Atypical Vancouver B1 Periprosthetic Fractures: The Unsolved Problem.

Atypical femoral fractures (AFF) are stress or insufficiency fractures induced by low energy trauma or no trauma, frequently correlated with prolonged bisphosphonate therapy. The diagnosis follows major and minor criteria, originally described by the Task Force of the American Society for Bone and Mineral Research in 2010 and updated in 2014. However, the definition of AFFs in the report excluded periprosthetic fractures. When atypical fractures occur close to a prosthetic implant the situation become critical, the surgical treatment is often demolitive and supported by medical treatment. Moreover, acute ORIF as a first line treatment is frequently burdened by a high failure rate , and often a stem revision is required as second line treatment. The healing process is long and difficult with poor functional results and impairing outcomes. We present a case treated at our institution of a 78 year old woman with a history of a femoral atypical periprosthetic fracture, complicated by multiple surgical revisions. Its arduous management reflects all the difficulties that these type of fractures could present to the surgeon, while its good final result may teach us how to approach them in a correct way.

Choice of treatments of the coronal shear fractures of the humerus. A national survey of Italian AO members.

INTRODUCTION: Coronal shear fractures of the distal humerus are uncommon injuries representing 6% of distal humeral fractures. There is no univocal consensus about the correct management of this type of fracture. A national survey was conducted to gain more insight into the current classification, diagnosis and treatment of coronal shear fractures in Italy. MATERIALS AND METHODS: A postal survey was sent to all AO Italian members including residency orthopaedic surgeons. The survey consisted of general questions about personal experience in the management of these fractures: types of classification systems used, surgical approaches, treatment options and rehabilitation programs. RESULTS: 114 orthopaedic surgeons answered a 13-items questionnaire. The most used classification system was AO/OTA (72,8%). Independent screws and if necessary plates were the most answered regarding surgical treatment (81,6%). The most encountered post-surgical complication was stiffening of the elbow (81,6%). CONCLUSION: An algorithm of treatment has been proposed. To better classify coronal shear fractures, the authors recommended the integration of two classification systems: AO and Dubberley classifications. In the case of posterior wall comminution, a Kocher extensile approach is recommended, otherwise, if a posterior wall is intact, Kocher or Kaplan approach can be used. The posterior transolecranic approach can be reserved to Dubberley type III or AO 13B3.3. The best treatment choice is represented by independent screws and plates placed according to fracture patterns while arthroplasty is indicated when a stable ORIF is not possible. Mobilization is postponed for about 2 weeks.

A Newly Identified Complication of Patellofemoral Arthroplasty: Case Report and Literature Review.

Background: Patellofemoral arthroplasty (PFA) is a surgical option for patients older than 40 years old who are affected by patellofemoral osteoarthritis. Regarding the complications of PFAs, few studies have investigated periprosthetic fractures. The purpose of this literature review was to highlight a previously overlooked complication of primary prosthetic surgery of the patellofemoral joint. Methods: Three literature databases were searched for studies published between 2000 to 2020 using relevant keywords. A total of 4,942 articles were originally identified. After excluding duplicates and analysing the titles and abstracts, 20 studies were considered. From these, data regarding the number of cases, clinical outcomes and complications were extracted. Results: Among the 20 selected articles, only one described periprosthetic fractures as a complication of PFAs. Herein, we also report an illustrative case of an unknown fracture complication. No cases in the literature were found that described the type of complications experienced by our patient during the postoperative period. Conclusions: This review confirms the lack of data about clinical outcomes and fracture complications of PFAs. In primary prosthetic surgery of the patellofemoral joint, patient selection and close consideration of demographic factors (such as BMI and age) and intraoperative factors (such as patellar thickness and size of the trochlear component) play a key role in optimising pre-operative planning to avoid intraoperative periprosthetic fractures.

Is the Posterior Approach With Posterior locking compression plate and Anterior Allograft Useful and Safe in the Treatment of Periprosthetic Humeral Fractures Following Reverse Total Shoulder Arthroplasty?

Introduction: As the reverse total shoulder arthroplasty (RTSA) surgery has dramatically increased in the last few decades, many complications have followed through. The periprosthetic fracture, at the moment, is still a subject of debate in the orthopedic world. In this monocentric study, along with a literature review of periprosthetic humeral fractures, we would present our institutional experience with the treatment of periprosthetic humeral fractures with a posterior humeral approach, posterior cortex plate fixation, anterior strut allograft, screws, and cerclage wires. Materials and Methods: Our study consisted in a prospective monocentric study based on 18 patients, with a mean age of 75.3 years (range 64-88), all following a reverse shoulder total arthroplasty (RTSA). Postoperative follow-ups were taken at 1, 6, and 12 months with objective measurement of shoulder motion and strength, while clinical outcome measures were assessed using the American Shoulder and Elbow Surgeons (ASES score) and visual analog scale (VAS) for pain. Together with that, we performed a literature review focused on the management of periprosthetic humeral fractures after shoulder arthroplasty. Results: All fractures consolidated without complication at a mean 4.2 months (range 3-6). At final follow-up, the average active shoulder flexion was 88° (range 62-129°), active abduction 73° (range 52-91°) and active external rotation 22° (range 3-56°). The average ASES score was 73 (range 59-97), while average VAS score was 1.1 (range 0-3). Discussion: Surgical treatment of periprosthetic humeral fractures following a shoulder arthroplasty remains a hard challenge for every surgeon, and their treatment must consider fracture's location, displacement, and local bone quality. Conclusions: The posterior approach with a posterior plate placement and anterior strut allograft, which is appliable only in case of a B or C type fracture according to Worland classification, could be a good treatment option for periprosthetic humeral fractures.

Use of the 95-degree angled blade plate with biological and mechanical augmentation to treat proximal femur non-unions: a case series.

BACKGROUND: Intertrochanteric and subtrochanteric non-union are rare but challenging complications. In the present study, we investigate the use of a 95° blade, in association with biological and mechanical augmentation, in the management of intertrochanteric and subtrochanteric femoral non-unions. METHODS: Between October 2015 and February 2021, a retrospective cohort study was conducted at our institution to investigate the use of a 95° blade, in association with biological and mechanical augmentation, in the management of intertrochanteric and subtrochanteric femoral non-unions, following the mechanical failure of the first device. All the patients underwent a clinical and radiographic follow-up at 6 weeks, 3, 6, 9, 12 and 18 months; at each follow-up, a plain radiograph of the femur was performed and patients were assessed using Harris Hip Score (HHS) and the Short Form-12 (SF-12) questionnaire. RESULTS: From October 2015 and February 2021, 40 proximal femur non-unions were managed at our Institution. Fifteen patients out of forty (37.5%) met the inclusion criteria. The main data of the study are summarized in Table 1; patients' mean was 57 years old (range 19-83); 10 males and 5 females were included in the study. All the patients completely healed clinically and radiologically at an average of 6.1 months (range 4-13). All these patients returned to their pre-injury mobility status. During an average follow-up period of 25 months (range 8-60), the observed complications included wound dehiscence, which was treated with a superficial surgical debridement, a below-the-knee deep vein thrombosis, and a blade plate failure 3 months after the first revision surgery. CONCLUSIONS: This study shows the treatment of inter-and sub-trochanteric non-unions with a 95° blade plate, medial strut allograft, and bone autograft obtained with RIA system, together with a varus malalignment correction, leads to a high percentage of bone healing, with a low incidence of complications and good clinical outcome.

Covalent assembly of nanoparticles as a peptidase-degradable platform for molecular MRI.

Ligand-conjugated microparticles of iron oxide (MPIO) have the potential to provide high sensitivity contrast for molecular magnetic resonance imaging (MRI). However, the accumulation and persistence of non-biodegradable micron-sized particles in liver and spleen precludes their clinical use and limits the translational potential of MPIO-based contrast agents. Here we show that ligand-targeted MPIO derived from multiple iron oxide nanoparticles may be coupled covalently through peptide linkers that are designed to be cleaved by intracellular macrophage proteases. The synthesized particles possess potential characteristics for targeted MRI contrast agents, including high relaxivity, unappreciable sedimentation, clearance from circulation and no overt toxicity. Importantly, we demonstrate that these particles are rapidly degraded both in vitro and in vivo, and that the targeted probes can be used for detection of inflammation in vivo using MRI. This approach provides a platform for molecular MRI contrast agents that is potentially more suitable for translation to humans.

Indole alkaloids synthesis via a selective cyclization of aminocyclopropanes.

The continuous progress in medicinal chemistry requires more versatile synthetic strategies for the generation of large libraries of active compounds and their analogues. As a result, the research for new effective cyclization and cycloaddition reactions is an essential task in organic chemistry. In 2008 we developed the first catalytic formal homo-Nazarov reaction starting from activated cyclopropanes. Herein we report the extension of the catalytic formal homo-Nazarov cyclization to aminocyclopropanes. Highly diastereoselective cyclizations were obtained via an acyliminium intermediate generated through opening of the cyclopropane. An excellent control over the regioselectivity of either the C-C or C-N cyclization in the case of free indoles as nucleophilic partners was achieved. The utility of the developed methodology was demonstrated by the generation of the polycyclic scaffolds of Aspidosperma and Gonioma natural products starting from a common intermediate. Based on this method, a formal total synthesis of the alkaloid aspidospermidine and the total synthesis of the alkaloid goniomitine are presented. Finally, the scope and limitations of our methodology are discussed on an extended range of vinyl-cyclopropyl ketones with cyclic or acyclic carbamates, as well as ethers as donor groups on the cyclopropane.

Formal homo-Nazarov and other cyclization reactions of activated cyclopropanes.

The Nazarov cyclization of divinyl ketones gives access to cyclopentenones. Replacing one of the vinyl groups by a cyclopropane leads to a formal homo-Nazarov process for the synthesis of cyclohexenones. In contrast to the Nazarov reaction, the cyclization of vinyl-cyclopropyl ketones is a stepwise process, often requiring harsh conditions. Herein, we describe two different approaches for further polarization of the three-membered ring of vinyl-cyclopropyl ketones to allow the formal homo-Nazarov reaction under mild catalytic conditions. In the first approach, the introduction of an ester group α to the carbonyl on the cyclopropane gave a more than tenfold increase in reaction rate, allowing us to extend the scope of the reaction to non-electron-rich aryl donor substituents in the ß position to the carbonyl on the cyclopropane. In this case, a proof of principle for asymmetric induction could be achieved using chiral Lewis acid catalysts. In the second approach, heteroatoms, especially nitrogen, were introduced ß to the carbonyl on the cyclopropane. In this case, the reaction was especially successful when the vinyl group was replaced by an indole heterocycle. With a free indole, the formal homo-Nazarov cyclization on the C3 position of indole was observed using a copper catalyst. In contrast, a new cyclization reaction on the N1 position was observed with Brønsted acid catalysts. Both reactions were applied to the synthesis of natural alkaloids. Preliminary investigations on the rationalization of the observed regioselectivity are also reported.

Cyclopropanes and hypervalent iodine reagents: high energy compounds for applications in synthesis and catalysis.

One of the major challenges faced by organic chemistry is the efficient synthesis of increasingly complex molecules. Since October 2007, the Laboratory of Catalysis and Organic Synthesis (LCSO) at EPFL has been working on the development of catalytic reactions based on the Umpolung of the innate reactivity of functional groups. Electrophilic acetylene synthons have been developed using the exceptional properties of ethynyl benziodoxolone (EBX) hypervalent iodine reagents for the alkynylation of heterocycles and olefins. The obtained acetylenes are important building blocks for organic chemistry, material sciences and chemical biology. The ring-strain energy of donor-acceptor cyclopropanes was then used in the first catalytic formal homo-Nazarov cyclization. In the case of aminocyclopropanes, the method could be applied in the synthesis of the alkaloids aspidospermidine and goniomitine. The developed methods are expected to have a broad potential for the synthesis and functionalization of complex organic molecules, including carbocycles and heterocycles.

Catalytic formal Homo-Nazarov cyclization.

The first catalytic method for the cyclization of vinyl-cyclopropyl ketones (formal homo-Nazarov reaction) is reported. Starting from activated cyclopropanes, heterocyclic, and carbocyclic compounds were obtained under mild conditions using Brønsted acid catalysts. Preliminary investigation of the reaction mechanism indicated a stepwise process.