Compressed Nerve In The Knee

A nerve becomes pinched/compressed when added pressure is placed on it by surrounding structures that can include muscles, bones, ligaments, tendons, or a combination. This injures and damages the nerve, causing functional problems, symptoms, and sensations in that area or in other parts of the body supplied by that nerve. Medical practitioners refer to this as nerve compression or entrapment. Although compressed nerves are more commonly associated with the neck, arms, hands, elbows, and lower back, any nerve in the body can be irritated, spasm, inflamed, or compressed. The causes and treatment of a compressed nerve in the knee.

Compressed Nerve In The Knee

There’s only one nerve that goes through the knee that has an increased risk of getting compressed. It’s a branch of the sciatic nerve called the peroneal nerve. The nerve goes around the outside of the knee before traveling down the outside of the lower leg. At the bottom of the knee, it lies between the bone and skin, making it vulnerable to irritation or compression from anything that applies pressure to the outside of the knee.

Causes

Over time, traumatic injuries can lead to pressure on the nerve inside the knee. Common causes of a compressed nerve in the knee include:

Frequently Crossing Legs

• Compression by the opposite knee, while the legs are crossed, is the most common cause.

Knee Brace

• A too-tight or strong brace can compress the leg and nerve.

Thigh-High Compression Stockings

• If too tight, these stockings, designed to maintain pressure on the legs, can compress the nerves.

Squatting Posture For Long Periods

• This position places pressure on the side of the knee.

Fractures

• A fracture of the large lower leg bone/tibia, or sometimes the small bone/fibula, near the knee can entrap the nerve.

Lower Leg Cast

• The portion of the cast around the knee can be tight and compress the nerve.
• Tell the doctor if a cast or brace feels tight or is causing numbness or pain in the leg.

Knee-High Boots

• The top of a boot can land right below the knee and be too tight, pinching the nerve.

Knee Ligament Injury

• The nerve can become compressed due to bleeding or inflammation from an injured ligament.

Knee Surgery Complications

• This is rare, but the nerve can inadvertently get pinched during knee replacement surgery or an arthroscopic procedure.

Prolonged Bed Rest

• When lying down, the legs tend to rotate outward, and the knees flex.
• In this position, the mattress can place pressure on the nerve.

Tumors or Cysts

• Tumors or cysts can develop directly on or adjacent to a nerve, irritating and compressing it.

Abdominal or Gynecologic Surgery

• The equipment used to keep the legs rotated outward, and the knees flexed for gynecologic and abdominal surgeries, can compress the nerve.

Symptoms

The peroneal nerve supplies sensation and movement to the outside of the lower leg and the top of the foot. When compressed, it becomes inflamed, causing the symptoms of nerve compression. Usually, only the nerve’s myelin sheath is injured. However, when the nerve becomes damaged, the symptoms are similar but more severe. Common symptoms include:

• A weakness that limits the ability to lift the foot toward the leg, aka dorsiflexion.
• This causes the foot to drag when walking.
• The ability to turn the foot outward and extend the big toe is also affected.
• Symptoms can be felt on the outside of the lower leg and on the top of the foot and include:
• Tingling or pins-and- needles sensations.
• Numbness.
• Loss of sensation.
• Pain.
• Burning.
• For individuals who have had a pinched nerve for two or more weeks, the muscles supplied by that nerve can begin to atrophy.
• Symptoms can be intermittent or continuous depending on the cause.
• The other common cause is a pinched nerve in the lumbar (lower) spine.
• When this is the cause, sensations and pain will present in the lower back, the back, or the outside of the thigh.

Diagnosis

A doctor will review medical history and perform an examination to make a diagnosis, determine the cause, and develop a personalized treatment plan. The nerve in the knee can be felt as it travels around the top of the tibia, so a doctor may tap on it. If there is shooting pain down the leg, a pinched nerve may be present. Tests a doctor may order can include:

Knee X-ray

• Shows any bone fractures or abnormal masses.

Knee MRI

• Can confirm the diagnosis
• Shows masses in the nerve.
• Shows details of fractures or other problems in the bones.

Electromyogram – EMG

• Tests the electrical activity in the muscles.

Nerve Conduction Test

• Tests the nerve’s signal speed.

Treatment

Treatment aims to reduce pain and improve mobility.

Over-the-Counter Pain Medication

• OTC medication can reduce inflammation and improve symptoms in the short term.

Ice and Heat

• Applying either heat or ice for 15 to 20 minutes at a time can provide relief from the symptoms.
• An ice pack can make symptoms worse if it adds more pressure on the nerve.

Chiropractic and Physical Therapy

• Chiropractic and physical therapy can relieve pressure on the compressed nerve, realign the structures, strengthen the muscles, and provide gait training.

Orthotic Boot

• If walking gait is affected because the foot cannot bend, an orthotic boot can help.
• This support maintains the foot in a neutral position to walk normally.

Corticosteroid Injection

• A corticosteroid injection can reduce inflammation and relieve pressure on the nerve.

Surgery

• The nerve can suffer permanent damage if it has been pinched for a long time.
• If that happens, surgery cannot repair the damage.
• A doctor can perform surgery to correct a fracture, tumor, or other invasive problem that is compressing a nerve.
• If conservative treatment doesn’t work, a peroneal nerve decompression procedure can be done to remove the pressure.
• If surgery is needed, symptoms can disappear immediately, but it takes around four months to recover and rehabilitate.

References

Krych, Aaron J et al. “Is peroneal nerve injury associated with worse function after knee dislocation?.” Clinical orthopedics and related research vol. 472,9 (2014): 2630-6. doi:10.1007/s11999-014-3542-9

Lezak B, Massel DH, Varacallo M. Peroneal Nerve Injury. [Updated 2022 Nov 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK549859/

Soltani Mohammadi, Sussan, et al. “Comparing the squatting position and traditional sitting position for ease of spinal needle placement: a randomized clinical trial.” Anesthesiology and pain medicine vol. 4,2 e13969. 5 Apr. 2014, doi:10.5812/aapm.13969

Stanitski, C L. “Rehabilitation following knee injury.” Clinics in sports medicine vol. 4,3 (1985): 495-511.

Xu, Lin, et al. Zhongguo gu Shang = China Journal of Orthopedics and Traumatology vol. 33,11 (2020): 1071-5. doi:10.12200/j.issn.1003-0034.2020.11.017

Yacub, Jennifer N et al. “Nerve injury in patients after hip and knee arthroplasties and knee arthroscopy.” American Journal of physical medicine & Rehabilitation vol. 88,8 (2009): 635-41; quiz 642-4, 691. doi:10.1097/PHM.0b013e3181ae0c9d