Anatomy Msk · Year 1 · from Anatomy Msk
Case 3: Femoral Nerve Injury
Clinical Image
Source: Wikimedia Commons - Femoral Nerve - CC BY-SA 4.0
Case Presentation
A 62-year-old man with atrial fibrillation on warfarin presents with sudden onset of right groin pain and anterior thigh numbness following a fall. He reports progressive weakness of his right leg over several hours. His INR is found to be supratherapeutic at 5.2. Physical examination reveals a tender, firm mass in the right groin region. His right leg rests in flexion at the hip. He has marked weakness of knee extension (quadriceps, 2/5) and hip flexion (iliopsoas, 3/5). Sensation is diminished over the anterior thigh (anterior femoral cutaneous) and medial leg (saphenous nerve). The patellar reflex is absent on the right. CT of the pelvis and thigh reveals a large iliopsoas hematoma compressing the femoral nerve within the iliacus compartment. His anticoagulation is reversed with vitamin K and prothrombin complex concentrate. Urgent surgical decompression is performed given the significant motor deficit. Post-operatively, he is enrolled in intensive physical therapy. At 6-month follow-up, he has recovered to 4/5 knee extension strength but continues to have mild sensory deficit.
Key Learning Points
- The femoral nerve (L2-L4) courses through the iliacus compartment and passes deep to the inguinal ligament
- It innervates iliopsoas (hip flexion), quadriceps (knee extension), and pectineus
- Femoral nerve injury causes weakness of hip flexion and knee extension with loss of patellar reflex
- Sensory distribution: anterior thigh (anterior femoral cutaneous) and medial leg to foot (saphenous nerve)
- Iliopsoas hematoma in anticoagulated patients is a recognized cause of femoral nerve compression