Safe and Efficacious Treatment of Spondylolisthesis via MIS TLIF Approach with the FlareHawk® Expandable Cage

IJSS-published review finds that the novel biplanar expandable cage provides effective vertebral body slip or spondylolisthesis reduction and improvement in radiographic and clinical parameters with no reported subsidence, migration, or endplate violation

PALM BEACH GARDENS, Fla., December 1, 2020 (GLOBE NEWSWIRE) – Integrity Implants Inc., a privately held medical device company dedicated to delivering innovative solutions for spine surgery, today announced the publication of another in a series of recent clinical articles in the International Journal of Spine Surgery ( highlighting its FlareHawk® expandable interbody cage. In their paper, Clinical and Radiographic Outcomes After Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS TLIF) – Early Experience Using a Biplanar Expandable Cage for Lumbar Spondylolisthesis (International Journal of Spine Surgery October 2020, 7125; DOI:, Lee A. Tan, Joshua Rivera, Xiao A. Tan, Vivian P. Le, Larry T. Khoo, and Sigurd H. Berven demonstrate favorable vertebral body slip or spondylolisthesis reduction accompanied by an increase in segmental lordosis and positive patient-reported outcomes.

The retrospective review of 13 patients treated during a one-year period found a mean slippage reduction of 6.0mm along with an improvement in segmental lordosis, increases in foraminal and posterior disc height, as well as improvement in all radiographic parameters postoperatively. Patient-reported outcome measures including VAS back, VAS leg, and EQ5D also improved across the board. There were no findings

of endplate violation, cage subsidence, or cage migration, and there were no reoperations or implant-related complications.

Lee Tan, M.D., Assistant Professor of Neurological Surgery at UCSF Medical Center in San Francisco, California, shares, “My early experience shows good short-term radiographic and clinical outcomes, with almost complete reduction of spondylolisthesis postoperatively in all cases. The absence of nerve root injury is suggestive that the biplanar expandable cage is safe and obviates the need for excessive nerve root retraction during cage insertion.”

As discussed in the article, one possible explanation for the clinical success is that the expansion of the cage in the horizontal plane increases surface area contact with the endplates to better distribute the load and reduce stress, while the multi-material cage design consisting of a titanium shim inserted into a PEEK shell allows the cage to contour to the patient’s endplates, further reducing the risk of endplate violation.

Sigurd Berven, M.D., Professor in Residence, Department of Orthopaedic Surgery at the University of California at San Francisco, adds, “A challenging aspect of the MIS TLIF procedure is inserting the cage through a relatively small surgical corridor with protection of the neural elements. Additionally, in a lordotic disc space, the posterior disc height is typically shorter than the anterior disc height, thus limiting the size of cage that can be inserted posteriorly, potentially limiting the amount of lordosis restoration. In these cases that often present with a collapsed disc space and bone-on-bone pathology, the low-profile, biplanar, and lordotically expanding FlareHawk cage is ideal for reducing risk to the neural elements on insertion of the implant, and for improving the surface area of the implant with the endplate and the restoration of segmental lordosis. After insertion, the cage and prepared disc space can be filled with allograft or autograft to optimize fusion. The results of the study are encouraging regarding the efficacy of MIS fusion using the technique.”

Dr. Tan concludes, “Remarkably, we had no cases of endplate violation or cage subsidence in this cohort. This is significantly lower than the rates reported in the current literature, which range from 6% up to 33%. I believe that the biplanar expansion is key to decreasing the likelihood of subsidence.”

The FlareHawk spinal implant is the flagship product for Integrity Implants and represents the first of its kind in the expandable cage market. Much like coronary stents that offer patients a less-invasive alternative to open-heart procedures, the FlareHawk expandable cage features a PEEK shell that is inserted in a compressed form that can be effectively passed through small neural pathways, and, once within the intervertebral disc space, expanded to a larger footprint and height. An open-architecture titanium shim inserted within the PEEK shell produces the expansion and creates a solid-state construct that is resistant to collapse yet has shown the ability to conform to endplate anatomy to increase surface contact area and lower stresses. The Adaptive Geometry™ and advanced multi-material composition embodied in the FlareHawk device respect patient anatomy both during insertion and for long-term stability. To date, over 8,500 FlareHawk cages have been implanted in more than 6,000 patients.

Chris Walsh, Integrity Implants CEO, adds, “Last month, we shared the encouraging results of a multi-center study highlighting the favorable fusion efficacy and endplate conforming geometry of the FlareHawk cage. This work by surgeons Lee Tan, Sig Berven, and Larry Khoo represents the third peer-reviewed study of the FlareHawk cage this year. Beyond intrinsic cage design and performance, the study addresses a specific pathology solution that resonates with surgeons. It is encouraging to see published literature echo surgeon confidence in the FlareHawk cage, and documenting the application of Adaptive Geometry to the important and increasingly popular MIS TLIF approach is yet another step in confirming our technology as a compelling clinical choice for surgeons.”