What Is External Fixation for Joint Distraction and How Does It Work?
External fixation is an experimental therapy that involves drilling fixation rods through the skin into the bones of the thigh and shin. An external fixation brace or surgical frame can promote joint distraction (pulling apart the joint). When used around a degenerated joint, the joint distraction appears to allow healing by strengthening and repairing cartilage.
Are Study Results Promising for External Fixation?
Study results for external fixation were shared at EULAR (the 2008 Annual Congress of the European League Against Rheumatism). Nineteen osteoarthritis patients under the age of 60 were involved in the study. An external fixation frame with springs was used to distract the knee joint by 5 mm over a two-month period. The goal of the procedure was to promote knee repair by taking away mechanical stress on the knee.
The patients had poor pain scores and functional ability scores before being placed in an external fixation brace. After the joint distraction, their scores approached what is considered normal within 6 months and the improvement was sustained for up to 2 years.
There was evidence of cartilage repair on MRI and digital x-rays after one year. Cartilage volume increased by 50% and subchondral bone (the layer of bone just below the cartilage) covered with cartilage increased by 40% -- as did cartilage thickness after one year of external fixation. Markers of increased level of turnover (degradation and synthesis) of cartilage and bone during distraction reverted to normal in the months that followed treatment.
What Is the Significance for a Patient With Severe Knee Osteoarthritis?
In this study, external fixation for joint distraction provided lasting pain relief, functional improvement, and reduced wear-and-tear on the knee. Researchers believe the benefits of the procedure will last for 10 years, at least, and allow people to resume normal function. While this would certainly delay the need for knee replacement surgery -- an absolute benefit for younger osteoarthritis patients -- it does not eliminate the need for knee replacement surgery.
So far, the procedure has only been used on a small number of patients. The same procedure, external fixation for joint distraction, has been used for ankle osteoarthritis and successfully reduced pain and restored function for up to four years. It also has been successful for hip osteoarthritis for up to 10 years.
If you have severe osteoarthritis of the knee and are choosing to delay knee replacement surgery for as long as possible, external fixation for joint distraction may be an option. Remember, it's still an experimental treatment option, so be sure to discuss the benefits and risks of the procedure with your doctor and orthopedic surgeon so you can make an informed decision.
Joint Distraction Promotes Structural Repair in Patients With Severe Knee Osteoarthritis. EULAR. June 11-14, 2008.