Biomechanical Study of Cervical Posterior Decompression

Hashiguchi, Akira; Kanchiku, Tsukasa; Nishida, Norihiro; Taguchi, Toshihiko

Abstract

STUDY DESIGN: Biomechanical study. PURPOSE: We examined the dynamic characteristics of different operative procedures using three-dimensional finite-element models. OVERVIEW OF LITERATURE: Cervical laminoplasty is often selected for patients requiring multilevel spinal decompression. Many laminoplasty techniques have been developed and are continually being improved.
METHODS
Images were extracted for the two intervertebral joints between C3 and C5 in domestic rabbits. The following models were created: preoperative, laminectomy, Z-plasty, open door laminoplasty, French open door laminoplasty, en-bloc laminoplasty, and double-door laminoplasty. The loads required for sagittal rotation of 2.5°, 5°, and 7.5° were measured in vitro and respectively placed at the bottom of the C5 model. Displacement of the plate in the X, Y, and Z coordinates was measured and the rotational angles of the plate were determined.
RESULTS
The sagittal rotation angle was greater in the laminectomy model than in the preoperative model, but was almost the same in the preoperative and Z-plasty models. Compared with the preoperative model, sagittal rotation angles were smaller in the French open door, open door, en-bloc, and double-door laminoplasty models.
CONCLUSIONS
Laminectomy and various types of laminoplasty are associated with different mechanical features, such as stability and mobility, allowing for selection of the most appropriate surgical procedure for each case.