The aim of this study is to print 3D polycaprolactone (PCL) scaffolds at high and low temperature (HT/LT) combined with salt leaching to induced porosity/larger pore size and improve material degradation without compromising cellular activity of printed scaffolds. PCL solutions with sodium chloride (NaCl) particles either directly printed in LT or were casted, dried, and printed in HT followed by washing in deionized water (DI) to leach out the salt. Micro-Computed tomography (Micro-CT) and scanning electron microscope (SEM) were performed for morphological analysis. The effect of the porosity on the mechanical properties and degradation was evaluated by a tensile test and etching with NaOH, respectively. To evaluate cellular responses, human bone marrow-derived mesenchymal stem/stromal cells (hBMSCs) were cultured on the scaffolds and their viability, attachment, morphology, proliferation, and osteogenic differentiation were assessed. Micro-CT and SEM analysis showed that porosity induced by the salt leaching increased with increasing the salt content in HT, however no change was observed in LT. Structure thickness reduced with elevating NaCl content. Mass loss of scaffolds dramatically increased with elevated porosity in HT. Dog bone-shaped specimens with induced porosity exhibited higher ductility and toughness but less strength and stiffness under the tension in HT whereas they showed decrease in all mechanical properties in LT. All scaffolds showed excellent cytocompatibility. Cells were able to attach on the surface of the scaffolds and grow up to 14 days. Microscopy images of the seeded scaffolds showed substantial increase in the formation of extracellular matrix (ECM) network and elongation of the cells. The study demonstrated the ability of combining 3D printing and particulate leaching together to fabricate porous PCL scaffolds. The scaffolds were successfully printed with various salt content without negatively affecting cell responses. Printing porous thermoplastic polymer could be of great importance for temporary biocompatible implants in bone tissue engineering applications.

Mesenchymal stem cells (MSC) have been used for bone regenerative applications as an alternative approach to bone grafting. Selecting the appropriate source of MSC is vital for the success of this therapeutic approach. MSC can be obtained from various tissues, but the most used sources of MSC are Bone marrow (BMSC), followed by adipose tissue (ASC). A donor-matched comparison of these two sources of MSC ensures robust and reliable results.

Despite the similarities in morphology and immunophenotype of donor-matched ASC and BMSC, differences existed in their proliferation and in vitro differentiation potential, particularly osteogenic differentiation that was superior for BMSC, compared to ASC. However, these differences were substantially influenced by donor variations. In vivo, although the upregulated expression of osteogenesis-related genes in both ASC and BMSC, more bone was regenerated in the calvarial defects treated with BMSC compared to ASC, especially during the initial period of healing. According to these findings, compared to ASC, BMSC may result in faster regeneration and healing, when used for bone regenerative applications.

Tropical pyomyosistis is an uncommon condition in the United Kingdom. Early diagnosis and appropriate treatment are crucial for a good outcome. We had seen 13 cases in our previously published series from 1998 to 2009. This is an update showing a significantly increased incidence from 2010 to 2016.

A retrospective review of all cases of pelvic pyomyositis in our centre from January 2010 to April 2016 was undertaken from case notes and radiology reports. All children with clinical and radiographic evidence of pyomyositis were included. Since our previous publication we had changed our practice to get an MRI scan in all children who presented with a limp, fever and raised inflammatory markers, and had no effusion in the hip ultrasound scan.

We identified 24 children with a mean age of 7 years (range, 1 week to 14 years). MSSA (Methicillin-Sensitive Staphylococcus aureus) was the most common cultured organism (n=8). Median hospital stay was 9 days (3 to 12). Obturator internus was the most common muscle affected. All patients had appropriate antibiotics with 2 patients requiring surgical drainage of abscesses. The majority of children (n=22) showed a complete recovery with antibiotics only.

Incidence of pyomyositis has increased dramatically in our population and early diagnosis can result in a good outcome. We recommend MRI scan in all patients who present with a clinical picture of septic arthritis of the hip but with no effusion.