Minimally Invasive Lumbar Interbody Fusion With an Expandable Meshed Allograft Containment Device: Analysis of Subsidence With 12-Month Minimum Follow-Up

John Paul G. Kolcun; George M. Ghobrial; Kenneth M. Crandall; Ken Hsuan-Kan Chang; Giacomo Pacchiorotti; Michael Y. Wang

doi:10.14444/6044

ABSTRACT

Study design Retrospective case series

Objective Describe subsidence in lumbar interbody fusion using an expandable meshed allograft containment device with 12-month minimum radiographic follow-up.

Background We have previously reported the use of a minimally invasive allograft-filled expandable meshed-bag containment system in the lumbar spine. Subsidence has not been reported with this device.

Methods Consecutive adult patients that underwent 1- or 2-level interbody fusion with at least 1 year of follow-up were included in this study. Preoperative, postoperative, and final follow-up lumbar radiographs were analyzed to measure disc height at the anterior and posterior margins of the disc space, as well as the neuroforaminal height.

Results Forty-one patients were identified, with a mean age of 63.4 years (± 11.8). A total of 61 levels were treated, with successful fusion observed in 54 levels (88.5%). The mean radiographic follow-up was 24.3 months (± 11.2). The mean disc height pre- and postoperatively was 6.9 mm (± 3.2) and 10.1 mm (± 2.9, P < .001), respectively. The mean disc height at final follow-up was 8.3 mm (± 2.4). Average disc height subsidence was 1.8 mm (± 1.7, P < .001). Overall, average disc height increased by a net 1.3 mm (± 2.5, P < .001). The mean neuroforaminal height pre- and postoperatively was 18.0 mm (± 3.3) and 20.7 mm (± 3.6, P < .001), respectively. The mean neuroforaminal height at final follow-up was 19.2 mm (± 3.4). Average neuroforaminal height subsidence was 1.3 mm (± 3.4, P = .012). Overall, average neuroforaminal height increased by a net 1.7 mm (± 2.8, P = .004). No significant difference in subsidence was observed between 1- and 2-level surgeries.

Conclusion An expandable allograft containment system is a feasible alternative for lumbar interbody fusion. Due to its biologic and mechanical nature, the surgeon using such constructs should account for an anticipated average of 18% loss of interbody height due to subsidence during the bony remodeling/fusion process.

Footnotes

Disclosures and COI: The senior author (M.Y.W.) serves as a consultant for Depuy Spine, Aesculap Spine, JoiMax, and K2M; receives royalties from Children's Hospital of Los Angeles, Depuy Spine, Springer Publishing, and Quality Medical Publishing; holds stocks in Innovative Surgical Devices and Spinicity; and has grants from the Department of Defense. There are no other potential conflicts of interest to report. The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article. No funding was received for this research.
The device that is the subject of this manuscript is being evaluated as part of an ongoing FDA-approved investigational protocol (IDE) or corresponding national protocol for lumbar interbody fusion. This device is currently FDA-approved for human use in vertebroplasty.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this type of study, formal consent is not required. This article does not contain any studies with animals performed by any of the authors.