Experimental research on biomechanical stability about L_5S_1 ALIF / 中国矫形外科杂志

[Objective] To evaluate the biomechanical stability of lumbar intact specimen,anterior lumbar interbody fixation(ALIF)specimen,ALIF specimen fixed with pedicle screw and ALIF specimen fixed with translaminar facets screw.[Method]Each of eight adult fresh cadaver specimen of lumbarsacral segmcnts was analyzed in four states(groups):intact,L5S1 ALIF,L5S1 ALIF fixed with pedicle screw or fixed with translaminar facets screw,test and compare its range of motion(ROM)in flexion,extension,lateral bending and axial rotation.[Result]The ROM of ALIF specimen in extension was larger than that of intact specimen(P

Ventral and Dorsal Stabilization of the Thoracolumbar Spine by Crossed-screw Fixation

For surgical stabilization of thoracolumbar instability either posterior transpedicular fixation or anterior interbody fixation is commonly performed. On some occasions, however, combined ventral and dorsal stabilization is needed, in which case surgery is usually performed in separate stages. To achieve this goal in a single operation, the authors used the crossed-screw fixation technique, with the pedicle screw-rod system, in eight patients. Their thoracolumbar instabilities were caused by trauma(n=6), tumor(n=1), and congenital deformity(n=1). In all patients, signs of myelo- and/or radiculopathy were present, and as this required extensive ventral and dorsal decompression, combined ventral and dorsal stabilizations was considered necessary. Surgery involved the lateral extracavitary approach: for dorsal stabilization, the conventional transpedicular fixation method, with pedicle screws of 5.5-mm diameter, was used. For ventral stabilization, interbody struts were grafted, using rib autograft or in the case of tumor fibula allograft, supplemented with transverse fixation of the vertebral body with pedicle screws of 7.5-mm diameter. The two stabilization systems, ventral and dorsal, were interconnected with cross-linking plates. Follow-up 12 to 26 (average 18) months after surgery revealed no hardware failures, and all patients showed improvement in their neurological functions during this period. Due to congenital deformity, graft dislodgement occurred in one patient. On the basis of these results the authors believe that the crossed-screw fixation technique is a viable option for three-dimensional stabilization of the thoracolumbar spine.