Mechanical and Biological Treatments for Annulus Fibrosus Repair and Closure: A Review of Clinical Studies

To address disc reherniation, several annular repair strategies have been developed, including implantable devices, suture-based techniques, and biomaterials. This review evaluates the clinical evidence supporting these strategies. A systematic search of PubMed, Cochrane, and Embase and MEDLINE via Ovid was performed from database inception to July 2025. A combination of keywords was used in the search string. Publications were included if they were clinical studies and described closing the annulus or blocking the annulus defect with biologics, sutures, or physical devices. Exclusion criteria were animal studies, in vitro studies, non-English articles, and abstracts. A single-arm proportional meta-analysis was performed for studies reporting extractable reherniation, reoperation, or complication data. The initial search identified 1,349 records. After removal of 315 duplicates, 1,034 studies underwent screening, with 84 full texts reviewed and 62 meeting inclusion criteria. Forty-one studies (66%) assessed implantable physical devices, of which 40 (98%) evaluated the Barricaid annular closure device (ACD) (Intrinsic Therapeutics, Inc., USA). Eighteen studies (29%) evaluated suture-based closure of the annulus fibrosus, using preloaded devices, bone-anchored systems, or manual suturing techniques. Three studies (5%) examined the use of biomaterials as either an adjunct or standalone method in the form of autologous conditioned plasma, bone marrow stromal cells, and fibrin sealant. For physical devices, the pooled reherniation, reoperation, and complication rates were 4.71%, 4.84%, and 1.76% respectively. Suture-based techniques had reherniation, reoperation, and complication rates of 1.37%, 0.35%, and 0.28%, respectively. For biomaterial-based approaches, only a pooled reherniation rate was calculated (2.11%), as insufficient data were available to pool reoperation and complication rates. Annular repair following discectomy is associated with low rates of reherniation, reoperation, and complications across physical devices, suture-based techniques, and biomaterial approaches. Physical devices and suturing techniques have robust clinical evidence and show generally favorable outcomes, but results remain mixed and heterogenous across techniques. Biomaterials demonstrate early promise but are limited by small study size and short follow-up. While pooled proportional meta-analysis supports the overall safety and effectiveness of annular repair, heterogeneity and limited comparative evidence prevent determination of relative superiority.