No abstract

Patients with a Type A3 thoracolumbar spine fracture without neurologic deficit should be treated by short-segment posterior stabilization.

Fluorodeoxyglucose positron emission tomography has the highest diagnostic accuracy for confirming or excluding the diagnosis of chronic osteomyelitis. Leukocyte scintigraphy has an appropriate diagnostic accuracy in the peripheral skeleton, but fluorodeoxyglucose positron emission tomography is superior for detecting chronic osteomyelitis in the axial skeleton.

The discovery of bone morphogenetic proteins marks a major step forward in the understanding of bone physiology and in the development of advanced methods in skeletal surgery. The cornerstones for successful growth-factor therapy in skeletal surgery remain biomechanical stability and biological vitality of the bone providing an adequate environment for new bone formation. Knowledge of the biological characteristics, mechanisms of action, and methods of delivery of growth factors will become essential for skeletal surgeons. The current clinical application of bone morphogenetic proteins is safe and efficacious as a result of a well-regulated cascade of events leading to bone formation. Clinical trials have not yet determined whether different clinical indications each require a specific bone-tissue-engineering format or if a single pathway for stimulating bone-healing with growth factors is sufficient.

No abstract

Autologous bone grafting is currently considered the treatment of choice for correction of large bone defects. However, to avoid morbidity associated with autologous bone harvesting many artificial bone-substitute materials have been developed over the years. A new generation of resorbable materials is emerging, with promising results so far. In order to investigate the possibility to use one of these new materials as an alternative with better results than hydroxyapatite, an experimental study was performed. A new resorbable calcium phosphate particles and paste forms, the latter of which hardens in situ after application. In 28 sheep, a 3-cm segmental tibial defect was made and intramedullary fixed by an interlocking nail. Twelve weeks after defect filling, radiological, biomechanical, and histological examinations were performed. Mean radiographic and biomechanical tests results were compared with the Mann-Whitney test. Significance was set at p<0.05. Radiographically, the resorbable paste group performed better than all other groups. Biomechanical investigations showed a higher torsional stiffness (p=0.049) for the resorbable calcium-phosphate paste group in comparison with autologous bone. On histological examination, no adverse effects were observed in the calcium-phosphate groups. Resorption by osteoclasts was seen in the resorbable implants. In conclusion, the current study shows an advantageous radiological and mechanical outcome for resorbable calcium phosphates. This indicates that these new materials might be a potential alternative for autologous bone grafting in humans.

Hydroxyapatite is a synthetic bone graft, which is used for the treatment of bone defects and nonunions. However, it is a rather inert material with no or little intrinsic osteoinductive activity. Recombinant human osteogenic protein-I (rhOP-I) is a very potent biological agent. that enhances osteogenesis during bone repair. Bone niiirrow contains inesenchynial stcm cells. which are capable of new bone formation. Biosynthetic bone grafts wcrc created by the addition of rhOP-I or bone marrow to granular porous hydroxyapatite. The performancc of these grafts was tested i n ;i sheep model and compared to the results of autograft, which is clinically the standard treatment of bonc dcfccts and nonunions. A 3 cni segmental bone dcfcct was made i n the tibia and fixed with an intcrlocking intraiiiedullary nail. There were five treatment groups: i i o implant ( n =: 6). autograft ( 1 7 = 8). liydroxyapatite alone ( n = 8). liydroxyapatite loaded with rhOP-I ( i i = 8). and hydroxyapatite loaded with autologous bone marrow ( n = 8). At 12 weeks, healing of the dcfcct was evaluated with radiographs, a torsional test to F~ilure, and histological examination of longitudinal sections through the defect. Torsional strength and stillness of the healing tibiae were about two to three times higher for autograft and hydroxyapatite plus rhOP-I or bone niiirrow compared to hydroxyapatite alone and empty defects. The mean values of both combination groups werc comparable t o those of autograft. Thew wcre more unions in defects with hydroxyapatite plus rhOP-l than in defects with hydroxyapatite alone. Although the diflcrences were not significant, histological examination revealed that there was inore oftcn bony bridging of the defect in both combination groups and the autograft group than in the group with hydroxyapatite alone. Healing of bone defects. treated with poroiis hydroxyapatite. can be enhanced by thc addition of rhOP-l or autologous bone marrow. The results of these composite biosynthctic grafts are equivalent to those of autograft.

Plain radiography provides poor parameters for monitoring the fracture healing process.