Narrow Results

Background: Ulnar styloid triquetral impaction (USTI), one of many causes of ulnar sided wrist pain, is a pathological entity with clear clinical and radiographic features, distinct and different from the impaction of the ulnar head against the lunate or ulno-carpal impaction (UCI). Pain is ulnar and point-tenderness is present precisely over the ulnar styloid as opposed to the proximal lunate in UCI. The provocative maneouvre of dorsiflexion in pronation followed by supination is markedly different from the ulnar deviation grind test maneouvres used to diagnose UCI. Multiple anatomical and pathological features interplay to produce a situation in which the distance between the tip of the ulnar styloid and the triquetrum is reduced resulting in USTI. The concept of ulnar styloid variance is introduced and anatomical variations of ulnar styloid length are demonstrated.

Methods: The clinical and radiographic features of 56 patients diagnosed with USTI were analysed. One thousand standardised film-file wrist radiographs were measured to determine the average length of the ulnar styloid in the population as well as the average projection of the styloid above the radius (ulnar styloid variance).

Results: An aetiological classification system for USTI was developed based on the clinical and radiographic features of the aforementioned patients and radiographs.

Conclusions: The causes of this syndrome are often complex and classification of the aetiological features is clinically useful. It is important for physicians and surgeons to recognise the clinical and radiographic features of this syndrome in order to properly manage the symptoms and prevent an iatrogenic production of USTI.

Peri-implant debris certainly lead to osteolysis, necrosis, pseudotumor formation, tissue granulation, fibrous capsule contractions, and even implant failure. For the three-dimensional (3D) printed cage, impaction during cage insertion is one of the most potential sources of fracture debris. A finite-element study was carried out to reduce the impact-induced debris of the 3D-printed cage. This study focused on the design strategy of solid and cellular structures along the load-transferring path. Using the finite-element method, the cellular structure of the transforaminal lumbar interbody fusion (TLIF) cage was systematically modified in the following four variations: a noncellular cage (NC), a fully cellular (FC) cage, a solid cage with a cellular structure in the middle concave (MC) zone, and a strengthened cage (SC) in the MC zone. Three comparison indices were considered: the stresses at the cage-instrument interfaces, in the MC zone, and along the specific load-transferring path. The NC and FC were the least and most highly stressed variations at the cage-instrument interfaces and in the MC zone, respectively. Along the entirely load-transferring path, the FC was still the most highly stressed variation. It showed a higher risk of stress fracture for the FC cage. For the MC and SC, the MC zone was consistently more stressed than the directly impacted zone. The further strengthened design of the SC had a lower peak stress (approximately 29.2%) in the MC zone compared with the MC. Prior to 3D printing, the load-transferring path from the cage-instrument interfaces to the cage-tissue interfaces should be determined. The cage-instrument interfaces should be printed as a solid structure to avoid impact-induced fracture. The other stress-concentrated zones should be cautiously designed to optimize the coexistence strategy of the solid and cellular structures.

The lung is an external organ forming the site of unwanted material or particles. In order to protect it, the airways have to be highly effective filters and if the particle deposit they need to be cleared. Inhaled particles can cause a variety of diseases. There are various factors on which the prediction of depositing particles depends, such as age, particle size, flow rate gender, the physics of the particles, the anatomy of the respiratory tract etc.