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Assessing the effects of near-field ground motions shows that the directivity effects in velocity histories of these ground motions leads to one or more impact pulses with large amplitudes that yield in increased ductility demand of rigid structures placed in near source areas. In this study, the cumulative Park-Ang damage index has been used for comparing the damage potential brought about by the two acceleration components of ground motions that are normal to the fault direction or parallel to it. Two-dimensional steel moment frames with 4, 7, 10, 15 and 20 stories have been nonlinearly modeled and analyzed using the Opensees software. The investigations have been performed in different performance levels corresponding to target ductility values equal to 2, 3 and 4. The utilized ground motion records include 40 records divided equally to the normal and parallel sets regarding the fault direction. The scaling of the record sets have been performed so that the studied frames have met the considered target ductility values. The results show that the lower stories are more frequently affected by the normal records, therefore, more intense damages are attributed to these records. That is while, the parallel records have been found to affect mostly intermediate and especially upper stories. The results also show that increasing the target ductility values leads to an increased damage potential for the studied structures.

A combination of polymeric nanofibrous scaffold and bioactive materials is potentially useful in bone regeneration applications. In the present study, Poly (lactide-co-glycolide) (PLGA) nanofibrous scaffolds, fabricated via electrospinning, were initially coated with Type I collagen and then with nano-hydroxyapatite. The prepared scaffolds were then characterized using SEM and their ability for bone regeneration was investigated in a rat critical size bone defect using digital mammography, multislice spiral-computed tomography (MSCT) imaging, and histological analysis. Electrospun scaffolds had nanofibrous structure with homogenous distribution of n-HA on collagen-grafted PLGA. After 8 weeks of implantation, no sign of inflammation or complication was observed at the site of surgery. According to digital mammography and MSCT, PLGA nanofibers coated simultaneously with collagen and HA showed the highest regeneration in rat calvarium. In addition, no significant difference was observed in bone repair in the group which received PLGA and the untreated control. This amount was lower than that observed in the group implanted with collagen-coated PLGA. Histological studies confirmed these data and showed osteointegration to the surrounding tissue. Taking all together, it was demonstrated that nanofibrous structures can be used as appropriate support for tissue-engineered scaffolds, and coating them with bioactive materials will provide ideal synthetic grafts. Fabricated PLGA coated with Type I collagen and HA can be used as new bone graft substitutes in orthopaedic surgery and is capable of enhancing bone regeneration via characteristics such as osteoconductivity and osteointegration.

Guidelines on implant removal are not clear and the routine removal of orthopaedic fixation devices after fracture healing remains an issue of debate. Few studies have evaluated long-term outcomes of patients with orthopaedic implants left in-situ and this lake of data has made the orthopaedic surgeons decide on implant removal differently. In order to add new data in this field, we designed this study.

In a follow up setting, patients with Tibial shaft fractures who had received orthopaedic implants in year 2008 and earlier were clinically examined for any surgical complications such as pain or limited range of motion. Quality of life of each patient was evaluated using short form 36.

The total SF-36 score of the patients was not statistically different from the normal population (P >0.05). 21 patients (31.2%) reported limited range of motion in ankle and 11 (14.9%) complained of weakness in the affected limb. Clinically, 68.9% of patients had full range of motion in ankle and 70.3% had no tenderness in the affected limb.

As most patients were clinically normal and had quality of life scores comparable to the normal population, removal of implants is not advisable in all patients. Fracture Fixation; Fracture Fixation, Intramedullary; Quality of life; Implant removal