Therapeutic ablation of the infrapatellar fat pad under ultrasound guidance: a pilot study

To describe the technique of ablation of the infrapatellar fat pad using alcohol injection under ultrasound guidance and to assess the efficacy of the procedure in the relief of pain arising from fat pad impingement.

Consecutive patients with anterior knee pain and pathology in the infrapatellar fat pad, confirmed on magnetic resonance imaging (MRI), were enrolled in the study. A mixture of alcohol and local anaesthetic was injected under ultrasound guidance, with repeat injections at three-weekly intervals. Twelve patients (seven men, five women), mean age 30.8 years, underwent the procedure. Visual analogue scale pain scores were recorded before treatment and at the end of the treatment course.

Before treatment, the mean (+/-SD) pain score was 7.75 (+/-1.14). Patients underwent a mean of four injections (range 2-6). After treatment, the mean pain score was 2.92 (+/-2.61), representing a decrease of 62% (p<0.001). Follow-up data were complete for all 12 patients. Other than short-lived pain at the time of injection, no serious side-effects were encountered.

In patients with pain due to inflammation of the infrapatellar fat pad, ultrasound-guided alcohol ablation of the fat pad can provide effective symptom relief. The results of this pilot study indicate that a larger study is warranted to assess the long-term benefits of this well-tolerated procedure.