AOA Critical Issues Symposium: Leadership and Education During and After COVID-19: Back to the Future or a New Normal.

ABSTRACT: The devastating impact of COVID-19 has reshaped how we lead and train our future surgeons in the field of orthopaedics. Overnight, leaders in our field had to dramatically shift their mindset to continue to lead a hospital, department, journal, or residency or fellowship program in the face of an unprecedented level of adversity in the history of the United States. This symposium discusses the role of physician leadership during and after a pandemic, as well as the adoption of technology for training surgeons in the field of orthopaedics.

Outcomes of sympathectomy and vascular bypass for digital ischaemia in connective tissue disorders.

All patients (36 hands) with connective tissue disorders who underwent periarterial sympathectomy of the hand alone or in conjunction with vascular bypass at our institution between 1995-2013 were reviewed. The durable resolution of ulcers was significantly higher in patients treated by periarterial sympathectomy and bypass than in patients treated by periarterial sympathectomy alone. Although there were more digital amputations in patients treated by periarterial sympathectomy alone, the difference was not statistically significant. Vascular bypass in conjunction with sympathectomy may be better than sympathectomy alone in patients with digital ischaemia related to connective tissue disorders. LEVEL OF EVIDENCE: IV.

A new approach to reach the best resolution of X-ray microanalysis in the variable pressure SEM.

A validation of our recent new approach is presented here in order to better interpret the EDS analysis results in low vacuum SEM. This approach is based on correlation between two concepts: the electron beam skirt radius in the gas characterized by RS and the X-ray emission volume radius in the material characterized by RX. If RS≤RX; then the skirt impact on the analysis is null and the best possible X-ray lateral resolution within the limitations imposed by gas scattering is obtained. In order to follow the relationship between RS and RX, two aluminum foils with different thickness (2 µm and 20 µm) embedded separately in epoxy resin were used. The results showed the existence of the optimal experimental conditions depending on the pressure and the energy that verify the condition of RS≤RX. The experimental and simulated results show the great consistency of this approach.

Skirting effects in the variable pressure scanning electron microscope: limitations and improvements.

A new approach has been initiated to improve the spatial lateral resolution of the X-ray microanalysis and the backscattered electrons modes in variable pressure or environmental scanning electron microscope (VP-ESEM). This approach is based on correlation between two concepts: the electron beam skirt radius in the gas (R(S)) and the generation volume radius (R(X)) of X-ray signals and the generation volume radius (R(BSE)) of backscattered electrons in the material. In order to follow the relationship between R(S), R(X) and R(BSE), PMMA polymer, silicon oxide and aluminium are used. The results of the simulation show the existence of the best lateral resolution conditions named R (P, E) depending on the pressure and the energy for each material. This approach will enable us to propose some optimal experimental conditions to characterize different materials.

Tuning the conditions for the deposition of nanocrystalline diamond by hot filament chemical vapour deposition.

Although large focus has been placed into the deposition of nanocrystalline and ultra-nanocrystalline diamond films, most of this research uses microwave plasma assisted CVD systems. However, the growth conditions used in microwave systems cannot be directly used in hot-filament CVD systems. This paper, aims to enlarge the knowledge of the diamond film depositing process. H2/CH4/Ar gas mixtures have been used to deposit micro, nano and ultra-nanocrystalline diamond films by hot-filament CVD systems. Additionally, the distance between the filaments array and the substrate was varied, in order to observe its effect and consequently the effect of a lower substrate temperature in the nucleation density and deposition. All the samples were characterized for microstructure and quality, using scanning electron microscopy and Raman spectroscopy.

Nanocrystalline diamond coatings for mechanical seals applications.

A mechanical seal is a type of seal used in rotating equipment, such as pumps and compressors. It consists of a mechanism that assists the connection of the rotating shaft to the housings of the equipments, preventing leakage or avoiding contamination. A common cause of failure of these devices is end face wear out, thus the use of a hard, smooth and wear resistant coating such as nanocrystalline diamond would be of great importance to improve their working performance and increase their lifetime. In this paper, different diamond coatings were deposited by the HFCVD process, using different deposition conditions. Additionally, the as-grown films were characterized for, quality, morphology and microstructure using scanning electron microscopy (SEM) and Raman spectroscopy. The topography and the roughness of the films were characterized by atomic force microscopy (AFM).

Peculiar reduction of graphene oxide into graphene after diffusion in exponentially growing polyelectrolyte multilayers.

In the present work, in situ reduction of graphene oxide (GO) into graphene was preformed, after diffusion in exponentially growing polyelectrolyte multilayers, using sodium citrate as the reducing agent. First, the graphene oxide was obtained by treating a commercial grade of Expanded Graphite (EG). Based on XRD and Raman spectroscopy results, a complete exfoliation of graphene nanopellets down to one layer was achieved during the oxidation process. Secondly, the diffusion of GO was carried out in an exponentially growing polyelectrolyte multilayer film made from poly(diallyldimethylammonium chloride) as the polycation and from poly(acrylic acid) as the polyanion. Electrical conductivity of the GO based films was measured during the reduction process as a function of time. The conductivity reached values of the order of 10(-4) S cm(-1), whereas the pristine polyelectrolyte multilayer was highly insulating (∼10(-8) S cm(-1)). The conductivity also reached a maximal value after about 24 h of reduction and decreased for longer reduction duration. Some tentative explanations for this peculiar finding will be given.

Comparative study of nanocrystalline diamond deposition on WC-Ni and WC-Co substrates.

Tungsten carbide alloys possess a large number of applications, due to its high hardness, high resistance to heat and to wear, which makes it ideal to be used in wear parts of machinery or on surfaces liable to corrosion, abrasion or high temperatures. For practical applications, it is alloyed with cobalt (Co) or nickel (Ni) in order to improve its properties. The increasing demand of broadening the operation limits of some components, impose the need to improve its life time. Coating these parts with hard and smooth diamond thin film may improve the wear performance and decrease their roughness and friction coefficient. In this work, a comparative study of nanodiamond films deposit onto WC-Co and WC-Ni, by means of a hot-filament Chemical Vapour Deposition (HFCVD) system, is presented. The study was accomplished by varying the CH4/H2/Ar gas ratio of the deposition process. The substrate temperature was kept low (< 700 degrees C) to minimize the thermal stress in the coating-substrate system. The microstructure of the deposited diamond film was characterized using Scanning Electron Microscopy (SEM), Raman spectroscopy and X-ray diffraction spectroscopy. Roughness of the working surfaces were also accessed prior and after the depositions.

Investigation of the stiffness and yield behaviour of melt-intercalated poly(methyl methacrylate)/organoclay nanocomposites: characterisation and modelling.

The elastic modulus and yield stress behaviour of a melt intercalated Poly(methylmethacrylate)/ organoclay (PMMA/C30B and PMMA/C20A) were studied using uniaxial tensile tests at different temperatures and different strain rate. The stress-strain response was obtained for different loading rates and different test temperature. Both the stiffness and the yield stress were then clearly identified as function of strain rate and temperature. Our experimental results show that the yield stress and modulus of both PMMA/C20A and PMMA/C30B organoclay nanocomposites are very sensitive to clay concentration, strain rate and temperature. A micromechanically-based composite approach was used to predict the yield stress of both PMMA/C20A and PMMA/C30B organoclay nanocomposites. The results obtained from the model are in good agreement with our experimental results. As expected, the activation enthalpy of cooperative model increased slightly while the activation volume decreases slightly with the clay concentration.

Hybrid layers deposited by an atmospheric pressure plasma process for corrosion protection of galvanized steel.

Finding alternative treatments to reproduce anticorrosion properties of chromated coatings is challenging since both physical barrier and self-healing effects are needed. Siloxane based treatments are known to be a promising way to achieve physical barrier coatings, mainly plasma polymerized hexamethyldisiloxane (ppHMDSO). In addition, it is known that cerium-based coatings can also provide corrosion protection of metals by means of self-healing effect. In this frame, innovative nanoAlCeO3/ppHMDSO layers have thus been deposited and studied. These combinations allow to afford a good physical barrier effect and active properties. Liquid siloxane and cerium-based particles mixture is atomized and introduced as precursors into a carrier gas. Gas mixture is then injected into an atmospheric pressure dielectric barrier discharge (DBD) where plasma polymerization of the siloxane precursor occurs. The influence of cerium concentration on the coating properties is investigated: coating structure and topography have been studied by scanning electron microscopy (SEM) and interferometry, and corrosion resistance of these different coatings is compared by electrochemistry techniques: polarization curves and electrochemical impedance spectroscopy (EIS). Potential self-healing property afforded by cerium in the layer was studied by associating EIS measurements and nanoscratch controlled damaging. Among the different combinations investigated, mixing of plasma polymerized HMDSO and AICeO3 nanoparticles seems to give promising results with a good physical barrier and interesting electroactive properties. Indeed, corrosion currents measured on such coatings are almost as low as those measured with the chromated film. Combination of nanoscratch damaging of layers with EIS experiments to investigate self-healing also allow to measure the active protection property of such layers.

Towards optimization of time modulated chemical vapour deposition for nanostructured diamond films on Ti6Al4V.

In this paper, we report the use of the TMCVD technique for the optimisation of deposited diamond films onto Ti6Al4V substrates. A number of samples were made varying the experimental parameters. The specimen surfaces were characterised using micro Raman spectra and SEM analyses. Results show that very different surface finish (from micro to nanostructures) and film characteristics can be obtained from the experimental parameters used. The quality of deposited diamond is very dependant on the experimental settings and process. It was found that lower residual stresses are developed using the TMCVD technique than with conventional CVD but depend on the structural diamond growth during the process. The quality of the deposited film was evaluated as a function of diamond to amorphous carbon ratio but showed no direct relation with the surface finish since it characterises the quality of the deposited diamond but not the quality of the film surface.

Use of functionalized nanosilica to improve thermo-mechanical properties of epoxy adhesive joint bonding aluminium substrates.

The present work is concerned with the improvement of thermal properties and mechanical strength of adhesive joints consisting of an epoxy adhesive layer bonding aluminium substrates by grafted nanosilica. Epoxy resin/silica nanocomposites were prepared by using functionalized silica. Silica was functionalized by amine group (SiO2-NH2). It was identified by Raman and Fourier Transform Infrared (FTIR). Effects of silica on viscoelastic properties for epoxy resin and its assemblies with aluminium substrates were studied by Dynamical Mechanical Analysis (DMA). Particles distribution was characterized by Scanning Electron Microscope (SEM). Our experimental results showed that functionalized silica presents a better distribution in the matrix than the pure silica. Our results also showed that grafting of functionalized silica improves the glass transition temperature (Tg) and the ultimate strength of aluminium/epoxy/aluminium assembly.

Game-based training in young elite handball players.

This study compared the effect of high-intensity interval training (HIT) versus specific game-based handball training (HBT) on handball performance parameters. Thirty-two highly-trained adolescents (15.5+/-0.9 y) were assigned to either HIT (n=17) or HBT (n=15) groups, that performed either HIT or HBT twice per week for 10 weeks. The HIT consisted of 12-24 x 15 s runs at 95% of the speed reached at the end of the 30-15 Intermittent Fitness Test (V(IFT)) interspersed with 15 s passive recovery, while the HBT consisted of small-sided handball games performed over a similar time period. Before and after training, performance was assessed with a counter movement jump (CMJ), 10 m sprint time (10 m), best (RSAbest) and mean (RSAmean) times on a repeated sprint ability (RSA) test, the V(IFT) and the intermittent endurance index (iEI). After training, RSAbest (-3.5+/-2.7%), RSAmean (-3.9+/-2.2%) and V(IFT) (+6.3+/-5.2%) were improved (P<0.05), but there was no difference between groups. In conclusion, both HIT and HBT were found to be effective training modes for adolescent handball players. However, HBT should be considered as the preferred training method due to its higher game-based specificity.

Release of the medial collateral ligament to improve flexion in post-traumatic elbow stiffness.

Contracture of the collateral ligaments is considered to be an important factor in post-traumatic stiffness of the elbow. We reviewed the results of isolated release of the medial collateral ligament in a series of 14 patients with post-traumatic loss of elbow flexion treated between 1998 and 2002. There were nine women and five men with a mean age of 45 years (17 to 76). They were reviewed at a mean follow-up of 25 months (9 to 48). The operation was performed through a longitudinal posteromedial incision centred over the ulnar nerve. After decompression of the ulnar nerve, release of the medial collateral ligament was done sequentially starting with the posterior bundle and the transverse component of the ligament, with measurement of the arc of movement after each step. If full flexion was not achieved the posterior half of the anterior bundle of the medial collateral ligament was released. At the latest follow-up, the mean flexion of the elbow improved significantly from 96 degrees (85 degrees to 115 degrees ) pre-operatively to 130 degrees (110 degrees to 150 degrees ) at final follow-up (p = 0.001). The mean extension improved significantly from 43 degrees (5 degrees to 90 degrees ) pre-operatively to 22 degrees (5 degrees to 40 degrees ) at final follow-up (p = 0.003). There was a significant improvement in the functional outcome. The mean Broberg and Morrey score increased from a mean of 54 points (29.5 to 85) pre-operatively to 87 points (57 to 99) at final follow-up (p < 0.001). All the patients had normal elbow stability. Our results indicate that partial surgical release of the medial collateral ligament is associated with improved range of movement of the elbow in patients with post-traumatic stiffness, but was less effective in controlling pain.

Complications associated with traction on the hip during arthroscopy.

We studied 16 hips (eight cadaver specimens) using arthrography, arthroscopy and anatomical dissection, under incremental traction of up to a maximum of 64 kg, to determine the relationship of the portals to nearby neurovascular structures. The distance of each arthroscopic portal (anterior, anterolateral, and posterolateral) to the associated neurovascular structures was measured after the application of 23 kg of traction. Traction of up to 64 kg on the lower limb failed to produce evidence of labral or capsular injury. Furthermore, traction of 23 kg resulted in little change in the position of adjacent neurovascular structures relative to the standard arthroscopic portals.

Secondary ion and laser ablation mass spectrometry for the quantitative characterization of styrene-butadiene copolymers.

Styrene-butadiene copolymers were analyzed by static secondary ion mass spectrometry (S-SIMS) and laser ablation Fourier transform ion cyclotron resonance mass spectrometry (LA-FTICRMS) to obtain quantitative information based on specific ions. Silver deposition was performed on polystyrene, butadiene rubber and styrene-butadiene rubber. Under these experimental conditions, new secondary ions were detected, in particular silver-cationized butadiene [M(butadiene) - Ag](+) and styrene [M(styrene) - Ag](+) monomers. In contrast, LA-FTICRMS experiments did not require pretreatment. At high laser power density, UV photons (193, 266 and 355 nm) allowed the detection of styrene and butadiene monomers at m/z 104 and 54, respectively. The use of the observed ions by SIMS or LA-FTICRMS ensures that quantitative information on the relative distribution of each monomer is obtained. However, the silver coating thickness in the SIMS experiment seems to have an important influence on the quantitative information obtained. For LA-FTICRMS experiments, the best results are obtained at a wavelength of 355 nm.

Arthroscopic excision of the radial head: Clinical outcome in 12 patients with post-traumatic arthritis after fracture of the radial head or rheumatoid arthritis.

PURPOSE: We performed arthroscopic radial head excision in a series of patients with either post-traumatic arthritis after a radial head fracture or rheumatoid arthritis of the elbow as an expanded indication for elbow arthroscopy. The purpose of the study was to critically examine the results of arthroscopic chondroplasty of the radial head to determine the safety and effectiveness of the procedure. TYPE OF STUDY: Outcome study and retrospective analysis. METHODS: From 1990 to 1997, arthroscopic radial head resection was performed in 12 patients with either post-traumatic arthritis (n = 10, Mason type II or III) or with rheumatoid arthritis (n = 2). Functional outcome and radiographs were analyzed after a mean follow-up period of 39 months (range, 12 to 97 months). Elbow arthroscopy was performed using a standardized technique. The anterior three quarters of the radial head and 2 to 3 mm of the radial neck were resected with the abrader in the anterolateral portal and the arthroscope in the proximal medial portal. For resection of the posterior portion of the radial head, the abrader may be transferred to the mediolateral portal. This permits resection of the remnants of the radial head posteriorly and also at the proximal radioulnar joint. RESULTS: Preoperatively, patients lacked 23 degrees (range, 5 degrees to 40 degrees ) of extension of the elbow on average. Mean flexion was 111 degrees (range, 60 degrees to 145 degrees ). Patients had unrestricted pronation (limitation of 5 degrees in 2 patients). Two patients had a lack of supination of 15 degrees and 30 degrees. Mean follow up was 39 months (range, 12 to 97 months). Postoperatively, patients lacked 9 degrees (range, 0 degrees to 20 degrees ) of extension of the elbow on average. Mean flexion was 136 degrees (range, 90 degrees to 150 degrees ). No patient had subjective or objective evidence of instability of the elbow. All patients except one reported significant improvement in pain relief and complete relief of mechanical symptoms. CONCLUSIONS: This technically demanding surgical procedure should be reserved for situations of persistent, restricted range of motion and chronic pain. Arthroscopic radial head resection combined with arthroscopic synovectomy relieves elbow stiffness. The surgeon is able to deal with the intrinsic joint pathology, as well as with accompanying symptoms such as synovitis, capsular contracture, or loose bodies.

Arthroscopic and open management of dynamic scaphoid instability.

This article focuses on the pathophysiology and treatment of dynamic scaphoid instability. Cadaver studies suggest that dynamic instability results from isolated injury to the scapholunate interosseous ligament without damage to the dorsal intercarpal and dorsal radial lunotriquetral ligaments. The diagnosis may be made by dynamic fluoroscopic examination, including stress and load views. The role of arthroscopy is twofold: (1) it enables the surgeon to distinguish between a complete, grossly unstable scapholunate interosseous space that requires open treatment and (2) it permits direct visualization of the reduction and percutaneous pinning of the articulation in an effort to stabilize the joint. Operative indications, open and arthroscopic techniques, and results are discussed.

The role of hip arthroscopy in the evaluation of avascular necrosis.

This prospective study evaluated the correlation between plain radiographs, magnetic resonance imaging (MRI), and diagnostic arthroscopy in the staging of avascular necrosis of the femoral head. Fifty-two hips in 46 patients were prospectively staged using radiographic and MRI staging systems. Patients subsequently underwent hip arthroscopy to visualize the articular surface prior to considering salvage of the femoral head and debride delaminated osteochondral fragments. Weighted Kappa analysis revealed only moderate correlation between MRI and plain radiographs (K=.11), MRI and arthroscopy (K=.21), and plain radiographs and arthroscopy (K=.19). Six (46%) of 13 patients with a radiographically apparent subchondral fracture demonstrated collapse of the articular surface at arthroscopy. Four (24%) of 17 hips with >2 mm of collapse of the femoral head on plain radiographs demonstrated fragmentation of the osteochondral surface of the femoral head at arthroscopy. In 5 patients with flattening of the femoral head, 3 patients had delamination of both the femoral and acetabular surfaces. In regard to labral pathology, 5 of 22 post-collapse hips also had large bucket handle tears of the labrum. Arthroscopy of the hip revealed osteochondral degeneration that was not detected by plain radiographs or MRI in 36% of post-collapse femoral heads.

Hinged elbow fixation for recurrent instability following fracture dislocation.

The purpose of this study was to evaluate the use of an articulated external fixator of the elbow in the management of instability after fracture dislocation. We retrospectively reviewed results of eight patients treated with an articulated external fixator between 1998 and 1999. Study inclusion criteria included recurrent/chronic dislocation following fracture dislocation. Patients were divided into two groups based on the onset of instability. Group I (n=3) included patients with acute instability. The indication for use of the articulated external fixator in this subset of patients was the inability to accomplish complete osseous and ligamentous repair secondary to high degrees of comminution and/or severe soft tissue defects. Group II (n=5) patients presented at least 6 weeks after the original injury; the indication for use of the external fixator was inability to maintain joint congruity following open reduction. Application of the fixator was performed as an alternative to reconstruction of both medial and lateral ligaments. Follow-up at 1.5 years consisted of radiographs, occupational therapy ROM and DASH outcome measurement. At follow-up, Group I patients maintained an average total arc of motion of 120 degree, average flexion contracture: 25 degree, average pronation: 90 degree, and average supination: 67 degree. Group II patients had an average total arc of motion of 84 degree, average flexion contracture: 33 degree, average pronation: 68 degree, and average supination: 43 degree. Radiographic appearance of patients in both groups revealed a congruent humero-ulnar joint. DASH forms indicated patients experienced mild difficulty with activities of daily living. In conclusion, global instability of the elbow after fracture dislocation remains a difficult problem. High-energy injuries may result in an inability to maintain a congruous humero-ulnar articulation despite osteosynthesis and direct repair of the medial collateral ligament (MCL) and LUCL. When repair of the coronoid process and MCL is not feasible secondary to excessive comminution or soft tissue defect, the use of an articulated external fixator permits concentric stability and reduction of the humero-ulnar articulation. In cases of chronic instability, application of an articulated external fixator provides an alternative to complete osseous and ligamentous reconstruction. In both acute and chronic situations, the use of the articulated elbow fixator results in most patients regaining very good functional use of the elbow.