Introduction

Civilian fractures have been extensively studied with in an attempt to develop classification systems, which guide optimal fracture management, predict outcome or facilitate communication. More recently, biomechanical analyses have been applied in order to suggest mechanism of injury after the traumatic insult, and predict injuries as a result of a mechanism of injury, with particular application to the field so forensics. However, little work has been carried out on military fractures, and the application of civilian fracture classification systems are fraught with error. Explosive injuries have been sub-divided into primary, secondary and tertiary effects. The aim of this study was to 1. determine which effects of the explosion are responsible for combat casualty extremity bone injury in 2 distinct environments; a) in the open and b) enclosed space (either in vehicle or in cover) 2. determine whether patterns of combat casualty bone injury differed between environments Invariably, this has implications for injury classification and the development of appropriate mitigation strategies.

We report the outcome of 161 of 257 surgically fixed acetabular fractures. The operations were undertaken between 1989 and 1998 and the patients were followed for a minimum of ten years. Anthropometric data, fracture pattern, time to surgery, associated injuries, surgical approach, complications and outcome were recorded. Modified Merle D’Aubigné score and Matta radiological scoring systems were used as outcome measures. We observed simple fractures in 108 patients (42%) and associated fractures in 149 (58%).

The result was excellent in 75 patients (47%), good in 41 (25%), fair in 12 (7%) and poor in 33 (20%). Poor prognostic factors included increasing age, delay to surgery, quality of reduction and some fracture patterns. Complications were common in the medium- to long-term and functional outcome was variable. The gold-standard treatment for displaced acetabular fractures remains open reduction and internal fixation performed in dedicated units by specialist surgeons as soon as possible.

Highly active anti-retroviral therapy has transformed HIV into a chronic disease with a long-term asymptomatic phase. As a result, emphasis is shifting to other effects of the virus, aside from immunosuppression and mortality. We have reviewed the current evidence for an association between HIV infection and poor fracture healing.

The increased prevalence of osteoporosis and fragility fractures in HIV patients is well recognised. The suggestion that this may be purely as a result of highly active anti-retroviral therapy has been largely rejected. Apart from directly impeding cellular function in bone remodelling, HIV infection is known to cause derangement in the levels of those cytokines involved in fracture healing (particularly tumour necrosis factor-α) and appears to impair the blood supply of bone.

Many other factors complicate this issue, including a reduced body mass index, suboptimal nutrition, the effects of anti-retroviral drugs and the avoidance of operative intervention because of high rates of wound infection. However, there are sound molecular and biochemical hypotheses for a direct relationship between HIV infection and impaired fracture healing, and the rewards for further knowledge in this area are extensive in terms of optimised fracture management, reduced patient morbidity and educated resource allocation. Further investigation in this area is overdue.

Introduction: Models of shoulder motion differ with intended application and shoulder models often simplify the complex movement. Therefore, the design often negates clinical usage, in which, for example, multidirectional instabilities are present. To aid the work of clinicians in treating articulations without simplifying physiological constraint, a full open-chain 6 Degrees Of Freedom per articulation has been suggested (Inui et al., 2002).

Aim: Develop a spatial linkage model in order to facilitate communication between surgeon and engineer, and to apply this model to image datasets.

Model Design: Modification of Grood and Suntay’s (1983) 3-cylinder open chain model of the Tibiofemoral articulation to faithfully determine spatial parameters throughout a large range of motion, about clinically relevant axes.

Method: A computer program was scripted (Matlab, Mathworks Inc.) to embed orthogonal coordinate frames in both Humerus and Scapula. These were specified in respect of the planes of clinical rotation and well defined anatomical landmarks. A floating axis was defined within the script as the bipolar common perpendicular to both fixed frames. The magnitude of relative rotations, α, β and γ – flexion, abduction and axial rotation respectively – between Scapula and Humeral frames are measured directly, whilst translations occur along the axis about which rotation is measured. Gimbal lock limitations were minimised.

Validation: A physical linkage was made to validate the computations resulting in further model modification to create continuous rotational data throughout the following range: α from −90° – 270°, β from −90° – 270° and γ from −180° – 180°. This model provided an iterative development and examination tool for enhancing the capabilities of the modelling program.

Application: The model was applied to functional images acquired from both Electron Beam Computed Tomography and MRI. Anatomical landmark coordinates were digitised and input into the customised software. The real-time output displays rotations and translations of the humerus relative to the scapula.

Conclusion: The model circumvents a rotational sequence dependent outcome by determining the joint displacements within the modelled system as independent of the order in which segmental translations and rotations occur: 2 axes are fixed within articulating segments, whist a third mutually perpendicular floating axis moves in relation to both. The method facilitates multi-disciplinary communication: the parameters have a rigorous mathematical description and they correspond to clinical measures of position and orientation. Finally, this method accounts for Codman’s paradox with geometric principles.

Purpose: The glenoid labrum is a significant passive stabiliser of the shoulder joint. However, its microstructural form remains largely unappreciated, particularly in the context of function. An understanding of the labral structure leads to mechanical hypotheses, and therefore functional role in stability and load distribution, will aid an educated approach to surgical timing and repair.

Method: Fresh frozen cadaveric shoulders were grossly harvested via an extended Deltopectoral incision. The Glenohumeral joint was arthroscoped using a modification of Snyders (1989) routine in order to determine the specific anatomy of the capsulolabral complex. The glenoid fossa was then osteotomised before using micro-surgical loupes to section the labrum. Specimens were analysed using Scanning and Transmission Electron Microscopy and Confocal microscopy. Standard processing procedures were used to examine TEM specimens and the data was quantified by computational analysis. Specimens for SEM were cryofractured and Extracellular Matrix removed using a cell maceration technique to expose collagen fibre networks. Images were evaluated qualitatively. Sliced specimens for confocal were serially analysed along their z-axis, and post-processed to form 3-D reconstructions of collagen fibres.

Results: Two distinct homogenous areas were identified: (1) a superficial tight meshwork of fibrils and (2) a deep layer with a densely packed fibrous braid which were circumferential in orientation. A third area showed varying distribution of loosely arranged collagen fibres ranging from small fibres apposing area 1 to larger interleaved groupings near area 2. In radial transverse section, both normal and abnormal (stellate and spiral) fibrils were identified.

Conclusion: Contrary to published evidence, our results suggest the glenoid labrum is subjected a number of mechanical environments. Possibly distinct regions of the labrum contribute to load sharing; a well vascularised hydrated compressive zone and a tensile component distributing circumferential hoop stress, whilst both braiding and region interfaces suggest shear conditions.