The condition you refer to is not a known or a recognized side effect from vessel harvesting, however, it can't be ruled out as there is a possibilty!
Your father should verify peripheral neuropathy. There is a procedure, an EMG, where a needle electrode is inserted through the skin into the muscle. The electrical activity detected by this electrode is displayed on an oscilloscope (monitor), and may be heard through a speaker.
After placement of the electrodes, your dad may be asked to contract the muscle (for example, by bending your arm). The presence, size, and shape of the wave form -- the action potential -- produced on the oscilloscope provide information about the ability of the muscle to respond when the nerves are stimulated.
Common causes of damage to the peroneal nerve include the following:
Trauma or injury to the knee
Fracture of the fibula (a bone of the lower leg)
Use of a tight plaster cast (or other long-term constriction) of the lower leg
Habitual leg crossing
Regularly wearing high boots
Pressure to the knee from positions during deep sleep or coma
Injury during knee surgery.
Another risk is being extremely thin or emaciated (for example, from anorexia nervosa). Systemic conditions such as diabetic neuropathy or polyarteritis nodosa can also cause damage to the common peroneal nerve. Charcot-Marie-Tooth disease (hereditary sensorimotor neuropathy) is an inherited disorder that affects all nerves, with peroneal nerve dysfunction apparent early in the disorder. Also, toxic exposure to chemicals such as polyvinyl chloride or styrene (made during the production of polystyrene) may lead to peroneal and other nerve damage.