Knee extension (L-4 Motor)

Name of test

Knee extension (via innervation of the four muscles of the quadriceps)

What it tests

Neuromuscular function in knee extension, namely, the four quadriceps muscles

How to do it

• In the sitting position, the patient extends his/her knee.
• The clinician tests the strength against resistance.

The normal response

5/5 strength

What it means if not normal

• Weakness in the quadriceps exhibited by weakness in extension of the knee, due to either muscular or neurologic origins.
• In walking without support, the affected knee will "give way" or buckle at heel strike and the flat foot stance phase of gait with the affected leg. The patient could fall.

Comments

Citations

Hoppenfeld, Stanley. Orthopaedic Neurology. Philadelphia: J.B. Lippincott Co., 1997.

K. Anderson, J. Hall. Sports Injury and Management: Philadelphia: Williams & Wilkins,1995.

Reider, Bruce. The Orthopaedic Physical Examination, 2nd Ed.: Philadelpiha: Elsevier Saunders, 2005.

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