[Biological response following alloplastic replacement of the anterior cruciate ligament with PET-ribbon (Trevira hochfest)].

A total of 97 cruciate ligament prostheses were implanted in 70 patients following acute and chronic cruciate ligament rupture; the average life of these prostheses being 3 years (8-53 months), 5 (5.15%) were removed due to failure after a mean of 9 (3-15) months. In 67 cases of chronic cruciate instability, 60 anterior and 7 posterior Trevira cruciate ligament prostheses were implanted, and 25 acute anterior and five acute posterior cruciate ligament ruptures were also treated with Trevira ligaments augmentations. The follow-up rate of patients with Trevira cruciate ligament repair was 97%. Of the explanted polyethylene-terephthalate (PET) devices, 4 had intra-articular ruptures at the bone tunnel entry and 1 had become unstable with no dislocation of staples. Investigation by scanning electron and light microscopy showed no bony ingrowth of the Trevira ligaments. Instead there was fibrous tissue ingrowth in all parts of the prostheses (intra-articular, bone tunnels and anchoring regions). The extent of foreign-body reaction at the Trevira ligament boundary differed with the intensity of mechanical strain at the three parts of the implants (intra-articular, bone tunnel, periosteum). Inflammatory cells and foreign-body giant cells were abundant close to the site of ligament rupture at the intra-articular entries of the bone tunnels. These cells were scarce at the intra-articular parts of the ligament prostheses and at the periosteal anchor points. Evaluation of the reasons for prosthetic ligament failure shows that (1) nonideal placement of bone tunnels and (2) inadequate strain during rehabilitation resulted in instability and rupture after anterior cruciate replacement with Trevira ligaments.