Biocompatibility and ingrowth of Trevira prostheses following replacement of the cruciate ligaments.

Five of 97 cruciate ligament prostheses (5.15 per cent) implanted for an average of 3 years (8-53 months) in 70 patients with acute chronic cruciate ligament instability were removed due to failure after a mean of 9 (3-15) months. Investigation of the explanted polyethylene terephthalate (PET)-grafts by scanning electron and light microscopy showed not bony but fibrous tissue ingrowth in all parts of the prostheses. The extent of local host response in the interface region differed with the intensity of mechanical strain at the three parts of the prostheses (intra-articular, bone tunnel, cortical). Inflammatory cells and foreign body giant cells were abundant close to the rupture sites at the intra-articular entries of the bone tunnels and scarce at the intra-articular part of the prostheses and at the cortical anchoring. Evaluation of the reasons for early prostheses failure indicates that (1) non-ideal placement of bone tunnels and (2) inadequate strain were responsible for reoccurring instability and rupture after prosthetic cruciate ligament replacement.