A clinical study led by UC San Francisco researchers has found that a new prosthetic device primarily used to save legs with cancer stimulates bone development. The device directs forces or stress on the leg bone rather than the metal implant and this, says the researchers, is necessary to prevent loosening and failure often seen in conventional implants. "With this new device, we've changed the whole picture of how forces go through the bone," said James Johnston, MD, UCSF professor of orthopaedic surgery, UCSF Stanford Health Care orthopaedic oncologist, and principal investigator of the study. "The fixation device produces an environment where bone appears to heal to a metal surface in a pattern similar to fracture healing." The novel device, known as the compliant pre-stress system (CPS), is under investigation at UC San Francisco and has been in development for over ten years.
"For patients with cancer of the leg, the findings suggest this device will not only prevent loosening of the prosthetic device but will also allow patients to function long term," said Richard O' Donnell, MD, UCSF assistant clinical professor of orthopaedic surgery and UCSF Stanford Health Care orthopaedic oncologist. UCSF researchers presented preliminary findings April 14 at the International Society of Limb Salvage Surgeons meeting in Cairns, Australia. Prior to the use of prosthetic devices, patients with cancer of the leg required amputation, said the researchers. Since the early 1970's, prosthetic devices have been used to replace cancerous bone and knee joints, allowing the leg to function normally.
The conventional system involves a titanium implant, a six inch stem that is
cemented in the canal of the femur or the thighbone.
"Previous research has shown that the conventional implants are becoming loose
and failing in approximately 50 percent of the cases after 10 years and 75
percent of the cases after 20 years," said Johnston.
When the implants become l
Contact: Lordelyn del Rosario
University of California - San Francisco