We have reported that most of lower cervical cord injury patients had either improved or remained the same neurology following early operative stabilization done in our hospital. However, a few patients deteriorated with ascending paralysis in acute stage. Purpose of this paper is to present such cases and discuss the outcomes.

Methods: 1) We have analyzed 10 pts of acute lower cervical cord injury who had deteriorated neurologic symptom ascending above C4 and complicated with respiratory quadriplegia. They accounted for 3.7 % out of 271 patients with bony injury. 2) They were 8 males and 2 females, aged 17~76, injury type C5/6 fracture-dislocation (Fx/Dx) in 4, C6/7 Fx/Dx in 4, C7/T1 in 1, and one C5 flexion tear drop Fx. 3) 2 patients were treated conservatively and 8 had operative reduction and fusion with careful technique.

Results: 1) All patients had complete quadriplegia. 2) 3 pts could not wean out of ventilator and other 2 of them eventually died. 3) Paralysis started to ascend in 3 days after injury needed ventilator in 24 hours thereafter. 4) 2 out of 10 patients underwent an excessive distraction being treated conservatively. 8 patients had operative fixation for bony injuries, 7 of them obtained solid spine with single operation, but one had redislocated in a few days after the operation and received restabilisation surgery.

Conclusion: 1) There are a few patients of acute lower cervical injury with complete quadriplegia deteriorated neurology ascending paralysis with respiratory distress. 2) Comparing to other cases an operative treatment would not a cause of such neurologic deterioration. 3) In most cases paralysis of diaphragm was passing symptom, but quite a few patients(1%) could not wean off ventilator. 4) Cause of ascending paralysis in such injury could not be identified definitely, therefore careful observation and prompt treatment such as tracheotomy should be recommended.

Using in situ hybridisation and the terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick end-labelling (TUNEL) reaction in rats with osteonecrosis of the femoral head we have studied the effect of ischaemia on the gene expression of the stress proteins oxygen-regulated protein 150 (ORP150) and haemoxygenase 1 (HO1) and the death mechanism of the cells involved in osteonecrosis. Both ORP150 and HO1 have been reported to have important roles in the successful adaptation to oxygen deprivation.

ORP150 and HO1 mRNA expression was induced by ischaemia in osteoblasts and osteocytes. In proliferative chondrocytes, these signals were detected constitutively. During the development of ischaemic osteonecrosis, the mechanism of cell death was apoptosis as indicated by DNA fragmentation and the presence of apoptotic bodies in osteocytes, chondrocytes and bone-marrow cells. After the initial ischaemic event, expression of ORP150 and HO1 mRNA, the TUNEL-positive reaction and empty lacunae were found sequentially. These findings were exclusive and may be considered to be markers for each stage in the development of osteonecrosis.

We developed a rat model of limb lengthening to study the basic mechanism of distraction osteogenesis, using a small monolateral external fixator. In 11-week-old male rats we performed a subperiosteal osteotomy in the midshaft of the femur with distraction at 0.25 mm every 12 hours from seven days after operation.

Radiological and histological examinations showed a growth zone of constant thickness in the middle of the lengthened segment, with formation of new bone at its proximal and distal ends.

Osteogenic cells were arranged longitudinally along the tension vector showing the origin and the fate of individual cells in a single section. Typical endochondral bone formation was prominent in the early stage of distraction, but intramembraneous bone formation became the predominant mechanism of ossification at later stages. We also showed a third mechanism of ossification, ‘transchondroid bone formation’. Chondroid bone, a tissue intermediate between bone and cartilage, was formed directly by chondrocyte-like cells, with transition from fibrous tissue to bone occurring gradually and consecutively without capillary invasion.

In situ hybridisation using digoxigenin-11-UTP-labelled complementary RNAs showed that the chondroid bone cells temporarily expressed type-II collagen mRNA. They did not show the classical morphological characteristics of chondrocytes, but were assumed to be young chondrocytes undergoing further differentiation into bone-forming cells.

We found at least three different modes of ossification during bone lengthening by distraction osteogenesis. We believe that this is the first report of such a rat model, and have shown the validity of in situ hybridisation techniques for the study of the cellular and molecular mechanisms involved in distraction osteogenesis.