North American Spine Society, Oct. 9-12
The annual meeting of the North American Spine Society was held from Oct. 9 to 12 in New Orleans and attracted approximately 5,000 participants from around the world, including orthopedic surgery, neurosurgery, neurology, radiology, and anesthesiology specialists as well as researchers, physical therapy specialists, and other spine care professionals. The conference featured presentations focusing on the latest advances in medical and surgical spine care.
In one study, Matthew Smuck, M.D., of Stanford University in Redwood City, Calif., and colleagues demonstrated that obesity was a strong risk factor for low back pain in Americans. Specifically, the investigators found that the likelihood of having low back pain increased in step with body mass index (BMI), from 2.9 percent for normal weight (BMI, 20 to 25 kg/m²) to 5.2 percent for overweight (BMI, 26 to 30 kg/m²), 7.7 percent for obese (BMI, 31 to 35 kg/m²), and 11.6 percent for morbidly obese (BMI, 36 kg/m²). However, the investigators also found that overweight and obese Americans can reduce this risk (even more than the general population) by increasing daily physical activity and reducing sedentary time.
"We showed that physical activity modulates this relationship, with overweight and obese Americans deriving the most protection from low back pain with improvements in physical activity," said Smuck. "Perhaps the best news out of this study is that big gains can be made by making very modest changes in physical activity behavior."
In another study, Trevor Scott, M.D., of the University of California in Los Angeles, and colleagues found that patients who undergo spine surgery may be able to return to driving as soon as two weeks postoperatively, as long as they are not on narcotics. The investigators aimed to determine when a patient's driving reaction time returns to normal following lumbar or cervical spine surgery.
"We performed a prospective trial and found an overall trend in lumbar spine patients toward decreased reaction time at the postoperative visit, which is typically two to three weeks post-operation. When we studied that group further, we found that this was mostly accounted for by the single-level surgery group and the decompression-only group," said Scott. "In the multi-level surgical groups and those involving fusion, the trend was not as strong."
In the cervical group, the investigators found an overall trend towards increased driver reaction time, expect in those who underwent an anterior approach. However, according to Scott, it was quite a small increase statistically. There was no actual difference in their driver reaction time pre-operation and at the two-to-three week post-operation visit.
"Potentially, cervical patients can return to driving postoperatively but this was a small group and further study in a larger group of patients is needed," said Scott.
Raja Y. Rampersaud, M.D., of the Toronto Western Hospital, and colleagues found that patients undergoing surgery for focal symptomatic spinal stenosis (FLSS) can expect a comparable long-term average improvement in health-related quality of life from baseline compared to their peers undergoing total knee arthroplasty (TKA) and, to a lesser extent, total hip arthroplasty (THA). The investigators also found that surgery for patients with FLSS provides comparable long-term value to that of TKA and THA.
"The results of this study provide relevant outcomes and decision making information for patients, surgeons, and payers regarding the surgical management of FLSS compared to two well accepted interventions (THA and TKA)," said Rampersaud.
Marios G. Lykissas, M.D., Ph.D., of the Hospital for Special Surgery and Weill Cornell Medical College in New York City, and colleagues found a strong association between recombinant human bone morphogenetic protein-2 (rhBMP-2) exposure of the lumbar plexus and neurologic complications during lateral lumbar interbody fusion (LLIF).
"The use of rhBMP-2 resulted in a higher number of patients with neural deficits during the immediate postoperative period as well as a higher number of persistent neurologic deficits at last follow-up, suggesting an adverse effect of rhBMP-2 on nerve physiology and an inhibitory action on nerve recovery," said Lykissas. "Increased postoperative pain after LLIF using rhBMP-2 compared to LLIF without rhBMP-2 supports previous findings of rhBMP-2-induced pain or hypersensitivity after spinal fusion in humans and mechanical hyperalgesia in rats."
The investigators aimed to evaluate acute and interim neurological sequelae following LLIF with and without rhBMP-2.
"Our results provide evidence of an increased rate of postoperative neurologic deficits and anterior thigh/groin pain after LLIF using rhBMP-2 compared to closely matched controls without rhBMP-2 exposure," said Lykissas. "Taken together, this study suggests a direct deleterious effect of rhBMP-2 on the lumbar plexus, which is not secondary to mechanical compression of the neural tissue by the maturing fusion mass."
In a large prospective study, Dino Samartzis, Sc.D., Ph.D., of Queen Mary Hospital in Hong Kong, and colleague Kenneth M. Cheung, M.D., also of Queen Mary Hospital, evaluated whether baseline magnetic resonance imaging (MRI) characteristics can predict, in asymptomatic individuals, who will develop first-time low back pain and the severity of the pain.
"This study identifies clinically relevant spinal phenotypes that are related to the development of low back pain and its severity," said Samartzis. "Patterns of degenerative spine changes may have predictive utility in the development of low back pain. These 'patterns' of disc degeneration may also shed light on predicting the severity of low back pain."
The investigators identified a low back pain risk profile based on baseline MRIs and environmental/lifestyle factors. This profile focused on the development of first-time low back pain episodes.
"In that risk profile, heavy workload increased the risk of first-time low back pain; however, being active and engaging in physical activity decreased the risk. Having overall disc degeneration or disc bulging/extrusion doubled the risk of developing low back pain," said Samartzis. "Having moderate to severe disc degeneration of the lumbar spine significantly increased the risk of developing first-time low back episodes. A 'dose response' of lumbar degeneration and pain profile was identified. The more lumbar disc degeneration, the more severe the pain."