The correct answer is "costochondritis." Costochondritis is an inflammation of the cartilage that bridges the sternum to the ribs. It is a very common cause of acute chest pain in young, healthy, physically active individuals without known cardiovascular disease. In this case, we have a very prototypical case: a young, physically active (especially with physical activity involving the chest like weight-lifting and rowing crew), otherwise healthy male with focal, reproducible chest pain in the parasternal area, and normal vital signs on presentation. When you see this history, this is a rather convincing case for costochondritis. There is no information given that would seem to indicate a personal or family history of cardiovascular disease, and thus, costochondritis would be the best answer choice. He can be treated conservatively with NSAID's for anti-inflammatory and pain control effects.

Acute coronary syndrome (e.g. myocardial infarction) is very unlikely in this patient as he is young and healthy, has reproducible, focal chest pain, is very physically active, and has stable vital signs. If there was a personal or family history of cardiovascular disease, or any report of recent drug use (particularly cocaine), then this could be higher on the differential.

Pulmonary embolism is very unlikely in this patient as there is no leg swelling reported, the chest pain is focal, the patient is healthy and active, and his vital signs are normal.

Peripheral vascular disease would not present with chest pain, and would be highly unlikely to be present in an otherwise healthy 19-year old.

There is nothing to suggest that this healthy, active 19-year old patient has diabetes mellitus from the information provided.

The correct answer is "ACL, MCL, and Medial meniscus." This is the only answer choice that correctly lists all three components of the "unhappy triad." The unhappy triad is frequently injured in athletes who participate in contact sports, such as football. The injury mechanism often involves a direct, forceful hit to a firmly planted leg. The hit is forceful enough to rupture two ligaments (ACL and MCL), as well as the medial meniscus. The treatment for such an injury involves surgical intervention and a lengthy recovery period, though for patients inclined to partake in the rehabilitation process, they can often return to their desired sports after completion of surgery and rehab.

The correct answer is "compartment syndrome." Compartment syndrome is a surgical emergency in which an injury results in hemorrhage or swelling in an enclosed space that causes dangerously high pressures to build within the enclosed space, resulting in compromised bloodflow to the muscles and nerves within and distal to the space. The symptoms include a cool, pale, pulseless extremity that may also experience paresthesias, and that is visibly swollen and tense. In this case, the patient's right arm exhibits all of these characteristics, and this presentation is highly consistent with compartment syndrome.

The other choices are incorrect. Vasculitis and lupus are both autoimmune conditions that may result in limb swelling, but would be unlikely causes of this patient's presentation, especially in the setting of a recent local trauma to the affected limb. Fat embolism would not account for the patient's constellation of symptoms.There is no evidence of limb necrosis at this stage of the patient's injury. Should the compartment syndrome not be addressed and vascular flow remain compromised by persistently high pressures, then limb ischemia and consequent necrosis could be a downstream effect.

Polymyalgia rheumatica is an inflammatory musculoskeletal condition that presents with pain or stiffness, usually in the neck, shoulders, and hips. Amyotrophic lateral sclerosis (ALS) is a genetic disorder of muscle wasting and neuronal death. Symptoms include progressive muscular weakness, leading to paralysis and death. Guillain–Barré syndrome is a rapid-onset condition of reversible muscle paralysis and weakness following infection, most commonly Campylobacter jejuni. Myositis is a general term for inflammation of the muscles, and can be due to various causes.

Duchenne's muscular dystrophy (DMD) is caused by dysfunctional production of dystrophin, a protein that is part of a complex of proteins that anchor the cytoskeleton of a muscle cell to the extracellular matrix, also known as the dystrophin-associated protein complex. Its absence disrupts multiple intracellular signaling pathways, leading to muscle necrosis. Dystroglycan is another protein in this complex, but it is unaffected in DMD. Actin and troponin are also unaffected in DMD.

Duchenne's muscular dystrophy is an X-linked recessive disease. Because of this, it is almost exclusively seen in males and rarely presents in females (girls would have to receive a recessive gene on both the X-chromosome from their mother and their father; historically, boys with a defective gene on their X-chromosome rarely lived past their teens, decreasing the likelihood of reproduction). 

Myasthenia gravis is a condition in which the immune system makes antibodies to aceytlcholine receptors, thus blocking receptors and preventing the stimulating effect of acetylcholine at the neuromuscular junction. This results in muscle weakness that progresses during activity and improves with rest. Anti-ro antibodies are commonly seen in Sjögren’s syndrome and systemic lupus erythematosus (SLE), and anti-dsDNA antibodies are highly specific for SLE.

Osteogenesis imperfecta is a genetic condition characterized by a deficiency of normal type-1 collagen, resulting in the formation of brittle, fragile bones. Bones fracture easily, often with no obvious trauma. Osteogenesis imperfecta has many sub categories that range in severity, several of which are not compatible with life.

Ehlers–Danlos syndrome is a collagen abnormality that primarily affects the skin, joints, and vasculature, causing lax joints and general instability. Marfan syndrome is also a condition of connective tissue abnormality, which largely effects the structure and function of smooth muscle in the cardiovascular system. Legg-Calvé-Perthes syndrome is a condition of necrosis in the femoral head, not related to any alterations in collagen formation. 

Active resistive range of motion is performed by the client against resistance (manual or mechanical). This exercise builds muscle strength. Isometric exercises are performed by the client without motion; rather, the client contracts and relaxes the muscle without moving the joint. This maintains strength in the muscle while the joint is immobilized. Passive range of motion is performed by the nurse without assistance from the client, which retains circulation and range of motion in the joint, Active range of motion is performed by the client without assistance of the nurse and maintains joint mobility and muscle strength. Active assistive range of motion is performed by the client with help of the nurse to increase motion in the joint.

The nurse should begin assessment to determine the cause of the complaint. Obtaining an x-ray for the leg is the best assessment; you need to rule out possible fracture before giving pain medication or bandaging the leg. Heat is inappropriate for this injury because ice is best for sports injuries such as sprains and breaks. Notifying the physician may be done after all assessments are completed.