Finding the Needle in the Osteoarthritic Knee

A new treatment for osteoarthritis of the knee is gaining in popularity. It is the injection of a liquid called hyaluronate. This is also known as Hyalgan or Hylan G-F 20. It is made from chicken combs and works by coating the joint lining to protect it during motion.

Once a new treatment has been used for awhile, doctors start studying its success or failure. Since the hyaluronate must be injected into the joint to work, it is important to know how often it gets directly into the joint.

There are three different places the doctor can insert the needle for the injection. The knee is either straight or bent depending on which site the doctor chooses. It is much easier to inject the knee when there is swelling present. However, the hyaluronate treatment works better when no swelling is present.

One doctor tested his results to see how accurate the injections were and which injection site worked best. Using an X-ray imaging method called fluoroscopy, the doctor was able to see right away if the needle went into the joint.

Two of the injection sites were only 75 percent correct. The knee was bent and the injection went in either side of the knee from the front. The doctor found the best results by keeping the knee straight and injecting just under the outside edge of the kneecap. There is less fat and soft tissue in this area.

These results are based on one doctor and should be repeated by other doctors. Comparing the results for different doctors will show if this one method is the best for everyone.



References: Douglas W. Jackson, MD, et al. Accuracy of Needle Placement Into the Intra-Articular Space of the Knee. In The Journal of Bone and Joint Surgery. September 2002. Vol. 84-A. No. 9. Pp. 1522-1527.