Inflammation of infrapatellar fat pad causing lower limb pain: case report

Abstract

We report a patient with infrapatellar fat pad syndrome causing pain in the lower limb who could not walk due to the pain. An 81-year-old man had pain in the extensor aspect of the thigh and the knee on the right. Magnetic resonance imaging (MRI) performed at another hospital showed the presence of a herniated lumbar disc at L3/4. L3 nerve root block and repeated caudal blocks did not alleviate the pain. MRI of the knee suggested a degenerated lateral meniscus. He received repeated intra-articular injections of a local anesthetic, which did not lessen the pain. He was referred to us because the pain did not improve and he could not walk due to the pain. The pain was 83 mm on a visual analog scale of pain. The right quadriceps femoris was atrophied. There was marked tenderness along the edges of the muscles and around the knee joint. There was no sensory impairment over the right thigh. Since the pain began in the knee and there was marked tenderness around the knee, in?ammation of the infrapatellar fat pad was suspected. Injection of 1% mepivacaine 3.5 ml with betamethasone 2.5 mg into the infrapatellar fat pad promptly relieved the pain and he became to be able to walk. Thereafter, injections of a local anesthetic with a steroid were repeated three times. The pain almost disappeared. The atrophied right quadriceps femoris gained muscle bulk after daily exercise of the thighs.