The overall conclusion is that joint distraction is clinically very effective in young patients with end-stage knee arthritis, with cartilage repair presumably responsible for the clinical benefit, he said. However, more prolonged follow-up is needed.
Some of the ankle patients have had a second distraction, but whether this will be feasible and advisable in the knee patients remains to be seen, because the follow-up is too short.
“It may be possible, and of course we hope [that] it's not just a delay before joint replacement, but that we can really cure the joint. That's only wishful thinking so far, though,” he said.
Dr. Lafeber acknowledged that his study was not placebo controlled.
“Of course it would be better to have a good control, which in this case would be placement of the complete frame but without the distraction,” he said.
Currently, however, they are offering this treatment only to patients with end-stage OA who otherwise would be considered for joint replacement. “We cannot ethically allow these patients to go without any treatment for 2 years,” he said.
Moreover, with benefits persisting for up to 10 years for the ankle patients, placebo effects are hardly likely to still be in play. “Maybe for the first year, because these patients are seeing their physicians more frequently than they would otherwise, but certainly after several years the placebo effect would have vanished,” he said.
This knee has OA at baseline on x-ray (top). Cartilage repaired itself after 2 years of treatment (bottom). Distraction may alleviate the need for total knee arthroplasty. Photos courtesy Dr. Floris P.J.G. Lafeber
Biomarkers of bone breakdown and synthesis increase during distraction. Courtesy Dr. Floris P.J.G. Lafeber
Iowa's Experience With Ankle OA
Ankle distraction also has been performed and is being evaluated in a randomized study led by Dr. Annunziato Amendola of the University of Iowa, Iowa City.
The study, funded by the National Institutes of Health, prospectively enrolled about 40 patients with posttraumatic OA of the ankle. They used the same ankle distraction technique as did Dr. Lafeber's group, but patients were randomized to distraction alone or with the addition of continuous passive joint motion.
Patients have been evaluated clinically and radiographically, and with a special three-dimensional CT scanning technique to look at cartilage regeneration.
All but three patients have now undergone 2- and 3-year evaluations, and the results thus far have been comparable to the results they have had in Utrecht in terms of relief of pain, according to Dr. Amendola. Additional improvements have been seen over time, and patients in the motion group did significantly better at every time point than did the non-motion group.
“I think this is quite an intriguing technique,” Dr. Amendola said.