Analysis of stored osteochondral allografts at the time of surgical implantation.
BACKGROUND
To date, the morphological, biochemical, and biomechanical characteristics of articular cartilage in osteochondral allografts that have been stored have not been fully described.


OBJECTIVE
Osteochondral allografts procured and stored commercially for a standard period as determined by tissue banking protocol will have compromised chondrocyte viability but preserved extracellular matrix quality.


METHODS
Controlled laboratory study.


METHODS
Unused cartilage from 16 consecutive osteochondral allografts was sampled during surgery after tissue bank processing and storage. Ten grafts were examined for cell viability and viable cell density using confocal microscopy, proteoglycan synthesis via 35SO4 uptake, and glycosaminoglycan content and compared with fresh cadaveric articular cartilage. Biomechanical assessment was performed on the 6 remaining grafts by measuring the indentation stiffness of the cartilage.


RESULTS
The mean storage time for the transplanted specimens was 20.3 +/- 2.9 days. Chondrocyte viability, viable cell density, and 35SO4 uptake were significantly lower in allografts at implantation when compared to fresh, unstored controls, whereas matrix characteristics, specifically glycosaminoglycan content and biomechanical measures, were unchanged. In addition, chondrocyte viability in the stored allografts was preferentially decreased in the superficial zone of cartilage.


CONCLUSIONS
Human osteochondral allografts stored for a standard period (approximately 3 weeks) before implantation undergo decreases in cell viability, especially in the critically important superficial zone, as well as in cell density and metabolic activity, whereas matrix and biomechanical characteristics appear conserved. The exact clinical significance of these findings, however, is unknown, as there are no prospective studies examining clinical outcomes using grafts stored for extended periods.


CONCLUSIONS
Surgeons who perform this procedure should understand the cartilage characteristics of the graft after 21 days of commercial storage in serum-free media.
Allen
R Todd
RT
University of California, San Diego, Department of Orthopaedic Surgery, 9500 Gilman Drive, Mail Code 0630, La Jolla, CA 92093-0630, USA.
Robertson
Catherine M
CM
Pennock
Andrew T
AT
Bugbee
William D
WD
Harwood
Frederick L
FL
Wong
Van W
VW
Chen
Albert C
AC
Sah
Robert L
RL
Amiel
David
D
D002358:Cartilage, Articular; D002470:Cell Survival; D019902:Chondrocytes / Q000502:physiology*; D016895:Culture Media, Serum-Free; D006025:Glycosaminoglycans / Q000032:analysis; D006801:Humans; D013048:Specimen Handling; D014184:Transplantation, Homologous
D016895:Culture Media, Serum-Free; D006025:Glycosaminoglycans