A Prospective, Single Arm Study of Patients Undergoing Posterolateral Lumbar Fusion (Without Interbody) Supplemented With ViviGen Cellular Bone Matrix

Lumbar spine fusion rates can vary according to the surgical technique. Although many studies on spinal fusion have been conducted and reported, the heterogeneity of the study designs and data handling make it difficult to identify which approach yields the highest fusion rate. Traditional posterolateral intertransverse fusion (PLF) still remains a good procedure with acceptable fusion rates for most degenerative conditions. For solid fusion, PLF can be combined with interbody fusion to circumferentially stabilize the relevant segment, even though it is unclear whether this improves fusion rates.

A bone graft or bone graft substitute is required to produce the fusion and can be implanted on its own, in the posterolateral gutters, or contained with an interbody device using either a posterior or anterior approach. Spinal laminectomy is most often the largest generator of bone graft product due to the nature of the procedure. The current gold standard is autograft bone, in which tissue is harvested locally or from the iliac crest and is then placed at the site. However, local bone graft may be relatively limited and harvesting at the iliac crest can easily lead to significant morbidity. Complications such as inflammation, infection, and chronic pain may outlast the pain of the original surgical procedure.

Autograft is the gold standard because it possesses all of the characteristics necessary for new bone growth-namely, osteoconductivity, osteogenicity, and osteoinductivity. Allograft tissues are alternatives to autografts and are taken from donors or cadavers, circumventing some of the shortcomings of autografts by eliminating donor-site morbidity and issues of limited supply. Osteoconductivity refers to the situation in which the graft supports the attachment of new osteoblasts and osteoprogenitor cells, providing an interconnected structure through which new cells can migrate and new vessels can form. Osteogenicity refers to the situation when the osteoblasts that are at the site of new bone formation are able to produce minerals to calcify the collagen matrix that forms the substrate for new bone. Osteoinductivity refers to the ability of a graft to induce nondifferentiated stem cells or osteoprogenitor cells to differentiate into osteoblasts. Using the 2 basic criteria of a successful graft, osteoconduction and osteoinduction, investigators have developed several alternatives, some of which are available for clinical use and others of which are still in the developmental stage. Many of these alternatives use a variety of materials, including natural and synthetic polymers, ceramics, and composites, whereas others have incorporated factor- and cell-based strategies that are used either alone or in combination with other materials.