Mechanical Properties Of A Knee Trochlear Implant
Focal chondral defects of the knee develop in hyaline cartilage when subjected to repetitive overloading or impact trauma. The degeneration of the articular surface results in joint pain and stiffness during daily activities such as walking. In most cases palliative non-invasive treatments can be used to alleviate pain; however, more severe lesions require restorative or replacement surgical interventions to repair the damaged cartilage. The use of a novel pyrolytic carbon knee trochlear implant aims to eliminate the aforementioned orthopedic pain by providing a focal replacement of lesions in the patellar sulcus. Pyrolytic carbon was the selected material due to its superior wear properties, mechanical strength, and biocompatibility. The purpose of this study was to develop a verified computational simulation in Abaqus to evaluate the experienced tensile stress of six different pyrolytic carbon trochlear implants undergoing two different physiologically relevant load conditions. This data was compared to an experimental conjugate study to provide insight into the implants strength. Regions of peak maximum principal stress were observed to be at the medial fillet and sulcus groove when undergoing a single- or two-point loading condition, respectively. The magnitude of tensile stress in the medial fillet was 2-3 times of that experienced at the sulcus groove. These findings reflected experimental data in which trochlear implants failed at either the medial fillet or sulcus groove during their respective loading conditions. Verified simulations allowed for computational testing of a modified implant and calculations of expected critical fracture loads.