Intramedullary nailing (IMN) has been frequently indicated to treat long bone open and closed fractures, but infection following internal fixation may have devastating consequences, with higher costs. Treatment of intramedullary nail-associated infections (IMNI) is challenging and based upon surgery and adequate antibiotic administration, which requires the correct identification of causative microorganisms. However, there have been difficulties for the microbial diagnosis of IMNI, as the peri-prosthetic tissue cultures may show no microbial growth, particularly in patients with previous use of antibiotics. Sonication have shown higher sensitivity and specificity for microbial identification on a variety of orthopedic implant-associated infections. Aim: To compare clinical and microbiological results and sensitivity for the pathogen identification obtained by conventional peri-implant tissue culture samples with culture of samples obtained by sonication of explanted IMN implants, among patients presenting IMNI of long bones.

Methods: Longitudinal prospective cohort study performed at a tertiary public hospital, ongoing since August 2011. We analyzed all patients with indication for IMN implant removal, and orthopedic-implant associated infections was defined according to previous publications addressing osteosynthesis-associated infections (Yano 2014). Minimal of 2 samples from the peri-implant tissue were taken and sent under sterile conditions to the laboratory for culture. Statistical analysis was performed McNemar's test for related proportions.

Results: We included 26 patients presenting clinical signs of IMNI, of which tissue and sonication cultures were performed for 26 (100%) and 20 (77%) patients, respectively. Among them, 88% were male, with mean age was 35.9 years (range, 19–59 yo). Causes of trauma were mainly motorcycle crashes accounting 54% of accidents; tibia and fibula were affected in 65% and 27%, respectively. Gustilo open fracture classification was grade II (35%) and IIIA (35%). First stage management with external fixation for fracture stabilization was performed in 75% of trauma patients. Sensitivity of peri-prosthetic tissue culture and sonication was 80.7% (21/26), and 95% (19/20) (p< 0.05), respectively. Only one infected patient presented negative tissue and fluid cultures. Gram-positive cocci were isolated in 75% and 79% in tissue and sonication fluid cultures, respectively. Staphylococcus aureus, coagulase-negative staphylococci, Enterococcus sp., were isolated from tissue and sonication culture in 43.5% and 36.3%, 8.7% and 22.7%, 13% and 13.7%, respectively. Polymicrobial infection was diagnosed in 3.8% (1/26) and 15.8% (3/19), patients by tissue and sonication fluid cultures (p< 0,01), respectively.

Conclusion: Sonication of retrieved infected intramedullary nails has the potential for improving the microbiological diagnosis of IMNI.

Summary

In contrast to the current literature, myofibroblasts are not present in chronic posttraumatic elbow contractures.

However, myofibroblasts are present in the acute phase after an elbow fracture and/or dislocation. This suggests a physiological role in normal capsule healing and a potential role in the early phase of posttraumatic contracture formation.

Osteoporosis following ovariectomy has been suggested to modulate bone response to polyethylene wear debris. In this work, we evaluate the influence of estrogen deficiency on experimental particle-induced osteolysis. Polyethylene (PE) particles were implanted onto the calvaria of wild-type (WT), sham-ovariectomized (OVX), OVX mice and OVX mice supplemented with estrogen (OVX+E2) (12 mice per group). Sham-implanted mice served as internal controls. After 14 days, seven skulls per group were analyzed with a high-resolution micro-computed tomography (CT) and by histomorphometry, and for tartrate-specific alkaline phosphatase. Five calvariae per group were cultured for the assay of IL-1, IL-6, TNF- and RANKL secretion using quantitative ELISA. The expression of RANKL and OPG mRNA were evaluated using real-time PCR. As assessed by CT and by histomorphometry, PE particles induced an extensive bone resorption and an intense inflammatory reaction in WT, sham-OVX and OVX+E2 mice. In OVX mice group, these features appeared considerably attenuated. In WT, sham-OVX and OVX+E2 mice, PE particles induced an increase in serum IL-6, in TNF-and RANKL local concentrations, and resulted in a two-fold increase in RANKL/OPG mRNA ratio. Conversely, these parameters remained unchanged in OVX mice after PE implantation. The combination of two well-known bone resorptive mechanisms ultimately attenuated osteolytic response, suggesting a protective effect of estrogen deficiency on particle-induced osteolysis. This paradoxical phenomenon was associated with a downregulation of pro-resorptive cytokines. It is hypothesized that excessive inflammatory response was controlled, illustrated by the absence of increase of serum IL-6 in OVX mice after PE implantation.

The nerve roots of the cauda equina may be visualised by contrast-enhanced CT scans and by surface-coil MRI. We have identified the pattern of anatomy from L2-L3 to L5-S1 in 10 human cadaver specimens and correlated this with anatomical dissections. Individual roots are slightly more distinct on contrast-enhanced CT than on surface-coil MRI. There is a crescentic oblique pattern of nerve roots at the lower lumbar levels which is still apparent in the more crowded proximal sections. In all cases, the axial images correlated precisely with the dissections. Current imaging modalities can help the clinical understanding and management of abnormalities in this region of the spine.

Prompt surgical decompression is the only means of preventing the late sequelae of ischaemic contracture in post-traumatic compartment syndromes. However, controversy exists regarding the length of dermotomy required for adequate decompression in the lower extremity. This study investigated the skin envelope as a potential contributing factor. Wide fascial releases were performed through limited 8 cm incisions in eight cases of post-traumatic lower extremity compartment syndrome. In nine of 29 compartments the pressure remained greater than 30 mmHg. Lengthening the skin incisions to an average of 16 cm decreased intracompartmental pressures significantly. This study documents the skin envelope as a contributing factor in acute compartment syndromes of the leg. The use of generous skin incisions is supported and the need for intra-operative compartment pressure measurements in the treatment of this condition is emphasised.

Hip rotation in extension and flexion was studied in 23 patients with idiopathic intoeing gait. In extension all the hips had markedly increased medial rotation and limited lateral rotation, fulfilling the criteria of excessive femoral anteversion. In flexion, however, rotation varied widely; in one group of patients medial rotation remained greater than lateral, but in the second group lateral rotation was equal to or greater than medial. CT scans showed that the hips in the first group were significantly more anteverted than those in the second. Clearly measurement of hip rotation in extension alone does not provide a dependable indication of femoral anteversion in children with intoeing gait; rotation in flexion also needs to be measured.