Object Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been approved for use in the lumbar spine in conjunction with the lumbar tapered cage. However, off-label use of this osteoinductive agent is observed with anterior fusion applications as well as with both posterior lumbar interbody fusion and transforaminal lumbar interbody fusion (TLIF). Complications using rhBMP-2 in the cervical spine have been reported. Although radiographic evidence of ectopic bone in the lumbar spine has been described following rhBMP-2 use, this finding was not previously believed to be of clinical relevance. Methods This study was a retrospective review of 4 patients who underwent minimally invasive spinal TLIF (MIS-TLIF) in which bone fusion was augmented with rhBMP-2 applied to an absorbable collagen sponge. Case presentations, operative findings, imaging data, and follow-up findings were reviewed. Results Four cases with delayed symptomatic neural compression following the off-label use of rhBMP-2 with MIS-TLIF were identified. Conclusions Although previously believed to be only a radiographic finding, the development of ectopic bone following rhBMP-2 use in lumbar fusion can be clinically significant. This paper describes 4 cases of delayed neural compression following MIS-TLIF. The reader should be aware of this potential complication following the off-label use of rhBMP-2 in the lumbar spine.

Differential diagnosis of etiologies causing the formation of sSOH in an adult without history of trauma should include metastatic neoplasm to the skull and warrants metastatic workup. Treatment options of sSOH have included observation with spontaneous resolution; however, we opted for surgical decompression of the eye and biopsy of the skull mass.

OBJECTIVE: to describe a new posterior minimally invasive method of facet stabilization for treatment of the degenerating lumbar motion segment. The biomechanics of this Percudyn (Interventional Spine; Irvine, CA) system are distinct from that of other interspinous dynamic stabilization systems as it acts bilaterally directly within the middle column of the spine. Based on biomechanical evalution, the paired prosthesis supports, cushions, and reinforces the facet complexes by limiting both extension and lateral bending thereby maintaining central and foraminal volumes. METHODS: the Percudyn device consists of a pedicle anchor upon which sits a cushioning polycarbonate-urethane stabilizer that serves as a mechanically reinforcing stop between the inferior and superior articular facets. A 1.5 cm skin incision is made bilaterally over the lower pedicle of the treated segment through which a Jamshidi needle is percutaneously targeted under biplanar fluoroscopic guidance into the caudal aspect of the superior articular process directly underneath the lip of the inferior facet from the level above. Progressive onestep tubular dilation is then performed to secure a small disposable working portal. Through this access, the Percudyn stabilizers are then placed over the wire and anchored bilaterally into the inferior pedicles of the degenerated motion segment. RESULTS: three patients (ages 26-41, male) with significant low back pain as well as radiculopathy with lateral recess stenosis from a large disc herniation/ ligamentum and facet hypertrophy (L4-5 and/or L5-S1) underwent a minimally invasive decompression/ discectomy and bilateral Percudyn placement at each disease level. Each patient had significant relief of both his radiculopathy and axial back pain post-operatively and was discharged home within 18 hours without sequelae. CONCLUSION: this novel technique of percutaneous posterior facet augmentation allows for safe placement of bilateral middle column prostheses that act as mechanical cushions between the articulating facets thereby limiting extension and lateral bending and also preventing compression of the neural elements. As the Percudyn device serves to reinforce the middle column directly at the level of the facet, it represents a new class of posterior motionpreserving stabilization which may serve to mitigate segmental axial back pain as has been described for other posterior dynamic stabilization systems.

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