The use of biodegradable scaffolds for articular cartilage repair has been
investigated by numerous researchers. The objective of this screening study
was to examine how the mechanical and physical properties of four multipha
se implants can affect the cartilage healing response. Multiphase implant p
rototypes were prepared using poly(D,L)lactide-co-glycolide as the base mat
erial. PGA fibers (FR), 45S5 Bioglass(R) (BG) and medical grade calcium sul
fate (MGCS) were used as additives to vary stiffness and chemical propertie
s. Osteochondral defects (3 mm dia. and 4 mm in depth) were created bilater
ally in the medial femoral condyle thigh-weight bearing) and the distal med
ial portion of the patellar groove (low-weight bearing) of 16 Spanish goats
. Half of the implants were loaded with autologous costochondral chondrocyt
es. Defect sites (total n = 64, 4 sites/treatment) were randomly treated an
d allowed to heal for 16 weeks, fully weight bearing. At euthanasia, gross
evaluations and biomechanical testing were conducted. Histological sections
of the defect sites were stained with H and E, Safranin O/Fast Green or pr
ocessed to analyze collagen architecture. Sections were semi-quantitatively
scored for repair tissue structure. Qualitative evaluations showed that al
l groups had a high percentage of hyaline cartilage and good bony restorati
on, with new tissue integrating well with the native cartilage. Gross and h
istology scoring indicated a significantly higher score for defect healing
in the condyle than in the patellar groove, but no difference in heating fo
r implant types or addition/omission of cells was found. This investigation
demonstrates that focal, osteochondral defects in caprine distal femurs tr
eated with various implant constructs were repaired with hyaline-like carti
lage and good underlying bone. The multiphase implants show potential for t
reatment of osteochondral defects and long-term studies need to be undertak
en to confirm the longevity of the regenerated tissue. (C) 2000 Elsevier Sc
ience Ltd. All rights reserved.