A modular transdermal assembly configured to couple an external prosthetic device to a bone stump. The assembly includes a modular transdermal portion and a bone fixator. The modular transdermal portion includes an interface portion configured to couple with the external prosthetic device. The bone fixator is configured to be secured to the bone stump and couple with the modular transdermal portion to retain the modular transdermal portion relative to the bone stump.