Biomechanical Study of Anterior Cervical Corpectomy and Step-Cut Grafting With Bioabsorbable Screws Fixation in Cadaveric Cervical Spine Model

In Brief Study Design. An in vitro biomechanical study. Objective. To determine the initial stability of a novel construct in a 1-level cadaveric cervical spine model by comparing it with a conventional method. Summary of Background Data. Lots of endeavors have been made to enhance fusion rates and reduce complications in the anterior cervical spine procedure. Methods. There were 12 fresh human cadaveric cervical spines (C3–C7) randomly divided into 2 groups: group 1, 1-level corpectomy of C5 and step-cut grafting with bioabsorbable screw fixation (SCAS); and group 2, 1-level corpectomy of C5 and strut grafting with anterior plate fixation (SP). For each specimen, the intact underwent a flexibility test first, followed by the instrumented construct. Rotational angles of the C4–C6 segment were measured to study the immediate stability of anterior cervical corpectomy and SCAS, compared with the intact and anterior cervical corpectomy and SP. Results. Both anterior cervical corpectomy with SCAS and with SP significantly (P < 0.01) decreased the motions of C4–C6 in all 6 degrees of freedom after instrumentation. Compared with anterior cervical corpectomy and SP, anterior cervical corpectomy and SCAS had higher stability (P < 0.05) in extension, and comparable stability (P > 0.05) in flexion and axial rotation, but lower stability (P ≤ 0.05) in lateral bending. Conclusion. Anterior cervical corpectomy and SCAS, a novel method of anterior cervical spine decompression and reconstruction, was introduced. The in vitro biomechanical study showed that anterior cervical corpectomy and SCAS had sufficient immediate stability except for the lateral bending, compared with anterior cervical corpectomy and SP, in a 1-level cadaveric cervical spine model. However, an animal experimental in vivo evaluation of anterior cervical corpectomy and SCAS still has to be performed. The technique of anterior cervical corpectomy and step-cut grafting with bioabsorbable screws fixation could provide sufficient stabilities in flexion, extension, and axial rotation, but lower lateral bending stability, compared with conventional strut graft and plate fixation in a 1-level cadaveric cervical spine model.