Thank you for that introduction, and thank you for having me, Anna. I'm a little bit under weather, so I apologize. Please bear with me. Myself and my co-authors have no relevant disclosures to study. Osteochondralograft transplantation has been performed for many decades to address osteochondral defects. Currently, there is no consensus on recommended dimensions of osteochondral plugs. Some of the proposed benefits of using shorter grafts is decreased recipient site morbidity, decreased immunoreactivity, the acellular cartilage of the grafts do not produce a host immune response, the subchondral bone underneath the cartilaginous surface is known to produce an immunogenic response. This has been linked to graft failure in some studies. Shorter grafts require decreased insertional forces. With decreased cumulative force of insertional impacts, there has been increased surface chondral viability shown. Also, using shorter grafts allow for increased allograft utilization. Some of the concerns of shorter plugs show that majority of resistance to deforming forces believe the rise from the subchondral bone. So using shorter plugs can lead to decreased stability. We also explored pulsatile lavage in the plugs. What are the proposed benefits of lavage grafts? Decreased immunoreactivity has been shown to be associated with pulsatile lavage grafts with less immunogenic subchondral bone. Also, improved host-osteous integration by increasing volume for interaction between the grafts and host has been seen with pulsatile lavage grafts. Some of the concerns of lavage in plugs, what is its effect on stability? Previous studies, as this one shown by Sun et al., show nearly loss of 36 to 55 percent of marrow volume after a 45 to 120 second pulsatile lavage. So previous studies have hypothesized that the majority of plug stability is coming from the subchondral bone. So what happens when you wash out this subchondral bone? The objectives of this study were to identify the minimum depth threshold for osteochondral allografts to resist deforming forces, as well as to investigate the effect of pulsatile lavage on the biomechanical stability of the osteochondral allograft. The methods, 10 grafts of each size of 4 millimeters, 7 millimeters, and 10 millimeters of depth for osteochondral allografts of 15 millimeters in diameter were harvested and implanted to test biomechanical factors. An additional cohort of 10 pulsatile lavage grafts of 7 millimeters of depth and 15 millimeters in diameter were also studied. The plugs were subjected to compressive tests until failure, which was qualified as 2 millimeters of subsidence, or tensile tests until failure, which was a maximal force required for graft pullout. Here are some of our results. For our tensile tests, an ANOVA was performed to really significant differences between our 7 millimeter and 10 millimeter plugs when compared to our 4 millimeter plugs. However, no difference was seen in our 7 millimeter and 10 millimeter plugs. There was a steep drop off when utilizing plugs of lower than 7 millimeters seen in this study. For compressive forces to failure, there were no significant differences seen between the 4 millimeter, 7 millimeter, and 10 millimeter plugs. For pulsatile lavage results, the average force for failure was 199 newtons for our normal group and 205 newtons for a pulsatile lavage group. There were no significant differences in tensile or compressive forces of failure when plugs were pulsatile lavaged. Some of the limitations of this study, only osteochondral allograft plugs of 15 millimeters in diameter were tested. With larger diameter plugs, smaller minimum depth would be anticipated due to increased circumferential contribution to all cross-sectional surface area. Due to prohibitive cost of a human cadaveric study, the pulsatile lavage component of this study was underpowered. Only tensile and compressive tests were evaluated in this study. No novel method was used to test shear stresses which are normally exposed to osteochondral allografts was performed. Conclusions from this study, a large drop off in resistance to tensile forces was seen when osteochondral allografts smaller than seven millimeters were utilized. A similar drop off was not observed between the seven millimeter and 10 millimeter plugs. It appears that seven millimeters is a functional cut off at least for 15 millimeter diameter plugs after which there is not a significant benefit to increasing graft size. Pulsatile lavage of allografts prior to insertion does not appear to take away from the structural integrity and the stability of the plug. Removal of immunogenic subchondral bone does not appear to be detrimental. Thank you.

osteochondral grafts

graft dimensions

shorter grafts

pulsatile lavage

graft stability