Chitosan crosslinked flat scaffolds for peripheral nerve regeneration.

Chitosan (CS) has been widely used in a variety of biomedical applications, including peripheral nerve repair, due to its excellent biocompatibility, biodegradability, readily availability and antibacterial activity. In this study, CS flat membranes, crosslinked with dibasic sodium phosphate (DSP) alone (CS/DSP) or in association with the γ-glycidoxypropyltrimethoxysilane (CS/GPTMS_DSP), were fabricated with a solvent casting technique. The constituent ratio of crosslinking agents and CS were previously selected to obtain a composite material having both adequate mechanical properties and high biocompatibility. In vitro cytotoxicity tests showed that both CS membranes allowed cell survival and proliferation. Moreover, CS/GPTMS_DSP membranes promoted cell adhesion, induced Schwann cell-like morphology and supported neurite outgrowth from dorsal root ganglia explants. Preliminary in vivo tests carried out on both types of nerve scaffolds (CS/DSP and CS/GPTMS_DSP membranes) demonstrated their potential for: (i) protecting, as a membrane, the site of nerve crush or repair by end-to-end surgery and avoiding post-operative nerve adhesion; (ii) bridging, as a conduit, the two nerve stumps after a severe peripheral nerve lesion with substance loss. A 1 cm gap on rat median nerve was repaired using CS/DSP and CS/GPTMS_DSP conduits to further investigate their ability to induce nerve regeneration in vivo. CS/GPTMS_DSP tubes resulted to be more fragile during suturing and, along a 12 week post-operative lapse of time, they detached from the distal nerve stump. On the contrary CS/DSP conduits promoted nerve fiber regeneration and functional recovery, leading to an outcome comparable to median nerve repaired by autograft.

Does lesser trochanter implication affect hip flexion strength in proximal femur fracture?

PURPOSE: In pertrochanteric and intertrochanteric femoral fractures, the avulsion of the lesser trochanter by the pull of the iliopsoas muscle is not uncommon. This fragment is not commonly fixed because the avulsion of the lesser is tough to not influence the clinical outcome but up to date there is no evidence to support this statement. The aim of this study is to evaluate if lesser trochanter implication affects psoas muscle strength in proximal femur fracture. MATERIALS AND METHODS: Patients with a consolidated intertrochanteric or pertrochanteric fracture associated or not with lesser trochanter fracture were enrolled, respectively, in group A and group B. Criteria of inclusion were the achievement of an anatomic reduction with gamma nail and a complete consolidation of the fracture. Criteria of exclusion were a follow-up shorter than 6 months and age over 65 years old at surgery. Patients were retrospectively reviewed for the purpose of this study. Range of motion, modified Harris Hip Score (mHHS), flexion strength with hip in neutral position, at 90° of flexion and in "figure four" position were evaluated on injured and healthy side. On the pre-operative X-rays, the vertical displacement of the lesser trochanter was calculated. RESULTS: Groups A and B showed no significant difference in age and follow-up. No statistical difference between the two groups was found in range of motion, mean mHHS, hip flexion strength at 90° of hip flexion. Lesser trochanter fracture group showed a significantly reduced strength in flexion with hip in neutral flexion (mean difference between two groups was 18.5 kgf). Lesser trochanter displacement showed a significant correlation with strength at 90° of flexion. CONCLUSIONS: Our results showed that lesser trochanter implication may result in decreased hip flexion strength. Lesser trochanter displacement is directly correlated with flexion strength. Further studies will be necessary to understand if lesser trochanter fixation may be a good solution for those patients.