Tag Archive | spinal fusion

JBJS Classics: Wiltse’s Paraspinal Muscle-Splitting Approach

JBJS Classics Logo.pngOrthoBuzz regularly brings you a current commentary on a “classic” article from The Journal of Bone & Joint Surgery. These articles have been selected by the Editor-in-Chief and Deputy Editors of The Journal because of their long-standing significance to the orthopaedic community and the many citations they receive in the literature. Our OrthoBuzz commentators highlight the impact that these JBJS articles have had on the practice of orthopaedics. Please feel free to join the conversation by clicking on the “Leave a Comment” button in the box to the left.

Almost 50 years ago, in a classic 1968 JBJS paper, Leon Wiltse and co-authors described a novel and innovative access route to the lumbar spine. At that time, the vast majority of approaches to the lumbar spine were performed through midline incisions. Wiltse´s approach, however, utilized a more lateral access route to the spine. In this beautifully illustrated paper, the authors described a curved incision of the fascia and the skin with direct access to the transverse processes, pedicles, and the lateral masses.

The advantages of this novel access were multifold. Although wide midline laminectomies represented the gold-standard decompression technique at that time, the lateral approach served to avoid a more challenging and risky midline revision access, adding an elegant access for salvage procedures. Two goals of Wiltse’s approach were to achieve solid, posterolateral fusions and to decompress the neural structures. Graft harvest from the posterior iliac crest was easily facilitated with this approach.

Additional advantages included reduced blood loss and less muscle ischemia, and the preservation of spinous processes and intra-/supraspinous ligaments, which served to maintain the stability of the lumbar spine. The main downside was the necessity of performing two skin incisions as opposed to just one midline incision.

Since its introduction, Wiltse´s approach and the anatomic planes have been studied in great detail.1,2 Considering the vast developments in spine surgery over the last years and decades, the Wiltse approach has stood the test of time, as it still represents one of the main access routes to the lumbar spine that any skilled spine surgeon needs to master.

With the arrival of instrumentation, Wiltse´s approach was later employed in interbody fusion and minimally invasive transforaminal lumbar interbody fusion (TLIF) techniques, as it allowed direct access to the pedicles and the disc space. It has also been used for various techniques of direct pars repair.3

With the addition of some minor modifications, Wiltse´s approach still reflects the main access for minimally invasive, microsurgical treatment of foraminal and extraforaminal disc herniations, including bony decompression of the neuroforamen.4 The far lateral access permits sufficient decompression of the exiting nerve roots while preserving the facet joints, which serves to avoid more invasive fusion techniques for a considerable number of patients.

Overall, Wiltse´s innovative approach advanced spinal care by reducing access–related morbidity. Dr. Wiltse passed away at age 92 in 2005. His major achievements in spine surgery and his great accomplishments will remain in our memories and will continue to impact spine surgery over the coming decades.

Christoph J. Siepe, MD
JBJS Deputy Editor

References

  1. Vialle R, Court C, Khouri N, et al. Anatomical study of the paraspinal approach to the lumbar spine. Eur Spine J. 2005;14(4):366-71.
  2. Palmer DK, Allen JL, Williams PA, et al. Multilevel magnetic resonance imaging analysis of multifidus-longissimus cleavage planes in the lumbar spine and potential clinical applications to Wiltse’s paraspinal approach. Spine (Phila Pa 1976). 2011;36(16):1263-7.
  3. Xing R, Dou Q, Li X, et al. Posterior Dynamic Stabilization With Direct Pars Repair via Wiltse Approach for the Treatment of Lumbar Spondylolysis: The Application of a Novel Surgery. Spine (Phila Pa 1976). 2016;41(8):E494-502.
  4. Mehren C, Siepe CJ. Neuroforaminal decompression and intra-/extraforaminal discectomy via a paraspinal muscle-splitting approach. Eur Spine J. 2016.

Are Ortho Patients Getting Too Many Pain Pills?

narc_usage_2016-10-03Surgeons often prescribe more postoperative pain medication than their patients actually use. That’s partly because there is limited procedure-specific evidence-based data regarding optimal amounts and duration of postoperative narcotic use—and because every patient’s “relationship” with postoperative pain is unique. Nevertheless, physician prescribing plays a role in the current opioid-abuse epidemic, so any credible scientific information about postoperative narcotic usage will be helpful.

The Level I prognostic study by Grant et al. in the September 21, 2016 issue of The Journal of Bone & Joint Surgery identified factors associated with high opioid use among a prospective cohort of 72 patients (mean age 14.9 years) undergoing posterior spinal fusion for idiopathic scoliosis.

Higher weight and BMI, male sex, older age, and higher preoperative pain scores were associated with increased narcotic use after surgery. Somewhat surprisingly, the number of levels fused, number of osteotomies, in-hospital pain level, self-reported pain tolerance, and surgeon assessment of anticipated postoperative narcotic requirements were unreliable predictors of which patients would have higher postoperative narcotic use.

Because the authors found that pain scores returned to preoperative levels by postoperative week 4, they say, “further refills after this point should be considered with caution.” Additionally, after reviewing the cohort’s behavior around disposing of unused narcotic medication, the authors conclude, “We consider discussion of narcotic use and disposal to be an important component of the 1-month postoperative visit…This important educational opportunity could help decrease abuse of narcotics.”

Mobility of Listhesis Key in Surgical Decision Making for Spondylolisthesis

OrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from Brett A. Freedman, MD, in response to two recent NEJM studies on treating spondylolisthesis.

The April 14, 2016 edition of The New England Journal of Medicine published results from two randomized clinical trials (RCTs) evaluating the benefits of laminectomy alone versus laminectomy and fusion for the treatment of specific spinal conditions in patients 50 to 80 years old, with at least 2-year follow-up. The larger study was conducted in Sweden and included 247 patients, 135 of whom had degenerative spondylolisthesis of some magnitude. In this study, the surgical technique varied and was left to the treating provider’s preference. The ultimate conclusion of this study was that adding fusion to the procedure did not result in better patient outcomes by any index measured.

Conversely, an essentially concurrent but unrelated RCT evaluating similar outcomes in a US patient population (n=66) with degenerative spondylolisthesis that measured at least 3 mm, but in which there was no instability, concluded that spinal fusion, using a standardized technique (pedicle screws and rods with iliac crest bone graft), did provide a significant clinical benefit. Specifically, this study found significant improvement in SF-36 physical-component summary scores (the primary outcome measure) and lower reoperation rates (14% vs. 34%; p=0.05) compared to decompression alone.

When two Level 1 studies published on the same day in the same high-impact journal come to divergent conclusions about the same clinical question, we must pause and look to the past. Spine surgeons have investigated decompression alone for spondylolisthesis, first by necessity (prior to the era of reliable spinal fusion) and then later in comparison to in-situ and instrumented fusion1,2. Consensus is consistent with anatomic reasoning. Dysfunctional lumbar mobile segments, especially those with preserved or excessive motion (i.e. >2 to 4 mm change on flexion-extension films), produce a mechanical pathoanatomic sequence of events that leads to critical and clinically symptomatic spinal stenosis. Addressing this first cause is paramount.

The immediate effect of surgery type is largely neutralized by the fact that the decompression component, which is common to both approaches, is principally responsible for acute improvement. Because most prospective studies are not able to reliably track patients beyond 2 to 5 years, the longer-term benefits of a solid arthrodesis of a dysfunctional spinal-motion segment compared to a simple decompression in which some of the incompetent posterior elements are further surgically removed remain largely unknown. Anecdotally, spine surgeons recognize that failures of decompression alone in mobile spondylolisthesis occur quite frequently—and that revision fusion surgery in this situation is significantly more complicated than primary decompression and fusion. That was the case in the Swedish study, where the majority of revision surgeries in the decompression-only cohort were performed at the same level as the prior surgery, versus adjacent levels in the fusion group. And, again, reoperation rates were significantly higher (>2x) in the decompression-only group in the US study.

Given conflicting data3, there likely are cofactors that need to be identified and further studied to select cases of spondylolisthesis that can be treated well with decompression alone, versus those that require the stabilizing effect of a fusion. Until then, surgeons must weigh the data available and provide the surgical option they feel is best for each individual patient.

Brett A. Freedman, MD is an orthopaedic surgeon specializing in spine trauma and degenerative spinal diseases at the Mayo Clinic in Rochester, MN

References

  1. Fischgrund JS, Mackay M, Herkowitz HN, Brower R, Montgomery DM, Kurz LT. Degenerative lumbar spondylolisthesis with spinal stenosis: a prospective, randomized study comparing decompressive laminectomy and arthrodesis with and without spinal instrumentation. Spine (Phila Pa 1976). 1997 Dec 15;22(24):2807-12.
  1. Bridwell KH, Sedgewick TA, O’Brien MF, Lenke LG, Baldus C. The role of fusion and instrumentation in the treatment of degenerative spondylolisthesis with spinal stenosis. J Spinal Disord. 1993 Dec;6(6):461-72.
  1. Joaquim AF, Milano JB, Ghizoni E, Patel AA. Is There a Role for Decompression Alone for Treating Symptomatic Degenerative Lumbar Spondylolisthesis?: A Systematic Review. J Spinal Disord Tech. 2015 Dec 24. [Epub ahead of print]

BMP vs Autograft for Instrumented Posterolateral Lumbar Fusion

In diligent efforts to improve osseous bridges when performing spinal fusion surgery, orthopaedists have been using harvested allograft bone for more than a century and bone morphogenetic protein (BMP) for nearly a half century. Now, a European multicenter, randomized trial by Delawi et al., in the March 16, 2016 Journal of Bone & Joint Surgery, has compared overall success (defined as a combination of CT-determined fusion rates and clinical results at 12 months) between the two approaches among 113 patients.

This was a non-inferiority trial, and the BMP formulation used (Osigraft BMP-7, known commonly as OP-1 and available in the US in a similar formulation known as OP-1 Putty) was not non-inferior to iliac crest autograft. To clarify the potentially confusing double negative: OP-1 was less successful than autograft, due primarily to lower fusion rates. There were no significant between-group differences in clinical outcomes as measured by scores on the Oswestry Disability Index, although the authors added that “our follow-up period of one year may have been too short to show differences in clinical results.”

Delawi et al. conclude that, based on their findings, “use of OP-1 in place of autologous iliac crest bone graft in instrumented posterolateral lumbar fusions cannot be recommended.” That conclusion is echoed by commentator Jeffrey Coe, MD, who sees these findings as “another bit of evidence against the use of rhBMP-7 as a substitute for [iliac crest bone grafts] in posterolateral spinal fusion.”

JBJS Classics: Harrington Ushered in Modern Spine Surgery in 1962

JBJS-Classics-logo

Each month during the coming year, OrthoBuzz will bring you a current commentary on a “classic” article from The Journal of Bone & Joint Surgery. These articles have been selected by the Editor-in-Chief and Deputy Editors of The Journal because of their long-standing significance to the orthopaedic community and the many citations they receive in the literature. Our OrthoBuzz commentators will highlight the impact that these JBJS articles have had on the practice of orthopaedics. Please feel free to join the conversation about these classics by clicking on the “Leave a Comment” button in the box to the left.

The JBJS Classic Treatment of Scoliosis: Correction and Internal Fixation by Spinal Instrumentation by Paul R. Harrington describes 15 years of investigation, beginning in 1947, soon after Dr. Harrington completed his residency in Kansas City and headed an Army orthopaedic unit during World War II. The importance of this paper can’t be overstated. With this description of instrumentation that improved deformity outcomes, Harrington ushered in modern spine surgery.  It was also one of the rare early examples of orthopaedic clinical science funded by a national grant.

The need for this daring, revolutionary instrumented approach was the polio epidemic, which left Dr. Harrington caring for many patients with severe, collapsing curves that threatened their health. Polio patients comprised 75% of the first series described in this paper.

This comprehensive study combines theory, basic science, surgical techniques, and outcomes. With it, Harrington started the still-continuing dialogue about indications for scoliosis surgery with the comment that “clinical indications for therapy are still being worked out.” As a partial answer to the indications quandary, he introduced the Harrington factor—the number of degrees of primary curve divided by the number of vertebrae in the primary curve. This calculation continues to be used (renamed) in some current research into risks of curve correction, while debate continues about other indications such as progression, pain, and pulmonary issues.

The technique of spinal instrumentation is extensively described in this landmark article. Noteworthy is Harrington’s gradual embrace of the need for fusion and well-molded body cast immobilization, both of which he credits with improved results. (Initially Harrington had hoped to avoid fusion in many cases.) Although “instrumentation” today is nearly synonymous with “fusion,” some of our most promising ideas in deformity correction now involve instrumentation without fusion.

Also impressive is the respect with which Harrington treated the spinal cord and dura. He describes careful insertion of the hooks and recommends against downward hooks above L2, where the conus ends. This paper reminds us that we should always pursue the lowest-risk approach to instrumentation that will serve our patients. Dr. Harrington was also cognizant of the importance of blood loss, and meticulously measured it by stage of surgery. He showed that most blood loss occurred during subperiosteal dissection, a fact that we still recognize today.

Harrington’s description of selective thoracic fusion was illustrated radiographically in Figure 7, which shows a dramatic result where a 55° unfused lumbar curve declined to 18° after correction of a larger thoracic curve. This concept was further developed by Moe, King, Lenke and others, but the idea of spontaneous correction of lumbar curves started with the power of Harrington’s instrumentation.

The benefits of our more “modern” instrumentation are evident when reading the recommended aftercare in Harrington’s paper: a 16-day hospital stay, 8 weeks of bed rest, and a Risser localizer cast for 3 to 5 months, only to find out whether the patient might need reoperation for instrumentation problems or pseudarthrosis.

A modern journal editor might have expended some red ink on Dr. Harrington’s paper. The organization was less formal than many scientific papers today, but this may reflect the multiple simultaneous investigations and changes that took place during this decade-plus of revolutionary work. Dr. Harrington emphasizes that the results improved with each iteration of the procedure and device, which underwent more than three dozen design modifications.

Details on the curve sizes were not given, but we now recognize that curve size does not correlate linearly with clinical parameters.  While Harrington does not describe the contributions of others who may have been involved in this work, neither does he use the eponymous term (“Harrington instrumentation”) that others attached to his spinal fixation device. While remarkable in its prescience, this paper did not anticipate the problems of distraction instrumentation in the lumbar spine, later characterized as Flatback Syndrome. It also did not elaborate on the need for differing mechanics in kyphoscoliosis or Scheuermann kyphosis.

Nevertheless, in this single article, Dr. Harrington laid the groundwork for three major themes that orthopaedists have further developed:

  • The safety and benefits of metal fixation in spine surgery
  • The use of growth guidance in patients < 10 years old
  • The idea of selective thoracic fusion for double curves

Each of these ideas has generated hundreds of additional studies and papers to get us to modern practice. Just as current hip arthroplasty techniques represent incremental improvements on the monumental contribution of Charnley, current techniques in scoliosis surgery, especially of the thoracic spine, are but stepwise improvements on Harrington’s classic work.

Paul Sponseller, MD, JBJS Deputy Editor for Pediatrics

Marc Asher, MD, Professor Emeritus, Department of Orthopaedic Surgery, University of Kansas Medical Center