Novel calcified gum Arabic porous nano-composite scaffold for bone tissue regeneration.

The aim of this study was to investigate the biomechanical and biological properties of a nanocomposite scaffold containing both mineral and polysaccharide constituents. Hydroxyapatite nanoparticles (n-HA) was synthesized from dead abra ovata shells using wet chemical methods and was used in different ratios in concert with gum Arabic, a branched plant polysaccharide. N-HA/gum nanocomposite was fabricated with freeze-drying process and characterized by FTIR and SEM for chemical structure and morphology. Porosity was estimated using liquid substitution method. The scaffold mechanical properties were evaluated by compressive test measurement. Osteogenic differentiation was assessed using alkaline phosphatase production and biomineralization was evaluated using Alizarin red assay. Results demonstrated that the hydroxyapatite/gum Arabic nanocomposite had favorable biocompatibility and a similar structure to natural bone matrix. Porous nanocomposite possessed macropore networks with a porosity 87-93% and mean pore size ranging between 164 and 230 µm. The gum/HA with a ratio of 50% w/w HA had the highest compressive modulus of ∼75.3 MPa Pa (MPa) and the ultimate compressive stress of ∼16.6 MPa. C2C12 cells cultured on a scaffold with higher percentage (40 and 50 w/w) of HA demonstrated increased ALP levels and calcium deposition. The data from the present study demonstrated significant changes to the biomechanical properties and osteoconductivity of the nanocomposite scaffold by modulating its mineral content. Nanocomposite scaffolds containing gum and n-HA of 40-50% exhibited highest mechanical properties, as well as supported increased biomineralization.

Knee dislocation of a morbidly obese patient: a case report.

Knee dislocations of morbidly obese patients after a trivial fall are not uncommon. We report a case of closed reduction for a dislocated right knee of a 26-year-old obese woman. After closed reduction under general anaesthesia, her knee was supported by pillows in 30 degrees flexion. No external splint was used because of the enormous size of the leg. At day 4 after reduction, the patient had numbness over the dorsum of the right foot and was unable to dorsiflex. She was diagnosed as having peroneal nerve palsy and was fitted with a foot drop splint. One week after reduction, she started active, assisted knee mobilisation and tip-toe weight bearing. At 24 months after reduction, the patient was able to walk unaided and had 100 degrees of knee flexion. She had a good foot function and a grade II in the Lachman's test, with no varus or valgus instability. This case highlights the importance of early mobilisation, which can result in good outcome even without operative treatment.