SpineUniverse Case Study Library

Rapidly Progressing Cervical Adjacent Segment Disease

History

A 56-year-old woman presents with a history of worsening neck and left shoulder pain. She has had some relief with C4-C5 epidurals, but her pain has persisted. She has had previous C6-C7 anterior cervical discectomy and fusion (ACDF) with plate in 2002. That was followed by explanation of instrumentation and subsequent C5-C6 ACDF in 2007. All procedures were done in another state.

Examination

Patient has increased neck pain with flexion and left lateral bending. Left deltoid is 4+/5. The remainder of her exam is normal.

Prior Treatment

She has undergone physical therapy (PT) and epidural steroid injections with no long lasting relief.

Pre-treatment Images

Well-healed fusions at C5-C6 with plate and C6-C7 without plate. Junctional disease is seen at C4-C5 with spondylosis and bridging osteophyte. There is a significant amount of prevertebral soft tissue at the previous operative sites, even accounting for the esophagus. (Figure 1)

Cervical spine x-ray

 Figure 1

Flexion-extension x-rays that demonstrate mobility at the index level with overriding C4 osteophyte. There is no movement at the previously-treated levels although interbody graft appears to have caused some osteolysis of the superior endplate of C6. (Figure 2)

Flexion-extension CT scan, C4 osteophyte

Figure 2

T2 axial MRI that shows significant neural foraminal narrowing from spondylosis. (Figure 3)

Cervical spine MRI

Figure 3


Diagnosis

The patient was diagnosed with junctional segment disease with C4-C5 spondylosis and anterior spur.

Her current plate position illustrates the problem of using long constructs in the cervical spine. The altered biomechanics of the plate buttressing an otherwise healthy disc, combined with the long moment arm from the two-level fusion below, may have accelerated the adjacent segment disease.

The current trend seems to be using as short a plate as possible or internal plated devices.

Suggest Treatment

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Selected Treatment

The patient underwent C4-C5 ACDF with integrated plate and spacer filled with calcium-phosphate ceramic bone graft with bone marrow aspirate.

The implant I elected to use has variable angle screws. The single screw up and down allowed greater flexibility in placing this kind of implant. Similar systems have more screws or locking cams that could not have been deployed in this case.

Post-treatment Images

Post-op anteroposterior (AP) films demonstrate well-placed graft. Note that the inferior screw does not contact the existing instrumentation. (Figure 4)

Post-operative cervical spine CT scan

Figure 4

The superior screw was intentionally inserted at a shallow angle to better capture the cortical endplate. Both screws could have been longer to afford bicortical purchase. (Figure 5)

Post-operative CT scan

Figure 5

 

Post-op CT ScanFigure 6

Outcome

The patient noted marked improvement in her radiculopathy and mechanical neck pain post-op. Follow-up at 1 year shows solid fusion and no further degeneration. The C3-C4 level remains disease free.

Case Discussion

The author utilized a relatively new type of instrumentation that is all intradiscal. These devices have advantages over the standard plating systems under several circumstances. Examples include cases in which a patient has a long plate with an adjacent-level disc herniation. Rather than remove the long plate, one can simply place one of these devices at the adjacent level. Another indication is at the upper cervical levels, where the no-profile nature of these devices have an advantage over a traditional plate.

There are also disadvantages to these types of devices. First, it is difficult to implant these devices at the extreme ends of the cervical spine (eg, C2-C3 or C7-T1). This is because the screws have to be angled away from the disc space. For example at C2-C3, angling the C3 screw caudally or at C7-T1, angling the C7 screw cranially may be quite challenging. Even with extensive soft tissue dissection, the jaw at C2-C3 and the clavicle at C7-T1 can interfere with drilling and screwing at these levels. Although the manufacturers of these devices have angled drills and screw drivers that can help facilitate this, it can nevertheless remain challenging and sometimes impossible.

A second disadvantage is that the cage portion of the device is made of PEEK, which is hydrophobic and will never bond to bone. Therefore, to achieve a solid fusion, one has to select a filler that has a high likelihood of fusing. While the author states that the use of a ceramic filler with bone marrow aspirate achieved a solid fusion at 1 year, there are no studies that I am aware of that has examined the success rate of such a combination for these devices. It would be helpful to see the 1 year post-operative dynamic x-rays to verify the fusion.

Author's Concluding Comments

Dr. Riew describes well the limitations of this technology. It is often touted as a viable alternative to removing hardware. However, in reality removing a typical plate with anteriorly directed screws is typically less challenging than matching the appropriate angles of these devices at either end of the exposure.

Additionally the lumen of these devices is restricted by the indwelling screw. Consequently the fusion mass is quite small as evidenced by the follow-up imaging.

Community Case Discussion (2 comments)

SpineUniverse invites spine professionals to share their thoughts on this case.


Excellent planning. This implant is similar to ZERO-P of synthes. I have experience with these and the results are encouraging. espesially in cases like just discussed as there is no profile so no dysphagia and no need to remove previous implant.

This is an ideally managed case.
Congratulations.

Couple points.

The prior C5-6 plate does appear to at least partially obstruct the C4-5 disc space, and perhaps removing the plate (especially just a single level plate in this case) would have provided better access to the C4-5 disc space.

The integrated system used here (Coalition) seems to work well in this case as there is a single medially-angled screw that can be placed between the bilateral C5 screws of the existing plated system. This spacer is completely contained with the disc space. I am not so sure other integrated systems would have worked just as well here. There simply may not be enough room for the dual screws of the Zero-P system especially if the existing C5 screws are close to the superior endplate. The prior plate likely still would have obstructed the inferior "lip" of the Prevail standalone system.

The integrated/standalone systems are an excellent option in adjacent level cases, but careful planning based on the nuances of each specfic system is still necessary.

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