Background: Fresh osteochondral allograft transplantation is a
well-established technique for the treatment of cartilage defects of the knee.
It is believed that the basic paradigm of the technique is that the
transplantation of viable chondrocytes maintains the articular cartilage
matrix over time. Allograft tissue is typically transplanted up to forty-two
days after the death of the donor, but it is unknown how the conditions and
duration of storage affect the properties of fresh human osteochondral
allografts. This study examined the quality of human allograft cartilage as a
function of storage for a duration of one, seven, fourteen, and twenty-eight
days. We hypothesized that chondrocyte viability, chondrocyte metabolic
activity, and the biochemical and biomechanical properties of articular
cartilage would remain unchanged after storage for twenty-eight days.
Methods: Sixty osteochondral plugs were harvested from ten fresh
human femoral condyles within forty-eight hours after the death of the donor
and were stored in culture medium at 4°C. At one, seven, fourteen, and
twenty-eight days after harvest, the osteochondral plugs were analyzed for (1)
viability and viable cell density by confocal microscopy, (2) proteoglycan
synthesis by quantification of 35SO4 incorporation, (3)
glycosaminoglycan content, (4) indentation stiffness, (5) compressive modulus
and hydraulic permeability by static and dynamic compression testing, and (6)
tensile modulus by equilibrium tensile testing.
Results: Chondrocyte viability and viable cell density remained
unchanged after storage for seven and fourteen days (p > 0.7) and then
declined at twenty-eight days (p < 0.001). Proteoglycan synthesis remained
unchanged at seven days (p > 0.1) and then declined at fourteen days (p
< 0.01) and twenty-eight days (p < 0.001). No significant differences
were detected in glycosaminoglycan content (p > 0.8), indentation stiffness
(p > 0.4), compressive modulus (p > 0.05), permeability (p > 0.3), or
equilibrium tensile modulus after storage for twenty-eight days (p >
Conclusions: These data demonstrate that fresh human osteochondral
allograft tissue stored for more than fourteen days undergoes significant
decreases in chondrocyte viability, viable cell density, and metabolic
activity, with preservation of glycosaminoglycan content and biomechanical
properties. The cartilage matrix is preserved during storage for twenty-eight
days, but the chondrocytes necessary to maintain the matrix after
transplantation decreased over that time-period.
Clinical Relevance: Fresh osteochondral allografting is well
established and increasingly used, but little information is available about
the changes in the tissue that occur during storage over a period of time.
Surgeons who perform fresh osteochondral allograft transplantation should
understand the consequences of prolonged storage on the quality of the