ABSTRACT
BACKGROUND: Orthopedic technique of ankylosing kyphosis is more mature. The surgeons can also choose different osteotomy methods according to the patients’ bending type and bending degree. However, due to the lack of widely recognized classification system, the description of ankylosing kyphosis and the formulation of operation strategy are confused. OBJECTIVE: To establish a three-dimensional finite element model of kyphosis osteotomy in ankylosing spondylitis using computer-aided software and analyze its biomechanical characteristics. METHODS: Image data of a patient with ankylosing kyphosis of type IIIA with strong 301 classification were obtained to establish a three-dimensional finite element model of ankylosing kyphosis. The osteotomy angles of T12, L1, L2 and L3 different segments were measured. Osteotomy of cancellous bone was simulated. The model after osteotomy was fixed with nail bar system. Biomechanical characteristics were analyzed. RESULTS AND CONCLUSION: (1) The closer the osteotomy segment was to the tail end, the greater the screw stress was, and the order of the screw stress distribution was L3 > L2 > L1 > T12. The stress distribution characteristics of different osteotomy segments were the same. The screw stress was concentrated on the adjacent upper/lower two segments of the osteotomy segment, and was significantly greater than that of other segments. (2) The order of the titanium rod stress was L2 > L3 > L1 > T12. (3) The closer the bone segment was to the head, the greater the stress was, and the order of the stress was T12 > L1 > L2 > L3. (4) The results show that for the type IIIA ankylosing kyphosis, the better degree of orthopedic can be obtained by selecting L2 osteotomy segment, and the complications caused by the concentration of internal fixation stress distribution can be reduced.
ABSTRACT
[Objeetive] To investigate the effect of minimally invasive V-shaped osteotomy instead of traditional operative technique for correction of ankylosing kyphosis.[Method]The C-arm X-ray was used under the local anaesthesia to select the space of osteotomy,the length of incision were 6~8 cm and only exposed one interlaminal space,the width of laminar V-shaped osteotomy were 8~10 mm.The operating table was changed from reverse V to type after finished osteotomy,the space of osteotomy would be automatica ly closed and replaced,if the space could not be automaticly closed,careful manipulation would be applied to close it.The bone mass of osteotomy was used in posterior bone graft of lamina.Postoperation,stric and standardized regulation were performed to send the patient back to ward.The fractional manual correction and external fixation of hyperextended plaster vest were performed respectivly 2 weeks after operation.[Result]Fifty patients of this group acquired more satisfied results except 1 case appeared recurrent deformity due to early removing of the plaster vest.[Conclusion]Minimal damage,lower medical expenses(without internal fixation)and satisfied results demonstrated the minimally invasive V-shaped osteotomy is a very effective method.It has advantages of Mutual intercalated V-shaped osteotomy space and better stability after reduction,posterior bone graft of lamina and external fixation of hyperextended plaster vest,therefore,all patients can acquire the bone graft fusion afer 6 months.