SYNTHETIC IMPLANTS FOR THE REPAIR OF OSTEOCHONDRAL DEFECTS OF THE MEDIAL FEMORAL CONDYLE - A BIOMECHANICAL AND HISTOLOGICAL-EVALUATION IN THE RABBIT KNEE
K. Messner et J. Gillquist, SYNTHETIC IMPLANTS FOR THE REPAIR OF OSTEOCHONDRAL DEFECTS OF THE MEDIAL FEMORAL CONDYLE - A BIOMECHANICAL AND HISTOLOGICAL-EVALUATION IN THE RABBIT KNEE, Biomaterials, 14(7), 1993, pp. 513-521
Polyurethane-coated and uncoated polytetrafluoroethylene (PTFE) (Teflo
n(R)) and polyester (Dacron(R)) felts were used for repair of full-thi
ckness cartilage defects in the rabbit knee. At 3 months the indentati
on characteristics and the histological appearance of the repairs were
compared with those of a sham-operation, natural repair, and perioste
al grafting. Joint compressive load-displacement and indentation chara
cteristics of the cartilage adjacent to the defect were normal for all
alternatives. All the repair sites had a higher compliance than had n
ormal cartilage-bone, but synthetic grafting had values closer to norm
al than periosteal grafting. The adjacent cartilage appeared macroscop
ically normal, except with periosteal grafting and coated PTFE implant
s where it showed surface irregularities in some cases. With periostea
l and uncoated synthetic implants the defects were completely filled,
but not in the natural repair sites. Most of the coated implants faile
d by separation within the implant. On histological examination, ingro
wth of trabecular bone from the base of the defect into the synthetic
material was seen in all the specimens. The neocartilage 'score' was e
qually low with all the repairs reaching only one-third of the maximum
points. All the repairs were associated with synovitis. Further, some
of the knees with the synthetic materials repair had debris particles
in the synovium. We conclude that none of the biological resurfacing
techniques described achieved normal articular cartilage characteristi
cs at 3 months, although the compliance of the repair site was closer
to normal with synthetic than with periosteal grafting.