Symptoms and Signs: Leg Pain

Leg pain can arise from any of the structures in the leg, such as skin, bones, muscles, tendons, nerves, or blood vessels. The causes of leg pain are very varied and include trauma or injury like broken bones or joint sprains, infections of skin or soft tissue, vascular disease, arthritis conditions, or blood clots. Leg pain can affect one or both legs, depending on the cause, and can be mild to severe in character.

Depending on the cause of the pain, many different kinds of signs and symptoms can accompany leg pain. Some of the typical associated symptoms can include weakness, burning, numbness, swelling, cramps, bleeding, or redness. Joint swelling, limited range of motion, gait disturbances, changes in skin color or other skin changes, and warmth or redness can also accompany leg pain, depending on the cause of the pain.

Depending upon the cause and the individual situation, symptoms of leg pain may have a wide range of presentation. The pain may be described in a variety of ways, including sharp, dull, heavy, aching, or burning. It may be constant or intermittent or made better or worse with activity or rest. There may be other associated symptoms, depending upon the cause.

• Pain from muscles and joints often can be felt or palpated, meaning that touching the area reproduces the pain. This may be difficult if the pain originates in one of the muscles deep in the buttock.
• Pain also may radiate from its source to another location, sometimes confusing the patient and the care provider.
• Patients who suffer from claudication develop pain with exercise, but as the blood vessels narrow over time, the amount of activity required to bring on the pain decreases. Also, this type of pain tends to resolve with rest. As the disease progresses, at some point, the patient may complain of pain at rest, not requiring exercise or activity to bring it on.
• Those who have a blood clot causing ischemia (decreased oxygen supply to the tissues) tend to have an acute onset of pain that is intense and involves the whole extremity below the area of the arterial blockage. There may be associated numbness or paralysis. Sometimes the body is able to dissolve the clot on its own and as the blood supply is restored, the pain resolves. Most often, though, this is a true emergency that requires treatment to dissolve or remove the clot to prevent loss of the leg.
• People with neuropathy tend to describe their pain as a burning sensation, while those who have sciatica describe the intense sharp pain.
• Nighttime symptoms of pain and leg cramps may be associated with restless legs syndrome, a sleep disorder.

• Joint pain
• Leg swelling
• Muscle cramps

Trauma

Trauma is the most obvious cause of leg pain. Falls near falls, and twisting injuries can damage bones, muscles, and joints of the leg or a combination of all three. Back pain, due to injury, can inflame the sciatic nerve and cause sciatica. This is a pain that radiates down the leg that follows the path of one of the many nerve roots that leave the spinal cord and make up the sciatic nerve. Sciatic pain usually begins in the back and radiates to the buttock and into the thigh.

Overuse injuries may cause pain and can be thought of as multiple minor traumatic injuries to muscles, tendons, and joints that occur over a longer time span.

• Fractures: When referring to a bone, the terms fracture, broken, and cracked all mean the same thing: The integrity of the bone has been compromised. The most common symptom is pain that occurs because the nerve endings located in the fibrous tissue lining of the bone, called the periosteum (peri=surrounding +osteum=bone), have become damaged and inflamed. As well, the muscles surrounding the bone go into spasm and intensify the pain.
• Stress fractures: Some fractures occur because of repetitive small traumas to a specific area of the body. March fractures describe a fracture of one or more of the metatarsal bones in the foot (the long bones at the base of the toes) that are caused by overuse that fatigues the bone. The name comes from the fact that they are found in soldiers who are forced to march long distances as part of their training.
• Shin splints are an overuse injury to the tibia or shinbone. This condition is also known as tibial stress syndrome. Running, jumping, and dancing are the most common causes. Microscopic fractures occur in the tibia, causing pain and swelling. If the person continues to exercise and disregards the pain, a shin splint can progress to completely break the bone.
• Sprains and strains: A ligament injury is called a sprain and occurs when the ligament fibers are stretched, or partially or completely torn. Muscles and tendons can also be stretched or torn, causing a strain. Both sprains and strains result in swelling and inflammation that causes pain. Sometimes a sprain or strain can occur at the location where the structures attach to bone, and a small fleck of bone can be pulled off at the insertion of the muscle, tendon, or ligament. This is called an avulsion fracture but often is treated in the same manner as a strain.
• Bursitis: There are small, fluid-filled sacs that cover large bony prominences and allow tendons to slide across the bone. Bursitis, or inflammation of the bursa sac, may occur with overuse or injury, like a direct blow. Two bursts in the leg that may commonly become inflamed are the trochanteric bursa that covers the bony prominence of the femur on the outside of the hip and the ischial bursa that covers part of the pelvic bone where we sit.
• Bleeding: Injuries can also cause bleeding into tissues and joints. Since blood, like any fluid, cannot be compressed, the swelling causes a significant amount of pain as the pressure increases. Blood is also very irritating to the surrounding tissues when it leaves blood vessels and causes pain by its presence alone.
• Compartment syndrome is a medical emergency. It describes the situation in which excessive swelling occurs within the sections or compartments of the leg that contain muscles. This may cause increased pressure within the compartment that is greater than the blood pressure generated when the heart beats. Blood supply is cut off within the compartment, causing pain, numbness, and an inability to move the foot or ankle. This is a true surgical emergency, requiring an opening of the compartments and relieving the pressure within to restore blood supply and prevent permanent disability. One of the hallmarks of the diagnosis is the finding of pain out of proportion to physical findings. The diagnosis is confirmed by measuring pressures within the compartment.

There are numerous causes of non-traumatic leg pain, and there is no single way of classifying all of these causes. Health-care providers often develop their own individual approach to help decide upon a diagnosis. Sometimes it can help to classify the potential causes based upon the part of the leg that hurts, whether the pain is in one leg or both, whether it is related to activity or occurs at rest, and whether underlying medical conditions exist that can precipitate leg pain.

Pain in only one leg would tend to be due to local problems and not necessarily due to a systemic (involving the entire body) illness. The presumption would be that such an illness would affect both legs. This is not necessarily always true. For example, gout (a defect in the body's ability to process uric acid) often attacks only one joint during an acute flare.

• Peripheral artery disease (PAD): Pain in one leg, or both, may be due to peripheral artery disease, a decrease in arterial blood supply to the leg due to narrowing of arteries. Often the pain comes on with activity since walking requires more oxygen for the muscles. If the arteries are narrow and can't supply that need, the muscles begin to ache. Blood vessels can be narrowed at any level, from the aorta (the large blood vessel that leaves the heart) to any of the branch arteries. Depending upon the level of narrowing and the particular muscles involved, the areas of perceived pain may be different.
• Leg pain from peripheral artery disease that occurs with walking is called claudication. Since peripheral artery disease often affects more than one blood vessel, both legs may be affected, although the pain may be of different severity in each leg. The blood supply may decrease to the point that pain occurs at rest, even without exercise. Poor blood supply to the legs may also compromise the integrity of the skin and may allow an infection to occur. As well, poor blood supply makes it difficult for wounds like lacerations or abrasions to heal.
• Blood clot: An arterial (in an artery) blood clot of a leg artery can completely obstruct blood supply, preventing tissues from getting oxygen-rich blood from the heart. This can cause the acute onset of pain. Aside from pain, the leg may become cool and pale. While there are many potential sources of a blood clot, one common place to look is the heart. If the cardiac arrhythmia known as atrial fibrillation is present, there is the potential that small clots can form on the lining of the heart and break off to travel through the arteries, obstructing blood flow at any points distant from the heart. Aside from the leg, the obstruction may occur in one of the blood vessels leading to the brain leading to stroke, or one of the arteries to the intestine, causing bowel ischemia. A blood clot can also occur acutely in an artery that is partially narrowed. Just like arteries in the heart that can narrow over time because of cholesterol or plaque buildup, the same situation may occur in the legs. If the plaque becomes irritated or ruptures, the body can form a clot at the site, occluding the artery and stopping the blood supply to the part of the leg beyond the clot.
• A venous (in a vein) blood clot can also cause pain. Veins return blood from the legs to the heart. There are two systems of veins in the leg: superficial and deep. If a blood clot occurs in a deep vein (deep venous thrombosis), it causes a "damming" effect, and blood is trapped behind the blockage. This causes redness, swelling, warmth, and pain in the affected area. Calf pain and swelling are common symptoms.
• Superficial veins can also clot and cause pain, but the risk of complication of a deep thrombosis (breaking off and embolizing to the lungs [pulmonary embolism]) is not often present. A superficial thrombosis (blood clot) may not be able to travel to the lung because of the valves in the perforator veins that connect the superficial vein system to the deep system act as a sieve. However, if the clot develops near the groin where the two systems come together, the clot can embolize to the lungs. Superficial veins can also chronically dilate and swell and form varicose veins. Varicose veins may cause pain from this swelling and inflammation.
• Low back pain: Low back pain from sciatica (inflammation of the sciatic nerve) may radiate into the buttocks and down the leg. The distribution of pain depends upon which nerve root is involved; therefore the pain may be felt in the foot, shin, or thigh. Sciatica may be caused by a variety of changes in the back from arthritis, a herniated disc, muscle spasm, or injury. The common outcome is that space where the nerve exits the spinal canal is narrowed and there is impingement upon the nerve. Less commonly, tumors and infection can cause nerve root and spinal cord inflammation and resultant leg pain.
• While a herniated disc or arthritis can pinch a nerve root that exits the back at one or more levels, spinal stenosis may affect long segments of the spinal cord because the spinal canal itself becomes narrow, not leaving enough room for the spinal cord itself. Spinal stenosis may result in pain, numbness, and weakness.
• Cauda equina syndrome describes a neurosurgical emergency in which back pain may be associated with weakness, numbness around the perineal area (rectum, scrotum, vagina), inability to urinate, and loss of bowel control. The spinal cord ends in a mass of nerve roots that appear like a horse's tail (cauda equina in Latin) that can become inflamed if there is damage to the area due to trauma or any other type of compression, including tumors.
• Neuropathy: Pain may occur from peripheral nerve inflammation not associated with the spinal cord. These conditions are known as peripheral neuropathies. This can occur from direct nerve irritation or from a medical illness. Examples of this type of isolated nerve injury include foot and toe pain from Morton's neuroma, most frequently a thickening and inflammation of a nerve that supplies the third and fourth toes, or meralgia paresthetica that causes pain in the anterior thigh resulting from entrapment of a nerve that leaves the pelvis. This neuropathy is also seen in pregnancy when the pressure of the uterus may cause the nerve to become inflamed. These types of pain tend to involve part of one leg only. Diabetes is a common cause of peripheral neuropathy that affects both lower extremities. Alcohol abuse is another common cause of peripheral neuropathy.
• Illness: Chronic illnesses like diabetes, alcoholism, cancer, and vitamin deficiencies (for example, B12 deficiency causing pernicious anemia) may also result in nerve pain that often affects both legs. There are some illnesses that cause leg weakness that may be associated with complaints of leg pain, including Guillain-Barré syndrome and multiple sclerosis.
• Skin: Skin inflammation may also cause significant pain, especially if there are underlying illnesses like diabetes or peripheral artery disease that prevent adequate healing. The inflammation may be due to infection often caused by Streptococcus or Staphylococcus bacteria. Skin that is stretched due to edema or fluid accumulation in the tissues underneath the skin can cause significant pain especially when the legs are not elevated.
• Shingles can cause significant pain due to inflammation of spinal cord nerve in the body. It is a reactivation of the chickenpox virus that resides in a dormant state in the nervous system following the patient being infected years previously. Since it is the nerve that is inflamed, there can be significant amounts of pain. As well, a rash can occur along the course of the nerve. The rash may appear a few days after the pain begins and may resolve before the rash goes away. Sometimes the pain persists chronically even after the rash resolves (postherpetic neuralgia).
• Joint pain: Joint pain may occur because of a local injury but may also be due to medical conditions that can cause inflammation and swelling. Joint pain associated with swelling is called arthritis (arth=joint+ it is=inflammation) while pain without swelling is called arthralgia (arthr=joint + algia= pain). Some examples include the following:
  • Patients with progressive osteoarthritis may have days in which affected joints may hurt.
  • Similarly, patients with rheumatoid arthritis may have episodes of joint inflammation when their disease flares.
  • Exacerbations of gout can cause joints to become inflamed if uric acid crystals start to deposit within the joint. It is often the joints that are under a significant workload that are affected. The joints in the great toe are commonly involved, but the ankle, knee, wrist, and fingers are also common sites of uric acid crystal deposition.
  • Pseudogout can also cause joint inflammation. Instead of uric acid, calcium pyrophosphate crystals deposited in joints are the cause of this condition. The knee is often affected by pseudogout, and the diagnosis is sometimes made when calcification of the cartilage is seen on plain X-rays of the knee joint (chondrocalcinosis).
  • Systemic illnesses (there are too many to discuss in this article) may also cause joint inflammation. Some common conditions that may cause joint pain include inflammatory bowel disease (SLE), psoriasis, hepatitis, inflammatory bowel disease, and Lyme disease.
  • Joints may become inflamed as part of the body's generalized reaction to an infection. Infections may cause synovitis or inflammation of the synovium (the lining tissue of a joint). Most often it is due to a virus, but in children, there is always a concern that a bacterial infection may be the cause.
  • People who take warfarin (Coumadin), prasugrel (Effient), enoxaparin (Lovenox), dabigatran (Pradaxa), rivaroxaban (Xarelto) or apixaban (Eliquis) for anticoagulation to thin their blood may spontaneously bleed into a joint or muscle, causing pain.
• Muscle pain: Muscle pain or myalgia (myo=muscle +algia=pain) is a common complaint and may be due to overuse (mild trauma) or associated with the generalized aches and pain of an infection. Muscles may also become inflamed for a variety of reasons (myositis: myo= muscle + itis=inflammation), including side effects of some cholesterol medications.
• Muscle cramps: Muscles may cramp, causing significant pain. This may be due to a lack of stretching or an imbalance of electrolytes in the bloodstream. The body needs to have the right amount of calcium, sodium, and potassium for muscles to function well. Calf and foot muscles are particularly prone to cramping, especially at night.
• Muscles will also go into spasm to help protect an injured site. For example, when a hip bone is broken, the muscles that move the hip will go into spasm to help minimize movement of the injury.
• Heat cramps occur as part of the spectrum of heat-related illness due to dehydration and electrolyte imbalances. They may occur immediately after exercising or working in a hot environment or their onset may be delayed for a few hours. Often it is the large muscles of the legs that are involved because of the amount of work they are asked to do.
• Muscle injuries: The muscles in the leg tend to be in balance with each other to promote joint stability and act as shock absorbers for the forces that are generated by walking and running. The quadriceps muscles on the front of the thigh extend or straighten the knee and are balanced by the hamstring muscles in the back of the thigh responsible for flexing or bending the knee. If this balance is lost, the muscle fibers may become overstretched and tear. This is called a strain.
• Hamstring injury: The hamstring (posterior thigh muscle group) is made up of a group of individual muscles known as the semitendinosus, the semimembranosus, and the biceps femoris. While the tendons can be felt at the back of the knee, the muscle originates and is anchored in the pelvis bone. When the muscle contracts, the knee bends, and the leg is able to generate power to push the foot away from the ground so that the body can walk. Walking also requires the quadriceps muscles to fully extend the knee so that the heel of the foot can strike the ground and begin the footstep.
• If the hamstring muscle-tendon fibers are not flexible or if there is too much stretch placed on the structure, these fibers may be damaged if the knee extends too much or too quickly. Muscle or tendon fibers may be stretched or even torn, causing pain and swelling. To protect itself, the muscle may go into spasm, which may cause even more pain.
• Skin abnormalities: Skin abnormalities may cause pain. Lacerations and skin tears, ranging from trauma to ulcers caused by poor blood flow, are among the causes of pain from skin conditions. The skin has numerous nerve fibers that can sense pain, and anything that damages the skin can cause pain. Skin infections may be painful, again because of inflammation and swelling.
• Leg pain in children: Leg pain in children is a special situation. While most leg pain in children is not serious, there are times when the pain has a significant cause. These may include a joint infection causing hip pain, trauma causing damage to growth plates, and pain due to systemic illnesses like Henoch-Schönlein purpura, juvenile rheumatoid arthritis, or rheumatic fever.
• "Growing pains" are most likely due to muscle overuse, although they may be associated with a mild stretching as the muscles grow along with the bone.
• Children with leg pain who limp or who will not bear weight on the leg should be seen urgently by a health-care provider.
• Some fractures in children may be difficult to diagnose because immature bones may not have completely calcified due to the presence of growth plates. Fractures may not be evident on plain X-rays, and clinical judgment may be needed to decide whether a broken bone is present.
• Legg-Calve-Perthes disease describes avascular necrosis or loss of blood supply to the femoral head (the ball of the hip joint). The cause is unknown, but it most commonly affects children from ages 4-8 and causes hip pain and a limp. Treatment involves resting the hip joint to prevent long-term arthritis, and care is usually supervised by an orthopedic specialist.
• Osgood-Schlatter syndrome describes an inflammation of the apophysis of the tibia, the bony protuberance where the patellar tendon attaches to the bone below the knee. This condition occurs because of excess strain on the growth plate of the upper tibia and is often due to excess jumping or running. It can cause a tender, swollen area just below the knee. The condition heals with ice and rest.
• Diabetes: Diabetes may cause leg pain in a variety of ways. If blood sugar levels are not well controlled over a period of many years, nerves and blood vessels deteriorate and lose their function. Often the damage occurs in the feet and progresses up the leg. With the loss of sensation, skin infections and foot injuries may occur without the affected person feeling much discomfort. Alternatively, the nerves may be so inflamed that the patient feels intractable pain. Diabetes also causes blood vessels to narrow and cause symptoms of PAD (peripheral artery disease) or claudication.

People with diabetes are also more prone to infection because of an impaired immune system. Along with poor blood supply to the legs, the ability to heal skin damage is decreased and increases the risk of foot and leg infections.