Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with a doctor.
Without the ability to examine and obtain a history, I cannot tell you what the exact cause of the symptoms is. However I will try to provide you with some useful information.
The symptoms you are describing are consistent with a sensorimotor neuropathy, meaning that both the sensation and motor nerves have been affected. Although I have not done the EMG, the impression supports this finding too.
Patients with neuropathy often have symptoms of hypersensitivity, pain, numbness, tight band sensation in the affected areas.
This neuropathy followed your TKR so it is possible the nerve was injured at some point during the surgery. The EMG notes that it is an “axonal” neuropathy. An axon is a nerve fiber which carries signal to and fro from the foot to the spinal cord. When an an axon is damaged, it can take a long time to heal.
What can help during this period is physical therapy and use of braces/supportive materials if you have anything like a foot drop. Also certain medications like gabapentin are good for pain/discomfort from neuropathic causes. I would recommend seeing a neurologist and getting physical therapy for that leg.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.