Which nerve repair has the worst prognosis?
Common peroneal nerve (Lateral popliteal nerve) has two main characteristics.

The most common nerve lesions of the lower limb.
Worst prognosis after nerve reconstructive surgery.

Recovery potential after nerve repair

Excellent: - Radial, Musculocutaneous, femoral, digital nerves
Moderate: - Median, Ulnar, Tibial
Poor : - Common peroneal (lateral popliteal)
Pure motor or pure sensory nerves, i.e., Unmixed nerves, like musculocutaneous nerve and digital nerves have the best prognosis.
Pure motor nerves to large muscle groups not requiring fine control have a better prognosis than motor nerves supplying the small muscles of hand & foot.
Ulnar
Radial
Median
Lateral popliteal