Calcium phosphate ceramics combined with rhBMP6 within autologous blood coagulum promote posterolateral lumbar fusion in sheep.

Posterolateral spinal fusion (PLF) is a procedure used for the treatment of degenerative spine disease. In this study we evaluated Osteogrow-C, a novel osteoinductive device comprised of recombinant human Bone morphogenetic protein 6 (rhBMP6) dispersed in autologous blood coagulum with synthetic ceramic particles, in the sheep PLF model. Osteogrow-C implants containing 74-420 or 1000-1700 µm ceramic particles (TCP/HA 80/20) were implanted between L4-L5 transverse processes in sheep (Ovis Aries, Merinolaandschaf breed). In the first experiment (n = 9 sheep; rhBMP6 dose 800 µg) the follow-up period was 27 weeks while in the second experiment (n = 12 sheep; rhBMP6 dose 500 µg) spinal fusion was assessed by in vivo CT after 9 weeks and at the end of the experiment after 14 (n = 6 sheep) and 40 (n = 6 sheep) weeks. Methods of evaluation included microCT, histological analyses and biomechanical testing. Osteogrow-C implants containing both 74-420 and 1000-1700 µm ceramic particles induced radiographic solid fusion 9 weeks following implantation. Ex-vivo microCT and histological analyses revealed complete osseointegration of newly formed bone with adjacent transverse processes. Biomechanical testing confirmed that fusion between transverse processes was complete and successful. Osteogrow-C implants induced spinal fusion in sheep PLF model and therefore represent a novel therapeutic solution for patients with degenerative disc disease.

Long-term posterolateral spinal fusion in rabbits induced by rhBMP6 applied in autologous blood coagulum with synthetic ceramics.

Autologous bone graft substitute (ABGS) containing rhBMP6 in autologous blood coagulum (Osteogrow) is a novel therapeutic solution for bone regeneration. This study is aimed to investigate the long-term outcome of ABGS with synthetic ceramics (Osteogrow-C) in rabbit posterolateral spinal fusion (PLF) model. Osteogrow-C implants were implanted bilaterally between rabbit lumbar transverse processes. We compared the outcome following implantation of ABGS with ceramic particles of different chemical composition (TCP and biphasic ceramics containing both TCP and HA) and size (500-1700 µm and 74-420 µm). Outcome was analyzed after 14 and 27 weeks by microCT, histology, and biomechanical analyses. Successful bilateral spinal fusion was observed in all animals at the end of observation period. Chemical composition of ceramic particles has impact on the PLF outcome via resorption of TCP ceramics, while ceramics containing HA were only partially resorbed. Moreover, persistence of ceramic particles subsequently resulted with an increased bone volume in implants with small particles containing high proportion of HA. ABGS (rhBMP6/ABC) with various synthetic ceramic particles promoted spinal fusion in rabbits. This is the first presentation of BMP-mediated ectopic bone formation in rabbit PLF model with radiological, histological, and biomechanical features over a time course of up to 27 weeks.

A novel autologous bone graft substitute containing rhBMP6 in autologous blood coagulum with synthetic ceramics for reconstruction of a large humerus segmental gunshot defect in a dog: The first veterinary patient to receive a novel osteoinductive therapy.

BACKGROUND: Management of large segmental defects is one of the most challenging issues in bone repair biology. Autologous bone graft substitute (ABGS) containing rhBMP6 within autologous blood coagulum (ABC) with synthetic ceramics is a novel biocompatible therapeutic solution for bone regeneration. CASE PRESENTATION: A 2-year old dog was brought to the veterinary clinics due to pain and bleeding from the right front leg after being unintendedly hit by a gunshot. Radiological examination revealed a large, 3 cm long multisegmental defect of the humerus on the right front leg with a loss of anatomical structure in the distal portion of the bone. The defect was treated surgically and an external fixator was inserted to ensure immobilization. Complete lack of bone formation 3 months following surgery required a full reconstruction of the defect site with a novel ABGS (rhBMP6 in ABC with ceramic particles) to avoid front leg amputation. The healing was then followed for the next 16 months. The callus formation was observed on x-ray images 2 months following ABGS implantation. The bone segments progressively fused together leading to the defect rebridgment allowing removal of the external fixator by 4 months after the reconstruction surgery. At the end of the observation period, the function of the leg was almost fully restored while analyses of the humeral CT sections revealed restoration and cortices rebridgment with a renewal of uniform medullary canal including structural reconstruction of the distal humerus. CONCLUSION: This large humeral gunshot segmental defect of the front leg in a dog was saved from amputation via inducing bone regeneration using a novel ABGS osteoinductive device containing BMP6 in ABC.

Distribution of coolant during drilling with open type internally cooled medical steel drill.

INTRODUCTION: Internally cooled bone drills with an open system, conduct coolant directly to the point of contact of cutting surface of the drill and the bone and lower the temperature at the drilling site. During bone drilling with internally cooled drills of open type, there is a possibility that coolant enters the intramedullary canal and has an adverse effect on intramedullary pressure. In this research, the intramedullary distribution of the coolant during and after drilling was analyzed. MATERIALS AND METHODS: Specially constructed open type internally cooled medical steel drills were used. Experimental studies were conducted on the porcine femoral bone diaphysis. Coolant (saline) was mixed with water-soluble contrast agent and x-ray images of the distribution of coolant during and after drilling were taken with different regimes of drilling (drill rotational speed from 1300 rpm to 5000 rpm, and coolant flow rate from 0,6 l/min to 1,35 l/min). RESULTS: An x-ray images showed that coolant did not spread from the borehole and has not spread intramedullary with any combination of coolant flow and drill rotation regimes. CONCLUSION: Coolant does not disperse into the intramedullary canal outside of the borehole in given flow ranges (0,6-1,35 l/min) and drill rotational speed regimes (1300-5000 rpm). Open type internally cooled can safely be used for bone drilling.

Evaluation of synthetic ceramics as compression resistant matrix to promote osteogenesis of autologous blood coagulum containing recombinant human bone morphogenetic protein 6 in rabbit posterolateral lumbar fusion model.

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.

Autologous blood coagulum containing rhBMP6 induces new bone formation to promote anterior lumbar interbody fusion (ALIF) and posterolateral lumbar fusion (PLF) of spine in sheep.

In the present study, we evaluated an autologous bone graft substitute (ABGS) composed of recombinant human BMP6 (rhBMP6) dispersed within autologous blood coagulum (ABC) used as a physiological carrier for new bone formation in spine fusion sheep models. The application of ABGS included cervical cage for use in the anterior lumbar interbody fusion (ALIF), while for the posterolateral lumbar fusion (PLF) sheep model allograft devitalized bone particles (ALLO) were applied with and without use of instrumentation. In the ALIF model, ABGS (rhBMP6/ABC/cage) implants fused significantly when placed in between the L4-L5 vertebrae as compared to control (ABC/cage) which appears to have a fibrocartilaginous gap, as examined by histology and micro CT analysis at 16 weeks following surgery. In the PLF model, ABGS implants with or without ALLO showed a complete fusion when placed ectopically in the gutter bilaterally between two decorticated L4-L5 transverse processes at a success rate of 88% without instrumentation and at 80% with instrumentation; however the bone volume was 50% lower in the instrumentation group than without, as examined by histology, radiographs, micro CT analyses and biomechanical testing at 27 weeks following surgery. The newly formed bone was uniform within ABGS implants resulting in a biomechanically competent and histologically qualified fusion with an optimum dose in the range of 100 µg rhBMP6 per mL ABC, while in the implants that contained ALLO, the mineralized bone particles were substituted by the newly formed remodeling bone via creeping substitution. These findings demonstrate for the first time that ABGS (rhBMP6/ABC) without and with ALLO particles induced a robust bone formation with a successful fusion in sheep models of ALIF and PLF, and that autologous blood coagulum (ABC) can serve as a preferred physiological native carrier to induce new bone at low doses of rhBMP6 and to achieve a successful spinal fusion.

Autologous blood coagulum is a physiological carrier for BMP6 to induce new bone formation and promote posterolateral lumbar spine fusion in rabbits.

In the present study, we describe autologous blood coagulum (ABC) as a physiological carrier for BMP6 to induce new bone formation. Recombinant human BMP6 (rhBMP6), dispersed within ABC and formed as an autologous bone graft substitute (ABGS), was evaluated either with or without allograft bone particles (ALLO) in rat subcutaneous implants and in a posterolateral lumbar fusion (PLF) model in rabbits. ABGS induced endochondral bone differentiation in rat subcutaneous implants. Coating ALLO by ABC significantly decreased the formation of multinucleated foreign body giant cells (FBGCs) in implants, as compared with ALLO alone. However, addition of rhBMP6 to ABC/ALLO induced a robust endochondral bone formation with little or no FBGCs in the implant. In rabbit PLF model, ABGS induced new bone formation uniformly within the implant resulting in a complete fusion when placed between two lumbar transverse processes in the posterolateral gutter with an optimum dose of 100-µg rhBMP6 per ml of ABC. ABGS containing ALLO also resulted in a fusion where the ALLO was replaced by the newly formed bone via creeping substitution. Our findings demonstrate for the first time that rhBMP6, with ABC as a carrier, induced a robust bone formation with a complete spinal fusion in a rabbit PLF model. RhBMP6 was effective at low doses with ABC serving as a physiological substratum providing a permissive environment by protecting against foreign body reaction elicited by ALLO.

Recombinant Human Bone Morphogenetic Protein 6 Delivered Within Autologous Blood Coagulum Restores Critical Size Segmental Defects of Ulna in Rabbits.

BMP2 and BMP7, which use bovine Achilles tendon-derived absorbable collagen sponge and bovine bone collagen as scaffold, respectively, have been approved as bone graft substitutes for orthopedic and dental indications. Here, we describe an osteoinductive autologous bone graft substitute (ABGS) that contains recombinant human BMP6 (rhBMP6) dispersed within autologous blood coagulum (ABC) scaffold. The ABGS is created as an injectable or implantable coagulum gel with rhBMP6 binding tightly to plasma proteins within fibrin meshwork, as examined by dot-blot assays, and is released slowly as an intact protein over 6 to 8 days, as assessed by ELISA. The biological activity of ABGS was examined in vivo in rats (Rattus norvegicus) and rabbits (Oryctolagus cuniculus). In a rat subcutaneous implant assay, ABGS induced endochondral bone formation, as observed by histology and micro-CT analyses. In the rabbit ulna segmental defect model, a reproducible and robust bone formation with complete bridging and restoration of the defect was observed, which is dose dependent, as determined by radiographs, micro-CT, and histological analyses. In ABGS, ABC scaffold provides a permissive environment for bone induction and contributes to the use of lower doses of rhBMP6 compared with BMP7 in bovine bone collagen as scaffold. The newly formed bone undergoes remodeling and establishes cortices uniformly that is restricted to implant site by bridging with host bone. In summary, ABC carrier containing rhBMP6 may serve as an osteoinductive autologous bone graft substitute for several orthopedic applications that include delayed and nonunion fractures, anterior and posterior lumbar interbody fusion, trauma, and nonunions associated with neurofibromatosis type I.

Metal projectile injuries in cats: review of 65 cases (2012-2014).

OBJECTIVES: The objective of this study was to compare the prevalence of different types of injuries caused by various types of projectiles among urban, suburban and rural cats of different ages in order to predict the type of injury sustained. METHODS: For the period 1 January 2012 to 30 April 2014, the medical records of cats with metal projectile injuries (PIs) were searched from the archive of the university's small animal diagnostic imaging centre. Age, sex, owner address, admission during a weekend or on a working day, month of admission, projectile position (head and neck; thoracic region; abdominal region, including lumbosacral spine; forelimbs; and hindlimbs, including tail), number of projectiles, presence of a wound and fracture related to the projectile, and the type of projectile were recorded for each cat. RESULTS: Sixty-five cats with PIs were admitted during the defined period. In 38.5% of cats the projectiles found upon radiography were incidental findings. The frequency of PIs peaked in March. Airgun projectiles were found in 80.0% of the cats. PIs in two or more body regions were found in 29.2% of the cats. Among the cats that had only been shot in one body region, the projectile was most frequently found in the abdominal region, including the lumbosacral spine (41.3%). CONCLUSIONS AND RELEVANCE: These results might prompt clinicians to evaluate closely and screen for feline PIs in emergency situations.

Review of 166 Gunshot Injury Cases in Dogs.

The study is aimed to establish predilection signalment and history data, and to investigate clinical findings and risk factors associated with a poor outcome in dogs with projectile injuries. A retrospective study was undertaken of 166 canine cases in which a projectile was found on radiograph in a university׳s diagnostic imaging center more than a 4-year period. The study included dogs with both apparent (obvious recent traumatic event) and incidental (traumatic event unknown to the owner) projectile injury. Radiographs were reviewed and data regarding projectile position according to body region, number and type of projectile(s), bone fracture(s), and wound(s) related to projectile were recorded. The dogs were divided into groups according to owner address, hunting accident vs. shooting unrelated to hunting, and projectile type found on radiographs. Overall, 160 dogs met the inclusion criteria, making 0.76% the incidence of gunshot injuries. Further, 91 dogs were received with incidental projectile injury, and 75 dogs had apparent projectile injury. Male dogs were overrepresented (74.1%). Hunting accidents were the cause of projectile injury in 12.7% of cases. Fractures were observed in 20.5% of dogs. Most of the dogs (62%) were from an urban area, and the most common projectile type was airgun projectile (62%). The risk of fatal outcome was 14.4 times higher in dogs with thoracic injuries. Projectile injuries are still a real cause of trauma, especially in urban areas and in male dogs. Most gunshot injuries do not cause fatalities, although the thoracic projectile injury was associated with a greater fatality risk.