Impact of the change of intervertebral height after anterior cervical discectomy and fusion with Zero-Profile implant system on clinical outcomes and imaging parameters

English Keywords:Cervical spondylosis  Anterior cervical discectomy and fusion  Zero-Profile implant system  Intervertebral height

English Abstract:

  【Abstract】 Objectives: To analyze the effect of changes in intervertebral height(IH) of surgical level on clinical outcomes and imaging parameters after anterior cervical decompression and fusion with the Zero-Profile implant system(Zero-P). Methods: The data of 123 patients with cervical spondylosis of cervical myelopathy or radiculopathy who underwent anterior cervical decompression and fusion with the Zero-P in our hospital from May 2014 to December 2017 and were followed up for at least 1 year were retrospectively analyzed. The IH of operative segment before surgery, at 1 week after surgery and at final follow-up was recorded, and according to the mean IH change value after surgery(difference between IH at 1 week after surgery and final follow-up) the patients were divided into IH maintaining group (IH change0.05), nor was there significant difference between the two groups in preoperative, postoperative 1 week, and final follow-up JOA scores, VAS, NDI, C2-C7 Cobb angle, or surgical segment curvature(P>0.05). Besides, no significant difference was found in dysphagia incidence or final follow-up fusion rate between the two groups(P>0.05). In the IH maintaining group, the IH was 5.65±1.69mm at preoperation, 8.33±0.78mm at 1 week after surgery, and 6.89±0.98mm at the last follow-up, with a mean change of 1.44±0.79mm. In the IH loss group, IH was 5.31±1.58mm preoperatively, 8.25±0.76mm 1 week postoperatively, and 5.50±1.01mm at the last follow-up, with a mean change of 2.75±0.52mm. The IH and IH change at the last follow-up were significantly higher in the IH maintaining group than those in the IH loss group(P<0.001). The fusion rate was 64.06% in the IH maintaining group and 42.37% in the IH loss group at 3 months postoperatively(P=0.019), and 81.25% in the IH maintaining group and 54.24% in the IH loss group at 6 months postoperatively(P=0.002). At the final follow-up, the inferior ASD incidence was 12.5% in the IH maintaining group, which was significantly lower than the 28.81% in the IH loss group(P=0.027). In addition, the incidence of implant subsidence was significantly lower in the IH maintaining group(3.13%) than that in the IH loss group(13.56%)(P=0.047). Conclusions: The incidence of IH loss of operative segements after anterior cervical decompression and fusion with Zero-P implant system is high, and the early postoperative fusion rate may decrease and the incidence of complications such as ASD and prosthesis subsidence may increase if IH loss ≥2mm.