A neuroma is a small knot of nerve endings, which can form when a nerve has been cut.
A neuroma can form in the tissues around the knee after an injury or after knee surgery. One of the commoner neuromas affecting the knee can follow a surgical injury to the infrapatellar branch of the saphenous nerve.
Tapping over the site of the infrapatellar branch of the saphenous nerve (Tinel's test) may elicit sharp pain if there is a neuroma developing.
"...surgeons should be concerned about [infrapatellar branch of the saphenous nerve] injury if they encounter a patient who has pain and stiffness after [total knee arthroplasty]....early diagnosis and treatment are of great significance....Tinel’s test and ROM change after local anesthetic injection could help in distinguishing [this] injury from intra-articular problems."