injuries poisoning
Overview of Fractures
Pathophysiology of Fractures
Fractures may be either Open: The overlying skin is disrupted, and the broken bone is in communication with the environment via a skin wound. Closed: The overlying skin is intact. occur when mild or minimal force fractures an area of bone weakened by a disorder (eg, osteoporosis, cancer, infection, bone cyst). When the disorder is Osteoporosis , these fractures are often called insufficiency or fragility fractures. Stress Fractures None Bone heals at various rates, depending on the patient's age and coexisting disorders. For example, children heal much faster than adults; disorders that impair peripheral circulation (eg, diabetes, peripheral vascular disease) slow healing. Fractures heal in 3 overlapping stages: Inflammatory Reparative Remodeling Theinflammatory stageoccurs first. A hematoma forms at the fracture site, and a small amount of bone in the distal fracture fragments is resorbed. If a fracture line is not evident initially (eg, in some nondisplaced fractures), one typically becomes evident about 1 week after the injury as this small amount of bone is resorbed. During thereparative stage,a callus is formed. New blood vessels develop, enabling cartilage to form across the fracture line. Immobilization (eg, casting) is needed during the first 2 stages to allow new blood vessels to grow. The reparative phase ends with clinical union of the fracture (ie, when there is no pain at fracture site, the injured extremity can be used without pain, and clinical examination detects no bone movement). In theremodeling stage,the callus, which was originally cartilaginous, becomes ossified, and the bone is broken down and rebuilt (remodeled). During this stage, patients should be instructed to gradually resume moving the injured part normally, including putting load-bearing stress on it. Serious complications of fractures are unusual but may threaten life or limb viability or cause permanent limb dysfunction. Risk of complications is high with open fractures (which predispose to infection) and with fractures that disrupt blood vessels, tissue perfusion, and/or nerves. Closed fractures that do not involve blood vessels or nerves, particularly those that are quickly reduced, are least likely to result in serious complications. Acute complications (associated injuries)include the following: Bleeding:Bleeding accompanies all fractures (and soft-tissue injuries). Rarely, internal or external bleeding is severe enough to cause hemorrhagic shock (eg, in pelvic, femoral, and some open fractures). Vascular injuries:Some open fractures disrupt blood vessels. Some closed fractures, particularly posteriorly displaced supracondylar humeral fractures, disrupt the vascular supply sufficiently to cause distal limb ischemia; this vascular disruption may be clinically occult for hours after the injury. Nerve injuries:Nerves may be injured when stretched by displaced pieces of a fractured bone, when bruised by a blunt blow, when crushed in a severe crush injury, or when torn by sharp bone fragments. When nerves are bruised (called neurapraxia), nerve conduction is blocked, but the nerve is not torn. Neurapraxia causes temporary motor and/or sensory deficits; neurologic function returns completely in about 6 to 8 weeks. When nerves are crushed (called axonotmesis), the axon is injured, but the myelin sheath is not. This injury is more severe than neurapraxia. Depending on the extent of the damage, the nerve can regenerate over weeks to years. Usually, nerves are torn (called neurotmesis) in open fractures. Torn nerves do not heal spontaneously and may have to be repaired surgically. Pulmonary Embolism (PE) : Fat embolism : Compartment Syndrome : Any fracture can become infected, but risk is highest with those that are open or surgically treated. Acute infection can lead to Osteomyelitis , which can be difficult to cure. Long-term complicationsof fractures include the following: Various fractures can lead to joint instability. Instability can be disabling and increases the risk of Osteoarthritis (OA) . Stiffness and impaired range of motion:Fractures that extend into joints usually disrupt articular cartilage; misaligned articular cartilage tends to scar, causing osteoarthritis and impairing joint motion. Stiffness is more likely if a joint needs prolonged immobilization. The knee, elbow, and shoulder are particularly prone to posttraumatic stiffness, especially in older people. Nonunion or delayed union:Occasionally, fractures do not heal (called nonunion), or union is delayed. Major contributing factors include incomplete immobilization, partial disruption of the vascular supply, and patient factors that impair healing (eg, use of corticosteroids or thyroid hormone). Malunion:Malunion is healing with residual deformity. It is more likely if a fracture is not adequately reduced and stabilized. Osteonecrosis:Part of a fracture fragment can become necrotic, primarily when the vascular supply is damaged. Closed fractures prone to osteonecrosis include scaphoid fractures, displaced femoral neck fractures, and displaced talar neck fractures. Osteoarthritis:Fractures that disrupt the weight-bearing surfaces of joints or that result in joint malalignment and instability predispose to joint cartilage degeneration and osteoarthritis. If a fracture in children involves a growth plate, growth can be affected, resulting in one limb that is shorter than the other. In adults, surgical repair of a fracture, especially femoral fractures, can result in leg length discrepancy ( Complications references ), which can lead to difficulty walking and the need for a lift in the shoe for the shorter leg. 1.McQueen MM, Gaston P, Court-Brown CM: Acute compartment syndrome. Who is at risk?J Bone Joint Surg Br82 (2):200–203, 2000. PMID: 10755426 2.Vaidya R, Anderson B, Elbanna A, et al: CT scanogram for limb length discrepancy in comminuted femoral shaft fractures following IM nailing.Injury43 (7):1176–1181, 2012. doi: 10.1016/j.injury.2012.03.022 