UCSF Study Aims to Protect Joints, on Earth and Off

Starting in January, a UCSF postdoctoral researcher will launch the first-ever study of the effects of prolonged nonuse on human cartilage. His findings could have significant implications not only for patients with debilitating conditions such as osteoarthritis, but also for a group of individuals with their own unique physical challenges: astronauts.

Richard Souza, PhD, a researcher in the Musculoskeletal and Quantitative Imaging Research (MQIR) group in UCSF’s Department of Radiology and Biomedical Imaging, was one of four scientists from around the country selected in December by the National Space Biomedical Research Institute for its 2008 postdoctoral fellowship program. The Houston-based institute, funded by NASA, examines health risks related to long-duration spaceflight.

While past studies have investigated the influence of spaceflight on human muscle and bone tissue, it remains unclear how zero-gravity conditions affect cartilage, Souza said.

“If [the astronauts’] cartilage is undergoing some biochemical changes in space, that may put them at risk of developing osteoarthritis later in life or immediately once returning to Earth,” he said.

Osteoarthritis is caused by the breakdown and eventual loss of cartilage in one or more joints, and is the leading cause of chronic disability in the United States. Normally, the breakdown of cartilage is associated with excessive use of a joint. But studies with animals have shown similar degeneration when the joints experience zero load for an extended period of time.

Now, Souza will have the chance to replicate those animal studies in humans. He will focus on the knee cartilage of 25 UCSF patients undergoing either hip replacement surgery or treatment for an ankle fracture, both of which require up to two months of little to no pressure on the injured leg. Using noninvasive magnetic resonance technology, Souza will collect images of patients’ knee cartilage composition at three stages: at the start of the study, after eight weeks of nonuse and, finally, four to six weeks after the subjects have resumed weight-bearing activity.

Souza expects to see signs of cartilage degeneration at the eight-week mark – a finding that would shed light on human cartilage behavior and help both land- and space-based individuals take preventive measures to protect their health. But it is the final set of cartilage images that Souza is most excited about.

“The literature tells us that canine cartilage composition begins to return to normal after that [four- to six-week] period of time,” he said. “In humans, we haven’t yet seen much evidence that weakened cartilage can improve in quality. So if that happens during our study, the implications for rehabilitation for osteoarthritis and other conditions would be significant.”

Souza, who joined UCSF in May 2008, said he hopes to start monitoring his first subject by mid- to late January, and to have his study completed or nearly completed by the summer. He will work under the supervision of MQIR Director Sharmila Majumdar, PhD, and will be assisted by several other researchers from Majumdar’s lab.