Biomechanical analysis of cervical multilevel oblique corpectomy: an in vitro study in sheep

Summary Background. Anterolateral oblique corpectomy is an alternative approach to treatment of multilevel cervical spinal disease. It is stated that the approach does not cause instability in the patients with hard discs, so fusion or instrumentation is not required. The authors undertook a study on stability of the cervical spine by an animal model to establish if this approach causes instability.Material and methods. Thirty-seven C3 to C6 spinal segments obtained from 3 to 4-year-old male sheep were used. In vitro maximal loading values were obtained from seven sheep cervical specimens for flexion, extension, lateral flexion in both directions, axial rotation in both directions and axial loading, and load deformation curves were drawn by an electrohydrolic testing machine. Other specimens were divided into three groups: Control (n=10), C4 (n=10) and C4–5 (n=10) groups. In two study groups, one or two level oblique corpectomies were performed. In the control and study groups, biomechanical tests were obtained according to the maximal loading values. Load-deformation curves were drawn and displacement amounts were determined for all seven movements.Results. No statistically significant differences were observed in load deformation curves and displacement amounts between all three groups for seven movements.Conclusion. These results support the opinion that anterolateral oblique corpectomy does not cause cervical instability.