The nerve that stimulates the muscle responsible for dorsiflexion (lifting the foot upwards at the ankle) is the peroneal nerve. Any damage to this nerve or the muscles it stimulates will cause these muscles to lose function. As a result, the foot cannot be moved upward at the ankle, causing a type of partial paralysis.

What is Foot Drop?
Foot drop syndrome is a condition resulting from muscle or nerve damage that leads to the loss of dorsiflexion (lifting the foot upwards) and eversion (turning the foot outward) abilities of the foot. A person with foot drop drags their foot on the ground while walking because they cannot lift it properly. This gait is called steppage gait.

What Are the Causes of Foot Drop?
Foot drop syndrome develops due to dysfunction of the muscles innervated by the peroneal nerve. It can arise from nerve or muscle-related causes. Therefore, causes may include central nervous system and spinal cord origins, direct damage to the peroneal nerve, or musculoskeletal system disorders.

Central nervous system causes (brain and spinal cord injuries) include pathologies affecting the peroneal nerve secondarily at higher levels. It is more commonly observed in diseases such as Multiple Sclerosis (MS), Cerebral Palsy (CP), and stroke. Foot drop is also common in Charcot-Marie-Tooth disease, a genetic disorder causing progressive muscle and nerve damage.

The most common cause of foot drop after central nervous system disorders is lumbar disc herniation (commonly known as a herniated disc). Especially herniations between the 4th and 5th lumbar vertebrae (L4-L5) affect the sciatic nerve. Since the sciatic nerve immediately gives off the peroneal nerve branch behind the knee joint, direct involvement of the peroneal nerve occurs. Consequently, untreated lumbar disc herniation patients may develop foot drop.

Sudden foot drop accompanied by acute pain is commonly referred to as a “burst disc” in layman terms. If the condition is accompanied by urinary incontinence and noticeable leg weakness, cauda equina syndrome should be immediately suspected. The key feature of this syndrome is that surgical intervention within the first 24-48 hours can result in full recovery.

Direct damage to the peroneal nerve often occurs due to fractures of the fibula bone’s head or shaft, located just below the knee, compressing the nerve. This is an important cause of foot drop. Trauma, blows, or cuts to the knee can also cause nerve damage resulting in foot drop.

Musculoskeletal diseases such as muscular dystrophies and Amyotrophic Lateral Sclerosis (ALS), which progress slowly with demyelination of nerves and progressive muscle weakness, can also cause foot drop.

Additionally, in metabolic diseases such as diabetes mellitus, peripheral nerve damage can cause painless foot drop. Caution is necessary in such cases. Painless foot drop may also occur in silent brain or spinal cord tumors.

One of the most important practical causes of foot drop is injuries to the sciatic nerve in the hip and thigh area. Common causes include injection errors in the hip (possibly due to anatomical variations in the sciatic nerve path), blunt and sharp traumas to the hip.

How Is Foot Drop Diagnosed?
Patients cannot walk using both heels properly. The affected foot cannot fully participate in walking. A detailed patient history should be taken, and a thorough neurological examination should be performed. After diagnosis, detailed tests for the underlying causes should be conducted.

X-rays should be taken if a fracture is suspected. For suspected herniated discs, spinal cord, or brain diseases, MRI or CT scans should be used. If musculoskeletal system involvement is suspected, differential diagnosis should be reached with diagnostic methods such as electromyography (EMG).

Detailed blood and urine tests should be requested for diseases that may cause peripheral nerve damage such as diabetes and vitamin deficiencies.

What Are the Non-Disease Causes of Foot Drop?
The peroneal nerve runs near the back and outer side of the knee, approximately 3-4 cm from the skin surface, and travels downwards. Due to its superficial location, it is easily affected by external factors.

• Sitting cross-legged for long periods.
• Activities requiring prolonged squatting such as farming, harvesting crops, laying tiles, eating at a floor table, etc.
• Casts and bandages; especially bandages and casts applied for bone fractures and tendon injuries can compress the peroneal nerve and cause foot drop.

How Can Foot Drop Be Treated?
Treatment should be planned according to the cause. In cases of sudden foot drop due to herniated disc and cauda equina syndrome, the first 24-48 hours are critical. If severe pain is accompanied by sudden urinary incontinence and foot weakness, this syndrome should be suspected immediately and emergency surgical consultation requested.

In slowly developing foot drop syndrome, the condition is usually irreversible by the time of diagnosis. Without timely and appropriate treatment, the problem may progress to this stage.

Treatment methods include:

• Splints and braces: Although they cannot reverse the condition, they help keep the ankle in a normal position, making walking easier and preventing secondary damage to other joints. The most commonly used splint is the AFO (Ankle Foot Orthosis), usually made from polyurethane or high-density carbon fiber. Orthotic devices continue to improve with advancing technology.
• Physical therapy: Exercises targeting the muscles responsible for dorsiflexion strengthen weakened muscles.
• Nerve therapy: Functional electrical stimulation applies continuous electrical impulses along the path of the peroneal nerve. It is a widely used and effective treatment method.
• Surgical treatment.