engleski

Biomechanical flaws of cutting edge approaches in ACL repair surgery tested on a sheep model

Objectives: Biomechanical importance of ACL lies in bone stabilization, restriction of excessive movement, but also in a contribution to healthy biomechanics of lower extremities and trunk. The once forgotten and almost abandoned ACL primary repair process is emerging, especially by developing new repair techniques. We hypothesized that there are important biomechanical issues of each currently available approach that prevents them to become reliable treatment option. The aim of this study was to perform investigation on a sheep model in order to examine the biomechanical properties of primary ACL repair methods and detection of biomechanical flaws. Methods: By reviewing literature it could be concluded that all state of the art methods have their own biomechanical weak points when performing primary ACL repair. For the purpose of biomechanical testing and analysis of existing solutions, we have simulated currently available methods under the same load and stress conditions in a servo-hydraulic mechanical testing machine. There was 2000 cycle loading protocol. Value of the load force increased from 50 to 200 N. Initially, we tested primary ACL repair. We have used sheep knees with proximally dissected ACL. Three groups, 4 knees each, have been established: 1) fixation with a non-absorbable suture in a bridging fashion fixed at far cortices – “bridging suture” ; 2) fixation with a non- absorbable suture in a bridging fashion with a distally placed spring – “dynamic bridge” and 3) fixation with a 3 end to end non-absorbable sutures. Results: All solutions that present the state of the art solution have shown certain biomechanical defects and flaws, visible through knee destabilization, unsatisfactory point of application of a force, or limiting the elasticity of the ligament itself, limiting the knee joint degree of freedom or producing ligament tear. Interestingly the “bridging suture” group in our study has shown to produce contact stress related wear of the bone at the articular level higher than the “dynamic bridge” group. The group with end to end sutures has shown failure to load in the testing setup. Conclusion: Based on the observed literature, it can be concluded that ACL repair has significant potential to be an alternative to ACL reconstruction. However, the existing new methods can be improved in order to avoid wear of the bone at the level of the joint what is important during the phase of ligament healing.

ACl repair, biomechanical testing, implant, support, experimental testing

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