Preventing lateral skin numbness after medial unicompartmental knee arthroplasty

The authors report the results of preserving the infrapatellar branch of the saphenous nerve during unicompartmental knee arthroplasty to prevent lateral skin numbness. All 100 cases had medial compartmental osteoarthritis and a minimally invasive technique had been used. The mean follow-up duration was two years and eight months (range, 24 to 42 months). The classification according to the location of this nerve was observed as either Mochida Type I with 76 cases (76%), Type II with 16 cases (16%), and unclassified type with 8 cases (8%). In Type I, the nerve was saved in 62 cases (82%), but could not be preserved in Type II because of the surgical procedure. These results showed that the mean distance from the joint line to the nerve of Type I was 9.13 mm (range, 4 to 15 mm) and the nerve passed inferiorly. This study showed the location of this nerve can be predicted ahead of the procedure, which will help preserve it during the surgery.