Periprosthetic proximal humerus fractures require an individualized treatment approach-results of a multicenter retrospective study.

BACKGROUND: In the last years, there has been increasing use of shoulder arthroplasty. As a result, an increasing incidence of periprosthetic humerus fractures (PPHF) is expected. Therefore, this retrospective, multicenter analysis aimed to collect demographic data from patients with PPHF, their treatment strategies, and associated complications. METHODS: Demographics of patients with PPHF were collected retrospectively from the database of six trauma hospitals between January 2000 and December 2020. All fractures were categorized according to the Wright and Cofield, and Worland classifications. In addition, the type of treatment for PPHF, as well as subsequent complications, were evaluated. RESULTS: A total of 72 patients with a PPHF were identified. The mean age of the 55 female and 17 male patients was 77 years. PPHF occurred a mean of 50 months after primary arthroplasty implantation, almost exclusively as a result of a fall from standing height (n = 67). In-situ implant was a RTSA in 40 patients and a hemiarthroplasty in 32 patients. More than half of the fractures (n = 38) were type B fractures, according to Wright and Cofield. According to Worland, the majority of patients also had a type B fracture (type B1 (n = 22), type B2 (n = 28), type B3 (n = 10)). Associated comorbidities were found in 21 patients. A total of 31 patients were treated non-operatively, 27 with Open Reduction Internal Fixation (ORIF), and 14 with a revision arthroplasty. Nine primary radial nerve palsies were found (pre-operatively), and seven secondarily (post-operatively). Nine patients suffered from non-union (ORIF 4, non operative 4, stem replacement 1). CONCLUSION: The treatment strategy for PPHF is primarily tailored to the individual patient. Decisive factors such as patient's age, fracture type, and primary palsies have to be considered for optimal treatment. In type B1 fractures, there is a recommendation for ORIF because of high non-union rates under non-operative treatment. In contrast, in type B2 fractures, a non-operative approach should be preferred, provided there are no radial nerve lesions. LEVEL OF EVIDENCE: Level IV, epidemiologic study.

Steering the multiexciton generation in slip-stacked perylene dye array via exciton coupling.

Dye arrays from dimers up to larger oligomers constitute the functional units of natural light harvesting systems as well as organic photonic and photovoltaic materials. Whilst in the past decades many photophysical studies were devoted to molecular dimers for deriving structure-property relationship to unravel the design principles for ideal optoelectronic materials, they fail to accomplish the subsequent processes of charge carrier generation or the detachment of two triplet species in singlet fission (SF). Here, we present a slip-stacked perylene bisimide trimer, which constitutes a bridge between hitherto studied dimer and solid-state materials, to investigate SF mechanisms. This work showcases multiple pathways towards the multiexciton state through direct or excimer-mediated mechanisms by depending upon interchromophoric interaction. These results suggest the comprehensive role of the exciton coupling, exciton delocalization, and excimer state to facilitate the SF process. In this regard, our observations expand the fundamental understanding the structure-property relationship in dye arrays.

Implant-free iliac crest bone graft procedure shows anatomic remodelling without redislocation in recurrent anterior shoulder instability after short-term follow-up.

INTRODUCTION: With the help of a J-shaped bicortical iliac crest bone graft, the morphology of the glenoid can be augmented without having to use screws to achieve glenohumeral stability. The aim of this retrospective clinical study was to evaluate the clinical stability and function of the shoulder joint as well as the radiological remodelling process and arthropathic outcomes following the J-bone graft technique. MATERIALS AND METHODS: 34 patients with recurrent shoulder dislocations and bony glenoid defects were treated with the J-bone graft technique between 2010 and 2018 at our level-I trauma centre. 15 patients (18 shoulders) could be recruited for the study. Pain levels, ASES, UCLA, SST, DASH, Rowe and WOSI Scores were collected using questionnaires. In 13 patients (16 shoulders) the Constant Score, ROM, CT with 3D reconstruction of the glenoid to assess the graft remodelling and X-rays were performed additionally. RESULTS: None of the patients suffered subluxations or recurrent dislocations during the follow-up period. The overall complication rate was 11%. The evaluation using objective and subjective shoulder function scores yielded good-to-excellent results. Radiological assessment at follow-up showed a low rate of moderate-to-severe arthritis (12%) and a high rate of shoulders without any signs of arthritic degeneration (53%). The CT scans all revealed an almost complete restoration of the glenoid with none of the grafts being resorbed. A rise in the average glenoid circumference and glenoid area could be demonstrated between preoperative measurements (81.6 and 82.4%, respectively) and follow-up measurements (104 and 102.5%, respectively). CONCLUSION: The results of this study show a successful stabilisation of the shoulder joint and a low complication rate following the J-bone graft technique. Remodelling of the bone graft could be demonstrated, which in turn led to an almost perfect glenoid surface area of 100%.

Tunable Low-LUMO Boron-Doped Polycyclic Aromatic Hydrocarbons by General One-Pot C-H Borylations.

Boron-doping has long been recognized as a promising LUMO energy-lowering modification of graphene and related polycyclic aromatic hydrocarbons (PAHs). Unfortunately, synthetic difficulties have been a significant bottleneck for the understanding, optimization, and application of precisely boron-doped PAHs for optoelectronic purposes. Herein, a facile one-pot hydroboration electrophilic borylation cascade/dehydrogenation approach from simple alkene precursors is coupled with postsynthetic B-substitution to give access to ten ambient-stable core- and periphery-tuned boron-doped PAHs. These include large hitherto unknown doubly boron-doped analogues of anthanthrene and triangulene. Crystallographic, optical, electrochemical, and computational studies were performed to clarify the effect of boron-doped PAH shape, size, and structure on optoelectronic properties. Our molecular tuning allowed the synthesis of molecules exhibiting visible-range absorption, near-unity fluorescence quantum yields, and, to our knowledge, the most facile electrochemical reductions of any reported ambient-stable boron-doped PAHs (corresponding to LUMO energy levels as low as fullerenes). Finally, our study describes the first implementation of a precise three-coordinate boron-substituted PAH as an acceptor material in organic solar cells with power conversion efficiencies (PCEs) of up to 3%.