Search Results (135)

Background/Objectives: Spacer dislocation is among the most frequent mechanical complications after revision total hip arthroplasty for periprosthetic hip infection. Spacer dislocations may be managed conservatively, but there are no guidelines on the rehabilitation of these patients, and the restriction of weight bearing is still under debate. Methods: We first report the case of a patient with hip spacer cranial dislocation, judged unfit to be surgically treated once more for a medium period, who started a rehabilitation program with partial weight bearing. Results: After two weeks of inpatient rehabilitation, the patient started to maintain the standing position with partial weight bearing on the affected side. Following hospital discharge we continued rehabilitation in the outpatient clinic. Despite the finding of the denervation of the ipsilateral quadriceps, three months after admission, she was able to walk for short distances using a walker, initially with the help of a therapist and then with supervision. About one year later, she was able to undergo the reimplantation of the definitive prosthesis. Conclusions: Despite the spacer dislocation, walking short distances is a feasible goal, even with assistance, wearing a brace and using a walker. Future research is needed to confirm and expand upon this observation and to understand the mechanisms underlying the development of neurological complications to implement effective prevention strategies. Full article

Background/Objectives: Acetabular fractures in older adults pose significant challenges due to bone fragility, complex fracture patterns, and increased comorbidities. Surgical management, including isolated open reduction and internal fixation (ORIF) and ORIF combined with acute total hip arthroplasty (THA) (combined hip procedure—CHP), have advanced considerably. Nevertheless, optimal postoperative rehabilitation and particularly weight-bearing (WB) recommendations remain controversial and inconsistent. This review aims to assess rehabilitation protocols, focusing on WB strategies following the surgical treatment of acetabular fractures in older adults. It also examines differences in WB restrictions by surgical technique (ORIF vs. CHP) and their impact on recovery, complications, reoperations, and mortality. Methods: A systematic review of PubMed, Embase, and the Cochrane Library (2006–2024) included studies involving patients aged ≥65 years treated surgically for displaced acetabular fractures. Data included WB protocols (full, partial, toe-touch), length of stay (LOS), healing, functional outcomes (mobility, Harris and Oxford Hip Scores), complications, reoperations, delayed THA, compliance, readmission, and mortality. Due to heterogeneity, findings were narratively synthesized. Risk of bias was assessed using ROBINS-I and RoB2. Results: Twenty studies involving 929 patients (530 isolated ORIF, 399 CHP) were analyzed. The overall mean follow-up was 3.5 years (range: 1–5.25 years). Postoperative WB protocols were reported in 19 studies (95%). Immediate full WB was permitted in 0% of isolated ORIF studies (0/13), with partial WB recommended by 62% (8/13) for durations typically between 6 and 12 weeks. On the other hand, immediate full WB was allowed in 53% (9/17) of CHP studies. Functional outcomes were moderate following isolated ORIF (mean HHS: 63–82 points), with delayed THA conversion rates ranging from 16.5% to 45%. CHP demonstrated superior functional outcomes (mean HHS: 70–92 points), earlier independent ambulation, and higher patient satisfaction (74–90%), yet increased orthopedic complications, including dislocations (8–11%) and implant loosening (up to 18%). LOS varied from 12 to 21 days (mean 16 days) for isolated ORIF and from 8 to 25 days (mean 17 days) for CHP. Readmission within 30 days was not explicitly reported in any study. Mortality at 1 year varied significantly (ORIF: 0–25%; CHP: 0–14%), increasing markedly at long-term follow-up (up to 42% ORIF, up to 70% CHP at five years). Compliance with WB restrictions was monitored in only two studies (11%). Conclusions: Postoperative rehabilitation after acetabular fracture surgery in older adults remains inconsistent and lacks standardization. Combining ORIF with acute THA may enable earlier weight-bearing and improved short-term function but carries risks such as dislocation and implant loosening. In contrast, isolated ORIF avoids these implant-related complications but often requires prolonged weight-bearing restrictions. Robust evidence is still missing. Future trials are essential to establish standardized protocols that balance mechanical protection and functional recovery. Full article

Material defects resulting from manufacturing and processing can significantly affect material properties. Voids and dislocations are material defects considered in this study, in which a numerical solution of the 3D stress field of a dislocation line (infinite or finite) outside a cylindrical void (either parallel to the cylinder axis or not) is developed using the collocation point method. The collocation point method is utilized to solve ordinary differential equations, partial differential equations, differential-algebraic equations, and integral equations by enforcing the solution at a set of spatial collocation points. Analytical solutions for such three-dimensional (3D) problems, e.g., a dislocation line or segment near an internal void of any shape, were not found. Therefore, a numerical solution for this problem has been constructed in this paper. The numerical solution developed is verified using an existing two-dimensional analytical solution. The numerical results and the 2D analytical solution are in perfect agreement as long as the cylindrical void is sufficiently long and the Saint-Venant’s principle is followed. Full article

Introduction: Monteggia fractures, first described by Giovanni Battista Monteggia, involve a fracture of the proximal ulna with anterior dislocation of the radial head. Bado’s 1967 classification divides these injuries into four types. Rare mixed patterns exist, overlapping with other forearm injuries such as Galeazzi and Essex–Lopresti lesions. These complex fractures/dislocations pose significant diagnostic and therapeutic challenges and are not adequately represented in current classification systems. Methods and Case Presentation: We report the case of a 56-year-old woman with a complex forearm injury sustained from a fall, presenting with radial head fracture/dislocation, mid-shaft radial fracture, distal ulna fracture, and ulnar collateral ligament rupture. Intraoperative imaging confirmed DRUJ stability and partial interosseous membrane disruption. Surgical management included radial head prosthesis implantation, radial shaft fixation with an anatomical locking plate, intramedullary nailing of the distal ulna, and ligament reconstruction. At two-year follow-up, the patient demonstrated full recovery of elbow flexion–extension and satisfactory forearm function. A narrative literature review was also conducted, focusing on hybrid injury variants. Results: Intraoperative examination under anesthesia revealed good elbow stability with 130° flexion, 15° extension lag, and forearm pronation/supination of 70°/60°. An initial Mayo Elbow Performance Score (MEPS) of 65 was recorded, limited by range of motion and stability. Pain during passive mobilization was mild, with a Visual Analogue Scale (VAS) score of 3/10. Postoperative recovery included 15 days of immobilization followed by structured rehabilitation. At two years, the patient regained full elbow flexion–extension but had residual deficits in pronation–supination, attributed to pre-existing conditions. Conclusions: This case illustrates a previously unreported hybrid Monteggia variant, combining features of Monteggia, Galeazzi, and Essex–Lopresti injuries. It highlights the limitations of current classification systems and supports the need for an expanded diagnostic framework. Successful management required a multidisciplinary surgical approach tailored to the injury’s complexity. Further studies are warranted to refine classification and treatment strategies for these rare combined injuries. Full article

Objectives: Intraocular lens dislocation is a well-recognized complication of cataract surgery, necessitating secondary interventions such as retropupillary iris-claw IOL implantation. While effective, this procedure requires larger incisions that may induce significant astigmatism. This study aimed to (1) evaluate anterior chamber changes following retropupillary ICIOL implantation and (2) compare surgically induced astigmatism between corneal and scleral incision techniques. Methods: In this prospective cohort study, patients with IOL dislocation underwent 25-gauge pars plana vitrectomy with ICIOL implantation. Anterior chamber depth, volume, and angle configuration were measured across 12 meridians preoperatively, at 1–1.5 months (short-term), and 5–6 months (long-term). Surgically induced astigmatism was compared between the corneal and scleral incision groups. Statistical analysis included Shapiro–Wilk, Mann–Whitney U, and repeated-measures ANOVA tests. Results: This prospective study included 40 patients (22 females, 18 males) with a mean age of 76.3 ± 5.38 years (range 65–86). Significant reductions in ACD and ACV occurred postoperatively (p < 0.05), with partial recovery at long-term follow up. Surgically induced astigmatism was markedly higher with corneal incisions versus scleral approaches (p < 0.01 short term; p < 0.05 long term). Anterior chamber angle changes varied by meridian but stabilized by 6 months. Conclusions: Retropupillary ICIOL implantation induces predictable anterior segment remodeling, with scleral incisions offering superior refractive stability. Surgical planning should prioritize scleral techniques to minimize surgically induced astigmatism while maintaining anatomical efficacy. Future innovations in IOL design may further reduce incision-related complications. Full article

This report examines the successful recovery of a feline that presented with multiple complex fractures and dislocations involving the facial and cranial structures resulting from a traffic accident. Diagnostic CT imaging identified significant injuries, including luxation of the left temporomandibular joint (TMJ), a mandibular symphyseal fracture, a hard palate fracture, and a left orbital fracture accompanied by severe exudate within the nasal cavity, compressing the left orbit and nasal passages. Importantly, no additional injuries were detected in the thoracic or abdominal regions, facilitating a more targeted treatment plan. The management of this case required extensive surgical intervention, including open reduction of the TMJ, stabilization of the mandibular symphysis, repair of the bony palate, and partial maxillectomy. After 20 days of ICU hospitalization, the feline fully recovered. This outcome is particularly noteworthy as the combination of severe injuries observed in this case is unprecedented in the veterinary literature. Consequently, it offers critical insights into both surgical techniques and postoperative management strategies applicable to similarly complex trauma cases. The feline’s full recovery, characterized by the restoration of normal daily functions, highlights the clinical significance of pursuing multiple, complex surgical procedures in cases of severe trauma. It serves as a valuable reference for advancing the understanding and management of severe facial trauma in veterinary practice. Full article

This study examines the mechanical behavior and deformation mechanisms of hot-forged 304L stainless steel for cryogenic applications such as LNG storage and low-temperature structural systems. Tensile testing revealed a significant strength increase from 618 MPa at room temperature to 1432 MPa at cryogenic temperatures, with elongation decreasing from 83.7% to 23.3%. Charpy impact testing showed a 28% reduction in absorbed energy at cryogenic temperatures due to enhanced strain-induced martensitic transformation (SIMT). The observed mechanical responses are attributed to reduced stacking fault energy (SFE) at lower temperatures, which promotes SIMT, deformation twinning, and dislocation interactions, affecting material strength and toughness. SEM and EBSD analysis confirmed extensive martensitic transformation, increased deformation twinning, and reduced remaining austenite, indicating a γ → ε → α’ transformation pathway that governs strain hardening. The high strain rate during Charpy impact testing induced localized adiabatic heating, partially suppressing SIMT and modifying fracture behavior by enhancing localized plasticity. These findings emphasize the interplay between SFE, strain rate, and phase transformation in governing the cryogenic mechanical performance of 304L stainless steel. Full article

Low-cost and low-alloy dual-phase (DP) steel with a tensile strength (TS) above 1000 MPa and high ductility is in great demand in the automobile industry. An approach to using a medium-carbon and fibrous DP structure for developing such new DP steel has been proposed. The microstructure and mechanical performance of fibrous DP steel obtained via partial reversion from martensite in Fe-C-Mn-Si low-alloy steel have been investigated. The TS of the as-quenched DP steel is above 1300 MPa, while the total elongation is less than 6%. The total elongation was increased to above 13%, with an acceptable loss in TS by performing additional tempering. The fibrous tempered-martensite/ferrite DP steel exhibits an excellent balance of strength and ductility, surpassing the current low-alloy DP steels with the same strength grade. Plate-like or quasi-spherical fine carbides were precipitated, and the relatively high-density dislocations were maintained due to the delay of lath recovery by the enrichment of Mn and C in martensite (austenite before quenching), contributing to the tempering softening resistance. In addition, nanotwins and a very small amount of retained austenite were present due to the martensite chemistry. High-density dislocations, fine carbide precipitation, and partially twinned structures strengthened the tempered martensite while maintaining relatively high ductility. Quantitative strengthening models and calculations were not included in the present work, which is an interesting topic and will be studied in the future. Full article

Additive manufacturing is increasingly used to produce metallic biomaterials, and post-processing is gaining increasing attention for improving the properties of as-built components. This study investigates the effect of work hardening followed by recrystallisation annealing on the tensile and nanoindentation behaviour of laser powder bed-fused (LPBF) 316L stainless steel, with the aim of optimising its mechanical properties. As-built and thermally stabilised (at 900 °C) specimens were prestrained in a uniaxially tensile manner at room temperature (0.12 plastic strain, ~75% of maximum work hardening) and subsequently annealed (at 900 °C or 1050 °C for 1 h). The microstructure and mechanical properties were then characterised by optical microscopy, SEM, EBSD, XRD, nanoindentation, and tensile testing. It was found that prestraining increased yield tensile strength (YTS) 1.2–1.7 times (to 690–699 MPa) and ultimate tensile strength (UTS) ~1.2 times (to 762–770 MPa), but decreased ductility 1.5 times. Annealing led to recovery and partial static recrystallisation, decreasing YTS (to 403–427 MPa), restoring ductility, and increasing the strain hardening rate; UTS and indentation hardness were less affected. Notably, the post-LPBF thermal stabilisation hindered recrystallisation and increased its onset temperature. Mechanical property changes under prestraining and annealing are discussed with respect to microstructure and crystalline features (microstrain, crystal size, dislocation density). All specimens exhibited ductile fractures with fine/ultra-fine dimples consistent with the as-built cellular structure. The combined treatment enhanced tensile strength whilst preserving sufficient ductility, achieving a strength–ductility product of 40.3 GPa·%. This offers a promising approach for tailoring LPBF 316L for engineering applications. Full article

Materials utilized in extreme environments, such as those necessitating protection and impact resistance at cryogenic temperatures, must exhibit high strength, ductility, and structural stability. However, most alloys fail to maintain adequate toughness at cryogenic temperatures, thereby compromising their safety during cryogenic temperature service. This study investigates the quasi-static mechanical properties of a CoCr₀.₄NiSi₀.₃ medium-entropy alloy (MEA) at room temperature, −75 °C, and −150 °C. The deformation behavior and mechanisms responsible for strengthening and toughening at reduced cryogenic temperatures are analyzed, revealing that decreasing cryogenic temperature enhances the strength of the as-cast MEA. Specifically, both the yield strength (YS) and ultimate tensile strength (UTS) of the MEA increase significantly with decreasing temperature during cryogenic tensile testing. Under tensile testing at −150 °C, the YS reaches 617.5 MPa, the UTS is 1055.0 MPa, and the elongation to fracture remains approximately 21.0% at both −150 °C and −75 °C. After cryogenic temperature tensile deformation, the matrix exhibits a dispersed distribution of nanoscaled tetragonal and orthorhombic phases, a coherent hexagonal close-packed phase, L1₂ phase and layered long-period stacking ordered (LPSO) structures, which are rarely observed in the cryogenic deformation of metals and alloys. The metastable phase evolution path of this MEA at cryogenic temperatures is closely associated with the decomposition of perfect dislocations into a/6<112> Shockley partial dislocations and their subsequent evolution at reduced cryogenic temperatures. At −75 °C, the a/6<112> Shockley partial dislocation interacts with the L1₂ phase to form antiphase boundaries (APBs) approximately 3 nm thick. At −150 °C, two phase transition paths from stacking faults (SFs) to nanotwins and LPSO occur, leading to the formation of layered LPSO structures and deformation-induced nanotwins. The dispersion of these coherent nanophases and nanotwins induced by the reduced stacking fault energy under cryogenic temperatures is the key factor contributing to the excellent balance of strength and plasticity in the as-cast MEA, providing an important basis for research on the cryogenic mechanical properties of CoCrNi-based MEAs. Full article

Background/Objectives: This report details a rare instance of an infant with achondroplasia developing acute tetraparesis after a cervical whiplash injury, highlighting key multidisciplinary management considerations and specific anesthetic strategies to mitigate potential risks. Case presentation: A 1-year-old boy with achondroplasia presented with acute tetraparesis after a whiplash injury. Initial craniocervical computed tomography demonstrated a reduced volume of the posterior fossa, foramen magnum stenosis, and ventriculomegaly, without any fractures or dislocations. Moreover, magnetic resonance imaging (MRI) revealed pathological signal changes in the medulla oblongata, cervical spinal cord in segments C1 and C2, and the posterior atlantoaxial ligament. After initial conservative therapy and head immobilization using a soft cervical collar, partial remission of the tetraparesis was achieved. Two weeks post-injury, microsurgical posterior fossa decompression extending to the foramen magnum and C1 laminectomy was performed under general anesthesia with intraoperative neuromonitoring. Following an unsuccessful intubation attempt using a fiberoptic bronchoscope, successful airway management was achieved using a combined technique incorporating video laryngoscopy. Venous access was secured under ultrasound guidance. The patient exhibited complete remission of neurological symptoms by the third postoperative month during follow-up. Conclusions: This case report underscores the crucial need for a multidisciplinary approach in managing children with achondroplasia, especially with foramen magnum stenosis and complex cervical spine injuries. Anesthetic management required meticulously planned airway strategies using advanced techniques like video laryngoscopy and fiberoptic bronchoscopy to reduce airway risks. It also highlights the importance of conservative therapy paired with timely neurosurgical intervention, resulting in the patient’s full recovery. Full article

The anomalous flow behavior of the γ′-Ni₃Al phase at high temperature is closely related to a cross-slip of $1/2⟨110⟩\left\{111\right\}$ super-partial dislocations. The acceleration of cross-slips induced by the addition of rhenium (Re) is known as Re-effects. In this work, by means of a series of lattice transitions, a hybrid model including a preexisting anti-phase boundary $\mathrm{APB}\left(111\right)$ was constructed to assess the difficulty of cross-slips of $1/2⟨110⟩\left\{111\right\}$ super-partial dislocations from $\left\{111\right\}$ planes to $\left\{001\right\}$ planes in the γ′-Ni₃Al phases, and the impact of the addition of Re on these dislocation mediated creep resistances was reinvestigated by first-principles calculations. The results showed that the addition of Re at preferential Al sublattice sites was indeed beneficial for the cross-slip of the first leading $1/2⟨110⟩\left\{111\right\}$ super-partial dislocations, and the existence of $\mathrm{APB}\left(111\right)$ could promote cross-slip of second leading $1/2⟨110⟩\left\{111\right\}$ super-partial dislocations. A detailed calculation of stacking fault energies demonstrated that an obvious Suzuki segregation of Re existed at $\mathrm{APB}\left(111\right)$ and $\mathrm{APB}\left(001\right)$, and Re preferentially occupied Ni sublattice sites. It is found Re-segregations at $\mathrm{APB}\left(111\right)$ were disadvantageous for the cross-slip of new $1/2⟨110⟩\left\{111\right\}$ super-partial dislocations, but the formation of more Kear-Wilsdorf dislocation locks could benefit from Re-segregations at $\mathrm{APB}\left(001\right)$. Full article

The effect of Nb on the microstructure evolution of the γ′ phase in Co-Ti-V alloys has been studied. The yield strength and ultimate strength of the alloys are measured via compression at 900 °C. This indicates that the alloys with 1% at. Nb present a dual γ and γ′ microstructure. A Co₃V phase exists in 2Nb and 3Nb alloys. The mismatch increases with the increment in Nb content. The yield strength of the alloys rises as the Nb addition increases. After compression at 900 °C, the <101>-type dislocation causes shearing of the γ′ phase in the plane of the base alloy. In the 1Nb alloy, the $<1\overline{1}$0>-type dislocation reacts at the γ/γ′ interface to generate 1/3<1$\overline{2}$1> super-partial dislocation, and then the γ′ phase is cut by this dislocation and stacking faults are formed. Full article

Industries operating in extreme conditions demand materials with exceptional strength, fatigue resistance, corrosion resistance, and formability. While AA5052 alloy is widely used in such industries due to its high fatigue strength and corrosion resistance, its strength frequently falls short of stringent standards. For AA5052 alloy, this study explores the combined use of solutionizing and cryo-rolling, followed by annealing, to improve strength. Although several alloys have been reported to undergo solution treatment before cryo-rolling, this study focuses on how post-processing via annealing can lessen the formability constraints usually connected to conventional cryo-rolling. The study sheds light on the ways that solutionizing, cryo-rolling, and annealing interact to affect the alloy’s mechanical characteristics. Microstructure analysis shows that solutionizing improves the grain structure by reducing dynamic recovery, promoting dislocation density, and facilitating precipitate formation. Sheets subjected to solutionizing + cryo-rolling and partially annealed at 250 °C produce optimal results. Interestingly, formability is decreased when cryo-rolling alone is used instead of cold rolling, whereas formability is successfully increased when solutionizing is used. Comparing solutionized + cryo-rolled sheets that are partially annealed at 250 °C to cold-rolled sheets that are annealed at the same temperature, the former show notable quantitative improvements: a notable 17% increase in ultimate strength, a 10% boost in yield strength, and a noteworthy 13% enhancement in microhardness. Formability has improved with the solutionized + cryo-rolled specimens by annealing. This proposed approach led to noticeable gains in formability, hardness, and strength, which would significantly improve material performance for industrial applications. Full article

Precipitation strengthening represents a crucial strengthening approach in the realm of metals, with particular significance for magnesium. In this study, a complex LPSO–precipitate structure, which is constituted of the principal secondary phases in Mg rare earth (RE) alloys, namely the Long-Period Stacking Ordered (LPSO) phase and the aging precipitate, was successfully fabricated within a Mg-11Y-1Al alloy. Subsequently, an in-depth investigation was conducted regarding the interaction between dislocations and this LPSO–precipitate structure under varying temperature conditions. The findings revealed that, at room temperature (RT), the aging precipitates effectively hindered the movement of basal dislocations, and the activation of non-basal dislocations is rather difficult, resulting in the alloy’s high strength and low plasticity. When the temperature was elevated to 200 °C, although non-basal slip could be initiated, the LPSO–precipitate structure was capable of blocking both basal and non-basal slips. Consequently, the alloy still demonstrated high strength and low plasticity. As the temperature further increased to 250 °C, dislocations could cut through the aging precipitate particles, and the interior of the grains could provide partial deformation. Hence, the tensile elongation of the alloy was significantly enhanced, increasing from 4% to 12% as the temperature was elevated from 200 °C to 250 °C. These results suggest that the LPSO–precipitate structure still exerts a remarkable strengthening effect at 200 °C. When the temperature reaches 250 °C, the plasticity of the alloy is improved but its strength decreases. The research outcomes presented in this paper offer a novel perspective for the precise tailoring of mechanical properties through precipitation strengthening within Mg-RE alloys. Full article