Noninvasively Relieving Joint Contracture by Using Ultrasound-Assisted Laser Technique to Remove Scar Tissues in the Knee Joint
Abstract
The Fiscal Year 2014 Peer Reviewed Medical Research Program Topic Area addressed by the proposed research is post-traumatic osteoarthritis. The objective of the project is to develop an ultrasound-assisted, pulsed laser technique for scar dissolving in the knee to relieve joint contractures and prevent the subsequent post-traumatic osteoarthritis. When a knee injury heals, just like injured skin tissue, it will scar. The excessive scars in joint can restrict the mobility of the joint, and eventually induce post-traumatic joint contracture and osteoarthritis. This complication is termed arthrofibrosis. Arthrofibrosis is one of the major complications of joint injuries and one of the most difficult to treat. In order to prevent the post-traumatic knee contracture and osteoarthritis, it is critical to remove the excessive scar tissues in the knee. Laser technique has been used to remove scars on the skin surface. Surface scar tissue can be burned off by laser and the remains may be absorbed by the surrounding tissues. However, this technique is not feasible for removing scars in the knee because scars in the knee are not on the surface of the skin. In the proposed technique, however, with the assistance of ultrasound, we will apply laser light with intensity level that is safe for skin exposure according to the standard of America National Standards of Institute. Scar tissues usually have different optical absorption spectra from the surrounding tissues. When laser light illuminates the joint with the peak optical absorption wavelength, the scar tissue will absorb much more optical energy than the surrounding tissues, resulting in a rapid temperature increase on the surface of the scar. Because human body liquid is originally saturated with air molecules such as nitrogen and the solubility of air decreases as temperature increases, the rapid temperature rise will create a local region that is super-saturated with gases on the scar surface, or sometimes localized vapor bubbles can be directly induced. This local region is unstable under ultrasound and will result in cavitation when low frequency ultrasound is applied. The collapse of cavitation can produce strong shock wave forces, which can effectively erode the surrounding tissue. As a result, the scar tissue will be removed. The key feature is that cavitation will be generated deep inside the joint noninvasively and only limited to the scar region. The proposed research is the first effort to combine laser and ultrasound to dissolve scar tissues deep inside the joint, not the surface scar. The main technical novelty of the proposed research is the combination of diagnostic-level laser light and ultrasound to induce cavitation. The major advantage of this technique is that the applied laser intensity is safe for skin exposure by the standard of America National Standards of Institute. In other words, the laser light by itself will not induce cavitation and damage tissue on its path. Cavitation will be induced only when the applied laser light is absorbed by the scar tissues and interacts with the applied ultrasound inside the joint at the scar surface. As a result, the technique can be applied noninvasively. It is expected that the proposed technique will be found effective in prevention and/or treatment of joint contracture and post-traumatic osteoarthritis by dissolving scar tissues inside the joint. As a result, the proposed research may significantly improve the quality of life of the relevant military Service members as well as patients in the general population.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 29, 2016
- Source ID
- W81XWH1510524
Entities
People
- Xinmai Yang
Organizations
- United States Army
- University of Kansas