Posterior lumbar interbody fusion for degenerative disc disease using a minimally invasive B-twin expandable spinal spacer: a multicenter study.

Acquired degenerative disc disease causes gradual disc space collapse, concurrent discogenic or facet-induced pain, and possible compression radiculopathy. Surgical treatment aims to re-expand the intervertebral space and stabilize the involved segment in balanced alignment until fusion is complete. The prevailing methods make use of a twin cage device of predetermined size. Their implantation requires extensive exposure, entailing the sacrifice of posterior stabilizing structures. The procedure also results in significant traction on the dural sac and the cauda equina and is thereby a potential source of neurologic damage. The new expandable spinal spacer (ESS) was designed to mitigate all the shortcomings alluded to above. A prospective multicenter clinical study was conducted of 87 patients with chronic low back pain due to degenerative disc disease, treated by posterior lumbar interbody fusion (PLIF) using a newly designed ESS. The study protocol was approved by the ethics committees of all the participating institutions. The objective was to test the safety and efficacy of the device. Each participant was followed periodically for >1 postoperative year. The ongoing record included intraoperative difficulties and complications, if any, radiologic evidence of fusion and clinical outcome as scored by pre- and postoperative questionnaires pertaining to pain intensity and degree of disability. No dural lacerations or neurologic deficit occurred. There were no mechanical failures of the spacer. Radiologic study demonstrated fusion in all but one patient. Disc space height that averaged 7.53 +/- 2.42 mm before surgery increased to 10.03 +/- 2.00 mm at the time of surgery and stabilized at 9.47 +/- 2.10 mm upon final follow-up. Visual Analog Scale and Oswestry Index decreased by 60% and 58%, respectively. PLIF using the ESS achieves the same ultimate outcome as do other methods currently in use but does not share the handicaps and hazards and is more user-friendly to the surgeon.