Application of structural autologous cervical laminae as bone graft in anterior cervical discectomy and fusion

Background: Autograft bone is still the gold standard as fusion substrate in anterior cervical discectomy and fusion (ACDF). In patients underwent combined posterior laminectomy and anterior discectomy surgery, whether the resected structural cervical laminae are suitable for bone graft in ACDF during the surgery remains unclear. The purpose of this study is to evaluate if the height and area of the structural cervical laminae are large enough for bone graft in ACDF by computed tomography (CT) scan. Methods: Computed tomography scan of the cervical spine was performed in fifty adult cases. There were 25 males and 25 females with an average age of 30.4 years (range, 20-40 years). The axial and sagittal planes of the cervical spine were harvested for anatomical measurement. The heights of bilateral laminae from C3 to C7 were measured and the area of the triangle composed by bilateral laminae was computed. Also, the anterior, middle and posterior heights of the intervertebral space from C3 to C7 were measured and the area of inferior vertebral endplate was calculated. Then, the parameters of the laminae were compared to those of the corresponding vertebrae body. Results: The height of the cervical laminae in male ranged from 11.47 mm to 14.09 mm on the left side and from 11.52 mm to 14.08 mm on the right side from C3 to C7. In the female, the height of the laminae ranged from 10.57 mm to 13.07 mm on the left side and from 10.54 mm to 13.13 mm on the right side. The area of the laminae triangle ranged from 161.79 mm2 to 183.87 mm2 in the male and from 148.53 mm2 to 155.89 mm2 in the female from C3 to C7, with an average of 164.60 mm2. The heights of the anterior, middle and posterior of the intervertebral space were from 4.30 mm to 4.77 mm, 5.55 mm to 6.25 mm and 3.88 mm to 4.03 mm, respectively. Significant differences were found between the heights of the laminae and the corresponding middle heights of intervertebral space (P < 0.05). From C3 to C7, the areas of the inferior vertebral endplate were from 209.01 mm2 to 223.48 mm2 with a mean value of 217.79 mm2. The average ratio of the laminae triangle area to that of endplate was 75.58%. Conclusions: The height and area of the structural cervical laminae are adequate for bone graft in ACDF. Autologous structural cervical laminae represent a viable alternative to traditional fusion graft in patients underwent combined postero-anterior cervical surgery.