Laboratory for Mineralized Tissues, School of Medicine, University of Zagreb, Zagreb, Croatia; Scientific Center of Excellence for Reproductive and Regenerative Medicine, Zagreb, Croatia.
Clinics for Surgery, Orthopedics and Ophthalmology, School of Veterinary Medicine, University of Zagreb, Zagreb, Croatia.
Bone. 2020 Nov;140:115544. doi: 10.1016/j.bone.2020.115544. Epub 2020 Jul 27.
Posterolateral lumbar fusion (PLF) is a commonly performed surgical procedure for the treatment of pathological conditions of the lumbosacral spine. In the present study, we evaluated an autologous bone graft substitute (ABGS) containing rhBMP6 in autologous blood coagulum (ABC) and synthetic ceramics used as compression resistant matrix (CRM) in the rabbit PLF model. In the pilot PLF rabbit experiment, we tested four different CRMs (BCP 500-1700 μm, BCP 1700-2500 μm and two different TCP in the form of slabs) which were selected based on achieving uniform ABC distribution. Next, ABGS implants composed of 2.5 mL ABC with 0.5 g ceramic particles (TCP or BCP (TCP/HA 80/20) of particle size 500-1700 μm) and 125 μg rhBMP6 (added to blood or lyophilized on ceramics) were placed bilaterally between transverse processes of the lumbar vertebrae (L5-L6) following exposition and decortication in 12 New Zealand White Rabbits observed for 7 weeks following surgery. Spinal fusion outcome was analysed by μCT, palpatory segmental mobility testing and selected specimens were either tested biomechanically (three-point bending test) and/or processed histologically. The total fusion success rate was 90.9% by both μCT analyses and by palpatory segmental mobility testing. The volume of newly formed bone between experimental groups with TCP or BCP ceramics and the different method of rhBMP6 application was comparable. The newly formed bone and ceramic particles integrated with the transverse processes on histological sections resulting in superior biomechanical properties. The results were retrospectively found superior to allograft devitalized mineralized bone as a CRM as reported previously in rabbit PLF. Overall, this novel ABGS containing rhBMP6, ABC and the specific 500-1700 μm synthetic ceramic particles supported new bone formation for the first time and successfully promoted posterolateral lumbar fusion in rabbits.
后路腰椎融合术（PLF）是治疗腰骶脊柱病变的常用手术方法。在本研究中，我们评估了一种含有 rhBMP6 的自体骨移植物替代物（ABGS），其与自体血凝块（ABC）和合成陶瓷一起用作抗压基质（CRM），用于兔 PLF 模型。在初步的 PLF 兔实验中，我们测试了四种不同的 CRM（BCP 500-1700μm、BCP 1700-2500μm 和两种不同形式的 TCP 平板），这些 CRM 是基于实现均匀 ABC 分布选择的。接下来，ABGS 植入物由 2.5mL 的 ABC 与 0.5g 陶瓷颗粒（TCP 或 BCP（TCP/HA 80/20）粒径为 500-1700μm）和 125μg rhBMP6（添加到血液或冻干在陶瓷上）组成，在 12 只新西兰白兔的腰椎（L5-L6）的横突之间双侧放置，在手术后 7 周内进行手术暴露和去皮质化。通过 μCT、触诊节段活动性测试分析脊柱融合结果，并对选定的标本进行生物力学测试（三点弯曲测试）和/或组织学处理。通过 μCT 分析和触诊节段活动性测试，总融合成功率均为 90.9%。在实验组中，TCP 或 BCP 陶瓷与不同 rhBMP6 应用方法之间的新骨形成体积相当。在组织学切片上，新形成的骨和陶瓷颗粒与横突结合，产生了更好的生物力学性能。与先前报道的兔 PLF 中同种异体脱钙骨的结果相比，这些结果被认为更好。总的来说，这种新型 ABGS 含有 rhBMP6、ABC 和特定的 500-1700μm 合成陶瓷颗粒，首次支持新骨形成，并成功促进了兔后路腰椎融合。
