This paper presents possible telemetry system architectures to evaluate the collateral ligaments imbalance for post Total Knee Arthroplasty (TKA) scenario. Two metrics are taken into account: the center of pressure and the net moments (varus-valgus and anterior posterior). Digital and analog system architectures are described for the COP metric and some are evaluated using high level models and experimental measurement. The architectures are designed considering that the implanted must be compliant with MICS standard and will be self-powered, implying a power source below 2 mW. In terms of hardware architecture, the paper shows that there is an interest for the analog architecture in terms of surface area and power consumption.