Spine Surgeons

We maintain >50% of the end plate surfaces with no cement in order to give sufficient surface area for fusion. Early results are very promising with solid bony fusion on CT much earlier than would be expected.

Yes, allograft is still utilized in the procedure to promote bony fusion.

There is ample room in both vertebral bodies to place pedicle screws should the cement construct not be sufficient. We look at the CemLIF procedure as an attempt to save patients from the posterior incision and pedicle screw placement, but all patients understand that in the event of CemLIF construct failure, the revision strategy would involve pedicle screw placement.

We have submitted several posters/oral presentations at various spine meetings. We are working on publishing our first cases as a retrospective study. We plan on beginning a formal prospective trial in the near future. We look forward to sharing our results with the spine community!

The rates of symptomatic cement extravasation in kyphoplasty are extremely low. Unlike in kyphoplasty, these vertebrae are not fractured with surrounding inflammation and vasodilation. We believe this is why we have seen almost no venous extravasation of cement in any of our cases. We have seen lateral extravasation of cement as the current interbody cages on the market are not optimally designed for this procedure. No patients have been symptomatic from this extravasation, which functionally is inconsequential, much like a lateral osteophyte underneath the psoas muscle.

The CemLIF procedure has all the same risks as a standalone ALIF or LLIF approach. In addition to that, it has risks similar to the cement augmentation of pedicle screws, which are well published in the literature and generally regarded as safe. There is ample evidence in the literature that the risk of cement extravasation into the canal increases the more posterior in the vertebral body the cement is placed, and so we place the cement anteriorly to decrease this risk.

CemLIF eliminates the risks associated with posterior incisions and instrumentation. These include the risks of neurological injury from pedicle screw placement and the risks of blood loss and infection from large incisions.

Early unpublished results appear to have increased rates of fusion (as measured by solid bony growth on CT) compared to those published in the literature for posterior instrumentation, and so we hope that long term results will confirm this to be true.

In short, we believe this procedure to actually have a lower risk profile than a combined anterior/lateral and posterior approach, but further study is needed.

We bill the standard CPT codes for anterior or lateral interbody fusions. We obviously do not bill posterior instrumentation or posterior onlay fusion codes and so reimbursement is much less than a comparable 360deg fusion. The placement of cement is not yet reimbursable for this use case and so patients are charged directly for this portion of the procedure.

Early results from biomechanical testing are very promising, especially when compared to posterior instrumentation. As we continue to develop implants specifically designed for this procedure, we will be publishing the results of our biomechanical testing.

What's right with pedicle screws?

-They have no where near a 100% fusion rate - some studies show incidences of pseudarthrosis as high as 50% in large constructs, and the real number for all-comers is almost certainly lower, but we should be striving for a 100% fusion rate. Fusion rates with pedicle screws have stagnated over the years, likely due to their biomechanical properties. For example, one biomechanical study (Song et al. Orthop Surg. 2021;13(2):517-529) demonstrated that an OLIF with posterior instrumentation still maintains as much as 61% of the normal range of motion of the segmental level.

-The often large posterior incisions required for pedicle screw placement increase risk of infection, length of postoperative opiate use, length of hospital stay, postoperative pain scores, intraoperative blood loss, and just about every other negative endpoint associated with spine surgery when compared to a standalone lateral or anterior approach.

-Neurologic injury from screw placement - It's not incredibly common, but we've all seen it. In some published case series, the rate of symptomatic screw malpositioning is as high as 10% (although in reality this is likely much lower).

-Adjacent segment disease - in the cervical spine, rates of adjacent segment disease are higher for posterior cervical fusions than for anterior fusions. Some literature in the lumbar spine suggest a similar trend.

-Patient preference - Patients don't want rods and screws. Many have friends who had horrible experiences with lumbar surgery for the reasons mentioned above and the general public is wary of them.

In short, we can do better. As a community, we should be looking for the long-term replacement for pedicle screws that can get us a 100% fusion rate with little patient suffering, not expending all efforts iterating on pedicle screw based techniques.

CemLIF is performed with FDA-approved devices and implants. The use of bone cement is in an off-label manner, which is allowed with FDA-approved implants. All patients are fully aware of the off-label use of cement and have an extensive additional consent form that is required.