Reconstruction of Anterior Cruciate Ligament (ACL)
The ACL connects two bones, the femur and tibia of your legs, to stabilize knee motions. Excess force on the joint can sometimes break the ligament during playing sports like succor football, basketball, or skiing. Injury of the ACL is popular among sport injuries. Once you have ACL rupture, you must undergo surgery on the rupture for reconstruction if you want to return to the sport. Every year, over eight hundred thousand patients around the world undergo reconstruction surgery.
Unfortunately, there is no medical device for healing ligament rupture; your doctor removes healthy hamstring tendon or patellar tendon from your leg and makes a graft for reconstruction. We call this autologous graft, or autograft. If you experience a rupture again, there is no more tissue available for reconstruction surgery. Besides, some patients do not have enough volume (length and diameter) for preparing autograft.
The problem of using autograft is that it causes pain, restricts motion, and causes adverse reaction related to the harvesting of tissue. There used to be several artificial ligaments made of synthetic fiber. However, since the performance was not good enough, it is hardly used in now. Therefore, orthopedic physicians and patients have long been looking for an effective medical device for reconstruction.
Development of Artificial Ligament for ACL Reconstruction
Our first target is an implantable medical device for treatment of the rupture of the ACL. Our concept is to make a medical device with animal tendon. Our tissue source is tendon from cow’s legs which is strong enough as an artificial ligament.
To prevent allergic reaction or graft rejection, we remove cells from the tissue. The tendon is freeze-dried and sterilized after removing the cells. The device is an off-the-shelf product that can be stocked in hospitals to be available at any time.
We utilize the following two key technologies invented by Prof. Kiyotaka Iwasaki. Ph.D., Waseda University:
1. Decellularization technology radiating microwave to the tissue and washing cell components with the palatized perfusion of detergent (MAPP method)
2. Lyophilization and sterilization technology maintaining the mechanical property of the artificial ligament and providing recovery to supple condition easily once immerse to the saline solution
These technologies could make it possible to develop the artificial ligament with biocompatibility and mechanical strength as the artificial ligament.