Anatomy
- Terminal sensory branch of the femoral nerve
- Passes through the adductor canal with the femoral vessels
- Emerges between sartorius and gracilis at the medial knee
- Infrapatellar branch crosses the front of the knee
- Descends with the great saphenous vein and passes anterior to the medial malleolus
- Becomes subcutaneous at the medial knee, posterior to sartorius
Sensory Supply
- Medial leg and medial border of the foot
- Skin below the patella through the infrapatellar branch
Clinical Features
- Infrapatellar branch injury after arthroscopy portals, hamstring graft harvest and knee arthroplasty incisions
- Numbness lateral to the scar or a painful neuroma
- Entrapment in the adductor canal gives medial knee pain
- Injured during saphenous vein harvest and medial ankle incisions
- Neuritis can follow inside out medial meniscal repair
Investigations
- Diagnostic local anaesthetic block
Differential Diagnosis
- Medial meniscal tear
- Pes anserine bursitis
- L4 radiculopathy
Management
- Most numbness is tolerated and improves
- Excision and burial of a painful neuroma
- Adductor canal block for knee arthroplasty gives analgesia while sparing quadriceps strength
Structures at Risk
- Vertical medial knee incisions
- Hamstring tendon harvest
- Anteromedial ankle arthroscopy portal
- Inside out medial meniscal repair, so use a posteromedial incision with retraction
- Great saphenous vein cutdown at the ankle
Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.