ABSTRACT
BACKGROUND: Single-segment and double-segment osteotomies are often used to treat ankylotic kyphosis. However, the selection of preoperative strategies, especially for segmental and osteotomy methods, often depends on clinical experience. At present; there are few reports on the biomechanics of double-segment vertebral column decancellation and vertebral column resection osteotomy. OBJECTIVE: To establish a two-segment osteotomy model for ankylotic kyphosis, and to compare and discuss the total displacement of the spine, stress analysis of the internal fixation system, and equivalent stress intensity of the osteotomy contact surface. METHODS: MIMICS software and Geomagic studio software were used to establish two kinds of models of ankylotic kyphosis with vertebral column resection osteotomy and vertebral column decancellation. Each kind of model was divided into single-segment osteotomy and double-segment osteotomy, i.e., L1 single-segment vertebral column resection osteotomy model, L1 single-segment decancellated osteotomy model, L2 single-segment vertebral column resection osteotomy model, L2 single-segment vertebral column decancellation model, T12L2 double-segment vertebral column resection osteotomy model, T12L2 double-segment vertebral column decancellation model, T12L3 double-segment vertebral column resection osteotomy model, and T12L3 double-segment vertebral column decancellation model. ANASYS software was imported to load model. The whole spine displacement, pedicle screw, connecting rod, and bone interface equivalent stress nephogram were recorded under different conditions of osteotomy. RESULTS AND CONCLUSION: (1) Whether it was vertebral column decancellation or vertebral column resection osteotomy model, the total spinal displacement of single-segment osteotomy was less than that of double-segment osteotomy. The displacement of vertebral column resection osteotomy was less than that of vertebral column decancellation in both single-and double-segment osteotomy models. L2 single-segment vertebral column resection osteotomy model had minimal displacement. (2) Whether it was vertebral column decancellation or vertebral column resection osteotomy model, equivalent stress of the single-segment osteotomy was less than that of the double-segment osteotomy. The equivalent stress of the internal fixation device of the vertebral column resection osteotomy was less than that of vertebral column decancellation in both single-and double-segment osteotomy models. The equivalent stress of the internal fixation device of the L1 single-segment vertebral column resection osteotomy was smallest. (3) The equivalent stress of the osteotomy contact surface of all single-segment osteotomy models was smaller than 28 MPa. In the two-segment osteotomy model, the equivalent stress of the osteotomy contact surface of the vertebral column resection osteotomy was less than that of vertebral column decancellation. (4) These results suggest that the biomechanical stability of the single-segment osteotomy model was better than that of the double-segment osteotomy model. The stability of vertebral column resection osteotomy was better than that of vertebral column decancellation.