Susan - has anyone suggested that may be the nerves that were cut, damaged or irritated during surgery healing? Nerves heal VERY slowly -less than one millimeter per day (less than one inch per month) which means a healing process. You can stimulate the nerves and lessen than discomfort - the technique that works may be different for each person.
Hear are some techniques:
Electrical Stimulation - aka TENS
Manual Stimulation - light massage, sometimes using a "bumpy" ball (like a dog toy)
Stroking along the affected area

Many years after hip replacements, I still have a small area in one thigh that is usually numb, but becomes painful when my arthritis flares. The funny thing is, it can't be arthritis because there is no joint there - just one of life's mysteries.

Sue