Biologic Annulus Fibrosus Repair: A Review of Preclinical In Vivo Investigations.

Publication Type	Review
Authors	Sloan S, Lintz M, Hussain I, Hartl R, Bonassar L
Journal	Tissue Eng Part B Rev
Volume	24
Issue	3
Pagination	179-190
Date Published	01/11/2018
ISSN	1937-3376
Keywords	Annulus Fibrosus, Implants, Experimental, Intervertebral Disc Degeneration, Intervertebral Disc Displacement, Low Back Pain
Abstract	Lower back pain, the leading cause of workplace absences and disability, is often attributed to intervertebral disc degeneration, in which nucleus pulposus (NP) herniates through lesions in the annulus fibrosus (AF) and impinges on the spinal cord and surrounding nerves. Surgeons remove extruded NP via discectomy when indicated by local/radicular pain supported by radiographic evidence; however, current interventions do not alter the underlying disease or seal the AF. The reported rates of recurrent herniation or pain following discectomy cases range from 5% to 25%, which has pushed spine research in recent years toward annular repair and closure strategies. Synthetic implants designed to mechanically seal the AF have been subject to large animal and clinical trials, with limited success in preventing recurrent herniation. Like gold standard interventions, purely mechanical devices fail to promote tissue integration, long-term healing, or restore native biomechanical function to the spine. Biological repair strategies utilizing principles of tissue engineering have demonstrated success in overcoming the inadequacies of current interventions and mechanical implants, yet, none has reached clinical or proof-of-concept trials in humans. In this review, we will discuss annular repair strategies promoting biological healing that have been implemented in small and large animal models in vivo, and ways to enhance the efficacy of these treatments.
DOI	10.1089/ten.TEB.2017.0351
PubMed ID	29105592