Molecular profiling of chordoma.

The molecular basis of chordoma is still poorly understood, particularly with respect to differentially expressed genes involved in the primary origin of chordoma. In this study, therefore, we compared the transcriptional expression profile of one sacral chordoma recurrence, two chordoma cell lines (U-CH1 and U-CH2) and one chondrosarcoma cell line (U-CS2) with vertebral disc using a high-density oligonucleotide array. The expression of 65 genes whose mRNA levels differed significantly (p<0.001; ≥6-fold change) between chordoma and control (vertebral disc) was identified. Genes with increased expression in chordoma compared to control and chondrosarcoma were most frequently located on chromosomes 2 (11%), 5 (8%), 1 and 7 (each 6%), whereas interphase cytogenetics of 33 chordomas demonstrated gains of chromosomal material most prevalent on 7q (42%), 12q (21%), 17q (21%), 20q (27%) and 22q (21%). The microarray data were confirmed for selected genes by quantitative polymerase chain reaction analysis. As in other studies, we showed the expression of brachyury. We demonstrate the expression of new potential candidates for chordoma tumorigenesis, such as CD24, ECRG4, RARRES2, IGFBP2, RAP1, HAI2, RAB38, osteopontin, GalNAc-T3, VAMP8 and others. Thus, we identified and validated a set of interesting candidate genes whose differential expression likely plays a role in chordoma.

Biomechanical in vitro comparison of different mono- and bisegmental anterior procedures with regard to the strategy for fracture stabilisation using minimally invasive techniques.

Endoscopic minimally invasive techniques have become an established method of fracture stabilisation in the spine. In view of this fact, anterior stabilisation strategies must be reconsidered, as monosegmental A 3.1 compression fractures are increasingly being stabilised endoscopically from the anterior aspect using minimally invasive techniques. This study investigated the biomechanical necessity of anterior two-point or four-point stabilisation in the instrumentation of mono- and bisegmental fractures. In three biomechanical in vitro studies, burst fracture stabilisation was simulated, and anterior short fixation devices were tested under load with pure moments up to 3.75 Nm to evaluate the biomechanical stabilising characteristics of different kinds of instrumentations in flexion/extension, lateral bending, and axial rotation. Only anterior four-point stabilisation resulted in sufficient primary stability both in mono- and bisegmental instrumentation and therefore represents the standard procedure in open as well as in minimally invasive spinal surgery.

Bone formation in a long bone defect model using a platelet-rich plasma-loaded collagen scaffold.

Platelet-rich plasma (PRP), a platelet concentrate made of autogenous blood, has been used in recent years to improve bone defect healing particularly in maxillofacial reconstructions. The aim of the present study was to assess the effect of PRP on new bone formation in a critical diaphyseal long bone defect. A critical size defect (2.5 cm) in the tibial diaphysis of 16 sheep was supplied either with autogenous PRP in a collagen carrier or with collagen alone (controls). Platelets were enriched about 3.5 fold compared to normal blood in the PRP. After 12 weeks, the explanted bone specimens were quantitatively assessed by X-ray, computed tomography (CT), biomechanical testing and histological evaluation. Bone volume, mineral density, mechanical rigidity and histology of the newly formed bone in the defect did not differ significantly between the PRP treated and the control group, and no effect of PRP upon bone formation was observed. It was suggested that PRP does not enhance new bone formation in a critical size defect with a low regenerative potential. Such bone defects might require more potent stimuli, e.g. combinations of functional biomaterials or autografts, precursor cells or osteoinductive growth factors.

Solvent-preserved, bovine cancellous bone blocks used for reconstruction of thoracolumbar fractures in minimally invasive spinal surgery-first clinical results.

We investigated the osseointegration of solvent-preserved, xenogenous cancellous bone blocks in the treatment of unstable fractures of the thoracolumbar junction. In 22 patients, the anterior repair procedure was performed by thoracoscopy or minimally invasive retroperitoneal surgery. Twenty-two patients had undergone monosegmental anterior fusion and were surveyed prospectively. Solvent-preserved, bovine cancellous bone blocks were used in 11 patients; iliac crest bone graft was used in the others. Follow-up after 12 months included CT scans, which revealed successful osseointegration in eight out of 11 patients who had received autogenous iliac crest bone grafts, while three patients showed a partial integration. There were no graft fragmentations. In patients who had received solvent-preserved, xenogenous cancellous bone blocks, complete osseointegration was achieved at the graft-bone interface in only two out of 11 cases, after 1 year. Partial integration was found in three patients. In view of these results, autogenous iliac crest bone grafts are still the unrivalled standard for defect repair in spinal surgery.

Buruli ulcer: a systemic disease.

We studied a 4-year-old boy from Angola who presented with 2 cutaneous ulcerations of the right hip and osteomyelitis of the left knee and right ankle. Mycobacterium ulcerans disease was confirmed by direct smear examination and by polymerase chain reaction. The patient was treated with antimycobacterial drugs, repeated surgical debridement, skin grafting, and daily hyperbaric oxygenation. Despite significant improvement of the local lesions in response to hyperbaric oxygenation, swelling of the right knee, without associated skin lesions, was noted. Radiological evaluation and open biopsy revealed extensive metaphyseal osteomyelitis of the right distal femur. A 99technetium bone scan revealed an additional focus in the diaphysis of the left humerus, without soft-tissue involvement. This case documents, for the first time (to our knowledge), the systemic spread of M. ulcerans, with subsequent multifocal osteomyelitis and secondary involvement of soft tissues and supports the hypothesis that low tissue oxygen levels promote hematogenous spread of M. ulcerans. Sickle cell anemia, with associated microthrombosis and microinfarction, may have contributed to tissue hypoxia.

A scanning electron microscopy study of human osteoblast morphology on five orthopedic metals.

Despite the long-standing use of metals as orthopedic implants there still are unsolved problems with these materials and open questions about their behavior in a biological environment. Cell-culture studies provide a useful tool for investigations. In addition to the determination of biochemical or molecular biological parameters, the morphology of adhering cells reflects their interaction with the substrata. This article describes an investigation of the morphology of human osteoblasts on stainless steel, cobalt chromium alloy, commercially pure titanium, Ti-6Al-4V, and Ti-6Al-7Nb with surface designs similar to those used as clinical implants. A cell culture plastic surface was used as a control material. The materials were examined by scanning electron microscopy at different points of time. The cells spread, proliferated, and formed nodules on all test substrates in a time-dependent manner, without signs of a disturbing influence from any of the materials. On the smooth surfaces the cells showed a flattened fibroblast-like morphology and only slight differences could be detected. Therefore, the cellular morphology seems not to be markedly affected by the different chemical material compositions. In contrast, the titanium alloy with a rough, sandblasted surface induced a three-dimensional growth. This three-dimensional cellular network could be the basis for the known earlier differentiation of osteoblasts on rough surfaces in vitro and a better osseointegration in vivo.

Biomechanische Untersuchungsergebnisse über die verbesserte Verankerung von Pedikelschrauben mit resorbierbarem / 华中科技大学学报（医学）（英德文版）

Die Prim?rstabilit?t von Pedikelschrauben im Knochen h?ngt in hohem Masse von der Knochendichte ab. Die Augmentation mit Zement ist ein klinisch einsetzbares Verfahren, um die Schrauben-Verankerung im osteoporotischen Knochen zu verbessern.In dieser Studie wurde eine neuartiges resorbierbares Knochenersatzmaterial (α-BSMTM) für diese Augmentation benutzt. Biomechanische Testungen wurden in vitro bei 16 Lendwirbelkorpern (L3-L5) aus 6 Individuen(75,2±13,7 Jahre) durchgeführt. Vor der biomechanischen Testung wurde bei allen Pr?paraten die trabekul?re Knochendichte mittels pQCT gemessen und beide Pedikel mit USS-Pedikelschrauben (5,0 mm × 45 mm) besetzt, von welchen eine mit α-BSMTM augmentiert war. Beim axialen Auszugstest wurden die maximale axiale Auszugskraft (F-max) sowie die Energieaufnahme bestimmt. Der Medianwert der F-max stieg beim Auszugstest durch die Zementierung mit α-BSMTM um 80 % von 370 N (ohne Zement) auf 665 N (mit Zement). Die Energieaufnahme bis zum Erreichen der F-max (E-F-max) und bei Dislokation bis 2,0 mm (E-2 mm) steigerte sich ebenfalls um 83 % und 68 %. Die Unterschiede waren signifikant. (Wilcoxon′s-Test, P<0,01) Die Ausreisskrafte F-max (ohne oder mit Zement) korrelierten eng mit der Knochendichte (r=0,9056 und r=0,9585). Unsere Resultate zeigen, da eine Augmentation mit dem α-BSMTM die prim?re Stabilit?t von Pedikelschrauben verbessern kann. Der Effekt scheint auf einer Optimierung der Kontaktfl?che und einer Aussteifung der schraubennahen Spongiosa zu beruhen. Das Material konnte geeignet sein, die Verankerung von Pedikelschrauben bei osteoporotischen Patieten zu verbessern.

Biomechanische Untersuchungsergebnisse über die verbesserte Verankerung von Pedikelschrauben mit resorbierbarem / 华中科技大学学报（医学）（英德文版）

Die Prim?rstabilit?t von Pedikelschrauben im Knochen h?ngt in hohem Masse von der Knochendichte ab. Die Augmentation mit Zement ist ein klinisch einsetzbares Verfahren, um die Schrauben-Verankerung im osteoporotischen Knochen zu verbessern.In dieser Studie wurde eine neuartiges resorbierbares Knochenersatzmaterial (α-BSMTM) für diese Augmentation benutzt. Biomechanische Testungen wurden in vitro bei 16 Lendwirbelkorpern (L3-L5) aus 6 Individuen(75,2±13,7 Jahre) durchgeführt. Vor der biomechanischen Testung wurde bei allen Pr?paraten die trabekul?re Knochendichte mittels pQCT gemessen und beide Pedikel mit USS-Pedikelschrauben (5,0 mm × 45 mm) besetzt, von welchen eine mit α-BSMTM augmentiert war. Beim axialen Auszugstest wurden die maximale axiale Auszugskraft (F-max) sowie die Energieaufnahme bestimmt. Der Medianwert der F-max stieg beim Auszugstest durch die Zementierung mit α-BSMTM um 80 % von 370 N (ohne Zement) auf 665 N (mit Zement). Die Energieaufnahme bis zum Erreichen der F-max (E-F-max) und bei Dislokation bis 2,0 mm (E-2 mm) steigerte sich ebenfalls um 83 % und 68 %. Die Unterschiede waren signifikant. (Wilcoxon′s-Test, P<0,01) Die Ausreisskrafte F-max (ohne oder mit Zement) korrelierten eng mit der Knochendichte (r=0,9056 und r=0,9585). Unsere Resultate zeigen, da eine Augmentation mit dem α-BSMTM die prim?re Stabilit?t von Pedikelschrauben verbessern kann. Der Effekt scheint auf einer Optimierung der Kontaktfl?che und einer Aussteifung der schraubennahen Spongiosa zu beruhen. Das Material konnte geeignet sein, die Verankerung von Pedikelschrauben bei osteoporotischen Patieten zu verbessern.