Causes and Risk Factors of Sharp Low Back Pain

Sharp low back pain can occur due to a sudden injury, such as a spinal fracture or sprain, or to issues like sciatica or degenerative damage of the vertebral discs. When the precise cause of sharp low back pain cannot be identified, it is described as "non-specific" back pain.

Low back pain that's sharp and severe tends to come on suddenly and can be acute—sometimes lasting for no longer than three months.

Sharp, piercing pain is usually associated with simple, seemingly benign movements such as twisting or lifting something heavy.

Causes include:

• Muscle strain
• Lumbar sprain
• Facet joint pain
• Spinal fracture
• Sacroiliac (SI) joint dysfunction
• Disc damage

Several lifestyle factors may increase or decrease your risk of developing sharp low back pain.

Muscle Strain

A strain is an injury in which tendon or muscle fibers are overstretched or torn, triggering inflammation. When the low back is affected, the pain often emanates from the buttocks and may extend down the back of one or both legs.

Other symptoms of muscle strain include:

• Stiffness
• Muscle spasms
• Difficulty moving

Lumbar Sprain

A lower back sprain, also called a lumbar sprain, occurs when ligaments—the tough bands of tissue that connect bones to bones—are injured.

Sprains can result from stretching or tearing a ligament from its attachment, often due to an injury such as a fall or an action that displaces the surrounding joint from its normal alignment.

A sprain can range from a mild ligamentous stretch to a complete tear. Common symptoms experienced after a sprain are:

• Bruising
• Swelling
• Instability
• Painful movement
• Painful muscle spasms

Facet Joint Pain

Facet joints are located behind the vertebrae and help to protect the spine from extreme movements in any direction.

They can be injured by a sudden jolt, such as whiplash, in which the spine is pulled out of alignment. Even the simple action of bending over to tie a shoelace can trigger facet joint pain.

Facet joints also are susceptible to degenerative arthritis (osteoarthritis), in which the cartilage around the joint that provides protective cushioning between vertebrae wears out. When the bones rub against each other, it causes pain.

The sharp pain caused by facet joint injury or degeneration can radiate from the lower back down to the buttocks and upper legs or up to the shoulder blades.

Spinal Fracture

One type of spinal fracture—a compression fracture—occurs when vertebrae collapse under a load of an external force. This is common in traumatic spinal injuries or due to a bad fall when a vertebra is squeezed or crushed.

In older adults, loss of bone density associated with osteoporosis can increase the risk of these fractures, which may not cause symptoms right away.

Spinal fractures tend to cause sharp low back pain when you're standing.

Sacroiliac Joint Dysfunction

The sacroiliac (SI) joints are located on either side of the lower back between the sacrum and the pelvic bones. They're shock absorbers, decreasing stress on the pelvis and spine.

When you stand or walk, the SI joints help transfer the load from your upper body to the lower body.

Repetitive stress from daily movement or injury can wear down the cartilage around the SI joints, causing low back pain and limiting motion in the lower back or hips.

The intensity of sacroiliac pain is typically related to the extent of joint damage. When the cartilage is damaged or worn away, the bones begin to rub against each other. 

Movements or positions that stress the joints—standing up from a chair, walking upstairs, bending, and twisting—can worsen pain in the lower back and hips. That pain may radiate to the buttocks, groin, thigh, or below the knee.

SI joint pain also can be caused by:

• Running, jogging, and other activities involving continuous and repetitive pounding
• Injury or trauma to the ligaments surrounding SI joints
• Spinal surgery
• Uneven leg length that affects walking patterns
• Pregnancy

Sciatica

Sciatica occurs when there's pressure on or damage to the sciatic nerve, which starts in the lower back and runs down the back of each leg.

The sciatic nerve controls the muscles in the back of the knee and lower leg, and makes it possible to feel sensation in the back of your thigh, lower leg, and even the soles of your feet.

When the sciatic nerve is compressed, you may feel a burning sensation and pain. If the nerve is pinched, you may also feel numbness and weakness in your leg due to an interruption of the nerve signal.

In some cases, sciatica may be caused by a tumor or cyst that is pressing on the nerve or nerve roots.

Disc Damage

Sharp low back pain from a herniated or ruptured disc can occur when the intervertebral discs become compressed and bulge outward, also described as a slipped disc.

When a disc slips, all or part of it exerts pressure on surrounding nerves or the spinal cord. A disc can also rupture due to an injury or strain.

Because they act as a cushion, intervertebral discs facilitate a full range of lower back movements, such as flexing, bending, or twisting. However, disc deterioration reduces that cushioning and leads to sharp pain. It also can cause some people to lose several inches of height.

Annular tears (tears of the ligament) that occur in the outer layer of the intervertebral disc can also cause acute low back pain. The pain can be severe, even if there is only a small amount of tissue damage.

Lifestyle Risk Factors

Lifestyle factors that can increase your risk of sharp low back pain include:

• Excess body weight
• Repetitive bending or twisting of the lower back
• Lifting heavy objects the wrong way
• Sitting or standing for hours in the same position
• A generally sedentary lifestyle

Some research suggests smoking may also up your risk of sharp low back pain.

A Word From Verywell

Low back pain is one of the most common medical conditions in the United States. Often, if you have a sprain or strain, the pain will resolve itself.

However, it can be caused by a serious injury, so it is important that you see a doctor. As you are recovering, seek medical guidance to ensure that you are reducing any of your risk factors for low back pain.