Summary
Our experience of ACL revision in 39 Patient after primary LARS ligament implantation has shown, that revision is much more difficult than it is after autologous ACL reconstruction and should be performed as a two-stage revision.
Abstract
Introduction
The LARS (Ligament Advanced Reinforcement System) ligament replacement for the anterior cruciate ligament (ACL) has been available as an artificial graft since the 1980s. It consists of a highly inert polyethylene terephthalate.
According to the manufacturer, the LARS ligament should have the following advantages: immediate stability and strength, superior tissue ingrowth into the free-fibre design, faster recovery by eliminating donor site morbidity, minimized iatrogenic injury, by smaller tunnel diameters.
Considering the long-term results after LARS ligament implantation, revision rates between 27.5% and 15,4% are reported.
In general, the following disadvantages have been described in the literature: chronic synovitis, recurrent effusions, cross-infections, instability, tunnel osteolysis and breakage are some of them.
Looking at the fact, that more than a quarter of the cases are expected to be revised after 10 years, it is clear that the revision of ACL reconstructions with LARS ligament is a relevant issue in everyday clinical practice.
Methods
From 2008 to 2018, 39 patients were revised at our clinic after a failed ACL reconstruction with LARS ligament. Revision reasons were: insufficiencies, recurrent effusions, lag of ROM, or persistent pain. As a result of our experience with these 39 revision surgeries, we would like to provide a short guide for everyday clinical practice.
Results
As a standard procedure, a native X-ray image (full length weightbearing, anteroposterior view and lateral view), a CT and MRI was performed preoperatively to plan the surgical procedure and to document concomitant pathologies. We recommend exact analysis of the failure reason. In our study group almost all cases had shown the use of the artificial ligament as the main failure reason. Our standardized procedure always involves a two stage revision. In the first session, the screw and graft removal is performed arthroscopically. After inspecting and refreshing the tibial drill canal, we were filling it with iliac crest cancellous bone. Intraoperatively taken tissue samples revealed in 80% of our cases a synovitis with giant cell granuloma in histology. All patients showed a ligament insufficiency without traumatically rerupture. The second session, with the reconstruction of the ACL, was performed after a prior CT inspection. ACL reconstruction was performed at the earliest, 6 months after first session. We used hamstrings, or quadriceps tendon as transplant by default. If necessary we also did a lateral tenodeses modified by Lemaire.
Difficulties were again and again the complete removal of the artificial ligament, as well as the massively widened drill channels. To counteract these two problems in the best possible way, we recommend a two-stage revision.
Conclusion
In conclusion, the revision after primary LARS ligament implantation is much more difficult than it is after autologous ACL reconstruction. In our study group we found a revision rate of almost 100%. Because of that fact, in our opinion, there is no primary indication to use LARS ligament for ACL reconstructions. Our experience has shown, that after a careful revision, with a sufficient time between first and second session, comparable results to primary ACL reconstruction can be achieved.