后路经椎弓根椎体截骨术及其改良术式在僵硬性脊柱后凸畸形中的应用进展

Application and progress of pedicle subtraction osteotomy and its modification for rigid spinal kyphosis deformity

僵硬性脊柱后凸畸形通常是指后凸Cobb角较大(≥70°),且椎体间柔韧性明显下降(弯曲的柔韧性<30°)的脊柱畸形,可由脊柱原发性疾病、外伤或其他疾病引起。严重的脊柱后凸畸形不仅影响患者美观,还会伴有脊髓或神经功能损害。三柱截骨术是目前治疗此类患者的唯一有效手段,其中以经椎弓根椎体截骨术(pedicle subtraction osteotomy,PSO)及其改良术式应用最为广泛。不对称PSO(asymmetrical pedicle subtraction osteotomy,APSO)不但能有效重建患者的矢状面、冠状面平衡,而且更容易实现截骨面完全闭合,有利于截骨面达到坚强的骨性融合及增强局部稳定性。保留椎弓根下壁的经椎弓根椎体截骨术(partial pedicle subtraction osteotomy,PPSO)可降低腰神经出口根损伤发生率,常应用于各类脊柱畸形矫正。保留椎弓根下壁的经椎弓根椎体+椎间盘截骨术(modified partial pedicle subtraction osteotomy,MPPSO)多用于伴椎间盘损伤的创伤后胸腰椎后凸畸形,其优势在于骨-骨接触降低了椎间盘源性腰痛的风险、提高了融合率。中柱闭合-前柱张开楔形截骨术(closing-opening wedge osteotomy,COWO)在闭合后柱的同时张开前柱,可实现更大的后凸矫正度数。经椎弓根椎体+椎间盘开合式楔形截骨术(modified closing-opening wedge osteotomy, MCOWO)多用于椎体楔形变的陈旧性胸腰椎骨折后凸畸形,可获得良好的矫形效果。经椎弓根椎体+椎间盘截骨术(bone-disc-bone osteotomy,BDBO)也可实现骨对骨的截骨面闭合,通常可获得较好的融合效果,但术中去除部分多、难度大、操作复杂,容易引起神经和血管损伤。明确各改良术式的截骨范围、矫形效果及优劣势有助于为患者个性化制定手术方案,获得理想的矫形效果和改善预后。

Rigid spinal kyphosis deformity is typically characterized by a large kyphotic Cobb angle(≥70°)and a significant decrease of intervertebral flexibility(bending flexibility<30°),due to primary spinal disease,spinal trauma or other diseases.Severe kyphotic deformity leads to a poor posture and spinal cord or neurological impairment.Three-column osteotomy,including pedicle subtraction osteotomy(PSO)and its modified methods,is the only effective treatment for such patients.For example,asymmetrical PSO(APSO)could not only achieve successful realignment of spinal biplanar balance,but also realize complete closure of osteotomy gap,which is conducive to realize solid bony fusion and provide better stability.In partial pedicle subtraction osteotomy(PPSO),the remaining cortical shell of pedicle could decrease the risk of neural injury without significant loss of correction amount,so PPSO could be a viable surgical option for spinal deformity.Besides,modified partial pedicle subtraction osteotomy(MPPSO)is commonly used for post-traumatic thoracolumbar kyphosis with an injured disc.The potential superiorities of MPPSO are that it not only increases regional stability by reserving the integrity of the lower facet joint,but also promotes direct interbody fusion in the upper disc space.For closing-opening wedge osteotomy(COWO),it could obtain more kyphotic corrections by closing posterior column and opening anterior column simultaneously.Modified closing-opening wedge osteotomy(MCOWO)is an ideal option in treating cases of thoracolumbar posttraumatic kyphosis with flat discs or wedge-shape vertebra,because great correction results were observed at follow-up with postero-superior triangular corner primarily resected.Although technically difficult and demanding,bone-disc-bone osteotomy(BDBO)is still a good option for achieving"bone-to-bone"closure of the osteotomy site to yield higher fusion rates and decrease the risk of pseudoarthrosis.A full understanding of the osteotomy range,correction effects and advantages for each type of modified PSO is essential for preoperative plans,optimal spinal sagittal reconstructions and excellent prognosis.