Material Properties of Fresh Cold-stored Allografts for Osteochondral Defects at 1 Year

Abstract

Little is known about the long-term properties of fresh cold-stored osteochondral allograft tissue. We hypothesized fresh cold-stored tissue would yield superior material properties in an in vivo ovine model compared to those using freeze-thawed acellular grafts. In addition, we speculated that a long storage time would yield less successful grafts. We created 10-mm defects in medial femoral condyles of 20 sheep. Defects were reconstructed with allograft plugs stored at 4°C for 1, 14, and 42 days; control specimens were freeze-thawed or defect-only. At 52 weeks, animals were euthanized and retrieved grafts were analyzed for cell viability, gross morphology, histologic grade, and biomechanical and biochemical analysis. Explanted coldstored tissue had superior histologic scores over freezethawed and defect-only grafts. Specimens stored for 1 and 42 days had higher equilibrium moduli and proteoglycan content than freeze-thawed specimens. We observed no difference among any of the cold-stored specimens for chondrocyte viability, histology, equilibrium aggregate modulus, proteoglycan content, or hypotonic swelling. Reconstructing cartilage defects with cold-stored allograft resulted in superior histologic and biomechanical properties compared with acellular freeze-thawed specimens; however, storage time did not appear to be a critical factor in the success of the transplanted allograft.

O uso do transplante osteocondral a fresco no tratamento das lesões osteocondrais do joelho

“…Freezing the joint cartilage leads to chondrocyte cell death and decreases the histological and biomechanical properties of the matrix (14)(15)(16) . Possible causes of incapacity to survive freezing include the small penetration of cryopreservation solutions in the tissue, different freezing speeds of the various layers of the matrix, and the high water content in the extracellular matrix.…”

The use of osteochondral allografts in the management of cartilage defects

“…Current recommendations therefore advise 42 days as the maximum storage period for a fresh allograft [24]. The ideal preservation medium and storage temperature for fresh osteochondral allograft tissue remains controversial [25].…”

Allogenic Serum Improves Cold Preservation of Osteochondral Allografts

“…Although the use of fresh osteochondral allografts initially was limited to a small number of institutions in North America, in 1998, commercial cold-stored osteochondral allografts became available for public use [10]. Unlike traditional fresh allografts, cold-stored specimens are maintained in a hypothermic nutritive medium and must undergo a 14-day sterility testing protocol for donor bacteria and viruses [18]. Currently, improvements of outcomes and function after transplantation of osteochondral allografts stored from 15 to 48 days for treating cartilage defects of the knee have been reported during an average followup of 3 to 4 years [9,23].…”

“…Currently, improvements of outcomes and function after transplantation of osteochondral allografts stored from 15 to 48 days for treating cartilage defects of the knee have been reported during an average followup of 3 to 4 years [9,23]. As articular cartilage matrix in grafted tissues is dependent on chondrocyte metabolism for long-term maintenance, metabolically viable chondrocytes are critical for the functional survival of allografts [6,18]. Therefore, establishing improved solutions that prolong storage periods is needed to increase the availability of higher-quality osteochondral allografts.…”