Evaluation of multiphase implants for repair of focal osteochondral defects in goats

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.