Updated: 4/6/2022

Lower Extremity Nerve Entrapments

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Topic
Snapshot
  • A 30-year-old woman presents to her primary care physician for left foot pain. The patient reports experiencing a dull ache in the plantar aspect of the left foot. The pain worsens when walking, especially when barefoot or when wearing heels. Her symptoms improve with rest. As the metatarsal heads are squeezed during the physical exam, a "click" is heard between the 3rd and 4th interdigital space. (Morton neuroma)
Introduction
  • Nerves of the lower extremity can be entrapped somewhere along its course
Lower Extremity Nerve Entrapments
Entrapped Nerve Mechanism
Presentation Management
Femoral 
  • Diabetic amyotrophy
  • Injury to the
    • inguinal region
    • intrapelvic structures
      • e.g., gunshot or knife injuries and surgery
  • Pain in the inguinal region
    • hip flexion and external rotation improves pain
  • Dysesthesia of the
    • anterior thigh
    • anteromedial leg 
  • Knee buckling and walking difficulty
  • Decreased patellar reflexes
  • Symptomatic management is less severe cases
    • knee brace to improve stability when walking
Lateral femoral
  • Entrapment typically occurs in the inguinal ligament
  • Causes include
    • intrapelvic causes
      • pregnancy
      • uterine fibroids
      • abdominal tumors
    • extrapelvic causes
      • trauma to the anterior superior iliac spine
    • mechanical
      • prolonged sitting or standing
  • Also known as "meralgia paresthetica"
  • Paresthesias and pain involving the 
    • lateral thigh
    • anterolateral thigh
  • Pain management
    • local anesthetic injection
    • gabapentin
    • NSAIDs
  • Lifestyle modification
    • avoiding prolonged standing
Obturator nerve 
  • Rare
  • Nerve compression by overlying fascia in the adductor compartment
  • Direct mass effect by tumor
  • Medial thigh pain, especially with activity
  • Sensory loss/paresthesias over the medial thigh 
  • Adductor weakness
  • Pain management
    • NSAIDs
  • Lifestyle modification
    • activity modification 
Saphenous nerve
  • Nerve compression as it courses through the adductor canal
  • Can be compressed more distally (e.g., at the medial leg)
  • Knee pain
  • Infrapatellar pain and numbness
  • Local anesthetic injection
  • Lifestyle modification
    • avoiding activities that aggravate pain
Common peroneal
  • Trauma
  • Most common location of injury is around the fibular head 
  • Impaired ankle dorsiflexion
  • Dorsal foot numbness
  • Improving mobility and function
    • pain management
    • brace, splint, or orthopedic shoes
Superficial peroneal
  • Trauma and nerve compression
  • Stretch nerve injury
    • e.g., repeated ankle sprains
  • Fascial defect
  • Vague pain in the dorsum of the foot
  • Supportive
    • pain management
    • physical therapy
    • braces
Posterior tibial  
  • Nerve compression distal to the ankle (most common)
  • Also known as "tarsal tunnel syndrome" 
  • Vague pain and discomfort in the plantar surface of the foot
  • Supportive
    • pain management
  • Directed at underlying etiology
Interdigital neuritis
  • Nerve compression at the level of the transverse intermetatarsal ligament
    • benign neuroma  
  • Also known as "Morton neuroma"
  • Burning pain between the 3rd and 4th digits of the foot (most common) 
  • Supportive
    • wide shoes and low heels
    • placement of a metatarsal pad
    • pain management

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Questions (3)

(M2.OR.17.4867) A 27-year-old woman presents to her primary care physician for foot pain. The patient states that she has pain in her foot and toes whenever she exerts herself or is at work. The patient is an executive at a medical device company and works 60 hours/week. She is currently training for a marathon. She has a past medical history of anxiety, constipation, and irritable bowel syndrome. Her current medications include clonazepam, sodium docusate, and hyoscyamine. Her temperature is 99.5°F (37.5°C), blood pressure is 100/60 mmHg, pulse is 50/min, respirations are 10/min, and oxygen saturation is 99% on room air. Cardiac and pulmonary exams are within normal limits. Examination of the lower extremity reveals 5/5 strength with 2+ reflexes. Palpation of the interdigital space between the third and fourth toes elicits pain and a clicking sound. Which of the following is the most likely diagnosis?

QID: 109541

Inflammation and damage to the plantar fascia

6%

(3/52)

Compression of the tibial nerve

2%

(1/52)

Intermetatarsal plantar nerve neuroma

88%

(46/52)

Damage to the trabeculae of the calcaneus

2%

(1/52)

Anterior talofibular ligament strain

2%

(1/52)

M 6 D

Select Answer to see Preferred Response

(M2.OR.15.84) A 28-year-old female presents to her primary care physician because of pain on her right foot. She says that the pain began 2 weeks ago and gets worse with weight bearing. She has been training for a marathon, and this pain has limited her training. On exam, there are no signs of inflammation or deformities on her foot. Compression of the forefoot with concomitant pressure on the interdigital space reproduces the pain on the plantar surface between the third and fourth toes and produces an audible click. What is the cause of this patient's condition?

QID: 106157

A bony outgrowth

6%

(2/32)

Inflammation of the bursa

0%

(0/32)

A benign neuroma

66%

(21/32)

A metatarsal compression fracture

19%

(6/32)

Inflammation and scarring of the plantar fascia

3%

(1/32)

M 6 E

Select Answer to see Preferred Response

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