Reducing lateral skin flap numbness after total knee arthroplasty.

One hundred and thirteen knees were assessed for lateral skin flap numbness, 5-227 weeks following IB2 total knee arthroplasty. The final 53 had the numb area measured. To define the anatomy of the cutaneous nerves we dissected four cadaveric knees. Eighty-six percent of patients had a numb area on objective assessment but only 60% had subjective numbness, 62% of which had improved. Patients had a larger numb area if they were aware of a numb patch, had a scar over 22 cm long or were less than 25 weeks following surgery. We conclude that not all patients will get lateral skin flap numbness and improvement occurs with time. The area of numbness can be reduced by using a shorter proximal incision, which preserves branches of the medial and intermediate cutaneous nerves of thigh.