[Flavectomy of cervical vertebrae in treating cervical spinal canal stenosis].

OBJECTIVE

To investigate the operational method of cervical vertebral flavectomy and its clinical application in the management of cervical canal stenosis.

METHODS

From June 1997 to June 2007, 25 patients suffering from cervical spinal canal stenosis caused by obvious flaval ligament hypertrophy were given flavectomy. There were 22 males and 3 females, with an age range of 32 to 68 years (average 54 years). The course of disease was from 3 weeks to 7 years, with an average of 3 years and 7 months. All patients had degenerative cervical canal stenosis; of them, 5 cases had a history of cervical injury 2 to 3 weeks before operation (3 cases of falling injury and 2 cases of traffic accident injury). The X-ray film, CT, and MRI examinations showed that the compression locations were C4-7 in 12 cases, C3-7 in 9 cases, C5-7 in 3 cases, and C6,7 in 1 case. Spinous process and vertebral lamella were exposed by central posterior approach. The insertions of flaval ligaments were cut off at the superior vertebral lamella border, then the starting points of which were cut down from the anterior side of the upper vertebral lamella at their inferior border after lifting up the flaval ligaments. The residual flaval ligaments in front of the vertebral lamella were scraped off by slope rongeur, the dura mater then could be seen to inflate from the intervertebral lamella space, showing the compression having been relieved. Twenty-five cases were all given posterior flavectomy. At 1 week to 3 months after operation, 12 patients received anterior cervical discectomy or vertebral gaining decompression with fusion by bone graft.

RESULTS

The time for flavectomy was from 60 to 180 minutes, with an average of 95 minutes. The blood loss during operation was from 90 to 360 mL, with an average of 210 mL. The dura matters were lacerated by knife tips during operation with the cervical vertebrae in hyperflexion in 2 cases. Immediate suture and repair were performed and there were no postoperative cerebrospinal fluid leakage. All the incisions healed by first intension after operation. All of the 25 cases were followed up from 2 to 10 years, with an average of 3 years and 9 months. All patients had no complication of axial symptoms, and no restenosis at their operation site of cervical canal stenosis. The section area ratios of functional spinal canal to spinal cord were 1.12 +/- 0.07 before operation and 2.11 +/- 0.19 at 24 months after operation, showing significant difference (P < 0.05). The range of motion of cervical vertebrae was (39.4 +/- 3.2) degrees before operation and (42.1 +/- 2.9) degrees at 24 months after operation in 13 cases without anterior cervical discectomy fusion, showing no significant difference (P > 0.05); was (34.3 +/- 3.4) degrees before operation and (29.2 +/- 3.6) degrees at 24 months after operation in 12 cases with anterior cervical discectomy fusion, showing significant difference (P < 0.05). The bone graft achieved bony union 3-5 months after operation (average 3.8 months). The Japanese Orthopaedic Association (JOA) scores were 7.9 +/- 2.2 before operation and 15.6 +/- 1.4 at 24 months after operation, showing significant difference (P < 0.05), with an average improvement rate of 86.3%.

CONCLUSION

Cervical flavectomy could relieve compression to spinal cord and nerves caused by the flaval ligament hypertrophy without damaging the normal integrality of bony canal, thus avoiding the complication of axial symptoms and so on which are encountered in open-door expansile cervical laminoplasty.