When Yue Wang arrived to work with the Common Spinal Disorders Research Group at the University of Alberta in pursuit of a doctoral degree, he brought with him something special: years of experience as an orthopedic surgeon. And that background has led to a discovery that may prove seminal in the understanding of back pain.
Earlier this year, Yue's research paper showing an association between back pain and lesions on the bony endplates of vertebrae earned him the premier award in back pain research, the International Society for the Study of the Lumbar Spine's ISSLS Prize.
While practicing as an orthopedic surgeon in his native China, Yue became frustrated by not knowing the cause of the back pain many patients were suffering. He says that in some instances the source of back pain is obvious-fractures, tumours or severe degeneration-but in most cases its origin is simply not known. "If we are going to treat these patients, we need to know where the pain is from," he says. "We need more research."
To advance this cause, Yue decided to return to studies, choosing to do so with the Common Spinal Disorders Research Group in the U of A's Faculty of Rehabilitation Medicine. He says he opted to study there with Michele Crites Battié and Tapio Videman for a simple reason: "These two are really the top scientists in spine research in the world."
When Yue arrived in the lab, he quickly realized that a tremendous resource was available to him-a rare collection of human spines assembled by Videman. "It was a real treasure," says Yue, whose clinical background gave him a particular appreciation for the lumbar spine archive comprising spinal bones from 157 middle-aged men. For 109 of the subjects, information is available about the condition of their spinal discs. In addition, for 69 of the men, information had been collected about their history of back pain and back injury.
The human spine is a column of 33 bones, known as vertebrae, and this column is given flexibility by discs that separate the bones, making articulation possible. Each of the discs has a gelatinous centre surrounded by a fibrous envelope, while the interface between the disc and the vertebra is a thin (about .6mm in thickness) layer of cartilage attached to a bony surface of the vertebra. Together, the cartilage layer and the bony vertebra surface form the endplate.
As Yue studied the vertebral endplates in the spine archive, his attention was drawn to disruptions in their generally smooth surface. (He was looking at only the bony surface; the cartilage layer is not preserved in the collection.) "I found that a lot of them were damaged," he says. "So I'm thinking, 'Why is this so common?'"
Yue explains that, despite the fact that endplates are rich in both blood supply and nerve endings, they have "kind of been ignored by spine researchers for years." In the spinal research literature, the imperfections that captured Yue's attention were generally referred to as fissures and had come to be lumped together under the term Schmorl's nodes, a pathology described as early as the 19th century.
With his background in orthopedic surgery-"I'm a bone doctor; I'm living on fractures, " he says-Yue was convinced that some of the endplate lesions (an appellation he prefers over "fissures") he was seeing were caused by fractures. After close analysis, he divided the lesions present on the endplates into four distinct categories: Schmorl's nodes, fractures, erosion or calcification. In his prize-winning paper, co-authored with Videman and Crites Battié, Yue examined associations among a variety of factors, including the type and severity of lesions, disc degeneration, occupation type and back pain.
His conclusion was that endplate lesions are associated with back pain, as well as being closely associated with adjacent disc degeneration, with a clear dosage effect. And, importantly, the association between endplate lesions and back pain went beyond what could be accounted for by disc degeneration.
"Yue has done a terrific job at looking at the interface between disc and bone," says Crites Battié, his doctoral supervisor. "We're really excited about his findings."
She adds a caveat, however: "Time will be needed for further investigation and replication of these findings and methods will be needed for their clinical utility." But that might not be easy, as the archive with which Yue worked may well be a unique resource, and common clinical imaging techniques (MRI and CT scans) currently don't provide detailed information about endplate lesions. However, Crites Battié, is confident new technologies will evolve. "Once we identify the clinical importance of endplates, bright minds will further develop the technology or methods we need," she says.
Yue's prize marks the fifth time that the ISSLS's most prestigious award has gone to the research group headed by Crites Battié and Videman. In addition, Videman won the prize (then known as the Volvo Award) prior to coming to Alberta as a co-founder of the Common Spinal Disorders Research Group-that 1990 prize was for research on the same spine archive on which Yue did his work.