Note: Trackside medicine is intended to provide a general medical guideline and is not intended to replace the clinical judgment of a doctor or take the place of the medical doctor’s diagnostic or treatment recommendations. These articles will always err on the conservative side for safety purposes.Motocross, what an addicting sport! No matter how many times you get hurt riding, as soon as the pain is gone you’re back at the track as if you had never been injured. Yet when you are hurt, the questions always seem to be the same: “How bad is it?”; “How long am I going to be off my bike?”; and more urgently, “Do I have to go to the ER or can I go home, ice up and see my own doctor some time in the next week (if at all)?”An ER evaluation for large bone fractures is a must. Smaller bones that are not obviously fractured may not need ER evaluation. A nonfracture involving larger joints may or may not require urgent evaluation. Many things can help the injured person in deciding if he or she needs to go to an emergency room. The best rule is to let pain be your guide.Ligaments, tendons, muscles and cartilage all receive a certain level of blood supply. Therefore, the more something is torn or damaged, the quicker and deeper the swelling and bruising can be. Swelling can occur in minutes to hours to days. It can be a helpful indicator as to the extent of an injury. Swelling can result from bleeding or from serious fluid collection within a joint or compartment. Caution must be taken when assessing swelling as an indicator of injury. Certain body parts and joints may not swell at all despite significant trauma.Bruising is the result of bleeding from an injured ligament, tendon, muscle or cartilage as a result of either rupture or tearing of the fibers of that unit. The more intense or severe the bruising, the more likely that significant injury has occurred. Rate and intensity of bruising is usually a better indicator of torn fibers of a unit than swelling.The range of motion of a joint can assist in judging severity. A joint that cannot be flexed or extended without severe pain or locks when testing range of motion usually indicates either a fracture or a significant ligament or cartilage injury despite the level of swelling or bruising.Each and every joint of the body is different in its presentation of trauma. A rapidly swelling joint with poor range of motion and bruising occurring within the first few hours almost always implies that a significant number of fibers have been compromised. In a scenario like this, it is important to evaluate the blood supply and any neurological deficiency. As swelling of a joint or extremity happens, there is internal pressure within the joint or muscle compartment that may compress the artery, resulting in decreased blood flow to more distal parts of the body. Additionally, this pressure can compress and cause damage to the nerve supply of the distal parts of the body. An example would be a knee injury that affects blood and nerve supply to the calf or foot.Blood supply can be assessed by a cool or discolored extremity, but this is a late sign. Decreased capillary refill is an early sign and can be discerned by squeezing the toes of the injured leg and counting how fast the blood refills the toe. An example would be to take your warm, pink fingertip and squeeze it and then let go. It should take 1-3 seconds for the pinkness to return to the fingertip; this is normal capillary refill. In the event of an injury, refill may be decreased to 4-5 seconds or longer. This test reveals vascular insufficiency (decreased blood supply), which may result in cell death if left untreated; in a worse-case scenario, vascular insufficiency can lead to loss of a limb. If you don’t pass this test, go to the ER ASAP.Nerve supply can be assessed by a decreased sensation to touch, numbness or tingling of the extremity. Nerves may be stretched, torn or compressed in an injury. The sooner the injury is treated, the more likely that symptoms from nerve trauma can be reversed. Nerve injuries demand ER evaluation ASAP.It’s easy to make the decision to go to an ER for an obvious bone fracture or significant injury. However, if you are questioning the need for medical attention for some injury, always err on the safe side. Pain can always be your guide to determine if you should to go to the ER. Blood supply and/or nerve compromise, on the other hand, always require a trip to the ER.