The main purpose of this paper is to demonstrate the capability to optimize the design of a previously developed prototype of instrumented knee implant. The proposed implant may postoperatively provide the clinician with significant information about the coronal and sagittal instabilities during normal walking without the need to be powered from an external source of electrical energy. The possibility to use the piezoceramics as energy harvesters, in addition to their use as instability sensors, within this implant has previously been investigated by means of theoretical modeling and experimental trials. The implant's design will be optimized in order to meet the sealing and lifespan requirements in addition to the increasing needs of generated energy. This optimization can also be made in such a manner that a moment-based approach can be used instead of the proposed Center-of-Pressure based approach to assess the ligament balance.