Why is the skin on the outside of my knee numb after ACL surgery?

Why it happens

The infrapatellar branch of the saphenous nerve crosses the front and inner side of the knee just under the skin, close to where hamstring or patellar tendon grafts are harvested. It only carries feeling to the skin, not power to muscles. When it is stretched or divided, an area beside or below the kneecap feels numb, tingly or oddly sensitive.

What to expect

• The numb area is usually largest in the first weeks and then gradually shrinks
• Tingling or pins and needles can appear as the nerve recovers
• In some people a small patch stays numb long term
• Kneeling may feel strange on the numb skin even when the knee itself is fine

None of this weakens the graft or limits rehabilitation.

Signs that are not normal

Numbness in the foot or toes, weakness lifting the foot, a cold or pale foot, or numbness with increasing calf pain and swelling should be checked promptly, as these are not caused by the small skin nerve. A wound that is red, hot, leaking or associated with fever needs review the same day.

Living with it

Gentle scar massage once the wound has healed can reduce sensitivity. When kneeling for work or prayer, a soft cushion helps on sensitive skin. If the area is painful rather than numb, mention it at follow-up; Dr. Gelber can examine it at Aman Hospital in Doha and advise on desensitisation or, rarely, further treatment.