EULAR: Joint Distraction Buys Time against Knee Replacement for Osteoarthritis

By Charles Bankhead

16 june 2008-- Mechanical joint distraction for osteoarthritic knees can restore near-normal function and help patients put off joint replacement, perhaps for years, according to a small study reported here.Among 25 patients followed for two years, a two-month stint with an external fixation brace has provided lasting pain relief and functional improvement and reduced wear-and-tear on knee cartilage, Floris Lafeber, Ph.D., of University Medical Center Utrecht in The Netherlands, reported at the European League against Rheumatism (EULAR) congress.The same procedure for ankles has reduced pain and restored function for as long as four years, and some patients with osteoarthritis of the hip have been followed for as long as 10 years after joint distraction procedures, Dr. Lafeber said.
"Within six months we see a significant decrease in pain and significant improvement in functional ability," said Dr. Lafeber. "Patients start at 80% of the maximum pain score, which is severe pain, and it decreases to about 20%. Functional ability improves to 80% or 90% within a short period after the distraction is stopped. Patients continue to improve over a period afterwards until they have almost complete normalization of the joint."
Joint distraction is not a replacement for arthroplasty, Dr. Lafeber emphasized. Instead, the procedure allows younger patients to maximize the potential lifespan of joint replacement by delaying the surgery as long as possible.
A prosthetic knee lasts about 15 years, said Dr. Lafeber. If a person has arthroplasty at age 55, for example, that person could outlive the functional life of the prosthesis.
Initially applied to the hip about 15 years ago and then to the ankle about five years ago, joint fixation for the knee began two years ago at Dr. Lafeber's center.
The procedure involves placement of a spring-containing external brace that bridges the knee joint and induces 5 mm of separation or distraction.
The brace remains in place for about two months.
Joint repair is believed to occur as a result of the combined effects of intermittent intra-articular fluid pressure, absence of mechanical stress on cartilage, and changes in periarticular bone turnover during distraction.
Before the procedure, the patients' functional ability and clinical condition were 39% and 31% of maximum, respectively, and increased to more than 80% within six months.
One-year evaluation by MRI and digital x-ray have demonstrated cartilage repair, including a 50% increase in mean cartilage volume, a 40% increase in subchondral bone covered with cartilage, and a 5% increase in cartilage thickness on covered bone.
"We expect the benefits to last for at least 10 years, including normal function," said Dr. Lafeber. "People who are very restricted can resume and maintain an active life."
The study was supported by the Dutch Arthritis Foundation. Dr. Lafeber had no disclosures.
Primary source: EULAR 2008Source reference:Intema F, et al "Joint distraction in the treatment of severe knee osteoarthritis: the first results on clinical efficacy and structural repair" EULAR Meeting 2008; Abstract OP0151.