Cervical anterior fusion with the Williams-Isu method: clinical review

Anterior decompression and fusion of the cervical spine is a widely accepted treatment for cervical canal disease. The Williams-Isu method involves cervical anterior fusion with autologous bone grafts from cervical vertebral bodies. Its advantages are a wide operative field, excellent graft fusion, the absence of problems related to the iliac donor site, and direct visualization of the nerve root. For detailed decompression of the cervical root, an ultrasonic bone curette (SONOPET, Stryker Japan K.K., Tokyo) may be useful. To prevent graft extrusion, bioabsorbable screws featuring a head are placed in 4 corners of the bone graft and are fixed with a tap on a part of the graft. The screws are visualized on postoperative X-ray, computed tomography, and magnetic resonance imaging studies. In 69 patients reported elsewhere there were no complications attributable to screw insertion, screw or graft extrusion, or surgery-related infections. When adequate bone cannot be harvested, a piece of ceramic hydroxyapatite is placed between the bone grafts. This sandwich method reinforces the graft, and radiological evidence suggests that it yields better results with respect to the angle and height of the fused segment. For the surgical treatment of cervical ossification of the posterior longitudinal ligament, a large vertebral bone window and a large bone graft are needed; this may result in postoperative radiological worsening. Radiological studies have shown that cervical ossification of the posterior longitudinal ligament can, as can cervical spondylosis, be addressed with the Williams-Isu method. Detailed radiological studies in patients treated with the Williams-Isu method have demonstrated that the range of motion and the disc height of the fused segment must be considered to prevent worsening in that segment after anterior fusion. The Williams-Isu method cannot completely correct cervical alignment, and great caution must be exercised in patients with preoperative malalignment. To reduce the levels to be fused in patients with multilevel lesions due to cervical disease, the Williams-Isu method can be combined with the transvertebral approach. The transvertebral approach facilitated by the wide Williams-Isu window allows the root bifurcation area to be confirmed during the early stage of surgery and possible decompression along the root. Radiological examination has shown that the combination of the Williams-Isu method and transvertebral approach does not affect the fusion level compared with the Williams-Isu method alone and produces better results than does the transvertebral approach alone.