What are Lumbar Stress Fractures?
Lumbar stress fracture often refers to a stress fracture in the pars interarticularis part of the lumbar vertebrae. This is the part of the bone between the two facets of the vertebrae. The facets connect the vertebrae to the vertebrae above and the vertebrae below. A stress fracture is a gradual softening of the bone due to stress (bone stress reaction) which progresses to a crack.
How do Lumbar Stress Fractures happen?
Stress fractures occur in mainly young athletes who extend their spine and rotate, especially in weight-bearing. Common in cricket fast bowlers, gymnasts, dancers, kicking sports (soccer and AFL) and some running styles.
During any activity involving the spine moving backwards, usually twisting as well, with the leg is on the ground there is extra pressure on this area of the spine. During adolescent years this area is still developing, and the bone can undergo torsion beyond what it can handle. As time goes on the bone softens and bruises (stress response) eventually progressing to a crack.
What are the symptoms of a Lumbar Stress Fractures?
Pain will often develop in the lower back region on the side that is on the ground (for example the left side of a right arm bowler or kicker). It is often painful to arch the spine backwards and may or may not be tender to touch. It will mainly be aggravated by the movement or activity that has caused the stress reaction, especially if you continue to push through as it will often progressively feel worse. Many athletes report not being as fast, confident or powerful in their activity.
Checking the Severity of the Fracture
MRI is often required to assess for the stress fracture but more importantly to assess how it heals. X-ray and CT scan can also provide useful information, but MRI is often best for ongoing monitoring.
The MRI will show if the fracture has developed or if it is a bony stress reaction. The bone stress can also help determine how new the defect may be. It can also show if it is on one side only, both sides or at multiple levels of the spine.
- Bone stress reaction only (no fracture)
- Partial or non-displaced pars fracture (+/- bone stress)
- Complete pars defect (+/- bone stress)
Some fractures may be chronic and as such there may be no bone stress present. These may not have any capacity to heal. Some others may be on both sides and if complete fracture may result in a spondylolisthesis, where the vertebrae slips forward or backwards relative to the one above and/or below.
Treating Lumbar Stress Fractures
Lumbar stress fractures require healing time and as such the athlete needs to avoid activity causing the stress on the spine. They can however often maintain strengthening and cardiovascular exercise that does not produce symptoms. They should generally avoid any spine extension which can happen in some peoples running styles.
Whilst the fracture is healing or the bony stress is symptomatic treatment should include managing the contributing factors to the problem including trunk and hip mobility, strength and control as assessed.
Once the fracture has healed then treatment is about monitoring return to sport and higher levels and demand for strengthening and cardiovascular fitness relevant to the activity or sport. Constant monitoring is important to make sure optimal strength and movement are maintained without symptoms returning.
How long will recovery take?
Bone stress can exist without symptoms and the appearance of the bone stress can stay on MRI long after the bone is healed. Generally, a period of 4 to 6 weeks is recommended to return to sport but clinical judgement is crucial. Progressive return to sport and passing tests can help determine when an athlete is ready.
If there is a partial fracture the bone can take 6 weeks for the fracture to heal if found early enough. From there the progression to return to sport is approximately 6 weeks, depending on strength and predisposing factors being managed. In total 3 months would be ideal.
Complete fractures can take up to 16 weeks to start show signs of starting to heal. This is often best monitored with MRI. Once signs of healing start then it is at least another 6 weeks to 3 months for healing and then another 3 months of re-conditioning the bone to the demands of the sport. In total 6 months is a good result but can take up to 12 months for return to sport.