Femoral Nerve Injury with Medial Thigh Sensory Loss

Anatomical Distribution of Femoral Nerve Injury

The femoral nerve provides sensory innervation to both the anterior and medial aspects of the thigh through its terminal branches, according to the American Society of Anesthesiologists, resulting in sensory loss in these areas when injured 1, 2
Medial thigh sensation is supplied by the saphenous nerve and medial cutaneous branches, which are terminal sensory branches of the femoral nerve, as stated by the American Society of Regional Anesthesia and Pain Medicine 1, 2

The spread of local anesthetic from regional blocks, such as femoral, fascia iliaca, or lumbar plexus blocks, can cause temporary femoral nerve dysfunction, as reported by the American Society of Anesthesiologists 1, 3

Femoral nerve blocks can cause significant quadriceps weakness and should be avoided in favor of fascia iliaca blocks, as recommended by the European Society of Regional Anaesthesia and Pain Therapy 4
Lumbar plexus blocks can affect femoral, obturator, and lateral cutaneous nerves simultaneously, according to the American Society of Regional Anesthesia and Pain Medicine 1, 3

Hip positioning during surgery, such as excessive flexion beyond 90 degrees or extension beyond comfortable range, can contribute to femoral nerve compression, though evidence for causation is limited, as noted by the American Society of Anesthesiologists 5

The American Academy of Neurology recommends considering electrodiagnostic studies (EMG/nerve conduction studies) to confirm femoral nerve injury and assess severity if motor deficits or sensory loss persist beyond 24-48 hours post-surgery, with a moderate level of evidence 5