By Larry Hand
Practitioners treating a patient with ankle osteoarthritis (OA) may want to ask if the patient has a history of back pain, according to a recent study that found an association between lumbar disc degeneration and ankle OA in cadavers.
The study was unable to determine, however, whether the lumbar pathology typically precedes the ankle OA or whether it’s the other way around.
Alex V. Boiwka, MD, an orthopedic surgical resident at the University of Buffalo in New York, and colleagues conducted a postmortem study involving 710 cadavers (583 male) who ranged in age from 17 to 105 years at the time of death.
A single spinal examiner graded lumbar disc degeneration disease (DDD) on a scale of 0 to 4 by Kettler and Wilke classification for vertebral endplate osteophytosis. Another single examiner graded tibiotalar joint arthritis on a scale of 0 to 4 by the Kellgren-Lawrence classification system.
Of 696 specimens with adequate bone available for bilateral ankle measurement, 586 had some degree of tibiotalar osteoarthritis, and 16% of these had severe arthritis. Of 516 specimens with lumbar data available, 443 showed disc degeneration, which was most prevalent at the L4-L5 and L3-L4 intervertebral levels. Thirty cadavers had degeneration at one level; 285 had degeneration at all five lumbar levels. Of the 516 with data, 152 had severe DDD.
Linear regression analysis revealed a significant association between lumbar DDD and tibiotalar osteoarthritis and that “the presence of three or more levels of lumbar DDD significantly increased the possibility of developing severe tibiotalar osteoarthritis,” the authors wrote. Logistic regression analysis found that severe lumbar DDD significantly predicted severe ankle arthritis and vice versa. The findings were published in April by the online journal American Journal of Orthopedics.
The authors, who did not respond to LER’s interview requests, postulated in the paper that the lumbar DDD likely precedes the tibiotalar OA, writing, “Because significant lumbar disc degeneration has long been known to result in both spinal nerve and cord compression, we hypothesize that this resultant neurocompression promotes altered gait and translation of atypical forces to the ankle and foot, thus predisposing to the onset and/or progression of osteoarthritis.”
Ram Haddas, PhD, director of research at Texas Back Institute Research Foundation in Plano, concurred.
“Which comes first, if you ask me, I think it’s the lumbar spine because the disc is usually the one that’s going to turn first due to the intervertebral disc hoop stress mechanism,” Haddas said.
However, he thinks the two disorders are associated, but not directly related, because of mechanical disadvantages in the structure of the spine compared to the ankle. Also, he added, forces on the spine actually come from above, from stresses related to lifting tasks, for example.
“In my opinion, mechanically, there’s not a direct relationship,” Haddas said.
Thomas C. Michaud, DC, author of the textbook Human Locomotion: The Conservative Management of Gait-Related Disorders, and a practicing chiropractor in Newton, MA, proposed several possible explanations for the associations.
“As the authors point out, it’s impossible to say if the osteoarthritis in the ankle was the result of spinal involvement reducing proprioception and thereby negatively affecting gait, or if long-term radicular pain damaged motor output, weakening the joints and accelerating the development of osteoarthritis. Or if people who get back arthritis also get arthritis in other joints,” Michaud said.
Haddas described the research as “a nice correlation study.”
“This is a first step and needed to be done, and they did a good job on that,” he said. “The next step is to study live people using a human motion-capture system or biomechanics lab.”
Boiwka AV, Bajwa NS, Toy JO, et al. Lumbar degenerative disc disease and tibiotalar joint arthritis: a 710-specimen postmortem study. Am J Orthop 2015;44(4):E100-E105.