Does subchondral bone affect the fate of osteochondral allografts during storage?
BACKGROUND
Osteochondral allografts currently are hypothermically stored for a minimum of 14 days to a maximum of 28 days before surgical implantation, making storage conditions increasingly important. Previous studies have suggested that graft deterioration during storage may result from degradative factors and residual marrow elements in the subchondral bone.


OBJECTIVE
Allografts stored with large bone-to-cartilage ratios will be compromised after prolonged storage compared with grafts with minimal bone.


METHODS
Controlled laboratory study.


METHODS
Osteochondral plugs were harvested from 16 fresh human femoral condyles and randomly assigned to 1 of 3 groups based on bone-to-cartilage ratios: 1:1, 5:1, or 10:1. These ratios were considered on the basis that the 1:1 ratio is the minimum bone necessary to press-fit an allograft and 10:1 is the present ratio used by tissue banks for allograft storage. After 14 and 28 days of storage at 4 degrees C, the specimens were assessed for viability and viable cell density using confocal microscopy, proteoglycan synthesis by (35)SO4 incorporation, and glycosaminoglycan content.


RESULTS
All grafts underwent a significant decline in viable cell density, proteoglycan synthesis, and chondrocyte viability (particularly in the superficial region) after 14 days of storage, but no differences were observed between the 1:1, 5:1, or 10:1 ratio groups at either day 14 or day 28. In addition, no significant difference was noted in the glycosaminoglycan content in any of the groups.


CONCLUSIONS
Osteochondral allografts stored with a 10:1 bone-to-cartilage ratio, similar to tissue-banking ratios, performed no worse than allografts stored with minimal bone, suggesting that the bone-to-cartilage ratio plays little to no role in the degradation of allografts during prolonged storage.


CONCLUSIONS
As the practice of osteochondral allograft resurfacing becomes more commonplace, it is important that surgeons understand the factors that affect graft quality.
Pennock
Andrew T
AT
Department of Orthopaedic Surgery, University of California, San Diego, La Jolla, CA, USA.
Robertson
Catherine M
CM
Wagner
Ferdinand
F
Harwood
Frederick L
FL
Bugbee
William D
WD
Amiel
David
D
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D016025:Bone Transplantation; D002358:Cartilage, Articular / Q000166:cytology / Q000378:metabolism / Q000637:transplantation; D019902:Chondrocytes / Q000502:physiology*; D005269:Femur; D006025:Glycosaminoglycans / Q000378:metabolism; D006801:Humans; D008875:Middle Aged; D011509:Proteoglycans / Q000378:metabolism; D014021:Tissue Preservation / Q000379:methods*; D020858:Tissue and Organ Harvesting / Q000379:methods; D014184:Transplantation, Homologous
D006025:Glycosaminoglycans; D011509:Proteoglycans