The purpose was to explore whether there were any pathological characteristics of the end-stage osteoarthritic sclerotic lesion that have potential to participate in cartilage repair. Specimens harvested following total knee surgery were examined for gross pathology including staining with Safranin O. Multiple small sections of the lesion were placed in tissue culture for 6 weeks. Gross examination and photographic documentation was made at 3 and 6 weeks. At 6 weeks the specimens from culture were subject to histological examination. The pathology of the end-stage osteoarthritic lesion showed sclerotic bone, dead osteons, hypervascularity and scattered cartilaginous aggregates. Additional observations showed multiple pitting on the sclerotic surface, which histologically was related to three events; fragmentation of dead bone, ruptured blood vessels, and eroded aggregates. There were no pathological or biological changes in the specimens following the time in tissue culture. The in-depth pathological evaluation showed the end-stage osteoarthritic lesion to have certain features with potential to facilitate cartilage repair. The cartilaginous aggregates may be a participant in cartilage repair following surgery. The cartilaginous aggregates remained unchanged in the tissue culture absent the normal synovial joint chemical and physical environment and therefore further testing with a different experimental model would be necessary to establish these aggregates as a source of cartilage regeneration. The multiple small depressions in this lesion may have potential to be a "home" for therapeutics.
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