DENVER, Colo. — Minimally invasive spinal surgery (MISS) is transforming lumbar spinal fusion surgery by reducing postoperative pain, shortening hospital stay, quickening recovery, and decreasing cost. However, these benefits come at a price: a greater risk the fusion will fail.
Approximately 210,000 lumbar fusions are performed annually in the US.1 They are usually performed for spinal stenosis, spondylolisthesis, and degenerative scoliosis. When bony fusion fails to occur, a condition called pseudoarthrosis, the cost of revision surgery is roughly $135,000 per case. With approximately a quarter of MISS lumbar spinal fusions failing, the annual cost for revision lumbar fusion is high.
Dr. Jeff Kleiner & Spinal Surgical Strategies LLC
An honor graduate of Stanford University and the University of Colorado School of Medicine, Dr. Jeff Kleiner completed a surgical internship at Rush/Presbyterian-St Luke’s in Chicago and a 2-year NIH funded postdoctoral fellowship in collagen biochemistry and orthopaedic residency at UCSD, six months of which were spent at Scripps Clinic with Dr. Roger Thorne.
Returning to Colorado, Dr. Kleiner completed a one-year fellowship at the University of Colorado and the Colorado Spine Center in adult and pediatric reconstructive spinal surgery. Following his training he opened a spinal orthopaedic practice at The Medical Center of Aurora in Aurora, Colorado.
As his clinical experience grew, Dr. Kleiner began contemplating the dilemma posed by MISS: the benefits gained versus the increased rate of pseudarthrosis. In 2013 he created Spinal Surgical Strategies LLC, a spinal instrumentation company focused on improving spinal surgery.
CyberMed News recently spoke with Dr. Kleiner about the company’s first product, a surgical device focused on the lumbar MISS dilemma.
Minimally invasive transforaminal lumbar interbody fusion (T-LIF)
For many years surgeons have performed lumbar fusions by separating muscles off the posterior spinal bone to the lateral edges of the spine (the transverse processors) where the bone graft is placed. While often effective in treating the patient’s presenting symptoms, some patients suffer persistent back pain from the resulting muscular weakness.
Overtime, a less invasive approach in which fusion graft is inserted within the involved disc space, or spaces, gained prominence. Known as a transforaminal lumbar interbody fusion (T-LIF), this approach reduces the amount of surgical muscle disruption. Disruption is further decreased using MISS to perform the T-LIF.
But why is the pseudarthrosis rate higher with MISS? The major reason, as noted by Dr. Kleiner, is the more demanding nature of the lumbar MISS technique:
“You can do it, but it’s harder than it needs to be.”
In an attempt to decrease the occurrence of pseudarthrosis, some spinal surgeons add bone morphogenetic protein (BMP) to the bone graft material. Unfortunately, this potent biologic agent has serious risks. Although low in number, these include “heterotopic ossification, osteolysis, infection, arachnoiditis, increased neurological deficits, retrograde ejaculation, and cancer.”2 In view of these additional risks, BMP is not approved by FDA in spinal surgery except for one type of spinal fusion, “anterior lumbar interbody fusion in titanium cylindrical cages.”2 Despite the risks, and if the patient provides consent, some surgeons use BMP in difficult cases in an “off label” fashion.
Graft First Delivery Funnel (GFDF)
Recognizing that a solid fusion is “the heart” of the lumbar spinal fusion procedure, Dr. Kleiner took a different approach to increasing the likelihood of a solid fusion. He began by measuring the amount of disc removed at surgery, the greater amount of degenerative disc that could be removed the larger the fusion surface available for grafting. He then reimagined the commonly used for bone graft delivery device itself.
Most spinal surgeons insert the bone graft material between the vertebral bodies by using a
funnel with a round-shaped cannula. Instead, the cannula of the Graft First Delivery Funnel (GFDF) developed by Spinal Surgical Strategies LLC has a rectangular shape. With this new shape, the cannula’s cross sectional area was able to be doubled thereby reducing frictional drag and increasing graft flow by 40%. Furthermore, together with its wedged tip, the rectangular cannula facilitates its insertion into the disc space.
Crucially, instead of having one portal at the tip as in a standard funnel, the GFDF was
designed with bilateral portals. While the standard funnel directs placement of bone graft material at the center of the disc space, the biportal design distributes the graft bilaterally:
“End dispensing devices essentially put the graft in the way of the bone cage. With the biportal design, the graft comes out on either side of the cannula, which leaves room for the cage.”
Made of Lexan, the components of this low cost disposable device are bonded by Mattel Pushpins and sealed with ultraviolet light. Biomechanical testing has shown the GFDF withstands 221 lbs. of force.
In order to determine benefits of the GFDF, Dr. Kleiner evaluated his spinal fusion cases before and after its development.3 Prior to the GFDF, he used the standard technique for preparing the disc space and inserted bone using a standard funnel. Of these 72 MISS T-LIF cases, 18 developed pseudarthrosis (25%). Following incorporation of a wider disc removal and the GFDF, 5 of 63 cases (7.9%) developed pseudarthrosis, a reduction of his pseudarthrosis rate by almost two-thirds.
The resulting 92% fusion rate of the GFDF technique equals that with BMP without BMP’s additional serious risks. The GFDF device and accompanying technique has the potential to significantly improve spinal care and reduce the annual cost of lumbar spinal fusions. Approved by the FDA, this new device was recently added to the formulary of Sky Ridge Medical Center in Denver. Currently, Spinal Surgical Strategies is evaluating a strategy to bring this innovation to a wider market.
GFDF is also the best available interbody device for bone graft application in “open” spinal fusion. Its value is independent of exposure technique.
- Rajaee, Sean S.; Bae, Hyun W.; Kanim, Linda E.A.; Delamarter, Rick B. Spinal Fusion in the United States. Spine. 37 (1): 67–76.
- Nancy E. Epstein. Complications due to the use of BMP/INFUSE in spine surgery: The evidence continues to mount. Surg Neurol Int. 2013; 4(Suppl 5): S343–S352.
- Kleiner JB, Kleiner HM, Grimberg Jr EJ, Throlson SJ. Evaluation of a novel tool for bone graft delivery in minimally invasive transforaminal lumbar interbody fusion. Medical Devices: Evidence and Research 2016, 9:105-114
John Oró, MD