The novel design of a deep muscle along the spinal column called the multifidus muscle may in fact be key to spinal support and a healthy back, according to researchers at the University of California, San Diego School of Medicine.
Their findings about the potentially important "scaffolding" role of this poorly understood muscle has been published on line in advance of the January issue of the Journal of Bone and Joint Surgery .
"The multifidus muscle was formerly thought to be relatively unimportant based on its fairly small size," said Richard L. Lieber, Ph.D., Professor and Vice Chair of UC San Diego's Department of Orthopedic Surgery and Director of the National Center for Skeletal Muscle Rehabilitation Research, based at UC San Diego. Lieber is also Senior Research Career Scientist at the Veterans Affairs San Diego Health System. "Our research shows that it's actually the strongest muscle in the back because of its unique design. It's like a long, skinny pencil packed with millions of tiny fibers."
The researchers discovered that the multifidus has a unique packing design consisting of short fibers arranged within rods, and that these fibers are stiffer than any other in the body. Using laser diffraction methods that they developed to measure muscle internal properties during back surgery, they demonstrated that the multifidus' unique design serves a critical function as a stabilizer of the lumbar spine. These findings could have implications for surgery, according to Steven R. Garfin, M.D., Professor and Chair of UCSD's Department of Orthopaedic Surgery.
"It is important to identify what each individual muscle does, and this is just a start, showing that the multifidus contributes significantly to spinal stabilization," said Garfin. "The more we know about what muscles do, the better we can devise therapeutic interventions such as physical therapy to target specific muscles."
Garfin explained that currently surgery to treat spinal disorders could actually disrupt the multifidus muscle, which could lead to decreased stabilization and lower back pain. Minimally invasive spine surgery techniques strive to minimize surgical trauma to these muscles in order to best preserve their function.