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AAOS Now

Published 12/1/2015

What Else Was New at NASS?

According to Steven D. Glassman, MD, of Louisville, Ky., transforaminal lumbar interbody fusion (TLIF) has replaced posterior spinal fusion (PSF) as the most commonly used fusion technique for the treatment of lumbar degenerative disorders. The shift, however, has often failed to show improved clinical outcomes, based on previous studies.
For that reason, Dr. Glassman and colleagues wanted to compare outcomes in patients with spondylolisthesis, spinal stenosis, or adjacent segment disease treated with TLIF or PSF. Their study, "Benefit of TLIF Versus PSF in Lumbar Spine Disorders," was among those that received recognition as a "best paper."

According to their results, patients with spondylolisthesis who underwent TLIF had better Oswestry Disability Index (ODI) outcomes. That was not the case for patients with spinal stenosis or adjacent segment disease who were treated with TLIF.

The improvement in ODI with TLIF among spondylolisthesis patients was first noted at 3 months after surgery. In addition, a greater number of these patients reached a minimum clinically important difference at 12 months, compared to patients treated with PSF.

The researchers found no differences in the length of operating room time or intraoperative blood loss between the two procedures, "potentially altering the long-standing assumption that PSF is a simpler procedure," Dr. Glassman said. Dr. Glassman's coauthors included Leah Y. Carreon, MD, MSc; Zoher Ghogawala, MD, FACS; Matthew J. McGirt, MD; Kevin T. Foley, MD, FACS; and Anthony Asher, MD, FACS.

Another "best paper" described the effects of insulin on 46 rabbits undergoing PSF. According to Michael J. Vives, MD, chief of spine surgery at Rutgers-New Jersey Medical School in Newark, soaking a collagen sponge with insulin and laying the sponge over the fusion bed during surgery enhanced posterolateral lumber fusion in a dose-dependent manner.

In this study, one group of rabbits was given either 5 or 10 units of insulin, while another group was given 20 or 40 units. Rabbits in the first group did not have a significant improvement in radiographic scores, but those that received the higher doses did show significant improvement. In addition, all the rabbits that received high doses attained fusion, and 6 out of 10 were judged solidly fused.

"This study demonstrates the potential role of local insulin as a bone-graft enhancer using a validated rabbit model. We have previously demonstrated that a time-release insulin implant enhances posterolateral fusion in a rat model. The current study demonstrates a dose-responsive effect for immediate-release insulin in a larger animal," Dr. Vives said.
"Exogenous insulin during the cell proliferation stage of bone formation (days 0 to 4) could lead to enhanced mineralized tissue formation in later stages when exogenous insulin is no longer present," he noted. Dr. Vives' coauthors included Jessica Cottrell, PhD; Sangeeta Subramanian, PhD; J. Patrick O'Connor, PhD; Sheldon S. Lin, MD; Saad Chaudhary, MD, MBA; Neel P. Shah, MD; and William Munoz, MD.

Measuring outcomes
"Does patient satisfaction reflect quantitative pain and function measurements in cervical spine surgery?" asked the Rothman Institute's Kris E. Radcliff, MD, during a session on patient-reported outcomes in spine surgery. Dr. Radcliff described a prospective, randomized, controlled clinical trial he conducted in patients diagnosed with degenerative disk disease at two levels of the cervical spine and no previous cervical fusions.

Patients were randomized to receive either total disk replacement or anterior cervical diskectomy and fusion. Patient satisfaction was assessed by a questionnaire that categorized patients as very satisfied, somewhat satisfied, somewhat dissatisfied, or very dissatisfied. The clinical outcome measures included improvements in Neck Disability Index (NDI) scores, Short-Form-12 (SF-12) Physical and Mental Component Summary scores, and Visual Analog Pain Scale (VAS) scores.

Adverse events found in the study included dysphagia or dysphonia, infection, nonunion, spinal disorders and nonsurgical medical complications, such as cardiovascular, gastrointestinal, genitourinary, or respiratory complications.

When comparing outcomes among the different satisfaction groups, "significant differences were found in NDI, VAS, and SF-12 scores," Dr. Radcliff said. "Very satisfied patients tended to have fewer adverse events.

"A qualitative measurement of patient satisfaction accurately reflects quantitative measurements of patient pain, function and quality of life," he concluded. Dr. Radcliff's coauthors were Domagoj Coric, MD, and Todd J. Albert, MD.

Harrison F. Kay, from the department of orthopedic surgery at Vanderbilt University School of Medicine in Nashville, presented research on the impact of depression or anxiety on patient-reported outcomes and satisfaction after spine surgery. The study involved 262 patients who underwent spine surgery for cervical myelopathy. The outcome measures included NDI, SF-12, and VAS neck-pain and arm-pain scores.

Based on data from a prospective longitudinal registry of cervical myelopathy patients treated between January 2011 and December 2012, the researchers found that patients with depression and anxiety have worse absolute pain and disability but similar 12-month change and satisfaction scores. A related study on the effects of drug allergies on patient-reported outcomes following surgery for degenerative lumbar spine disease found that a greater number of drug allergies was significantly associated with both depression and anxiety, as well as worse 12-month outcomes.

Coauthors for both papers included Silky Chotai, MD; Joseph Wick, BA; David Stonko; Matthew J. McGirt, MD; and Clinton J. Devin, MD. Ahilan Sivaganesan, MD, was a coauthor for "Does Depression or Anxiety Affect Patient-reported Outcomes and Satisfaction following Operative Treatment for Cervical Myelopathy?" Anthony Asher, MD, FACS, was a coauthor for "Does Number of Reported Drug Allergies Affect Patient-reported Outcomes and Satisfaction following Operative Treatment for Degenerative Lumbar Spine Disease?"

Additional Information:
NASS Final Program