Thank you for your query at DoctorSpring.com
I sincerely apologize for the late reply.
In such cases it will be better to remove the calcaneus and other bone talus and make a flap of heel skin.
Your surgeon knows well about this technique .With this a good planter flap will form and even he may walk on this amputee stump alone.The prosthetic foot also can be made over this.
Hope this will help you.
Feel free to discuss further,