Serious Condylar Head Absorption in Children With Intracapsular Condylar Fractures Treated Operatively With Long Screws.

OBJECTIVE: This study was performed to explore bone remodelling in children with intracapsular condylar fractures after the condylar fracture fragments were fixed using long screws and to offer possible explanations about the underlying mechanism. PATIENT AND METHODS: Records of children (less than 12 y old) who sustained intracapsular condylar fractures and fixed with long screws from May 2012 to January 2015 were retrieved. Age, gender, dates of injury, admission, and discharge, mechanism of trauma, location and pattern of fracture, other mandibular fractures, treatment methods, and time of review were recorded and analyzed. Image dates of pretreatments and posttreatments, including the date of review, were also recorded. RESULTS: A total of 8 patients completed their follow-up, and all patients (n=5) who were followed up after more than 3 months showed serious resorption of the condylar head. The condylar head resorbed until the height (or articular surface) dropped and aligned with the surface of the screw. The shortest time of absorption, as shown by the computed tomography scan was 106 days, and the longest time was 171 days (average time of 141.8 d). CONCLUSIONS: Intracapsular condyle fractures in children should be managed conservatively as much as possible. However, if the height of the fracture fragments drops remarkably, open reduction and rigid internal fixation become possible choices.

Co-transduction of dual-adeno-associated virus vectors in the neonatal and adult mouse utricles.

Adeno-associated virus (AAV)-mediated gene transfer is an efficient method of gene over-expression in the vestibular end organs. However, AAV has limited usefulness for delivering a large gene, or multiple genes, due to its small packaging capacity (< 5 kb). Co-transduction of dual-AAV vectors can be used to increase the packaging capacity for gene delivery to various organs and tissues. However, its usefulness has not been well validated in the vestibular sensory epithelium. In the present study, we characterized the co-transduction of dual-AAV vectors in mouse utricles following inoculation of two AAV-serotype inner ear (AAV-ie) vectors via canalostomy. Firstly, co-transduction efficiencies were compared between dual-AAV-ie vectors using two different promoters: cytomegalovirus (CMV) and CMV early enhancer/chicken ß-actin (CAG). In the group of dual AAV-ie-CAG vectors, the co-transduction rates for striolar hair cells (HCs), extrastriolar HCs, striolar supporting cells (SCs), and extrastriolar SCs were 23.14 ± 2.25%, 27.05 ± 2.10%, 57.65 ± 7.21%, and 60.33 ± 5.69%, respectively. The co-transduction rates in the group of dual AAV-ie-CMV vectors were comparable to those in the dual AAV-ie-CAG group. Next, we examined the co-transduction of dual-AAV-ie-CAG vectors in the utricles of neonatal mice and damaged adult mice. In the neonatal mice, co-transduction rates were 52.88 ± 3.11% and 44.93 ± 2.06% in the striolar and extrastriolar HCs, respectively, which were significantly higher than those in adult mice. In the Pou4f3+/DTR mice, following diphtheria toxin administration, which eliminated most HCs and spared the SCs, the co-transduction rate of SCs was not significantly different to that of normal utricles. Transgene expression persisted for up to 3 months in the adult mice. Furthermore, sequential administration of two AAV-ie-CAG vectors at an interval of 1 week resulted in a higher co-transduction rate in HCs than concurrent delivery. The auditory brainstem responses and swim tests did not reveal any disruption of auditory or vestibular function after co-transduction with dual-AAV-ie vectors. In conclusion, dual-AAV-ie vectors allow efficient co-transduction in the vestibular sensory epithelium and facilitate the delivery of large or multiple genes for vestibular gene therapy.

Self-reinforced polyethylene blend for artificial joint application.

By means of purposeful material design and melt manipulation, we present a highly feasible approach to simultaneously improve the mechanical properties, fatigue and wear resistance of an ultrahigh molecular weight polyethylene (UHMWPE)-based self-reinforced polyethylene (PE) blend for artificial joint replacement. The fluidity of the PE blend was achieved by blending low molecular weight polyethylene (LMWPE) with radiation cross-linked UHMWPE. The use of the cross-linked UHMWPE restrained the molecular diffusion between the LMWPE and UHMWPE phases, and hence increased the content of UHMWPE up to 50 wt% under the premise of desirable fluidity for injection molding. The combination of the shear flow field and pre-additive precursors successfully induced numerous interlocking shish-kebab structures in the LMWPE phase. Mechanical reinforcement was thus attained, where the ultimate tensile strength was significantly improved from 27.6 MPa for the compression-molded UHMWPE to 81.2 MPa for the PE blend, and the impact strength was increased from 29.6 to 35.2 kJ m-2. The fatigue and wear resistance were far superior to those of the compression-molded UHMWPE. Compared to the results reported in our previous study (40 wt% UHMWPE), the increased UHMWPE content caused the LMWPE phase melt to flow faster, thus amplifying the shear rate in the interfacial region between the two phases and depressing the relaxation of oriented molecular chains. The crystalline orientation was preserved, especially in the inner layer, leading to further enhancement of the mechanical properties. These results suggest that such a self-reinforced PE blend is of benefit to lowering the risk of failure and prolonging the life span of the implant under adverse conditions.