4 Posterior Interbody Cages



Adam B. Wiggins, Benjamin Khechen, Brittany E. Haws, Ankur S. Narain, Fady Hijji, Kamran Movassaghi, Kaitlyn L. Cardinal, Jordan A. Guntin, and Kern Singh

4 Posterior Interbody Cages



4.1 Introduction



4.1.1 Interbody Cage Overview


Interbody cage technology has continued to evolve since its first use in spinal fusion. Initially, autologous bone graft was utilized to induce fusion; however, this was often associated with substantial postoperative complications. 1 , 2 , 3 , 4 , 5 Interbody cages were eventually developed as a standalone construct to improve stability and distraction within the intervertebral space while also promoting bone ingrowth. 6 , 7 As such, interbody cages have allowed for improved fusion rates while decreasing postoperative pain, hospital length of stay, and complication rates. 8 Indications for posterior lumbar interbody cages are provided in ▶ Table 4.1.


A variety of lumbar interbody cages have been developed to maximize the implant’s ability to correct deformity, provide mechanical stability, and provide the optimal environment for vertebral arthrodesis. In order to perform this, a cage must exhibit a small material volume in order to maximize the volume for bone graft. 9 Additionally, the interbody cage must exhibit a large footprint to optimize the interface between the prepared vertebral end plates and interbody cage. 10 Finally, the interbody cage should provide restoration of disk height and lordosis along with the restoration of load bearing to the anterior column. 11



4.1.2 Interbody Cage Classification



Interbody Cage Geometry—Standard Cages

Interbody cages are classified by one of three different structures: horizontal cylinders (HCs), vertical rings (VRs), and open boxes (OBs). HCs were one of the first structures to be developed and have been considered successful in correcting deformity and providing stability. 12 However, these interbody cages are not frequently utilized in today’s surgical setting.


A VR is another type of interbody cage. These interbody cages are utilized with anterior and lateral approaches to the lumbar spine. The design of VR cages was initially adapted from the design of femoral cortical rings. 13 This structure of cage has exhibited moderate ability to correct mechanical deformation. Disk height has previously been demonstrated to be maintained well with this implant, typically exhibiting an average loss of 1 mm at 1 year postoperatively. 9 Additionally, the increase in neuroforaminal area is similar to that provided by HCs. 9











Table 4.1 Overview of surgical indications for posterior lumbar interbody cages

Indications




  • Degenerative disk disease (one or two level)



  • Spondylolisthesis (Grade 1 only)



  • Spinal stenosis



  • Spinal deformity

Fig. 4.1 Open box interbody cage.

OB cages are the third type of geometry for interbody cages (▶ Fig. 4.1). They are one of the most frequently utilized interbody cage structures, and are often used for minimally invasive transforaminal lumbar interbody fusions (MIS TLIFs). 14 OB cages have exhibited satisfactory outcomes in correcting mechanical deformity, achieving stability, and promoting arthrodesis. 9 With appropriate surgical technique, OB cages can restore disk height and potentially increase neuroforaminal area. 9 Restoration of lumbar lordosis with OB cages has also been demonstrated to be similar to that achieved with HC cages. 14 These cages have recently been developed to exhibit a wedge shape in order to improve lordosis. OB cages have also demonstrated successful fusion rates, likely due to the sufficient volume available for bone graft and wide surface area for contact with the vertebral end plates. 9



Interbody Cage Geometry—Expandable Cages

Expandable interbody cages have recently been developed in attempts to overcome some of the challenges associated with minimally invasive techniques. 15 Due to the narrow surgical access corridor and anatomic positioning of minimally invasive posterior approaches, the interbody cages utilized in these techniques are often limited in size. 15 , 16 These smaller implants reduce the contact surface area between the vertebral end plates and the interbody cage, increasing the risk for subsidence and pseudarthrosis. 16 , 17 , 18


Some expandable interbody cages are capable of expansion in both the medial-lateral and cranial-caudal planes. These attributes may facilitate fusion and reduce the rate of subsidence by increasing the surface area of the vertebral end plate that is in contact with the implant. However, despite these theorized benefits, there remains limited data regarding the clinical efficacy of expandable cages. 15 , 19



Interbody Cage Materials

Two predominant materials are typically utilized for interbody cages: metal and carbon fiber. Titanium is the predominant material utilized for metal cages, and polyetheretherketone (PEEK) is typically utilized in carbon fiber cages. To determine the success of a particular material for use as an interbody cage, the biologic response, biomechanical strength, and radiographic characteristics are typically assessed.


Both titanium and PEEK cages have exhibited favorable outcomes for arthrodesis and biomechanical strength. Due to the material’s strength, titanium cages are thought to have increased stability and reduced micromotion when compared to PEEK cages. 9 However, PEEK cages may exhibit several advantages over titanium cages, including the avoidance of metal allergies, radiolucency, and reduced artifact on MRI. 20 , 21 , 22 , 23 , 24 These radiographic advantages allow for better analysis of arthrodesis postoperatively. PEEK cages also exhibit moderate stiffness with some elasticity, potentially increasing fusion rates. 21 However, despite these proposed benefits, superiority of PEEK cages over titanium cages remains controversial. 25 Previous studies have demonstrated varying results, with similar fusion rates between titanium and PEEK cages. 25



4.1.3 Minimally Invasive Transforaminal Lumbar Interbody Fusion


Since its introduction by Holly et al, 26 MIS TLIF has been demonstrated to reduce blood loss, postoperative pain, and length of hospital stay when compared to traditional open posterior techniques. 27 , 28 , 29 , 30 , 31 , 32 As such, MIS TLIF has been increasingly utilized for the treatment of degenerative lumbar disease, trauma, and deformity. However, this technique requires surgeon experience with a variety of MIS instrumentation as well as comfortability with the approach.



4.2 Static Carbon Fiber Interbody Cages




































Table 4.2 Alphatec Spine Novel® SD

Design


Cage type


Static


Composition


PEEK


Design feature


Multiple insertion points allow for added flexibility


Modular aspects and variations


Width


9 mm


Length


22, 25, 28 mm


Height


8–15 mm (1-mm increments)


Lordotic angle



Procedures


MIS TLIF


Supplemental fixation systems


Alphatec Spine Zodiac® Polyaxial Spinal Fixation System




































Table 4.3 Alphatec Spine Novel® Tapered TL

Design


Cage type


Static


Composition


PEEK


Design feature


Biconvex shape allows for increased endplate contact


Modular aspects and variations


Width


10 mm


Length


24, 28, 30 mm


Height


6–15 mm (1-mm increments)


Lordotic angle



Procedures


MIS TLIF


Supplemental fixation systems


Alphatec Zodiac® Polyaxial Spinal Fixation System




































Table 4.4 DePuy Synthes OPAL™ Spacer System

Design


Cage type


Static


Composition


PEEK


Design feature


Design variations allow for two insertion options


Modular aspects and variations


Width


9 and 10 mm


Length


28 and 32 mm


Height


7–17 mm (1-mm increments)


Lordotic angle



Procedures


MIS PLIF


Radiographs unavailable


Supplemental fixation systems


DePuy Synthes posterior stabilization system for MIS


































Table 4.5 DePuy Synthes T-PAL™ Interbody Spacer System

Design


Cage type


Static


Composition


PEEK


Design feature


Incorporated TRACK technology improves implant stability


Modular aspects and variations


Width


10 and 12 mm


Length


28 and 32 mm


Height


7–17 mm (1-mm increments)


Lordotic angle



Procedures


MIS TLIF


Supplemental fixation systems


DePuy Synthes posterior stabilization system for MIS




































Table 4.6 Globus Medical SUSTAIN®-R Arch

Design


Cage type


Static


Composition


PEEK


Design feature


Unique shape designed to follow contour of vertebral body


Modular aspects and variations


Width


10 mm


Length


27 and 30 mm


Height


7–17 mm (2-mm increments)


Lordotic angle



Procedures


MIS TLIF


Radiographs unavailable


Supplemental fixation systems


Globus Medical REVOLVE® posterior stabilization system




































Table 4.7 Globus Medical SUSTAIN®-O

Cage design


Cage type


Static


Composition


PEEK


Design feature


Superior and inferior surfaces feature directional teeth to resist expulsion


Modular aspects and variations


Width


8, 10, 12 mm


Length


22, 26, 30 mm


Height


8–13, 15, 17 mm


Lordotic angle



Procedure


MIS TLIF


Radiographs unavailable


Supplemental fixation systems


Globus Medical REVOLVE® posterior stabilization system for MIS




































Table 4.8 Globus Medical SUSTAIN®-R Small and Small Narrow

Design


Cage type


Static


Composition


PEEK


Design feature


Large axial window for graft material


Modular aspects and variations


Width


8 and 10 mm


Length


22 mm


Height


7–17 mm (2-mm increments)


Lordotic angle



Procedures


MIS TLIF


Radiographs unavailable


Supplemental fixation systems


Globus Medical REVOLVE® posterior stabilization system for MIS




































Table 4.9 K2 M ALEUTIAN® AN and AN Oblique Interbody Systems

Design


Cage type


Static


Composition


PEEK


Design feature


Bulleted nose with convex design to minimize endplate preparation


Modular aspects and variations


Width


8.5 mm Oblique: 8.5, 10, 12 mm


Length


22 and 28 mm Oblique: 28 and 32 mm


Height


6–13 mm, 15, 17 mm Oblique: 7–15 mm


Lordotic angle



Procedures


MIS TLIF


Supplemental fixation systems


K2 M Terra Nova® Minimally Invasive Access System


































Table 4.10 K2 M ALEUTIAN® TLIF 2

Design


Cage type


Static


Composition


PEEK


Design feature


Articulating inserter allows for variable angulation from 0 to 60° in situ


Modular aspects and variations


Width


10 and 12 mm


Length


28, 32, 36 mm


Height


7–15 mm (1-mm increments)


Lordotic angle


0 and 7°


Procedures


MIS TLIF


Radiographs unavailable


Supplemental fixation systems


K2 M Terra Nova® Minimally Invasive Access System




































Table 4.11 NuVasive CoRoent® Large Contoured

Design


Cage type


Static


Composition


PEEK


Design feature


Cage curvature matches contour of vertebral body


Modular aspects and variations


Width


9 and 11 mm


Length


25 mm


Height


8–14 mm (2-mm increments)


Lordotic angle



Procedures


MIS TLIF, MIS LLIF


Radiographs unavailable


Supplemental fixation systems


NuVasive Precept® posterior stabilization system




































Table 4.12 NuVasive CoRoent® Large Narrow and Wide

Design


Cage type


Static


Composition


PEEK


Design feature


Designed for utilization in transforaminal, posterior, or lateral approach


Modular aspects and variations


Width


9 and 11 mm


Length


25 and 30 mm


Height


8–14 mm (2-mm increments)


Lordotic angle



Procedures


MIS PLIF, MIS TLIF


Radiographs unavailable


Supplemental fixation systems


NuVasive Precept® posterior stabilization system




































Table 4.13 NuVasive CoRoent® Large Oblique (LO) Interbody Cage Device

Design


Cage type


Static


Composition


PEEK


Design feature


Designed specifically for oblique placement


Modular aspects and variations


Width


10 mm


Length


25, 30, 35, 40 mm


Height


8, 10, 12, 14 mm


Lordotic angle



Procedures


MIS TLIF, MIS LLIF


Supplemental fixation systems


NuVasive Precept® posterior stabilization system




































Table 4.14 NuVasive CoRoent® Large Tapered Interbody Cage Device

Design


Cage type


Static


Composition


PEEK


Design feature


Anatomical lordotic design induces proper sagittal balance


Modular aspects and variations


Width


9 mm


Length


20 mm


Height


8–14 mm (2-mm increments)


Lordotic angle


8 and 15°


Procedures


MIS PLIF, MIS LLIF


Radiographs unavailable


Supplemental fixation systems


NuVasive Precept® posterior stabilization system




































Table 4.15 NuVasive CoRoent® MAS® PLIF

Design


Cage type


Static


Composition


PEEK


Design feature


Contoured lateral edge designed to avoid the exiting nerve root


Modular aspects and variations


Width


9 mm


Length


23 and 28 mm


Height


8–14 mm (1 mm increments)


Lordotic angle


4, 8, 12°


Procedures


MIS PLIF


Supplemental fixation systems


NuVasive Precept® posterior stabilization system


































Table 4.16 RTI surgical bullet-tip

Design


Cage type


Static


Composition


PEEK


Design feature


Bullet-shaped tip provides self-distraction


Modular aspects and variations


Width


8–17 mm (1-mm increments)


Length


22, 26, 32 mm


Height


8–17 mm (1-mm increments)


Procedures


MIS TLIF


Radiographs unavailable


Supplemental fixation systems


RTI Surgical Streamline® MIS spinal fixation system


































Table 4.17 RTI surgical T-Plus™

Design


Cage type


Static


Composition


PEEK


Design feature


Cage curvature matches contour of vertebral body


Modular aspects and variations


Width


10 mm


Length


27 and 36 mm


Height


7–15 mm (1-mm increments)


Lordotic angle


0 and 6°


Procedures


MIS TLIF


Supplemental fixation systems


RTI Surgical Streamline® MIS spinal fixation system


































Table 4.18 SeaSpine Hollywood™

Design


Cage type


Static


Composition


PEEK


Design feature


Cage curvature matches that of vertebral end plate


Modular aspects and variations


Width


11 mm


Length


27 mm


Height


7–18 mm (1-mm increments)


Lordotic angle



Procedures


MIS TLIF


Supplemental fixation systems


SeaSpine posterior stabilization systems for MIS


































Table 4.19 SeaSpine Ventura™

Design


Cage type


Static


Composition


PEEK


Design feature


Convex surfaces for a more secure interbody fit


Modular aspects and variations


Width


9 and 11 mm


Length


28 and 32 mm


Height


7–13 mm (1-mm increments), 15, 17 mm


Lordotic angle



Procedures


MIS TLIF


Supplemental fixation systems


SeaSpine posterior stabilization systems for MIS




































Table 4.20 Zimmer Biomet Zyston® Curve Interbody Spacer System

Design


Cage type


Static


Composition


PEEK


Design feature


Articulating mechanism allows for multiple insertion angles


Modular aspects and variations


Width


10 mm


Length


27 and 32 mm


Height


7–18 mm (1-mm increments)


Lordotic angle


0 and 6°


Procedures


MIS TLIF


Radiographs unavailable


Supplemental fixation systems


Zimmer Biomet posterior stabilization systems for MIS

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Jan 25, 2021 | Posted by in NEUROSURGERY | Comments Off on 4 Posterior Interbody Cages

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