The returned graft was received and inspected.Two segments were found inside the bio-hazards bags: a full length segment with gds attached, and a short delaminated graft segment.The initial examination revealed that the cover layer of the short graft segment was completely delaminated and separated off the wrapped base graft layer.The delaminated segment measured approximately 7cm in length, while the returned graft measured 38cm in length, excluding gds.Both returned graft segments didn't exhibit any ingrowth of biological tissues, except for a few blood spots on the delaminated segment.Two test samples were then trimmed of the long graft segment and tested for mechanical strength.One test sample was taken from the end of the graft, while the second test sample was taken from the center.The radial tensile strength (rts) and the suture retention strength (srt) were evaluated on these two test samples.The average rts test result of two test samples, which were taken from end and the center of the graft, was 66.87 lbf, while the average srt value was 1.347 lbf.According to product specifications of the graft, the minimum rts value is 60 lbf, while the minimum srt value is 0.6 lbf.Engineering summary/conclusion: the sst graft is a tri-laminate graft.The third layer, which is the cover, is a thin material applied over a wrapped base graft layer.The three layers form a graft with an average wall thickness of 0.011".The internal investigation did not reveal the root cause of the delamination.The device history record and manufacturing process steps of this lot were reviewed and there were no discrepancies found.The rts and srt tests conducted on the returned graft indicated the graft met the required mechanical specifications.
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