New Joint Replacement Material Prevents Deterioration

Surgeons at Massachusetts General Hospital performed the first total hip replacement with a new material invented at the hospital. This material is being heralded as a significant advancement from first generation joint replacement materials, which often allowed the joint to loosen after the first five years.

The new material is expected to be used in wider variety of joints and aid a larger and more diverse group of patients.

"We think this material could be used for any joint in the body and in any implant design, even those demanding higher flexion and more mobility," says Orhun Muratoglu, PhD, co-director of the Harris Orthopædics Biomechanics and Biomaterials Laboratory (OBBL) at Massachusetts General Hospital in a press release. Muratoglu was one of the researchers who helped develop the new material while working with scientists at the Cambridge Polymer Group.

Total joint replacements were first developed in the late 1960's, when it was quickly realized that the joint would loosen after only five years. The loosening would eventually lead to total failure.

At the time, William Harris, MD, DSc, lead a team to determine the cause of the joint failure. They discovered that the friction of the head of the implant against the polyethylene-lined joint socket would wear down the joint.

The friction would cause tiny particles to break off the polyethylene and the body would react against the foreign matter. This caused adjacent bone tissue to be destroyed, a condition called periprosthetic osteolysis that also caused the loosening of the joint.

Muratoglu discovered that by diffusing the antioxidant vitamin E throughout the material, it prevented the deterioration of the polyethylene. Mechanical testing and animal studies confirmed that the new material is comparable in wear to the first generation polyethylene, but is much stronger. The vitamin E stabilized material has also been approved by the FDA.

"This material will allow us to offer our patients very long-term, high-performance joint replacements," says Andrew A. Freiberg, MD, chief of the Arthoplasty Service, who performed the first implant with Vitamin E stabilized material. "It should be suitable for higher-stress applications in younger patients, those who are more active and those who are heavier."

Massachusetts General Hospital orthopaedic surgeons will study the new material in the long term, focusing on determining the long term performance of the Vitamin E stabilized surface. Patients can enroll in the study if they meet certain entrance requirements and follow up with a participating hospital for at least five years.

SOURCES:

URL: (http://www.massgeneral.org/news/releases/072307muratoglu.html)