Project Details
Projekt
The Graft Monitor: An in-vivo load sensor for anterior cruciate ligament reconstruction - development and rigorous validation.
Subject Area
Measurement Systems
Orthopaedics, Traumatology, Reconstructive Surgery
Orthopaedics, Traumatology, Reconstructive Surgery
Term
since 2025
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 567431050
Background: Currently, there is no possibility to measure the in-vivo load of an anterior cruciate ligament (ACL) reconstruction without significant limitations. One idea to overcome these limitations would be to integration a load sensor in the suspension fixation button of an ACL reconstruction (Graft Monitor). Such a sensor could set the stage for clinical studies to evaluate and improve the early rehabilitation and healing phase of ACL reconstructions. Aim of this project: The overall aim of the present research project is the development and rigorous biomechanical validation of a prototype of such a load sensor femoral suspension device for ACL reconstruction. Methods: To achieve this goal, a prototype of the Graft Monitor will be developed (development phase). A preliminary finite element analysis shows that carbon fibre reinforced polyether ether ketone (PEEK) has similar structural properties to titanium and can therefore be used as a biocompatible base for the graft monitor. To transmit the force, a dielectric and a coil will also be integrated into the graft monitor. A material testing of these three components will be carried out in the first work program (WP1). The development of a mobile readout device, which can send data to a personal computer or smartphone, will be the subject of WP2. The graft monitor will then be calibrated in a temperature range of 36-41° using a material testing machine between 0 and 600N corresponding to the published forces acting during gait(WP3). In the validation phase, the structural properties (load to failure in N) of the graft monitor will be compared with a standard ACL suspension device button (Endobutton, Smith & Nephew) (WP4). The accuracy of the Graft Monitor will then be compared to the material testing machine in the laboratory (WP5). It is aimed to achieve an interclass correlation coefficient of 0.8. The final validation work program (WP6) includes the in-vitro testing of the Graft Monitor using a six-degree of freedom robotic setup with a force/torque sensor in cadaveric knee joints. An ACL reconstruction with quadrupled semitendinosus tendon will be performed and the data from the Graft Monitor is compared with the data of a calibrated force sensor. An interclass correlation coefficient of 0.8 will be aimed for this WP. Due to the low-cost production of the prototype (3D printing), potential weaknesses can be quickly assessed and eliminated by returning to the development phase of this project. Results and conclusion: At the end of this project, a validated in-vitro prototype of the graft monitor should have been developed. Future projects include complex biomechanical validation and the evaluation of an in-vivo application. The data will be published in open access publications wherever possible.
DFG Programme
Research Grants
