The main cause of foot drop is compression of the peroneal nerve, a vital nerve in the leg responsible for controlling the muscles that lift the front part of the foot.
Foot drop is characterized by an inability to lift the front part of the foot, leading to a tendency to drag the foot or to raise the thigh when walking (steppage gait) to avoid tripping. This condition is primarily a symptom of an underlying problem, rather than a disease itself.
Understanding the Role of the Peroneal Nerve
The peroneal nerve, also known as the common fibular nerve, branches off the sciatic nerve near the back of the knee and extends down the leg. Its crucial role includes:
- Dorsiflexion: Lifting the foot upwards towards the shin.
- Eversion: Turning the sole of the foot outwards.
- Toe Extension: Lifting the toes.
When this nerve is compressed or damaged, the signals to the muscles responsible for these actions are interrupted, leading to weakness or paralysis, which manifests as foot drop.
Common Scenarios Leading to Peroneal Nerve Compression
Compression of the peroneal nerve can occur due to various reasons, often related to direct pressure or injury to the leg around the knee area. Some of the most common scenarios include:
- Serious Knee Injuries: Significant trauma to the knee can directly impact or compress the peroneal nerve as it passes close to the joint.
- Surgical Complications: The nerve can be inadvertently injured or compressed during certain surgical procedures, particularly:
- Hip replacement surgery
- Knee replacement surgery
In these situations, the delicate nature of the nerve and its proximity to the surgical site make it susceptible to damage, which can lead to the onset of foot drop post-surgery. Other less common causes of foot drop can include brain or spinal cord disorders, but nerve compression, especially of the peroneal nerve, remains the most frequent culprit.
