Page 200 - Demo

Chapter 7198They examined the use of β-tricalcium phosphate (β-TCP) as a matrix material for seeding and which specific osteogenic cells can improve osteoinductivity. They found that in the group where the β-TCP cylinders were mixed with BMA mixed with crushed bone, the β-TCP is largely replaced with osseous tissue and the cylinder becomes hard and inflexible. The use of venous blood or solely BMA results in significantly less or even no bone formation. They concluded that the combined use of cancellous bone and BMA provides the best results for in vivo heterotopic bone regeneration.(30) Mommaerts applied this technique in humans but one of the downsides to BMA usage is that it is an expensive procedure.(7) One of our goals was to exclude the use of MSCs and bone marrow aspirate (BMA) at the scaffold site, to evaluate if it has any merit over only using autologous grounded bone, to establish a reconnection of the enthesis.While all three factors for bone regeneration and integration were mostly provided, only two of the sheep had radiological bone formation that was up against the scaffold. There was no formation of soft tissue in between the scaffold and the enthesis. Three sheep had a connection that was both soft tissue and bony. A first remark that has to be made concerning these findings, is the spherical hindrance by the UHMWPE part of the fossa during surgery. While the height was reduced, there was still some difficulty as to achieve proper positioning of the LPM enthesis. Due to the height and width, other than in its human counterpart, it was not always possible to evaluate if the fixation of the enthesis was directly against the scaffold, forming a potential cause for non-integration. Furthermore, in addition to creating an optimal environment for osteogenesis, implant stability is also important. Pilliar et al.(31) and Burke et al.(32) found that movement between the bone and the implant should be less than 28 µm for bone ingrowth to occur. Fibrous tissue can form if movement is more than 150 µm, especially when repetitive micromotion occurs. During orthopedic surgery, large compressive forces are applied to achieve good fixation to prevent the forces to which the implant is exposed to during post-operative loading from exceeding the forces necessary to dislodge the implant. The amount of stability can be increased by increasing surface roughness and the total contact surface Nikolas de Meurechy NW.indd 198 05-06-2024 10:14