Comparison of Cortical Ring Allograft and Plate Fixation with Autologous Iliac Bone Graft for Anterior Cervical Discectomy and Fusion

Abstract

Study design: A retrospective cohort study.

Purpose: To compare the clinical and radiological outcomes of patients who underwent anterior cervical discectomy and fusion (ACDF) supplemented with plate fixation using allograft with those who underwent ACDF using tricortical iliac autograft.

Overview of literature: As plate fixation is becoming popular, it is reported that ACDF using allograft may have similar outcomes compared with ACDF using autograft.

Methods: Forty-one patients who underwent ACDF supplemented with plate fixation were included in this study. We evaluated 24 patients who used cortical ring allograft filled with demineralized bone matrix (DBM) (group A) and 17 patients who used tricortical iliac autograft (group B). In radiological evaluations, fusion rate, subsidence of grafted material, cervical lordosis, fused segmental lordosis, and radiological adjacent segment degeneration (ASD) were observed and analyzed with preoperative and postoperative plain radiographs. Clinical outcomes were evaluated using the Neck Disability Index score, Odom criteria, and Visual Analog Scale score of neck and upper extremity pain. Radiological union was determined by dynamic radiographs using cutoff values of 1 mm of interspinous motion as the indication of pseudarthrosis.

Results: There was no significant difference in the fusion rate, graft subsidence, cervical lordosis, fused segmental lordosis, and ASD incidence between the groups. Operative time was shorter in group A (136 min) than in group B (141 min), but it was not significant (p>0.05). Blood loss was greater in group B (325 mL) than in group A (210 mL, p=0.013). There was no difference in the clinical outcomes before and after surgery.

Conclusions: In ACDF with plate fixation, cortical ring allograft filled with DBM group showed similar radiological and clinical outcomes compared with those of the autograft group. If the metal plate is reinforced, using cortical ring allograft could be a viable alternative to autograft.

Keywords: Anterior cervical discectomy and fusion; Cortical ring allograft; Demineralized bone matrix; Plate fixation; Tricortical iliac autograft.

Fig. 1.

Plain lateral radiographs of a 53-year-old patient’s cervical spine. (A) Preoperative lateral view, (B) immediate postoperative lateral view, and (C, D) postoperative 1-year follow-up measurement of interspinous interval difference by flexion and extension lateral view.

Fig. 2.

Measurement of fused segmental height for measuring subsidence.

Fig. 3.

Measurement of (entire) cervical lordosis (C2 and C7) using Harrison posterior tangent method.

Fig. 4.

Postoperative 1-year computed tomography of C5–C6 anterior cervical discectomy and fusion. (A) Sagittal view and (B) coronal view showing continuity of bony fusion mass between C5–C6.

Fig. 5.

Three-year follow-up postoperative lateral radiographs of a 39-year-old patient’s cervical spine. (A) Flexion view and (B) extension view showing solid fusion of C4–C5–C6.