What is the most common clinical manifestation of an injury to the common peroneal nerve?

The most common clinical manifestation of an injury to the common peroneal nerve is foot drop with diminished dorsiflexion of the ankle. This occurs because the common peroneal nerve innervates the muscles responsible for dorsiflexion of the foot, particularly the tibialis anterior, as well as the muscles that extend the toes. When this nerve is injured, the patient typically presents with an inability to dorsiflex the foot, leading to the characteristic "foot drop," where the foot drags or hangs during ambulation.

Patients often compensate for this loss by lifting the knee higher during walking (steppage gait) to prevent the toes from dragging. The loss of control over dorsiflexion is a direct result of the nerve damage, highlighting its crucial role in maintaining normal ankle function.

In contrast, the other manifestations listed do not directly correlate with common peroneal nerve injuries. The inability to plantarflex the foot is primarily associated with tibial nerve injuries, while loss of sensation in the heel involves different nerve pathways, including the sural nerve. Lastly, the inability to adduct the toes would involve more proximal nerve lesions affecting the lumbar or sacral plexus innervation rather than being specifically related to common peroneal nerve