Advances in implants and bone graft types for lumbar spinal fusion surgery

Abstract

The rising occurrence of spinal disorders globally necessitates advanced treatments, particularly interbody fusion for severe cases not resolved by non-surgical methods. This procedure, especially 360° lumbar interbody fusion, employs an interbody cage, pedicle screw-and-rod instrumentation, and autologous bone graft (ABG) to enhance spinal stability and fusion. Despite significant advancements, a 10% incidence of non-union persists, resulting in suboptimal patient outcomes and increased healthcare costs. Innovations in lumbar stabilisation seek to mimic the properties of natural bone, with evolving implant materials like titanium (Ti) and polyetheretherketone (PEEK) and their composites offering new prospects. Additionally, biomimetic cages with reflective porosities and interconnectivity have gained popularity, as they improve osteogenic differentiation, promote osteogenesis and reduce stress-shielding. The limitations of ABG, such as harvesting morbidities and limited fusion capacity, have spurred the exploration of sophisticated solutions involving advanced bone graft substitutes. Currently, demineralised bone matrix and ceramics are in clinical use, forming the basis for future investigations into novel bone graft substitutes. Bioglass, a promising newcomer, is under scrutiny despite its observed rapid absorption and foreign body reactions in preclinical studies. Its clinical applicability remains undetermined, with ongoing research addressing challenges related to burst release and dosing. Conversely, the well-documented favourable osteogenic potential of growth factors is encouraging, with current efforts directed at mitigating complications associated with their release dynamics. In this evidence-based narrative review, we provide a comprehensive overview of the evolving landscape of non-degradable spinal implants and bone graft substitutes, emphasising their applications in lumbar spinal fusion surgery. We highlight the necessity for continued research to enhance clinical outcomes and patient well-being.