The purpose of this study was to evaluate the influence of glenohumeral conformity on interface micromotions in a metal backed glenoid implant. A force controlled experiment was performed in which a metal backed glenoid component with various PE inlay radii was subjected to a simulated joint reaction force. Local interface micromotions, rim displacement and bone substitute deformation were measured using DVRT sensors. All measured variables were significantly larger (p<0.05) in the non-conform inlay with radial mismatch 6 mm, compared to the conform inlay. These findings are contrary to previous reports by other authors who found that a larger mismatch not only reduces interface micromotions but translational forces and bone strains as well. The reason for these contradicting findings is the fact that in the present study a force controlled experiment was performed as opposed to a displacement controlled experiment. A non-conform inlay allows for a larger humeral head translation in the inlay. This causes a larger resultant moment on the metal back that opens the bone-implant interface. It is concluded that as glenohumeral mismatch increases relative micromotions, rim displacements and bone deformations increase, reducing the chance of vital bone ingrowth to occur.