Exploration and decompression of the spinal canal using split laminotomy and its modification, the "archbone" technique.

OBJECTIVE: To develop a novel minimally invasive approach suitable for exploring different pathologies located in the spinal canal, allowing moderate enlargement of the canal with preservation of the majority of posterior structures so muscle attachments remain intact and postoperative complications are reduced.
METHODS: The authors developed a multilevel spinous process splitting and distracting laminotomy technique with or without complementary corticocancellous iliac crest "archbone" autografting. Technical details are discussed. The multilevel spinous process splitting and distracting laminotomy technique with or without complementary iliac bone grafting was used in 19 patients with different pathologies of the spinal canal.
RESULTS: Satisfactory surgery of the lesions located within the spinal canal, especially intramedullary, was achieved in all patients using this new approach. The affected area of the spine was cervical in seven patients, cervicothoracic in four patients, thoracic in five patients, and thoracolumbar in three patients. The average number of split laminae was three (range, 2-6). Histological results were as follows: seven intramedullary astrocytomas, eight ependymomas, two cavernous hemangiomas, one dural arteriovenous malformation, and one hemangioblastoma. Of the eight ependymomas, 75% were removed completely and 25% were partially removed. Of the seven astrocytomas, 28.7% were removed completely, 14.3% were removed subtotally, and 57% were partially removed. The cavernous hemangiomas and the hemangioblastoma were completely removed. The approach used did not affect the extent of resection or neurological outcome. The spinous processes were closed directly in 13; in six cases, a tricortical iliac bone graft was placed between the facing bony parts of the spinous processes. The mean duration of splitting and distracting the spinous process was 16 minutes (range, 11-28 min) for the first process and 8 minutes (range, 5-14 min) for each additional spinous process. The mean duration of the whole surgical procedure, including intraspinal surgery, was 159 minutes (range, 90-290 min). The mean blood loss was 158 ml (range, 48-442 ml). The average length of hospital stay was 7.2 days. The average follow-up period was 15.4 months. Fifty-one of the 57 (89.5%) spinous process computed tomographic scans demonstrated bony healing with or without a graft between the osteotomized faces. Of the 57 spinous process computed tomographic scans, fracture of the spinous process was seen in nine (15.8%) and traumatic bony changes of the body of the vertebra in the midline in three (5.2%); these were without clinical significance and they later showed complete healing.
CONCLUSION: This surgical approach fulfills the requirements of other laminotomy techniques and helps prevent damage to the crucial posterior stabilizers of the spine. In contrast to conventional spinal canal approaches, preservation of the majority of posterior structures leaves muscle attachments on the spinous processes and laminae completely intact. Furthermore, the technique for exposure and decompression of the spinal canal is a suitable method for all spinal segments, the cervical, thoracic, and the lumbar spine in all age groups.