UMEM Educational Pearls

Category: Neurology

Title: Lower Leg Nerve Deficit from Knee Injury

Keywords: neuropathy, knee injury, sural nerve, peroneal nerve, tibial nerve (PubMed Search)

Posted: 7/23/2008 by Aisha Liferidge, MD (Updated: 8/11/2020)
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  • Don't forget to check for distal lower extremity neurologic deficit after knee injury, particularly when there is a direct blow to the popliteal fossa.
  • The common peroneal and tibial nerves exit from the lateral and middle sections of the popliteal fossa, respectively.
  • The common peroneal nerve wraps laterally around the fibula (where it's palpable), primarily supplying the lateral portions of the lower leg and foot.
  • The tibial nerve primarily supplies the muscles of the posterior compartment of the lower leg (i.e. gastrocnemius, soleus, popliteus).
  • Both the common peroneal and tibial nerve fibres branch into the sural nerve, which supplies the lateral foot.
  • Common peroneal also splits into deep and superficial branches which supply the muscles of the anterior lower leg compartment and lateral lower leg compartment, respectively.  The deep branch also provides cutaneous innervation of the cleft between the great and second toes.

--  IN SUMMARY:

  • Neurologic deficit of the posterior lower leg muscles likely = tibial nerve injury.
  • Neurologic deficit of the anterior and lateral lower leg muscles likely =  peroneal nerve injury.
  • Decreased sensation in the web space between the great and 2nd toes likely = (deep) peroneal nerve injury.
  • Decreased sensation over the lateral dorsum of the foot likely = sural nerve injury.

*** Speaking of such deficits by naming the affected nerve distribution is particularly helpful when consulting orthopedists, neurologists, etc.