We applied a mathematical model to calculate chest wall forces during coughing, in order to determine the force placed upon a sternotomy closure. We conclude that severe coughing may cause wires to untwist. We discuss potential applications of different wire closures based on their characteristics.

Forty patients with acute complete rupture of the calcaneal tendon were managed conservatively and randomly allocated to treatment groups using either cast immobilisation for eight weeks, or cast immobilisation for three weeks, followed by controlled early mobilisation in a Sheffield splint. The splint is an ankle-foot orthosis which holds the ankle in 15 degrees of plantar flexion, but allows some movement at the metatarsophalangeal joints. It is removed to allow controlled movement during physiotherapy. Patients treated with the splint regained mobility significantly more quickly (p less than 0.001) and preferred the splint to the plaster cast. The range of dorsiflexion at the ankle improved more rapidly after treatment in the splint (p less than 0.001), and patients were able to return to normal activities sooner. Recovery of the power of plantar flexion was similar in the two treatment groups, and no patient had excessive lengthening of the tendon. One re-rupture occurred in each group.

Successful limb lengthening requires serial radiological evaluation of the progression of healing of the regenerate bone. However, there is no radiographic classification system that shows how the regenerate should progress during treatment in adults. The study aimed to address this need. A series of radiographs were studied from 92 patients (125 segments) who had undergone bone lengthening. A radiographic classification of osteogenesis was developed based on callus shape and radiographic features that occur between osteotomy and fixator removal. This classification system used both shape and type of feature to condense and record the radiographic information, but type of feature alone was sufficient to predict outcome. The concurrence and reproducibility of the classification system was tested by inter-and intra-observer studies. The degree of consistent repetition and agreement between observers suggests that the classification system is reliable, reproducible, and therefore should be robust in use. This classification system provides an insight into osteogenesis; it allows the progress of the bone healing to be assessed against a successful pattern of healing. Hence, potential problems can be predicted and clinical changes made to improve outcome. The classification can be simplified to make it more appropriate for clinical use. ß

This paper presents a numerical investigation of the ballistic performance of monolithic, double-and triple-layered metallic plates made of either steel or aluminium or a combination of these materials, impacted by a 7.62-mm APM2 projectile in the velocity range of 775-950 m/s. Numerical models were developed using the explicit finite element code LS-DYNA. It was found that monolithic plates have a better ballistic performance than that of multi-layered plates made of the same material. This effect diminishes with impact velocity. It was also found that doublelayered plates with a thin front plate of aluminium and thick back steel plate exhibit greater resistance than multi-layered steel plates with similar areal density. These predictions indicate multi-layered targets using different metallic materials should be investigated for improved ballistic performance and weight-savings. Keywords INTRODUCTIONIn recent years, the ongoing threat of ammunition and explosively-formed projectiles to civil and military structures has increased the need to optimise protective structures. Armoured shields normally consist of a monolithic high-strength metallic plate; however, multi-layered plate configurations are often used because armour materials are not always manufactured to the required thickness, and multiple layers are necessary to fabricate shields that meet design specifications [1]. Although there are a number of studies dealing with the ballistic behaviour of multi-layered plates, their scope is limited when compared to studies of monolithic plates [2][3][4]. Moreover, the study of multi-layered plates remains an open research topic since conclusive results of its effectiveness have not been obtained to date, as is remarked in recent investigations [3][4].A numerical study conducted by Zukas and Scheffler [1] shows that 31.8 mm thick monolithic steel targets exhibit greater resistance than that of multi-layered targets with equal thickness when impacted by 65-mm long hemi-spherical nosed rods with a diameter of 13 mm and an initial velocity of 1164 m/s. They found that the weakening of the multi-layered configuration is due to the reduction of bending stiffness in the structure. They also found that the reduction of resistance in multi-layered targets becomes more apparent when the number of plates is increased while keeping the total thickness constant [1], which has also been observed experimentally [5][6]. Almohandes et al. [5] reported that monolithic steel plates are more effective than multi-layered plates of the same total thickness when impacted by a 7.62-mm projectile with an initial velocity of 826 m/s.An investigation conducted by Dey et al.[2] on the ballistic resistance of Weldox 700E steel in the sub-ordnance velocity range shows that 12 mm monolithic plate has better ballistic performance against ogival projectiles when compared with double-layered plates with same thickness, while the opposite effect is observed when blunt projectiles are used. Borvik et al. [7] studied experimentally the...