CG) scaffold would improve the outcome of the treatment of full thickness osteochondral defects in sheep.
Materials and Methods
Osteochondral defects (5.8×6mm) were created in the medial femoral condyle (MFC) and the lateral trochlea sulcus (LTS) of the stifle joints of 24 sheep. Defects were either left empty or filled with a 6×6mm CG scaffold, either on its own or in combination with PRP or CBMA (n=6). At 6 months the sheep were euthanised, and the repair tissue subjected to mechanical testing, gross morphological analysis, semi quantitative histological scoring and immunohistochemical staining including types I, II and VI collagen.
Results
Degenerative change
Lower degenerative scores were found in the LTS + PRP group at 6 months compared to all other groups (p=0.042).
ICRS gross repair score
A trend towards improved scores was noted with the PRP and CBMA, particularly in the MFC, but no statistical significance was observed.
Mechanical properties
No differences in mechanical properties were observed throughout the four groups.
Histology
No statistically significant improvements in the modified O'Driscoll score were observed. The PRP group exhibited excellent tissue fill of the defects with more characteristics of hyaline cartilage than the other groups.
Immunohistochemistry
Only the PRP defects showed pericellular type VI collagen staining. They also demonstrated a hyaline like appearance with positive type II collagen and reduced positive type I collagen staining, compared to fibrous or fibrocartilage morphology in the other groups.
Discussion
Qualitative improvements in tissue morphology were observed with PRP in combination with the CG scaffolds. Growth factor release from PRP seems to influence the cell phenotype of the osteochondral repair tissue, and may also have a chondroprotective role with regards to perilesional degeneration.
