Biplanar expandable cage may be safe, efficacious for lumbar spondylolisthesis
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Minimally invasive transforaminal lumbar interbody fusion performed with a biplanar expandable cage may be a safe and efficacious treatment method for patients with symptomatic lumbar spondylolisthesis, according to results.
Lee A. Tan, MD, and colleagues analyzed patient demographics as well as preoperative and postoperative clinical and radiographic outcome measures among 13 patients with symptomatic lumbar spondylolisthesis who underwent minimally invasive transforaminal lumbar interbody fusion with a biplanar expandable cage (FlareHawk, Integrity Implants Inc.).
Results showed improvements in all postoperative radiographic parameters. Researchers found patients had a mean preoperative slippage of approximately 7 mm vs. a mean postoperative slippage of approximately 1 mm. Patients had a mean segmental lordosis of approximately 5.18 preoperatively vs. 6.88 postoperatively, according to results. Researchers also noted patients had preoperative mean anterior, posterior disc and foraminal height of approximately 9.1 mm, 5.7 mm and 11 mm, respectively, compared with postoperative mean anterior height of approximately 11.4 mm, posterior disc height of 7.8 mm and foraminal height of 12.3 mm.
Results showed improvements in mean VAS back pain and VAS leg pain from preoperatively to the latest clinic follow-up visit, as well as improvements in mean EuroQol-5D. Researchers found no subsidence, endplate violation, cage migration or other implant-related complications, as well as no reoperations.
“Biplanar expandable cages, such as FlareHawk, may decrease the incidence of cage subsidence due to the increased contact surface area based on my early experience. The small profile of the cage in the non-expanded state obviates the need for excessive nerve root retraction during cage insertion, which can decrease the incidence of nerve root injury,” Tan told Healio Orthopedics. “In the future, biplanar expandable cages may provide a footprint similar to that of an [anterior lumbar interbody fusion (ALIF)] cage, which avoiding the potential complications associated with anterior approaches. It is a useful tool in the spine surgeons’ armamentarium.”
Perspective
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The authors present a small (13 patients) consecutive series on a biplane expandable cage with a short (6-month) follow-up. The authors do a great job accomplishing their goal in a well-written study showing that minimally invasive transforaminal lumbar interbody fusion (TLIF) with this specific cage is not kyphogenic. Additionally, the concept of expandable cages, especially biplanar, as well as these preliminary results, hold some promise for future use.
It is well-known that I thoroughly enjoy “new tools” and “new technology” in spine surgery. That being said, I have several reservations regarding this type of technology regarding widespread use. First is the incremental cost. To date, most expandable cages carry an exorbitant cost that is hard to justify for mainstream (every case) usage. Second is the importance of bone quality in appropriate patient selection. An expandable TLIF cage, even if biplanar, still has a relatively smaller footprint than an anterior lumbar interbody fusion or lateral-based cage, and if the bone quality is not adequate in conjunction with suboptimal carpentry (release) work, the result will be a very expensive cage die punch.
Overall, this type of technology can be helpful in well-selected cases, but we should tread cautiously before recommending this costly technology for every TLIF without appropriate cost-effectiveness studies.
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