Pathological fractures
Result from minor trauma to diseased bone. These preexisting processes include metastatic lesions, bone cysts, advanced osteoporosis, etc. Fracture-dislocations
Severe injury in which both fracture and dislocation take place simultaneously. Gunshot wounds
Caused by high-speed projectiles, they cause damage as they go through the tissue, through secondary shock wave and cavitation. Diagnosis
The initial evaluation for open fractures is to rule out any other life-threatening injuries. Advanced Trauma Life Support (ATLS) is the initial protocol to rule out such injuries. Once the patient is stabilised, orthopedic injuries can be evaluated. Mechanism of injury is important to know the amount energy that is transferred to the patient and the level of contamination. Every limb should be exposed to evaluate any other hidden injuries. Characteristics of the wound should be noted in detail. Neurology and the vascular status of the affected limb are important to rule out any nerve or blood vessels injuries. High index of suspicion of compartment syndrome should be maintained for leg and forearm fractures.There are a number of classification systems attempting to categorise open fractures such as Gustilo open fracture classification, Tscherne classification, and Müller AO Classification of fractures. However, Gustilo open fracture classification is the most commonly used classification system. Gustilo system grades the fracture according to energy of injury, soft tissue damage, level of contamination, and comminution of fractures. The higher the grade, the worse the outcome of the fracture. However, Gustilo system is not without its limitations. The system has limited interobserver reliability at 50% to 60%.
Dysbaric osteonecrosis or DON is a form of avascular necrosis where there is death of a portion of the bone that is thought to be caused by nitrogen embolism (blockage of the blood vessels by a bubble of nitrogen coming out of solution) in divers. Although the definitive pathologic process is poorly understood, there are several hypotheses:

Intra- or extravascular nitrogen in bones, "nitrogen embolism". Osmotic gas effects due to intramedullary pressure effects. fat embolism
hemoconcentration and increased coagulability. Presentation
The lesion begins as a localised area of infarction, usually without symptoms. Early identification of lesions by radiography is not possible, but over time areas of radiographic opacity develop in association with the damaged bone. Symptomatic lesions usually involve joint surfaces, and fracture where attempted healing occurs. This process takes place over months to years and eventually causes disabling arthritis, particularly of the femoral head (hip).Dysbaric osteonecrosis lesions are typically bilateral and usually occur at both ends of the femur and at the proximal end of the humerus. Symptoms are usually only present when a joint surface is involved, which typically does not occur until a long time after the causative exposure to a hyperbaric environment. The initial damage is attributed to the formation of bubbles, and one episode can be sufficient, however incidence is sporadic and generally associated with relatively long periods of hyperbaric exposure, and aetiology is uncertain.