What is a Lumbar Stress Fracture?
Stress fractures are referred to as tiny cracks in a bone. A lumbar stress fracture is a stress fracture in the pars interarticularis section of the lumbar spine or lumbar vertebrae. This is the section of the bone between the 2 facets of the vertebrae. The facets join the vertebrae to the vertebrae below and the vertebrae above. A lumbar stress fracture is a gradual softening of the bone due to stress (bone stress reaction) which progresses to a crack.
Causes of Lumbar Stress Fracture
During any activity involving the lumbar spine moving backward, typically twisting as well, with the leg on the ground there is additional pressure on this region of the spine. During adolescent years, the lumbar area is still developing, and the bone can undergo torsion beyond what it can handle. As time progresses, the bone softens and bruises (stress response) ultimately progressing to a crack.
Lumbar stress fractures occur mainly in young athletes who rotate and extend their spine, particularly in weight-bearing activities. It is common in weightlifters, gymnasts, kicking sports (soccer and AFL), baseball, and lacrosse.
Most commonly, lumbar stress fractures occur in the fifth vertebra of the lumbar spine, although they can also occur in the fourth lumbar vertebra. A fracture can occur on one side or both sides of the “pars” bone. In more severe cases, spondylolisthesis can develop. Spondylolisthesis is a condition characterized by displacement of one vertebra over the other. Excessive displacement may compress the surrounding spinal nerves and cause pain.
Signs and Symptoms of Lumbar Stress Fracture
The main symptom of a lumbar stress fracture is low back pain that worsens with activity and improves with avoiding activity or sports that require repeated back bending. Additional symptoms can include back stiffness, muscle spasms, tight hamstrings, trouble standing or walking, and pain radiating down one or both legs. Patients can also experience weakness, tingling, and numbness in their legs. Symptoms can progress to interfere with normal daily activities.
Risk Factors for Lumbar Stress Fracture
Factors that can increase your risk of developing lumbar stress fractures include:
- Weakened bones: Conditions such as osteoporosis can weaken your bones and make it easier for lumbar stress fractures to occur.
- Previous stress fractures: Having had one or more lumbar stress fractures puts you at increased risk of having more.
- Increased activity: Lumbar stress fractures usually occur in individuals who suddenly change from a sedentary lifestyle to an active training regimen or who quickly increase the frequency, duration, or intensity of training sessions.
- Certain sports: Lumbar stress fractures are more common in individuals who participate in high-impact sports, such as gymnastics, football, weight-lifting, and track and field.
- Lack of nutrients: Eating disorders and lack of calcium and vitamin D can make the lumbar spine more likely to develop stress fractures.
Diagnosis of Lumbar Stress Fracture
Often an X-ray is sufficient to detect a lumbar stress fracture. However, if pain persists despite rest and physical therapy, your physician may order additional imaging tests. These may include a CT scan, an MRI, or a nuclear medicine bone scan with SPECT of the lumbar spine for a conclusive diagnosis.
Treatment for Lumbar Stress Fracture
The primary treatment for a lumbar stress fracture is always conservative. The goal of conservative treatment is to reduce the pain, allow the fracture to heal, and improve spinal function.
Conservative treatment options include:
- Rest: Adequate rest should be taken and strenuous activities should be avoided until the symptoms subside.
- Medications: Non-steroidal anti-inflammatory drugs (NSAIDs) may be prescribed to reduce the pain and inflammation. If NSAIDs do not provide relief, epidural steroid injections may be administered to the lumbar spine to reduce pain, numbness, and tingling in the legs.
- Physical therapy: An exercise program helps to strengthen the abdominal and back muscles, improve flexibility, and increase the range of motion of the lower back.
- Use of braces: In severe cases of a lumbar stress fracture, a brace or back support may be used to stabilize the lower back during fracture healing.
Surgery to treat a lumbar stress fracture is rarely required, as the pain is expected to fade over time in most cases. However, surgery may sometimes be an option in patients whose symptoms persist despite undergoing conservative treatment and if the stress fracture has progressed into spondylolisthesis. The goal of the surgery is to remove any abnormal bone compressing a nerve and to stabilize the spine.
Spondylolisthesis is treated with two procedures during surgery. First, a decompression laminectomy will be done. In this procedure, a portion of the bone or lamina imparting pressure on the nerves is removed. A surgical incision is made in the back, then part of the bone and thickened tissue pressing on the spinal nerves is removed. This allows more space for the nerves, thus relieving pain and pressure. This procedure makes the spine unstable and therefore spinal fusion will be performed to stabilize the spine.
Spinal fusion is the procedure of joining two adjacent vertebrae. During the procedure, a piece of bone, taken from elsewhere in the body or donated from a bone bank, is transplanted between the adjacent vertebrae. As healing occurs, the transplanted bone fuses with the spine. This stimulates the growth of a solid mass of bone which helps to stabilize the spine. In some cases, metal implants such as rods, hooks, wires, plates, or screws are used to hold the vertebra firm until the new bone grows between them.