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NeuroNow - Back - to the future

NeuroNow Spring 2011

Back - to the future

Date: June 1, 2011

Risheng Xu and Ali Bydon
Risheng Xu and Ali Bydon test hardware used in spine surgeries using a machine that twists and bends cadaver spines repeatedly to simulate long-term wear.
photo by Keith Weller

Ali Bydon and his colleagues at Johns Hopkins perform about 1,000 spine surgeries a year. Around two-thirds of these surgeries require instrumentation—screws, rods, and the like—to fuse or stabilize one or more of the spine’s 33 joints. But, Bydon says, experience alone doesn’t always hold all the answers.

“I’ve encountered many things in the operating room that we don’t always have a clear solution for,” he says. “Should I use this rod or another to stabilize someone’s spine? Is one length of screw better than another?”

To get answers that could improve patients’ outcomes, in 2007, Bydon and Risheng Xu, a fourth-year Hopkins M.D./Ph.D. student Bydon had recruited to work with him in Xu’s first year, came up with a novel idea: Why not test various pieces of instrumentation to determine their validity and durability?

That’s the concept behind the team’s Spinal Column Biomechanics and Surgical Outcomes Laboratory. Using cadaver spines obtained from the Maryland Anatomy Board, Bydon, Xu and their colleagues implant the various types of hardware they would use in an operation, then put each backbone in a machine that can twist and bend it repeatedly to simulate long-term wear.

The researchers recently reported results of one of their tests comparing two different screws commonly used to fuse vertebrae in the neck. Most surgeons consider one, called a pedicle screw, to be stronger than the other screw. However, pedicle screw placement can be challenging because the screw is inserted close to a nerve that controls the function of the hand—bringing a small but worrisome risk of paralyzing the hand if things go wrong.

Bydon, Xu and their colleagues showed that the more easily placed screw did the job just as well in a select population of patients. In certain conditions, says Bydon, “we don’t need to go the extra mile to place the tougher screws.”

They’ve also been studying surgical outcomes with different procedures meant to accomplish the same thing. For example, to treat synovial cysts, a common back problem in which fluid-filled sacs develop between vertebrae and press painfully on spinal nerves, surgeons can perform one of two operations. They can remove the cyst and small pieces of the vertebra to give more room for the nerves, known as a decompression, or they can do the same surgery and fuse the affected joints, known as decompression with stabilization.

After reviewing data from 167 patients treated at Hopkins, Bydon and his team found that stabilizing the joint led to significantly less back pain down the road, with minimal additional risk for patients.

“Before this paper came out,” Bydon explains, “surgeons thought it might be too risky and unwarranted to do a fusion for synovial cysts. For the first time, we showed that fusion leads to better long-term outcome in patients with synovial cysts.”

This new knowledge is changing the way Bydon and his colleagues treat patients—and the hope, says Xu, is that it will change practice at other institutions as well.

“Part of what I love about academic medicine is that you’re not only able to help the patients you see,” he says, “but you’re able to advance the care other patients receive.”

For information: 410-502-6103

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