This patient has a right foot drop with weakness of the ankle or foot dorsiflexion and preservation of plantarflexion. Foot drop is most commonly due to a peroneal nerve or L5 nerve root lesion. Peroneal nerve palsies are usually due to compression of the nerve against the fibular head in the lateral knee. Patient with foot drop due to an L5 radiculopathy have weak foot inversion unlike patients with peroneal nerve palsies who have strong foot inversion.