Factors stimulating bone formation

Abstract

IntroductionOsseous spinal fusion remains a cornerstone of surgical treatment of severe spinal disorders. However, the success rate is still debated and difficult to assess in the presence of metal implant material. A general failure rate of 5-30% is reported in lumbar spinal fusion [58]. Fusion capacity is influenced by numerous factors: individual biological factors, the bone graft material, and biomechanical and external factors. Predictive factors for good osseous fusion are uniformly associated with good functional outcome, for which psychosocial factors, the presence of neurodeficit, and the primary diagnosis also seem to have major importance.The individual biological factors governing spinal fusion are related to bone homeostasis and thereby to age. Little is known about individual variations in spinal fusion capacity, although it is generally accepted that young patients heal well. Recent studies have shown that all osteotropic growth factors known to be sequentially involved in the spinal fusion process [6] are present in iliac crest bone autografts of all age groups but with higher variation in older people [3, 16]. Other growth factors that regulate vascular ingrowth have not been addressed and might be equally important. Osteotropic growth factors such as TGF β, BMP2, and BMP7 have been shown experimentally to induce/provide sufficient bone formation for both intracorporal and posterolateral spinal fusion at the level of bone autografts in sheep, rabbits, and baboons [9, 22], but the clinical effectiveness has yet to be determined in controlled studies and negative and positive results have been reported [7, 38,39]. At present, the cost effectiveness of osteotropic growth factors for humans seems very high compared to combined femoral ring allograft and autograft for anterior interbody fusion or to morselized human allograft in posterolateral fusion.Bone autograft harvesting is associated with high donor site morbidity (15-20%), even in long-term follow-up. Limited amounts of material are available in osteoporotic patients and for multilevel procedures. Bone cement, structural bone allograft, and metal spacers are viable alternaAbstract The aim of this review is to describe major approaches for stimulating bone healing and to review other factors affecting bone healing. Spinal bone fusion after surgery is a demanding process requiring optimal conditions for clinical success. Bone formation and healing can be enhanced through various methods. Experimental studies have revealed an array of stimulative measures. These include biochemical stimulation by use of hormones and growth factors, physical stimulation through mechanical and electromagnetic measures, and bone grafting by use of bone tissue or bone substitutes. Newer biological techniques such as stem cell transplantation and gene therapy can also be used to stimulate bone healing. Apart from bone transplantation, clinical experience with the many stimulation modalities is limited. Possible areas for clinical use of these novel methods are discu...

Autologous versus allogenic bone grafts in instrumented anterior cervical discectomy and fusion: a prospective study with respect to bone union pattern

“…Allografts are considered to be highly osteoconductive [20], weakly osteoinductive and non-osteogenic [13,21]. Therefore, fusion rates in allogenic grafting can be expected to be inferior to that of autologous bones.…”

Effect of Pulsed Electromagnetic Field on the Consolidation of Posterolateral Arthrodeses in the Lumbosacral Spine: A Prospective, Double-Blind, Randomized Study

“…Since that time, several studies have been conducted with PEMF with differing results, 49,50 but all favorable to the effect of PEMF. In animal models, increased mineral bone density, 51 increased bone stiffness, 22,52 and more rapid incorporation of bone grafts were observed with the use of PEMF, but no significant improvement was found in the final consolidation rate. 21,23 In a prospective, double-blind, randomized clinical study, Mooney 50 observed a bone consolidation rate of 92% in interbody lumbar arthrodesis surgeries with the use of PEMF versus 65% in the control group.…”

“…16,17 The use of autograft obtained from the site of decompression offers consolidation rates equivalent to those of iliac autografts when the arthrodesis involves one or two levels. 12,[17][18][19] Several methods are described to optimize posterior intervertebral fusion, such as electrical stimuli application, [20][21][22] the use of autologous growth factors and the use of recombinant proteins with osteoinductive potential (rhBMP). Electrical stimulation results in bone consolidation via mechanisms related to the increased activity of osteoblasts and osteocytes.…”

“…Electrical stimulation can be applied directly or indirectly, with indirect electrical stimulation being generated from a pulsed electromagnetic field (PEMF). 22 The use of a PEMF was found to be effective in studies that evaluated bone consolidation in long bone fractures, cervical interbody arthrodesis, and interbody arthrodesis associated with posterolateral lumbar arthrodesis. 2,3 This application is based on the fact that the bone tissue responds when exposed to the electrical current.…”

In vivo evaluation of a novel nanocomposite porous 3D scaffold in a rabbit model: histological analysis

“…1,7,8 Engineered bone tissue constructs ought to have two major roles when implanted in vivo: 1) they offer structural sustenance to neo tissues and 2) promote osteoinduction; these simple properties stimulate cell migration, differentiation, and osteogenesis that result in the formation of new bone. 9 In the recent years, biomaterial composites have turned out to be a viable substitute of metallic implants. These biomaterials offer many possibilities for vascular grafting and stents, fracture fixations, tendons attachments, and replacement of small bone defects.…”