ZERO-P ChronOS
Fig 1 ZERO-P ChronOS provides strong osteoconductive and osteopromotive benefits Stability is a clear prerequisite for an implant to guarantee optimal healing results. Current state-of-the-art solutions for anterior cervical discectomy and fusion (ACDF) include existing nonfilled zero-profile devices, such as ZERO-P and ZERO-P VA, but also include cervical cages with anterior cervical plate fixation.
So far, biomechanical testing has already shown the stability of ZEROP to be similar to that of traditional cage and plate constructs [1]. Further, clinical studies have demonstrated that ZERO-P implants filled with standard ChronOS cylinders for ACDF show excellent fusion results [2].
Now, the ZERO-P ChronOS is available. ZERO-P ChronOS (Fig 1) is prefilled with a bioresorbable synthetic beta-tricalcium phosphate cancellous bone substitute (ChronOS). ChronOS is osteoconductive and osteopromotive when perfused with bone marrow.
ZERO-P ChronOS is based on the ZERO-P surgical technique and no additional instruments are needed.
The indications for ZERO-P ChronOS are identical for those for the existing ZERO-P implant:
- Degenerative disc diseases
- Spinal stenosis
- Pseudoarthrosis.
In addition, ZERO-P ChronOS provides the following helpful features:
- Reduced OR time
- Less donor site morbidity
- Increased safety
- Enhanced fusion.
With no extra filling step required, there is reduced OR time as implants can be directly used after unpacking (to ensure rapid onset of fusion of the prefilled ZERO-P and subsequent remodeling of the ChronOS insert). The implant must be augmented with autologous blood or bone marrow aspirate. Soaking in blood should be done for at least 15 seconds to ensure sufficient perfusion of the ChronOS insert (Fig 2).
There is less donor site morbidity as there is no need for secondary surgery to remove autologous bone.
There is increased safety as the device is 100?% synthetic, with no risk of cross infection. The synthetic bioresorbable material converts to vital bone within 6-18 months and is an alternative to allograft.
Finally, the device provides enhanced fusion for patients with expected or already experienced difficulties in fusion due to its osteoconductive features (macropores facilitate bone ingrowth, interconnected micropores allow an optimum supply of nutrients) and osteopromotive features (saturation with the patient's own blood or bone marrow during surgery supports bone integration and ensures rapid ongrowth to the implant) (Fig 1).
For optimal adoption to the patient anatomy, ZERO-P ChronOS is available in two sagittal spacer shapes (convex, lordotic), one standard footprint size, and multiple height options (512 mm in 1 mm increments).
References
- Scholz M, Reyes PM, Schleicher P, et al. A new standalone cervical anterior interbody fusion device: biomechanical comparison with established anterior cervical fixation devices: Spine 34, 2009: 156160.
- Scholz M, Schnake KJ, Pingel A, et al. A New Zero-profile Implant for Standalone Anterior Cervical Interbody Fusion. Clin Orthop Relat Res. 2011 March; 469(3):666673.
Fig 1 ZERO-P ChronOS provides strong osteoconductive and osteopromotive benefits. 
Fig 2 Presoaking in blood Case: Cervical radiculo-myelopathy
(Case provided by Frank Kandziora, Frankfurt am Main, Germany)
A 51-year-old woman was affected by cervical radiculo-myelopathy due to spinal and neuroforaminal stenosis. The preoperative CT scans are shown at Fig 4 and MRI at Fig 5.
The patient was treated by anterior cervical decompression and fusion (ACDF) with ZERO-P filled with ChronOS. No autologous bone graft was used. Postoperative images are shown (Fig 69).
Fig 4a-b Preoperative CT scans 
Fig 4c-e Preoperative CT scans 
Fig 5a-b Preoperative MRI 
Fig 5c-d Preoperative MRI 
Fig 6a-b Postoperative x-rays at 3 months 
Fig 7ab Postoperative x-rays at 6 months 
Fig 8a-b Postoperative x-rays at 12 months 
Fig 9ab Postoperative CT at 12 months 
Fig 9cd Postoperative CT at 12 months 
Fig 9ef Postoperative CT at 12 months Enhanced fusion performances in Zero-P through prefilled -tricalcium phosphate
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