Investigation on anatomical factors inhibiting the posterior shift of the thoracic spinal cord and the development of reliable methods of posterior decompression of the spinal cord for the thoracic OPLL-myelopathy

作为治疗胸腰椎脊髓病的一种安全可靠的脊髓减压术，选择了后路入路，消除了抑制胸椎脊髓后移的三大解剖因素，改善了后路手术的缺点，即胸椎后凸所致的减压程度不足。它们是：(1)纵向因素，即脊髓节段在OPLL上方和下方的前牵拉效应；(2)纵横向因素，即硬脑膜部分的牵拉效应；(3)横向因素，即胸根和齿状韧带的前系留效应。消除这些因素的方法是：(1)广泛的颈胸段椎板成形术，(2)纵行硬膜外切开，(3)小关节切除和根OPLL松解术。必要时行OPLL切除或前路移位术。对15例胸椎OPLL脊髓病患者进行了后路分期手术。平均年龄56岁(范围42-68岁)，平均随访42个月(范围5-100个月)。所有病例神经功能均有改善，术后并发症较少。X线片证实了消除后移位抑制因素对脊髓减压术的有效性。

As a method of safe and reliable decompression of the spinal cord for thoracic-OPLL myelopathy, the posterior approach was selected and its disadvantage, I.e., the insufficient degree of decompression caused by thoracic kyphosis, was improved by elimination of three major anatomical factors which inhibited the posterior shift of the thoracic spinal cord. They were: (1) longitudinal factor, I.e., anterior pulling effects of spinal cord segments, above and below OPLL, (2) longitudotransverse factor, I.e., holding-down effect of the parts of dura; mid-dorsal part and lateral part which extended into nerve-sheath, (3) transverse factor, I.e., anterior tethering effect of thoracic roots and denticular ligaments. Means of elimination of these factors were: (1) extensive cervicothoracic laminoplastic decompression, (2) longitudinal durotomy, (3) facetectomy and root-OPLL release. OPLL resection or anterior transfer was finally performed if necessary. These procedures were performed through staged posterior approaches in fifteen cases of thoracic OPLL-myelopathy. A mean age was 56 years (range: 42-68 years) and a mean follow-up was 42 months (range: 5-100 months). Neurology improved in all cases, with little postoperative complications. Radiological pictures proved the effectiveness of elimination of posterior-shift-inhibiting factors for the spinal cord decompression.