Damien McCormack

Intra-articular calcaneal fractures: effect of open reduction and internal fixation on the contact characteristics of the subtalar joint.

Intra-articular calcaneal fractures are associated with significant long-term morbidity, and considerable controversy exists regarding the optimum method of treating them. The contact characteristics in the intact subtalar joint were determined at known loads and for different positions of the ankle and subtalar joint, using pressure-sensitive film (Super Low; Fuji, Itochu Canada Ltd, Montreal, Quebec). We measured the contact area to joint area ratio (pressure > 5 kg force/cm2 [kgf/cm2]) which normalizes for differences in joint size and the ratio of high pressure zone (>20 kgf/cm2) as a reflection of overall increase in joint pressure. Three simulated fracture patterns were then created and stabilized with either 1 or 2 mm of articular incongruity. Eight specimens were prepared with a primary fracture line through the posterior facet, eight with a joint depression-type fracture, and six with a central joint depression fracture. A measure of 1 to 2 mm of incongruity in the posterior facet for all three fracture patterns produced significant unloading of the depressed fragment, with a redistribution of the overall pattern of pressure distribution to parts of the facet that were previously unloaded.

Quantification of the coupled motion that occurs with axial rotation and lateral bending of the head-neck complex: An experimental examination

Abstract The vertebrae of the cervical spine exhibit out-of-plane or coupled motion during axial rotation and lateral bending. Quantifying the range of motion (ROM) of this occurrence can aid the understanding of cervical spine injury mechanisms and disorders, as well as the development of new treatment methods. Previous studies have formulated ratios to describe coupled motion obtained from in-vitro examinations. The aim of the present study was to use in-vivo test data to develop mathematical relationships to quantify the coupled motion that occurs with axial rotation and lateral bending of the head-neck complex. Using a three-dimensional motion analyser it was possible to trace the coupling effect throughout the full range of unrestricted head-neck motion. Values for primary and coupled ROMs were obtained, showing no significant difference between male and female primary ROMs but a small disparity between male and female coupled ROMs. Regression equations were found to quantify coupled motion throughout the range of axial rotation and lateral bending. The present experimental study also examines the range of horizontally fixed axial rotation of the head to determine the minimum amount of coupled lateral bending that takes place, which has not been measured previously.

Juxtaposition artefact in a forearm radiograph: a cautionary note in the interpretation of a multiply exposed radiographic plate.

This case report outlines the risks associated with double plate exposure radiographs in follow up images of a childs forearm fracture. Protocols need to be established between radiology and orthopaedic departments for adequate imaging techniques of childrens forearms.

Persistence of Axial Rotation in Idiopathic Scoliosis Due to the Structural Changes of the Intervertebral Disc

There is some research about the morphological changes, spinal instability and causal factors influencing the mechanism of idiopathic scoliosis, however, there remains some controversy about its aetiology and pathogenesis [1,2] and complementary research is required to better identify the causal factors and pathologic mechanism(s) involved in the initiation and development of idiopathic scoliotic deformities of spine. In this study, a validated three-dimensional, anatomically accurate, mathematical model of the mid-thoracic motion segment (T7-T8), which consists of all bony element, soft tissues and articular contact surfaces is utilized, enabling investigation the influence of collagen deficiency in the initiation and progression of idiopathic scoliosis deformity. Alteration in the structure of the intervertebral disc is applied to the model and the resulting geometrical changes together with the coupling behaviour are computed.