Due to well-known disadvantages of the autologous bone graft, many alternatives have been studied for a reliable spinal fusion. Herein, we aimed to investigate the effects of human recombinant epidermal growth factor (EGF) on posterolateral lumbar fusion in a rat model. 36 male SD rats underwent posterolateral fusion at L4-5 level. They were randomly assigned to 3 groups: Sham control group, Hydoxyapatite β-tricalcium phosphate (HA/β-TCP) group and HA/β-TCP + EGF group. Rats were euthanized at 8 weeks post-surgery. 6 rats from each group were selected for manual palpation examination, micro-computed tomography analysis and histologic analysis; and the rest was used for biomechanical analysis. Based on manual palpation, there was no fusion in the sham control group. Fusion rate was 33.3% in the HA/β-TCP group and 66.7% in the HA/β-TCP + EGF group (p=0.085). Micro-CT results revealed that new bone formation was higher in the HA/β-TCP + EGF group (BV/TV: 40% vs. 65%) (p=0.004). Histologically newly formed bone tissue was more pronounced in the EGF group and compacted and bridging bone spicules were observed. The median maximum bending moment values were 0.51 Nmm (0.42– 0.59), 0.73 Nmm (0.49– 0.88) and 0.91 Nmm (0.66– 1.03) in the sham control, HA/β-TCP and HA/β-TCP + EGF groups, respectively (p=0.013). The median stiffness values were 1.69 N/mm (1.12–2.18), 1.68 N/mm (1.13–2.74) and 3.10 N/mm (1.66–4.40) as in the previous order (p=0.087). This study demonstrates that EGF enhances posterolateral lumbar fusion in the rat model. EGF in combination with ceramic grafts increased the fusion rates

Background context

Fusion is a fundamental procedure in spine surgery. Although autogenous grafts have ideal bone graft characteristics, their use may remain limited due to various morbidities. Even though ceramic based synthetic bone grafts are used commonly at present, in order to enhance their efficacy, their combined use with other materials has been investigated. The use of carbon nanotubes (CNTs) together with synthetic bone grafts such as hydroxyapatite (HA) has contributed to positive developments in bone tissue engineering.

Background. Posterolateral fusion (PLF) is a commonly accepted surgical procedure and overall the most common technique performed to obtain fusion in the lumbar spine. Harvesting autologous bone from the iliac crest is associated with increased operation time, blood loss, and chronic donor site pain. Allograft material has an insufficient osteoinductive potential. Bone marrow concentrate (BMC) could be an option how to promote allograft PLF healing. The purpose of the presented study was to investigate the validity of BMC addition to allografts in instrumented lumbar PLF surgery. Methods. The study was prospective, randomised, controlled and blinded. Eighty patients with degenerative disease of the lumbar spine underwent instrumented (S. 4. , Aesculap, Tuttlingen, Germany) lumbar or lumbosacral PLF. In forty cases, the PLF was done with spongious allograft chips alone (Group I). In another forty cases, spongious allograft chips were mixed with BMC (Group II), where the mesenchymal stem cell (MSCs) concentration was 1.74 × 10. 4. /L at average (range, 1.06–1.98 × 10. 4. /L). Patients were scheduled for anteroposterior and lateral radiographs at 12 and 24 months after the surgery and for CT scanning at 24 months after the surgery. Fusion status and the degree of mineralization of the fusion mass were evaluated separately by two radiologists blinded to patient group affiliation. Results. In Group I at 12 months, the bone graft mass was assessed in X-rays as fused in no case (0 %) and at 24 months in 4 cases (10 %). In Group II, 6 cases (15 %) achieved fusion at 12 months and 14 cases (35 %) at 24 months. The statistically significant difference between both groups was proven for complete fusion at 12 months (p = 0.041) and at 24 months (p = 0.011), too. CT scans showed that 16 cases (40 %) in Group I and 32 cases (80 %) in Group II had evidence of at least unilateral continuous bridging bone between neighboring vertebrae at 24 months (p < 0.05). We have confirmed the hypothesis that the autologous BMC together with the allograft is a better alternative for the PLF than the allograft alone. Conclusions. The use of autologous MSCs in form of the BMC in combination with allograft is an effective option how to enhance the PLF healing. Allograft by itself is not an effective material as a posterior onlay graft for the PLF in adult surgery

Aternatives to autogenous bone graft for spinal fusion have been investigated for many years. It has been shown that osteoconductive materials alone do not give a rate of fusion which is comparable to that of autogenous bone graft. We analysed the effectiveness of porous ceramic loaded with cultured mesenchymal stem cells as a new graft material for spinal fusion in an animal model. Posterolateral fusion was carried out at the L4/L5 level in 40 White New Zealand rabbits using one of the following graft materials: porous ceramic granules plus cultured mesenchymal stem cells (group I); ceramic granules plus fresh autogenous bone marrow (group II); ceramic granules alone (group III); and autogenous bone graft (group IV). The animals were killed eight weeks after surgery and the spines were evaluated radiographically, by a manual palpation test and by histological analysis. The rate of fusion was significantly higher in group I compared with group III and higher, but not significantly, in group I compared with groups II and IV. In group I histological analysis showed newly formed bone in contact with the implanted granules and highly cellular bone marrow between the newly formed trabecular bone. In group II, thin trabeculae of newly formed bone were present in the peripheral portion of the fusion mass. In group III, there was a reduced mount of newly formed bone and abundant fibrous tissue. In group IV, there were thin trabeculae of newly formed bone close to the decorticated transverse processes and dead trabecular bone in the central portion of the fusion mass. In vitro cultured mesenchymal stem cells may be loaded into porous ceramic to make a graft material for spinal fusion which appears to be more effective than porous ceramic alone. Further studies are needed to investigate the medium- to long-term results of this procedure, its feasibility in the clinical setting and the most appropriate carrier for mesenchymal stem cells