Knee Procedure: 80% Relief, but No Control Group

Analysis. A 194-patient study from Berlin reports that 80% of patients had meaningful knee pain relief 12 months after a catheter procedure called genicular artery embolization. It had no comparison group. A Dutch trial that did have one points the other way.

What the Berlin study measured

The study, published in Radiology on June 16, 2026 by Florian Fleckenstein and colleagues at Charité, followed 194 people with knee osteoarthritis that had resisted at least three months of standard care. A radiologist blocked small arteries around the knee with dissolving gelatin particles. Median pain on a 0 to 10 scale fell from 7 to 3 at 12 months, and 80% of those assessed passed the authors' threshold for a meaningful change. Follow-up was 79% at 12 months (154 of 194), and mild side effects such as transient skin discoloration followed 6.7% of procedures.

The authors state the main limit themselves: with no comparison group, the design cannot separate a treatment effect from placebo response, regression to the mean or natural swings in symptoms.

What the sham-controlled trial found

A randomized trial at Erasmus MC in Rotterdam, published in European Radiology on April 20, 2026, enrolled 58 patients with mild to moderate osteoarthritis. Half got the real procedure and half got a sham: the same groin incision, imaging and ice packs, with no embolization. Both groups improved on the KOOS pain score. The embolization group went from 44.4 to 65.6, and the sham group from 42.3 to 58.2. The between-group difference at 12 months was 7.46 points, with a confidence interval from -13.63 to 28.56, so it was not statistically significant. Synovitis on MRI did not change in either group.

What the headlines leave out

The two studies used different particles, different patients and different outcome scales, so one does not overturn the other. The Dutch authors also say their trial was small and may have missed a modest real effect. What the Rotterdam result does show is how large the improvement can be when the knee is treated with nothing at all inside the artery.

The cost matters too. The Dutch paper cites estimates of about $3,095.75 per procedure from a U.S. study and about 3,432 euros from a Spanish one.

The questions that remain

Would the gelatin particles beat a sham in a controlled trial of their own? Which patients, if any, respond beyond placebo? And who should pay for a procedure at this price before that trial exists?