Metal failure and nonunion at L5-S1 after long instrumented fusion distal to pelvis for adult spinal deformity: Anterior versus transforaminal interbody fusion

Purpose Pseudoarthrosis and metal failure at L5-S1 following long fusion surgery for adult spinal deformity (ASD) remain major issues. Few studies report on which anterior column support technique is better in terms of achieving fusion and avoiding metal failures. Our study aimed to evaluate the fusion status and metal failure rate at L5-S1 after anterior lumbar interbody fusion (ALIF) versus transforaminal lumbar interbody fusion (TLIF). Methods The study population included patients aged >50 years who underwent surgery for ASD. Anterior column supports at L5-S1 using ALIF and TLIF were compared with ≥ 2-year follow-up. Fusion status on 2-year computed tomography (CT) scan, metal failure, visual analog scale (VAS), and Oswestry disability index (ODI) were evaluated. Results 98 patients were included in this study (53 ALIF group and 45 TLIF group). We achieved solid fusion on 2-year CT scans in 88.9% and 69.8% patients in the TLIF and ALIF group, respectively. Metal failure developed in nine (17.0%) and six (13.3%) patients in the ALIF and TLIF group, respectively. The most common failure type was unilateral L5-S1 rod fracture (7 and five patients in the ALIF and TLIF group, respectively). Only one patient with bilateral rod fractures in the ALIF group required revision surgery. There were no differences in the VAS and ODI scores at the last follow-up. Conclusions TLIF showed a better fusion rate than ALIF at L5-S1 after long instrumented fusion for ASD. However, the capacity to restore sagittal parameters was greater in the ALIF group. There were no differences between the groups regarding metal failure rate, revision surgery, or clinical outcomes.

The epidemiology of pelvis and acetabular fractures in Kuwait

Objectives: Pelvis fractures (PF) and acetabular fractures (AF) are major challenges in orthopedics. Epidemiological figures are not available for Kuwait, making it difficult to evaluate the success of future plans. This study aimed to analyze the epidemiology of pelvis and AF in Kuwait. Methods: A retrospective cross-sectional design was used by reviewing the Database of PF and AF of level II trauma center, Kuwait. Results: From October 2018 to September 2019, 2046 patients were admitted to the orthopedic wards of our hospital. PF prevalence was 3.66%; mean age (standard deviation) was 37.56 (18.09) years, and 74.5% were men. AF prevalence was 1.71%; mean age was 28.08 (17.77) years, and 71.6% were men. The most frequent mechanism of injury was motor vehicle accidents. Using the OTA/AO classification, the most frequent fracture of the PF was B1.1 fractures at 60.7%, and A1 fractures for AF at 80.0%. PF and AF were associated with other injuries in 54.4% and 38.2%, respectively. In terms of management, 24.3% of the patients with PF were managed operatively and the reported complications were metal failure (2.7%), post-operative infection (1.4%), and wound dehiscence (1.4%). The management of AF was operative in 54.3%, and the identified complication was only metal failure (2.9%). The mortality of PF was 2.7% and 0.0% for AF. Variables related to the ICU length of stay, mortality, and postoperative complications were explored. Conclusion: The epidemiological figures explored could help determine PF and AF’s burden in Kuwait and direct future management and preventive plans.

EXPERIMENTAL AND NUMERICAL FATIGUE ANALYSIS OF BRASS SHAFT SPECIMEN UNDER CYCLIC BENDING MOMENTS

Fatigue is a form of failure that occurs in structures subjected to dynamic and fluctuating stresses, where failure can occur at a stress level significantly lower than the tensile or yield strength of a static load under these circumstances. The term “fatigue” is used because, after a long period of repetitive stress or stress cycling, this form of failure typically occurs. Fatigue is important because it is the single largest cause of metal failure, estimated to account for about 90% of all metal failures; polymers and ceramics (except glasses) are also prone to this form of failure. This research is studying the failure analysis, fatigue life and endurance limit of brass metal experimental and numerical under cyclic bending moments

PHILOS plate fixation with polymethyl methacrylate cement augmentation of an osteoporotic proximal humerus fracture

PHILOS plate fixation in osteoporotic proximal humerus fracture of old age is well-known for high complication rate, especially metal failure, providing various augmentation techniques, such as calcium phosphate cement, allogenous or autologous bone graft. We report a case of PMMA augmentation to provide appropriate reduction with a significant mechanical support. This can be a treatment option for displaced unstable osteoporotic proximal humerus fracture with marked bony defect.

Energy Absorption Capability and Ballistic Resistance of Metallic Plates Subjected to High Velocity Impact

Energy absorption capability and ballistic resistance are the main parameters considered while choosing the material against impact loading. The need for light weight structures with high strength against impact loading is increased in automobiles and military application. In this paper, the energy absorbing capacity and ballistic resistance of the aluminium, steel and combination of steel composite plate is studied. 300300mm metallic plate is subjected to rigid projectile impact under high velocity. The energy absorbed during plastic deformation, residual velocity, ballistic limit and metal failure is obtained from the numerical analysis using advanced finite element code LS Dyna and validated with analytical method. From the results, it is observed that the monolithic steel plate provides better resistance than the aluminium plate and steel aluminium composite plate.

ANALISIS INTENSITAS DAN COVERAGE PROSES SHOT PEENING TERHADAP TEGANGAN SISA DAN KEKERASAN PADUAN AL 7075 T7351

AbstrakShot peening merupakan metode pengerjaan dingin dengan menumbukkan permukaan logam menggunakan partikel-partikel bulat yang berukuran kecil dan berkecepatan tinggi. Dengan proses shot peening dapat dikurangi inisiasi dan propagasi retak yang menyebabkan terjadinya kegagalan terhadap logam. Tujuan penelitian ini adalah untuk mengetahui pengaruh intensitas dan coverage shot peening terhadap tegangan sisa dan kekerasan pada permukaan Al 7075 T7351. Penelitian dilaksanakan dengan menembakkan permukaan logam dengan intensitas 0,0062 A dan 0,0091 A, serta coverage masing-masing 100% dan 200%, kemudian dilakukan pengujian kekerasan permukaan dan tegangan sisa. Hasil penelitian menunjukkan bahwa shot peening menyebabkan terjadinya perubahan tegangan sisa, yaitu 92,5021 MPa pada keadaan tanpa shot peening menjadi -111,8726 sampai -170,5675 MPa setelah dilakukan dishot peening. Selain itu kekerasan pada permukaan meningkat antara 23,4% sampai dengan 44,7%. Meningkatnya kekerasan menunjukkan bahwa terjadi pengerjaan dingin yang besar pada permukaan logam. Pengaruh pelapisan (coverage) 200% ternyata meningkatkan besarnya tegangan sisa dan kekerasan permukaan walaupun belum melampaui intensitas yang lebih besar. Kata kunci : shot peening, intensitas, coverage, kekerasan permukaan, tegangan sisa AbstractShot peening is a cold working method by striking metal surfaces using small, high-speed and round particles. Shot peening can reduce the initiation and propagation of cracks that cause metal failure. The purpose of this analysis is to determine the effect of shot peening intensity and coverage on residual stress and hardness on the surface of Al 7075 T7351. The research was carried out by firing metal surfaces with intensities of 0.0062 A and 0.0091 A, and coverage of 100% and 200%, respectively, then testing surface hardness and residual stress. The results showed that shot peening caused a residual stress change, which was 92.5021 MPa in the state without shot peening to -111.8726 to -170.5675 MPa after it was shot peening. In addition, surface hardness increased from 23.4% to 44.7%. Increased hardness indicates that there is large cold working on the metal surface. The effect of 200% coverage apparently increases the amount of residual stress and surface hardness even though it has not exceeded the greater intensity. Keywords: shot peening, intensity, coverage, surface hardness, residual stress