Biomechanical Inlay Testing of a Cemented Modular Inlay Cup(C-MIC) for Total Hip Arthroplasty in the Elderly

The biomechanical inlay testing of a newly developed modular cemented acetabular component system is under investigation. The aim of this study, was to determine how strong the bondage of the inlay with the metal shell is in in-vitro testing. A Cementable Metal-Cup (C-MIC) was crafted in the commonly used sizes. Its material (cobalt-chromium-molybdenum alloy) was configured to the needs of cementation. For biomechanical inlay testing standard test methods for determining the axial disassembly force of a modular acetabular device were used. Push in/out and Torsion as well as lever-out inlay tests were performed. The mean maximal push-out force for the 28mm inlay was: 1.140 kN; for the 32mm test inlay was 2.483 kN. Mean results for the lever-out torque for test inlay 28 mm were 14.40 Nm, for the test inlay with 32 mm it was 45.93 Nm. The test results for the torsion tests: Inlay 28 mm: 17.545 Nm and 53.252 Nm for test Inlay 32 mm. The results of these biomechanical experiments have proven a high stability for the anchorage of the inlays in this newly developed C-MIC-cup.