There are many causes of back pain. Often it is difficult to diagnose the source of a person’s pain. However, several factors have been associated with either triggering new back problems or exacerbating existing problems. These include:

• Injury. Various injuries can cause spasms, sprain or strain in muscles or ligaments of the abdomen and the back, such as a sacroiliac sprain. Sources of injury include athletics, household chores, repetitive stress injuries incurred on the job and sudden trauma such as fractures or spinal cord injuries suffered in motor vehicle accidents and other mishaps.

Repeated injuries can result in the formation of scar tissue that is not as strong or flexible as the tissue it replaced. This can leave the back vulnerable to additional injuries in the future.

• Poor posture. Failure to sit or stand properly shifts the body out of balance, forcing just a few muscles and joints to support the entire body. This increases the vulnerability of these muscles to the types of stresses that cause back pain.
  
  
• Poor body mechanics and ergonomics. Bending the back rather than the knees when lifting objects is a common source of back pain.
  
  
• Emotional stress. People who are under stress experience a tightening of the back muscles that can worsen back problems.
  
  
• Excessive weight and obesity. Too much weight places strain on the back and stomach muscles, causing them to weaken and stretch.
  
  
• Poor muscle tone in the back and abdomen. Weakened muscles cannot properly support the back, leaving the back vulnerable to stresses and injuries.
  
  
• Age. As people age, bone strength and muscle elasticity and tone tend to decrease. Intervertebral discs begin to lose fluid and flexibility, reducing their ability to cushion the vertebrae. As a result, back injuries are more likely after age 30.
  
  
• Use of heavy packs. Back pain is typically uncommon in children. However, backpacks overloaded with schoolbooks and supplies can strain the back and cause muscle fatigue, resulting in injuries to the back. Oversize purses, heavy briefcases or luggage are common causes of back pain in adults.

In addition, there are many illnesses and disorders that have been associated with back pain. These include:

• Herniated discs. If the spine becomes strained or compressed, an intervertebral disc may bulge or rupture, depriving the vertebrae of the “shock absorbers” they need. Cartilage from the disc may protrude into the space containing the spinal cord and nerve root, resulting in pain. In more serious cases, disc material may compress the bundle of lumbar and sacral nerve roots at the end of the spinal cord, known as the cauda equina. This condition is called cauda equina syndrome, and it may cause permanent neurological damage if left untreated.
  
  
• Sciatica. In some cases, a herniated disc may press on one or both of the sciatic nerves, large nerves that exit the spinal column in the pelvis. The sciatic nerves carry nerve fibers to the leg. When the nerve is compressed, it causes shock-like or burning low back pain, as well as pain through the buttocks and down one leg to below the knee. In some cases, it may reach the foot. Sciatica can involve a pinched nerve between a disc and an adjacent bone. Symptoms in such cases are not only painful but may also include numbness and loss of motor control over the leg.
  
  
• Degenerative disc disease. Deterioration of intervertebral discs. This condition is common as people age and can press on nerves.
  
  
• Spinal stenosis. Narrowing of spinal passages, producing pressure on the spinal cord or nerve roots.
  
  
• Arthritis. Pain within a joint. Each vertebra is joined to the vertebra above and below by a joint called facet or zygapophyseal joint.  Forms of arthritis that can cause back pain include:
  
  
• • Osteoarthritis. Characterized by chronic degeneration of the cartilage of the joints. Osteoarthritis of the spine may be referred to as spondylosis. This may involve bone spurs (osteophytes).

• • Rheumatoid arthritis. Chronic disease marked by stiffness and inflammation of the joints, weakness, loss of mobility and deformity.
    
    
  • Ankylosing spondylitis. Chronic inflammation of the spinal joints and ligaments.
    
    
• Skeletal irregularities. These produce strain on the vertebrae and supporting muscles, tendons, ligaments and tissues. They include:
  
  
• • Scoliosis. Abnormal sideways curve of the spine.

• • Kyphosis. Severely rounded forward curve in the upper back.
    
    
  • Lordosis. Abnormally accentuated inward arch in the lower back.
    
    
• Osteoporosis. Abnormal loss of bony tissue resulting in porous and brittle bones. Osteoporosis most often affects women after menopause but is also common in elderly men.  Osteoporosis may lead to vertebral compression fracture, which can cause severe back pain and kyphosis (“dowager’s hump”).

• Spondylolysis. A stress fracture in a posterior vertebral area called the pars interarticularis. This usually affects the fifth (lowest) lumbar vertebra and is a common source of low back pain in school-age athletes but can affect anyone. Sometimes the damaged vertebra becomes so weak it slips out of place, which is known as spondylolisthesis.
  
  
• Enthesitis.  Inflammation of entheses, which are sites where tendons or ligaments attach to bone. Enthesitis is often related to other musculoskeletal conditions such as arthritis or tendinitis.
  
  
• Polymyalgia rheumatica. Disorder marked by muscular pain and stiffness in the shoulders, neck and pelvic area.
  
  
• Fibromyalgia. Syndrome marked by chronic pain in the muscles and soft tissues surrounding joints, fatigue, and tenderness at specific sites in the body. Patients experience “tender points” in the neck, spine, shoulders and hips.
  
  
• Chronic fatigue syndrome. Debilitating condition that frequently involves joint pain and muscle pain.
  
  
• Systemic lupus erythematosus. An autoimmune disease that affects many areas of the body. Back pain may result from damage to the kidneys or joints.
  
  
• Sickle cell anemia. Inherited blood disease that can cause pain in the back and throughout the body.
  
  
• Lyme disease. Infectious tickborne disease that can lead to widespread joint and muscle pain.

• Whiplash. Injury to the neck resulting from a sudden jerking of the head. Whiplash is a common cause of neck pain and can cause back pain as well.
  
  
• TMJ disorder. This syndrome, involving the temporomandibular joint of the jaw, can cause orofacial pain, headaches, ear pain, neck pain, back pain and shoulder pain.
  
  
• Gait disturbances. Abnormal patterns of walking. Some gait disturbances cause or are caused by back pain.
  
  
• Paget’s disease. Disease in which bones become enlarged and weakened, often resulting in fracture or deformation.
  
  
• Aortic aneurysm. Bulging of part of the wall of the aorta, the large artery that directs blood from the heart to the rest of the body. Thoracic and abdominal aneurysms seldom produce symptoms but in some cases can cause back pain. A ruptured aneurysm is often marked by sudden and severe abdominal or back pain.
  
  
• Prostate problems. Conditions such as prostatitis can cause back pain as well as pelvic pain or sexual pain.
  
  
• Kidney infection, stones or disease, such as polycystic kidney disease.
  
  
• Diseases of the intestines and pancreas.
  
  
• Diabetes. Several conditions related to diabetes can cause back pain, including focal neuropathy and diffuse idiopathic skeletal hyperostosis (DISH, in which spinal or other ligaments become bony).

• Cancer pain. This can be due to cancer originating in or near the spine, cancer that has spread (metastasized) from another area (e.g., prostate cancer, breast cancer) or referred pain from some cancers, such as testicular cancer. Benign tumors can also cause back pain.
  
  
• Porphyria. A group of inherited disorders in which enzyme abnormalities impair the production of an important substance called heme. Heme’s functions including carrying oxygen in the blood. Acute porphyrias affect the nervous system and can cause pain in the back, chest and elsewhere.