CONDUIT™ Cervical Cages—Part of the CONDUIT™ Interbody Platform
Maarten Spruit
The Cellular Titanium Cervical Cages are intervertebral body fusion devices intended for use for anterior cervical interbody fusion in skeletally mature patients with cervical disc degeneration and/or cervical spinal instability, as confirmed by imaging studies (radiographs, computed tomography [CT], and magnetic resonance imaging [MRI]), which results in radiculopathy, myelopathy, and/or pain at multiple contiguous levels from C2-T1.
The Conduit Cellular Titanium Cervical Cages can also be used with supplemental anterior fixation systems that have been cleared for use in the cervical spine. The cages are designed for use with autogenous and/or allogeneic bone graft to facilitate fusion.
The proprietary design of the CONDUIT cages with the interconnected porous structure that mimics cortical and cancellous bone, implant surface features, and implant stiffness is specified extensively here.
To allow optimal fit for patients and to address anatomical requirements to correct spinal alignment and sagittal profile, the CONDUIT Cervical System is offering various footprint sizes (12 x 16 mm and 14 x 18 mm), lordotic angles (4° and 8°), and heights (4−10 mm in 1 mm increments). They come in asymmetric design dome-shaped cranial surface and flat caudal surface, the width and depth of the vertebral end plate is in ratio of 1.3–1.4, the anterior rim is larger than the posterior width, and the lateral wedge design allows maximal contact of the uncovertebral joint (Fig 2).
Due to the implant's porous structure the height of the implant is slightly (0.25 mm) higher than the trial.
The texture and architecture of the CONDUIT Implants facilitate fusion by acting as cellular titanium scaffold. The porosity of the implants (approximately 80%) provides excellent clinical imaging on radiographs, MRI, and CT and is leading to a Modulus of Elasticity like bone.
The cages are designed for central grafting. An implant retrieval case study (n = 1, cervical system explant 2 years postoperatively) displayed extensive bone in-growth end plate-to-end plate, indicating mechanical loading throughout the implant and mature, lamellar bone, and healthy bone marrow in direct contact with the titanium scaffold without fibrous tissue interface formation.
Conclusions
The Conduit Cervical cage is a 3D printed titanium cage design that allows graft and facilitates anterior cervical interbody fusion surgery. The cellular titanium material as such is attractive to bone, and the cage line addresses individual anatomical variety and creates optimal end plate to cage interface.
Case 1
(kindly provided by Maarten Spruit, MD, St Maartenskliniek, Nijmegen, Netherlands)
A 70-year-old man presented with neck pain, but predominantly arm pain bilateral L>R for 4 years. The patient experienced loss of sensation in C6 dermatome L. The conservative care and pain management was not effective. A medical examination revealed the following:
Multidirectional decreased range of motion
Spurling test positive L
Loss of sensation C6 L
Symmetrical reflexes, no hyperreflexia
No pathological reflexes
Romberg negative
Adson negative
No shoulder impingement
Numerical Rating Scale (NRS) neck 3 and arms 7
Neck Disability Index (NDI) 28
Electromyography: radiating signs C6, but no denervation
The radiograph indicated:
Degenerative discs and spondylosis C3-4-5-6-7
No translational instability on flexion-extension
Loss of lordosis (Fig 4)
A magnetic resonance imaging demonstrated a cervical spinal stenosis with cord compression C5-6 L, foraminal stenosis C5-6 L, and C6-7 bilateral (Fig 5).
A computed tomographic scan showed large posterior osteophytes C5-6 and spondylosis anterior (Fig 6).
The diagnosis made was cervical radiculopathy L>R C5-6 and C6-7 and non-symptomatic spinal cord compression C5-6.
Surgical treatment
The patient underwent anterior decompression and fusion C5-6-7 with Conduit stand-alone cages C5-6-7. Restoration of lordosis C5-7 (Fig 7).
Follow-up at 3 months
The patient had an uneventful recovery, with neither neck nor arm pain, but with good residual range of motion. He had persistent loss of sensation C6 dermatome L.
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