Inferomedial cortical bone contact and fixation with calcar screws on the dynamic and static mechanical stability of proximal humerus fractures.

BACKGROUND: This study aimed to explore the effect of retaining inferomedial cortical bone contact and fixation with calcar screws on the dynamic and static mechanical stability of proximal humerus fractures treated with a locking plate. METHODS: Twelve Synbone prosthetic humeri (SYNBONE-AG, Switzerland) were used for a wedge osteotomy model at the proximal humerus, in four groups. In the cortex contact + screw fixation group and cortex contact group, the inferomedial cortical bone contact was retained. In the screw fixation group and control group, the inferomedial cortical bone contact was not retained. Calcar screw fixation was implemented only in the screw fixation groups. The dynamic and static mechanical stability of the models were tested with dynamic fatigue mechanics testing, quasi-static axial compression, three-point bending, and torsion testing. RESULTS: The cortex contact + screw fixation group showed the longest fatigue life and the best stability. There was 35% difference in fatigue life between the cortex contact + screw fixation group and the cortex contact group, 43%between the cortex contact + screw fixation group and screw fixation group, and 63% between the cortex contact + screw fixation group and screw fixation group (P < 0.01). The cortex contact + screw fixation group showed the best axial compressive stiffness, bending stiffness, and torsion stiffness; these were successively decreased in the other three groups (P < 0.01). CONCLUSION: Retaining inferomedial cortical bone contact and fixation with two calcar screws maintained fracture stability with the highest strength and minimum deformation. Of the two methods, restoration of the inferomedial cortical bone support showed better dynamic and static biomechanical properties than placement of calcar screws alone.

Electrospun fibrous membranes featuring sustained release of ibuprofen reduce adhesion and improve neurological function following lumbar laminectomy.

Electrospun fibrous membranes provide suitable physical anti-adhesion barriers for reducing tissue anti-adhesion following surgery. However, often during the biodegradation process, these barriers trigger inflammation and cause a foreign body reaction with subsequent decrease in anti-adhesion efficacy. Here, a facile strategy comprising the incorporation of ibuprofen (IBU) into implantable membranes and its sustained release was proposed in order to improve anti-adhesion effects and neurological outcomes, namely to prevent failed back surgery syndrome (FBSS). The combination of free IBU and a newly synthetized polymeric prodrug of IBU, namely poly(hydroxyethyl methacrylate) with ester-linked IBU, was successfully used in order to reduce initial burst drug release and provide sustained drug release from fibrous membranes throughout several weeks. Such release profile was shown useful in preventing both acute and chronic inflammation in rats following laminectomy and membrane implantation. Moreover, histological analysis provided evidence of an excellent anti-adhesion effect, while associated neurological deficits were effectively reduced. Furthermore, the assessment of macrophage density, neovascularization, and related gene expression at the lesion site revealed that a sustained anti-inflammatory effect was achieved with the IBU-loaded proposed fibrous membranes. Results suggested that the COX2 pathway plays an important role in the development epidural fibrosis and arachnoiditis. Overall, this study provided evidence that precisely engineered IBU-loaded electrospun fibrous membranes may be useful in preventing FBSS and able to potentially impact the outcome of patients undergoing spine surgery.