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BACKGROUND AND IMPORTANCE Symptomatic lumbar disc herniation is common. Migration of a free disc fragment is usually found in rostral, caudal, or lateral directions. Posterior epidural migration is very rare. We report the first case with posterior epidural migration and sequestration into bilateral facet joints of a free disc fragment. CLINICAL PRESENTATION A 78-year-old female presented with low back pain and right leg pain. Plain radiographs showed lumbar spondylolisthesis. Magnetic resonance imaging revealed a posterior epidural mass and intrafacet mass, which was hypointense on T1-weighted images and hyperintense on T2-weighted images. The lesion in the left L3-4 facet joint had rim enhancement, whereas the right one was not contrasted after gadolinium injection. Preoperative differential diagnosis included abscess, tumor, hematoma, or synovial cyst. An interbody cage fusion at L3-4 and L4-5 for spondylolisthesis was performed, and a hybrid technique was applied with the Dynesys flexible rod system at L3-S1 for multisegment degenerative disc disease. The lesion proved to be an epidural disc fragment with sequestration into bilateral facet joints. CONCLUSION A free disc fragment should be considered in the differential diagnosis of posterior epidural lesions, and even in the facet joint.

Anterior discectomy and fusion to treat cervical degenerative disc disease is the preferred procedure for many spine surgeons. The ideal device for structural reconstruction of the anterior cervical spine remains controversial. The purpose of this prospective study was to investigate the effectiveness of a non-threaded titanium cage in performing anterior spinal fusion for cervical degenerative disc disease. The clinical and radiologic data of 78 consecutive patients were reviewed. Neurologic outcome was assessed using Odom's criteria. Neck pain was graded using a 10-point visual analog scale. The cervical spinal curvature, the height of foramina, and fusion status were evaluated on preoperative and postoperative radiographs. Mean follow-up was 24.9 (range 18-35) months. An excellent or good result was found in 92% of the patients with radiculopathy, 69% of those with myelopathy, and 73% of those with myeloradiculopathy. Statistical analyses also showed improvement of cervical pain after surgery (P < 0.001) and a significant increase in foraminal height (P = 0.035). Cervical kyphosis was present in 27 (34%) patients before surgery; it was corrected to lordosis in 9. The fusion rate at 12 months and 24 months was 91% and 95%, respectively. No surgery or cage-related complication occurred in these patients. Non-threaded interbody cage fusion in this study achieved a high fusion rate and had a good neurologic outcome. These results suggest that non-threaded cage fusion is a safe and effective method for anterior cervical discectomy.