Granular crystals as strong and fully dense architectured materials.

Dense topologically interlocked panels are made of well-ordered, stiff building blocks interacting mainly by frictional contact. Under mechanical loads, the deformation of the individual blocks is small, but they can slide and rotate collectively, generating high strength, toughness, impact resistance, and damage tolerance. Here, we expand this construction strategy to fully dense, 3D architectured materials made of space filling building blocks or "grains." We used mechanical vibrations to assemble 3D printed rhombic dodecahedral and truncated octahedral grains into fully dense face-centered cubic and body-centered cubic "granular crystals." Triaxial compression tests revealed that these granular crystals are up to 25 times stronger than randomly packed spheres and that after testing, the grains can be recycled into new samples with no loss of strength. They also displayed a rich set of mechanisms: nonlinear deformations, crystal plasticity reminiscent of atomistic mechanisms, geometrical hardening, cross-slip, shear-induced dilatancy, and microbuckling. A most intriguing mechanism involved a pressure-dependent "granular crystal plasticity" with interlocked slip planes that completely forbid slip along certain loading directions. We captured these phenomena using a three-length scale theoretical model which agreed well with the experiments. Once fully understood and harnessed, we envision that these mechanisms will lead to 3D architectured materials with unusual and attractive combinations of mechanical performances as well as capabilities for repair, reshaping, on-site alterations, and recycling of the building blocks. In addition, these granular crystals could serve as "model materials" to explore unusual atomic scale deformation mechanisms, for example, non-Schmid plasticity.

Bio-Inspired Interlocking Structures for Enhancing Flexible Coatings Adhesion.

The flexible protective coatings and substrates frequently exhibit unstable bonding in industrial applications. For strong interfacial adhesion of heterogeneous materials and long-lasting adhesion of flexible protective coatings even in harsh corrosive environments. Inspired by the interdigitated structures in Phloeodes diabolicus elytra, a straightforward magnetic molding technique is employed to create an interlocking microarray for reinforced heterogeneous assembly. Benefiting from this bio-inspired microarrays, the interlocking polydimethylsiloxane (PDMS) coating recorded a 270% improvement in tensile adhesion and a 520% increase in shear resistance, approaching the tensile limitation of PDMS. The elastic polyurethane-polyamide (PUPI) coating equipped with interlocking structures demonstrated a robust adhesion strength exceeding 10.8 MPa and is nearly unaffected by the corrosion immersion. In sharp contrast, its unmodified counterpart exhibited low initial adhesion and maintain ≈20% of its adhesion strength after 30 d of immersion. PUPI coating integrated with microarrays exhibits superior resistance to corrosion (30 d, |Z|0.01HZ ≈1010  Ω cm2 , Rct ≈108  Ω cm2 ), cavitation and long-term adhesion retention. These interlocking designs can also be adapted to curved surfaces by 3D printing and enhances heterogeneous assembly of non-bonded materials like polyvinylidene fluoride (PTFE) and PDMS. This bio-inspired interlocking structures offers a solution for durably bonding incompatible interfaces across varied engineering applications.

Digitally enhanced hands-on surgical training (DEHST) enhances the performance during freehand nail distal interlocking.

PURPOSE: Freehand distal interlocking of intramedullary nails remains a challenging task. Recently, a new training device for digitally enhanced hands-on surgical training (DEHST) was introduced, potentially improving surgical skills needed for distal interlocking. AIM: To evaluate whether training with DEHST enhances the performance of novices (first-year residents without surgical experience in freehand distal nail interlocking). METHODS: Twenty novices were randomly assigned to two groups and performed distal interlocking of a tibia nail in mock operation under operation-room-like conditions. Participants in Group 1 were trained with DEHST (five distal interlocking attempts, 1 h of training), while those in Group 2 did not receive training. Time, number of X-rays shots, hole roundness in the X-rays projection and hit rates were compared between the groups. RESULTS: Time to complete the task [414.7 s (range 290-615)] and X-rays exposure [17.8 µGcm2 (range 9.8-26.4)] were significantly lower in Group 1 compared to Group 2 [623.4 s (range 339-1215), p = 0.041 and 32.6 µGcm2 (range 16.1-55.3), p = 0.003]. Hole projections were significantly rounder in Group 1 [95.0% (range 91.1-98.0) vs. 80.8% (range 70.1-88.9), p < 0.001]. In Group 1, 90% of the participants achieved successful completion of the task in contrast to a 60% success rate in Group 2. This difference was not statistically significant (p = 0.121). CONCLUSIONS: In a mock-operational setting, training with DEHST significantly enhanced the performance of novices without surgical experience in distal interlocking of intramedullary nails and hence carries potential to improve safety and efficacy of this important and demanding surgical task to steepen the learning curve without endangering patients. LEVEL OF EVIDENCE: II.

Water and Air Stable Copper(I) Complexes of Tetracationic Catenane Ligands for Oxidative C-C Cross-Coupling.

Aqueous soluble and stable Cu(I) molecular catalysts featuring a catenane ligand composed of two dicationic, mutually repelling but mechanically interlocked macrocycles are reported. The ligand interlocking not only fine-tunes the coordination sphere and kinetically stabilizes the Cu(I) against air oxidation and disproportionation, but also buries the hydrophobic portions of the ligands and prevents their dissociation which are necessary for their good water solubility and a sustained activity. These catenane Cu(I) complexes can catalyze the oxidative C-C coupling of indoles and tetrahydroisoquinolines in water, using H2O2 as a green oxidant with a good substrate scope. The successful use of catenane ligands in exploiting aqueous Cu(I) catalysis thus highlights the many unexplored potential of mechanical bond as a design element for exploring transition metal catalysis under challenging conditions.

Ionic Liquid-accelerated Growth of Covalent Organic Frameworks with Tunable Layer-stacking.

Layer-stacking behaviors are crucial for two-dimensional covalent organic frameworks (2D COFs) to define their pore structure, physicochemical properties, and functional output. So far, fine control over the stacking mode without complex procedures remains a grand challenge. Herein, we proposed a "key-cylinder lock mimic" strategy to synthesize 2D COFs with a tunable layer-stacking mode by taking advantage of ionic liquids (ILs). The staggered (AB) stacking (unlocked) COFs were exclusively obtained by incorporating ILs of symmetric polarity and matching molecular size; otherwise, commonly reported eclipsed (AA) stacking (locked) COFs were observed instead. Mechanistic study revealed that AB stacking was induced by a confined interlocking effect (CIE) brought by anions and bulky cations of the ILs inside pores ("key" and "cylinder", respectively). Excitingly, this strategy can speed up production rate of crystalline powders (e.g., COF-TAPT-Tf@BmimTf2N in merely 30 minutes) under mild reaction conditions. This work highlights the enabling role of ILs to tailor the layer stacking of 2D COFs and promotes further exploration of their stacking mode-dependant applications.

Interlocking intramedullary nail for forearm diaphyseal fractures in adults-A systematic review and meta-analysis of outcomes and complications.

PURPOSE: The purpose of this systematic review is to examine the outcomes, complications, and potential advantages of using anatomical interlocking intramedullary nails (IMN) in the treatment of radius and ulnar shaft diaphyseal fractures in adults. METHODS: Medline, Embase, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases were searched between January 2000 and January 2023. Studies meeting criteria were observational or randomized controlled trials evaluating outcomes in IMN for adult diaphyseal forearm fractures. Standardized data extraction was performed and a quality assessment tool was used to evaluate individual study methodology. Descriptive statistics for interventions, functional outcomes, and complications were reported. Meta-analysis was performed for patient-reported outcome measures and operative time. RESULTS: A total of 29 studies involving 1268 patients were included with 764 (60%) undergoing IMN, 21% open reduction and internal fixation (ORIF), and 9% hybrid fixation. There was no significant difference between groups in DASH and Grace-Eversmann scores. Operative time was significantly shorter in IMN compared with ORIF. The DASH scores were: 13.1 ± 6.04 for IMN, 10.17 ± 3.98 for ORIF, and 15.5 ± 0.63 in hybrids. Mean operative time was 65.3 ± 28.7 in ORIF and 50.8 ± 17.7 in IMN. Complication rates were 16.7% in the IMN group, 14.9% in ORIF, and 6.3% in hybrid constructs. There were 11 cases of extensor pollicis rupture in the IMN group. Average IMN pronation and supination were 78.3° ± 7.9° and 73° ± 5.0°, respectively. Average ORIF pronation and supination was 82.15° ± 1.9° and 79.7° ± 4.5°, respectively. CONCLUSIONS: Similar functional outcomes and complication rates along with shorter operative times can be achieved with IMN compared with ORIF. The use of IMN is promising, however, higher quality evidence is required to assess appropriate indications, subtle differences in range of motion, implant-related complications, and cost-effectiveness. Trail Registration PROSPERO (International Prospective Register of Systematic Reviews) (ID: CRD42022362353).

Racism and Health: Three Core Principles.

Policy Points Racism operates in conjunction with interlocking forms of oppression, so it must be addressed relationally. Racism catalyzes processes of cumulative disadvantage as it extends across multiple policy domains along the life course, so it necessitates multifaceted policy solutions. Racism is a function of power relations, so the redistribution of power is a necessary precursor to health equity.

Holding in the stream: convergent evolution of suckermouth structures in Loricariidae (Siluriformes).

Suckermouth armoured catfish (Loricariidae) are a highly speciose and diverse freshwater fish family, which bear upper and lower lips forming an oral disc. Its hierarchical organisation allows the attachment to various natural surfaces. The discs can possess papillae of different shapes, which are supplemented, in many taxa, by small horny projections, i.e. unculi. Although these attachment structures and their working mechanisms, which include adhesion and interlocking, are rather well investigated in some selected species, the loricariid oral disc is unfortunately understudied in the majority of species, especially with regard to comparative aspects of the diverse oral structures and their relationship to the ecology of different species. In the present paper, we investigated the papilla and unculi morphologies in 67 loricariid species, which inhabit different currents and substrates. We determined four papilla types and eight unculi types differing by forms and sizes. Ancestral state reconstructions strongly suggest convergent evolution of traits. There is no obvious correlation between habitat shifts and the evolution of specific character states. From handling the structures and from drying artefacts we could infer some information about their material properties. This, together with their shape, enabled us to carefully propose hypotheses about mechanisms of interactions of oral disc structures with natural substrates typical for respective fish species.

Year-round monitoring of chloride releases from three zero-exfiltration permeable pavements and an asphalt parking lot.

Winter deicers, though essential for maintaining safe pavement conditions in winter, increase chloride (Cl-) concentrations in receiving water bodies above recommended environmental guidelines. Zero-exfiltration or lined permeable pavement is an important technological innovation for controlling particulate-bound pollutants at the source. As stormwater does not infiltrate into the ground, soluble pollutants like Cl- are ultimately discharged into receiving water bodies. Our aim was to examine Cl- concentrations in effluents from three zero-exfiltration permeable pavement cells (Permeable Interlocking Concrete Pavement (PICP), Pervious Concrete (PC), Porous Asphalt (PA)) and compare them with runoff from a Conventional Asphalt (ASH) cell. The study conducted at a parking lot in St. Catharines, Ontario, Canada, from January 2016 to May 2017 observed that the permeable pavements provided only temporary attenuation of Cl- during winter but exhibited a quick release during spring melt. Cl- concentrations and loadings were different for each permeable pavement system in terms of timing and magnitude. Cl- concentration in ASH runoff frequently had very high spikes (21,780 mg/L); however, the median winter Cl- concentration in ASH runoff was lower than Cl- levels in the permeable pavements' effluents and later declined drastically after spring melt, but in few instances, was above the chronic water quality guideline (120 mg/L). The average event mean concentration (EMC) of Cl- was 1600 and 120 mg/L in the permeable pavements' effluents during salting and non-salting season, respectively. In one year, each permeable pavement system released approximately 67-81 kg of Cl- with significant differences being observed in Cl- loads between the 2016 and 2017 seasons. Therefore, a multi-year data collection and monitoring plan captured the variability in winter conditions. The study provided insights into the behaviour, retention and release of Cl- from traditional and permeable hardscape surfaces and possible avenues for Cl- attenuation, source control and aquatic habitat conservation.

Preoperative estimation of humerus intramedullary nail length using clinical landmarks.

PURPOSE: Intramedullary interlocking nailing is one of the accepted methods of treating humerus diaphyseal fractures. Appropriate nail length and diameter are of paramount importance to achieve a stable fracture fixation. Estimating the nail length can be as challenging in certain cases as it is important. This study aims to provide an easy-to-use formula utilizing clinical measurements from contra lateral arm to accurately estimate humeral nail length. METHODS: This descriptive cross-sectional study was conducted at 3 tertiary care hospitals in Mangalore, India. Patients above the age of 18 years coming to the outpatient department with elbow, shoulder or arm complaints requiring radiological investigation from July 2021 to July 2022 were included. Patients with fractures or dislocations of upper limbs, malunited or non-united fractures of upper limbs, congenital or developmental deformities and patients with open growth plates were excluded. Patients' variables (like age and gender), radiological humerus length and contralateral arm clinical measurements were recorded. An independent samples t-test was used for univariate analysis, and linear regression analysis was done to estimate the desired nail length using the clinical measurement of the humerus (cm) in both genders separately. The significance level was set at p < 0.05. RESULTS: Our study included 204 participants of which 108 were male and 96 were female. The formula for predicting humeral nail length in males is (-2.029) + (0.883 × clinical measurement). The formula for females is 1.862 + (0.741 × clinical measurement). A simplified formula to determine humeral nail length is 0.9 clinical length - 2 cm (in males) and 0.7 × clinical length + 2 cm (in females). CONCLUSION: To improve the stability of fixation with intramedullary nails it is imperative to select the appropriate nail length. There have been studies that devised reliable methods of determining nail lengths in the tibia and femur using preoperative clinical measurements. A similar clinical method of determining humeral nail length is lacking in the literature. Our study was able to correlate radiological lengths of the humerus medullary canal with clinical measurements performed using anatomical landmarks to arrive at a formula. This allows for a reliable and easy nail length determination preoperatively.

A comparison of functional and radiological outcome of combine compression antegrade intertrochanteric nail (InterTan) and proximal femoral nail anti-rotation II (PFNA-II) in elderly patients with intertrochanteric fractures.

Objective: To compare the functional and radiological outcome of combine compression interlocking intramedullary nail (InterTan) and proximal femoral nail anti-rotation II (PFNA-II) in the treatment of elderly patients with intertrochanteric fractures. Methods: As a retrospective cohort study, records of 88 patients with intertrochanteric fractures treated in our hospital from January 1st, 2019 to July 31st, 2021 were retrospectively reviewed. According to treatment records, it included 45 patients treated with InterTan (Group-A) and 43 patients treated with PFNA-II (Group-B). The operation safety and functional rehabilitation of the two groups were compared and analyzed. Results: This study included 88 patients with intertrochanteric fractures (mean [SD] age, 68.72 [0.10] years at baseline), of whom 52 (59.09%) were males and 36 (40.91%) were females. Operation time and intraoperative blood loss in Group-B were less than Group-A, while fracture healing time was shorter in Group-A. The fracture separation distance was measured four weeks after the operation. The widening rate of the fracture line in Group-A was lower than Group-B (4.4% vs.18.6%; P<0.05). The incidence of complications in Group-A was lower than Group-B (4.4% vs.18.6%; P<0.05). At three, six and twelve months after the operation, the Harris hip score of the two groups was higher than at discharge (P<0.05), with no significant difference between groups (P>0.05). Conclusions: We found no significant difference in the functional outcome in elderly patients with intertrochanteric fractures treated with InterTan and PFNA-II. Early fracture healing and reduced complication rate however has been noted with InterTan.

Energy mapping of the genetic code and genomic domains: implications for code evolution and molecular Darwinism.

When the iconic DNA genetic code is expressed in terms of energy differentials, one observes that information embedded in chemical sequences, including some biological outcomes, correlate with distinctive free energy profiles. Specifically, we find correlations between codon usage and codon free energy, suggestive of a thermodynamic selection for codon usage. We also find correlations between what are considered ancient amino acids and high codon free energy values. Such correlations may be reflective of the sequence-based genetic code fundamentally mapping as an energy code. In such a perspective, one can envision the genetic code as composed of interlocking thermodynamic cycles that allow codons to 'evolve' from each other through a series of sequential transitions and transversions, which are influenced by an energy landscape modulated by both thermodynamic and kinetic factors. As such, early evolution of the genetic code may have been driven, in part, by differential energetics, as opposed exclusively by the functionality of any gene product. In such a scenario, evolutionary pressures can, in part, derive from the optimization of biophysical properties (e.g. relative stabilities and relative rates), in addition to the classic perspective of being driven by a phenotypical adaptive advantage (natural selection). Such differential energy mapping of the genetic code, as well as larger genomic domains, may reflect an energetically resolved and evolved genomic landscape, consistent with a type of differential, energy-driven 'molecular Darwinism'. It should not be surprising that evolution of the code was influenced by differential energetics, as thermodynamics is the most general and universal branch of science that operates over all time and length scales.

Holding on or falling off: The attachment mechanism of epiphytic Anthurium obtusum changes with substrate roughness.

PREMISE: For vascular epiphytes, secure attachment to their hosts is vital for survival. Yet studies detailing the adhesion mechanism of epiphytes to their substrate are scarce. Examination of the root hair-substrate interface is essential to understand the attachment mechanism of epiphytes to their substrate. This study also investigated how substrate microroughness relates to the root-substrate attachment strength and the underlying mechanism(s). METHODS: Seeds of Anthurium obtusum were germinated, and seedlings were transferred onto substrates made of epoxy resin with different defined roughness. After 2 months of growth, roots that adhered to the resin tiles were subjected to anchorage tests, and root hair morphology at different roughness levels was analyzed using light and cryo scanning electron microscopy. RESULTS: The highest maximum peeling force was recorded on the smooth surface (glass replica, 0 µm). Maximum peeling force was significantly higher on fine roughness (0, 0.3, 12 µm) than on coarse (162 µm). Root hair morphology varied according to the roughness of the substrate. On smoother surfaces, root hairs were flattened to achieve large surface contact with the substrate. Attachment was mainly by adhesion with the presence of a glue-like substance. On coarser surfaces, root hairs were tubular and conformed to spaces between the asperities on the surface. Attachment was mainly via mechanical interlocking of root hairs and substrate. CONCLUSIONS: This study demonstrates for the first time that the attachment mechanism of epiphytes varies depending on substrate microtopography, which is important for understanding epiphyte attachment on natural substrates varying in roughness.

Calcaneous interlocking nail treatment for calcaneous fracture: a multiple center retrospective study.

BACKGROUND: Minimally invasive treatments for calcaneous fractures have the same outcomes and fewer complications. However, they are technically demanding, and there are a lack reduction tools. To overcome these problems, a calcaneous interlocking nail system was developed that can make reduction and fixation minimally invasive and effective. We retrospectively studied the calcaneous fracture variables intraoperatively and followed up to evaluate the outcomes of patients treated with the calcaneous interlocking nail system. METHODS: All patients in 7 institutions between October 2020 and May 2021 who had calcaneous fractures treated with calcaneous interlocking nails were retrospectively analyzed. The patient characteristics, including age, sex, injury mechanism, Sanders type classification, smoking status, and diabetes were recorded. The calcaneous interlocking nail and standard surgical technique were introduced. The intraoperative variables, including days waiting for surgery, surgery time, blood loss, incision length, and fluoroscopy time, were recorded. The outcomes of complications, AOFAS scores and VAS scores were recorded and compared with other similar studies. RESULTS: Fifty-nine patients were involved in this study; 54 were male; 5 were female; and they had an average age of 47.5 ± 9.2 years (range 25-70). 2 of these fractures were Sanders type I, 28 of these fractures were Sanders type II, 27 of these fractures were Sanders type III, and 2 of these were Sanders type IV. The surgery time was 131.9 ± 50.5 (30-240) minutes on average. The blood loss was 36.9 ± 41.1 (1-250) ml. The average incision length was 3.5 ± 1.8 (1-8) cm; 57 were sinus tarsi incisions; and 2 were closed fixations without incisions. The average fluoroscopy time was 12.3 ± 3.6 (10-25) seconds during the surgery. The VAS score of patients on the day after surgery was 2.4 ± 0.7 (1-3). The AOFAS ankle-hindfoot score in patients who had a follow-up of at 12 months was 93.3 ± 3.6(85-99). During the follow-up, all patients' functional outcomes were good. One patient had a superficial infection. The rate of complications of the 59 patients was 1.7% (1/59). CONCLUSION: The calcaneous interlocking nail system can have satisfactory reduction and fixation in calcaneous fractures, even in Sanders type IV. The outcomes of follow-up showed good function. The calcaneous interlocking nail could be an alternative method for minimally invasive calcaneous fracture fixation.

Applicability of Magnetic Sensors in Interlocking Systems.

Rail interlocking systems follow the progress of technology and train speeds. Nowadays, new systems are designed based on microcontrollers and reliable software, requiring many hours of testing to ensure their proper functionality and bug-free coding. However, in many countries, there are still older relay solutions implemented that are not envisaged to be upgraded in the near future partially due to costs but mainly due to the fact they function very well, being based on a highly reliable element: the relay. However, specialized maintenance personnel are becoming more difficult to find, so automation systems that check the proper relay functionality are a key element to ensure a longer lifetime of existing systems. In this article, the authors present a monitoring solution based on magnetic sensors that proved capable of provide reliable information about the relays, hence revealing the first step in a relay automated control system.

Use of a locking stem for reverse shoulder arthroplasty is a rare but reliable option.

INTRODUCTION: RSA is widely used in the treatment of complex trauma or degenerative changes of the shoulder. Strong primary fixation of the stem is necessary to prevent any loosening of the stem and subsequent revision. Presently, cement fixation or press-fit fixation are two options for humeral fixation, though each has its own limitations and risks. The aim of the current study is to evaluate the effectiveness of an alternative option involving a distal screw interlocking system for fixation of the humeral stem from initial implantation. METHODS: We performed a retrospective multicenter study of patients implanted with the Humelock Reversed® stem RSA that can be locked with distal humeral screws in cases of operative poor press fit or to modulate the lengthening of the arm via prosthetic humeral height. Seventy-two patients with a minimum two year follow-up were included, 13 for acute trauma, 42 for degenerative changes, and 17 for revision surgery. RESULTS: No difference was seen in radiological or clinical results for patients with or without interlocking screw primary stabilization. For non-trauma patients, the mean raw Constant score improved significantly from 31 (± 12) to 71 (± 12). For trauma patients, the mean raw Constant score for trauma (63.4) was significantly lower than for non-trauma cases (72.1) (p < 0.001). Analysis of the filling ratio demonstrated that interlocking screws were not used for lower filling ratios and that midterm fixation of the stem is not negatively impacted by distal interlocking screw fixation. DISCUSSION: Even if use of a distal interlocking screw fixation system is rare, it can be useful for patients with poor quality fixation of stemmed RSA. CONCLUSION: Use of an interlocking screw system to stabilize the stem in RSA provides good immediate and midterm stability of the implant allowing for clinical and radiological outcomes comparable to those obtained with press-fit fixation alone.

Focus on interlocking intramedullary nailing without fluoroscopy in resource-limited settings: strategies, outcomes, and outlook.

INTRODUCTION: Closed static interlocking nailing with c-arm guidance is the standard procedure for the treatment of closed diaphyseal fractures. In low-income settings, it is still very difficult to carry out such procedures because of few or absent image intensifiers (c-arm) despite the necessity. Authors provide a review of the literature on interlocking intramedullary nailing without fluoroscopy in resource-limited settings, followed by strategies, outcomes, and outlook. MATERIALS AND METHOD: A comprehensive search of the PubMed, Web of Science, Embase, and Cochrane Library databases was performed with the help of a biomedical information specialist. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed. RESULTS: We identified 15 series of interlocking intramedullary nailing without fluoroscopy in resource-limited settings. All papers focused on the care for long bones (humerus, femur, tibia). All studies discussed the quality of the nailing operative procedure. The entry point was described in five series; the nail insertion in the proximal and distal medullary canal was good in all studies. The distal locking was missed between 0 and 27%. DISCUSSION: Intraoperative strategies depend on the type of bone affected, the opening of the fracture site, the fracture line, and the availability of a functional orthopaedic table. Three techniques to insert the nail in the proximal and distal fracture fragment with reduction of the fracture site are described. Insertion of distal screws is possible by using ancillary devices. Outcomes are comparable to those of the series using c-arm guidance. In low-income countries, it can been proposed as an alternative to the gold standard in resources constraints settings. In high-income setting this technique can help to reduce exposure of X-ray. CONCLUSION: There is a need to improve equipment in low-income countries hospitals to make trauma surgery with c-arm a gold standard with a minimal exposure to radiation.

Treatment of tibial shaft nonunion with a retained nail in morbidly obese patients.

PURPOSE: Morbid obesity is a rising worldwide health problem. Tibial shaft nonunion with retained intramedullary nail (IMN) in the morbidly obese is a challenging orthopaedic problem. Prolonged immobilization carries a significant risk of complications. This study aimed to investigate whether decortication and cancellous bone grafting with the application of a circular external fixator (CEF) over the preexisting IMN can achieve fracture union and avoid serious complications. METHODS: We retrospectively reviewed 27 consecutive morbidly obese patients treated for tibial diaphysis aseptic nonunion after failed IMN. All cases were treated with osteoperiosteal decortication, cancellous bone grafting, and fixation with CEF over the IMN. Peri-operative multidisciplinary patient evaluation included internal medicine, cardiology, chest, vascular surgery, and anesthesia consultations. The union rate, bone results, functional results, and complications were recorded. RESULTS: The mean age of the patients was 37.9 years. The mean BMI was 45.8. Sixteen cases (59.3%) were treated for hypertrophic nonunion, while 11 cases (40.7%) were treated for atrophic nonunion. Seven cases (25.9%) had open initial injury, 14 cases (51.9%) had associated comorbidities, and seven cases (25.9%) were smokers. Twenty-six cases united. The mean time to union was 5.2 months. Bone results and functional results were good to excellent in 96.3% of the cases. We recorded 25 complications in 21 patients. However, most of the complications were minor. CONCLUSION: Decortication and cancellous bone grafting with the application of CEF over the preexisting nail is a safe and reliable treatment method for aseptic tibial shaft nonunion with retained IMN in morbidly obese patients.

Biomechanical analysis of recently released cephalomedullary nails for trochanteric femoral fracture fixation in a human cadaveric model.

BACKGROUND: Recently, two novel concepts for intramedullary nailing of trochanteric fractures using a helical blade or interlocking dual screws have demonstrated advantages as compared to standard single-screw systems. However, these two concepts have not been subjected to a direct biomechanical comparison so far. The aims of this study were to investigate in a human cadaveric model with low bone quality (1) the biomechanical competence of nailing with the use of a helical blade versus interlocking screws, and (2) the effect of cement augmentation on the fixation strength of the helical blade. METHODS: Twelve osteoporotic and osteopenic human cadaveric femoral pairs were assigned for pairwise implantation using either a short TFN-ADVANCED Proximal Femoral Nailing System (TFNA) with a helical blade head element or a short TRIGEN INTERTAN Intertrochanteric Antegrade Nail (InterTAN) with interlocking screws. Six osteoporotic femora, implanted with TFNA, were augmented with bone cement. Four groups were created: group 1 (TFNA) paired with group 2 (InterTAN), both consisting of osteopenic specimens, and group 3 (TFNA augmented) paired with group 4 (InterTAN), both consisting of osteoporotic specimens. An unstable trochanteric AO/OTA 31-A2.2 fracture was simulated and all specimens were tested until failure under progressively increasing cyclic loading. RESULTS: Stiffness in group 3 was significantly higher versus group 4, p = 0.03. Varus (°) and femoral head rotation around the femoral neck axis (°) after 10,000 cycles were 1.9 ± 1.0/0.3 ± 0.2 in group 1, 2.2 ± 0.7/0.7 ± 0.4 in group 2, 1.5 ± 1.3/0.3 ± 0.2 in group 3 and 3.5 ± 2.8/0.9 ± 0.6 in group 4, being significantly different between groups 3 and 4, p = 0.04. Cycles to failure and failure load (N) at 5° varus or 10° femoral head rotation around the neck axis in groups 1-4 were 21,428 ± 6020/1571.4 ± 301.0, 20,611 ± 7453/1530.6 ± 372.7, 21,739 ± 4248/1587.0 ± 212.4 and 18,622 ± 6733/1431.1 ± 336.7, being significantly different between groups 3 and 4, p = 0.04. CONCLUSIONS: Nailing of trochanteric femoral fractures with use of helical blades is comparable to interlocking dual screws fixation in femoral head fragments with low bone quality. Bone cement augmentation of helical blades provides significantly greater fixation strength compared to interlocking screws constructs.

Validity of a Novel Digitally Enhanced Skills Training Station for Freehand Distal Interlocking.

Background and Objectives: Freehand distal interlocking of intramedullary nails is technically demanding and prone to handling issues. It requires precise placement of a screw through the nail under fluoroscopy guidance and can result in a time consuming and radiation expensive procedure. Dedicated training could help overcome these problems. The aim of this study was to assess construct and face validity of new Digitally Enhanced Hands-On Surgical Training (DEHST) concept and device for training of distal interlocking of intramedullary nails. Materials and Methods: Twenty-nine novices and twenty-four expert surgeons performed interlocking on a DEHST device. Construct validity was evaluated by comparing captured performance metrics-number of X-rays, nail hole roundness, drill tip position and drill hole accuracy-between experts and novices. Face validity was evaluated with a questionnaire concerning training potential and quality of simulated reality using a 7-point Likert scale. Results: Face validity: mean realism of the training device was rated 6.3 (range 4-7). Training potential and need for distal interlocking training were both rated with a mean of 6.5 (range 5-7), with no significant differences between experts and novices, p ≥ 0.234. All participants (100%) stated that the device is useful for procedural training of distal nail interlocking, 96% wanted to have it at their institution and 98% would recommend it to colleagues. Construct validity: total number of X-rays was significantly higher for novices (20.9 ± 6.4 versus 15.5 ± 5.3, p = 0.003). Success rate (ratio of hit and miss attempts) was significantly higher for experts (novices hit: n = 15; 55.6%; experts hit: n = 19; 83%, p = 0.040). Conclusion: The evaluated training device for distal interlocking of intramedullary nails yielded high scores in terms of training capability and realism. Furthermore, construct validity was proven by reliably discriminating between experts and novices. Participants indicate high further training potential as the device may be easily adapted to other surgical tasks.