The peroneal nerve is crucial in the movement of everything from the knee down. Therefore, it is critical to understand the types of things that put the peroneal nerve at risk, as to avoid the long-term complications associated with peroneal knee injury like foot drop or chronic pain. 

Whether you’re recovering from surgery, managing a fracture, caring for someone on extended bed rest, knowing the main causes of peroneal nerve injury is key. These risk factors include surgical trauma, prolonged pressure from immobility or poor positioning and direct injuries like fractures and dislocations. Other medical conditions like diabetes or extremely low body fat can also contribute to this condition. Keep reading for a deeper look at how these factors contribute to peroneal nerve injury and how to best reduce your risk of developing it.

Introduction

The common peroneal nerve, or peroneal nerve, is a nerve located in the lower leg. It is a branch of the sciatic nerve (the nerve that runs from the lower back down the legs) and is responsible for the movement (like raising the ankle or lifting toes) and sensations of the leg below the knee. The peroneal nerve is susceptible to injury and is considered the third most common nerve disease/damage, due to its anatomical location. This leads to symptoms like:

• Weakness, numbness and pain in the shin and top of the foot
• Inability to lift the ankle and toes up
• Inability to move the foot 
• Foot drop gait - A distinctive walk in which the knee must be lifted higher to make a step due to an inability to lift the foot 

Therefore, it is important to know the risk factors contributing to this disorder to best lower the chances of developing it and to increase chances of recovery. 

Surgical risk factors

Peroneal nerve injury, as the name suggests, is dependent on sustaining injury to the peroneal nerve. This means that there is a possibility of sustaining such an injury during surgery (for example directly sustained injuries from surgical instruments), or as an effect of surgery (for example compression of the nerve by implants). 

Orthopaedic surgeries

Orthopaedic surgeries are surgeries of the muscles, bones, joints and associated body parts. During these surgeries, nerves can be accidentally cut or compressed in the following ways:¹

Initial cuts can sometimes damage nerves that are close to the surface of the skin - Especially if there is heavy bleeding, the operation is complex or the patient has unusual anatomy. 

• If the surgeon opts for a minimally invasive procedure (one that requires smaller cuts), the limited visibility to the inside of the body increases the risk of damaging nerves

This also applies in the case of arthroscopic surgeries (surgeries that use a small cut into which a camera is inserted). 

Procedures that involve cutting of the bone can lead to accidental nicking of the nerve behind them. 

When tools are used to move tissues out of the way, they run the risk of trapping the nerve and causing damage. 

In joint replacement therapies (arthroplasty), the e risk of injury can increase in a few different ways:

• Longer operation times increase the risk of nerve damage overall
• More complicated surgeries (for example if there is a joint deformity) may stretch nerves in unnatural ways
• Joint replacement parts (implants), if shaped or placed incorrectly, can press on nearby nerves

In surgeries of the hip, the peroneal nerve is at risk, as this is where the peroneal nerve branches off from the sciatic nerve. 

In surgeries where bone cement is used, it can damage the peroneal nerve, as it heats up when it hardens. 

Neurosurgical and spine procedures

The peroneal nerve is a branch of the sciatic nerve, which is located in the spine. Upstream injuries to the sciatic nerve can cause problems with the peroneal nerve. During surgeries to remove discs, fix the curvature of the spine or to provide support to the spine with metal screws, surgeons run the risk of stretching, pinching or damaging nerves.¹ 

Vascular surgery

Sometimes surgeries for varicose veins can result in the injury of the peroneal nerve.² However, this is a very rare occurrence. Furthermore, some surgeries aimed to resolve aneurysms near the peroneal nerve (like, for example popliteal artery aneurysm), can possibly damage it.³ 

Prolonged pressure-related risk factors

Prolonged pressure on the area of the peroneal nerve from the outside can increase the likelihood of developing peroneal nerve injury, as the peroneal nerve sits relatively close to the surface of the skin. Below we will explore the effects of improper body positioning, extended bed rest and immobilisation and external compression on the peroneal nerve. 

Improper positioning

Positions like prolonged or habitual crossing legs, squatting or kneeling are associated with a higher risk of peroneal nerve injury, as in these positions, the peroneal nerve is put under pressure. Those most at risk are athletes, those who must be in these positions for prolonged times due to work and those who have a habit of crossing their legs. 

Extended bed rest or immobilised patients

Patients that are immobilised or are undergoing extended bed rest are also at risk of developing peroneal nerve injury.⁴ Extended beds rest can lead to compression of the peroneal nerve and lack of movement can lead to insufficient resolution of any compressesion that occurs. In addition, prolonged immobilisation can lead to loss of muscle, which lessens the protection of the peroneal nerve.⁵

External compression 

As the peroneal nerve runs near the surface of the skin, it is especially susceptible to external compression. Examples of external compression sources include tight plaster casts or splints and compression wrappings or bandages. 

Fractures and trauma

Peroneal nerve injury can sometimes happen due to fractures and trauma to the area. Injuries that can lead to peroneal nerve injury include:

• Knee dislocation - There is a significant risk of peroneal nerve injury with outer knee dislocations.⁶
• Impact or wound to the area where the peroneal nerve is close to the surface of the skin. 
• Fibula fracture. 
• Tibia fracture. 

Other contributing factors

There are also a few other risk factors that do not fit into the above categories. These are:

• Diabetes
• Certain inflammatory conditions that affect the nerves
• Extremely low body fat
• Nerve tumours
• Ganglion cysts
• Genetics - Certain people have anatomical differences that increase the risk of developing peroneal nerve injury

Prevention and risk factor management 

To manage the risk factors associated with peroneal nerve injury:

• Avoid sitting with legs crossed or squatting for prolonged periods of time
• Reposition regularly during bed rest or immobility
• Use proper padding and support when using casts/splints
• Carefully examine the risks of orthopaedic, spinal and vascular surgeries
• Make sure to do the physiotherapy given for trauma recovery
• Be aware of the complications associated with fractures
• Manage associated medical conditions

Summary

Peroneal nerve injury is a condition that affects the movement and sensations in the lower leg and foot. Because the peroneal nerve runs relatively close to the surface of the skin around the knee, it is particularly susceptible to damage. 

Risk factors include surgical complications (for example in orthopaedic, spinal and vascular procedures), in which the peroneal nerve can be stretched, compressed or accidentally cut. Prolonged pressure from poor positioning, extended bed rest or external sources like tight casts can also compress the nerve, leading to injury. In addition, injuries of the leg, especially around or below the knee, can damage the nerve directly. Other contributing factors include diabetes, nerve tumours and very low body fat. 

To minimise the risks of developing peroneal nerve injury, it is essential to understand all risks associated with surgeries before undergoing them, ensuring minimal pressure on the peroneal nerve for example by ensuring casts are properly padded or by avoiding sitting with legs crossed for a long time) and managing associated medical conditions. Understanding these risk factors is key in the prevention of injury and promotion of better recovery outcomes.