Stress Fracture of the Lower Back
Very active adolescents that play high volumes of sports involving end of range lower back movements (think gymnastics, dancing, tennis, surfing, fast bowlers in cricket, volleyballers …) are prime candidates to develop stress fractures in their lower vertebrae. The part of the spine called the pars interarticularis gets overloaded and the bone undergoes a stress reaction or a hot spot on the bone. These can be quite painful. Stress reactions in the spine usually occur down the bottom of your lower back at your 4th or 5th lumbar vertebra. This usually presents in active adolescents as localised lower back pain with no particular mechanism of injury, and it gets worse with activity (especially the sport in question) and better with rest.
What is a stress reaction versus a stress fracture?
Normal bone health relies on constant remodelling of the bone. It is constantly being broken down and rebuilt in a healthy manner. When this mechanism gets thrown out by too much heavy compressive load, the bone begins to develop a stress reaction. If allowed to continue, the bone will eventually weaken to the point where a fracture occurs, which generally does not need much force.
Stress fractures most commonly occurs at the pars area in the spine. All engineers know that structural vulnerabilities occur in the small links that join big parts together and the spine is no exception to this rule. The red line in the below picture is where the pars is.
You can see from this picture that each vertebra has a big body at the front and a long spinous process at the back that is linked via a relatively small area called the pars interarticularis. This is the smallest and weakest link in the vertebra, especially in activities that extend and rotate your back, and this area is vulnerable to stress reactions and can eventually result in a stress fracture or spondylolysis.
So what causes the stress reaction to begin with?
- Activities that put a lot of stress through the pars interarticularis in your lower back. This is generally activities where you are extending, side flexing and rotating your lower back such as:
- Fast bowling in cricket
- Serving in tennis (second most common overuse injury in tennis)
- Specific tricks in gymnastics or acrobatics
- Figure skating
- Degenerative changes in your lumbar spine, natural ageing of the lumbar vertebra as well as osteoarthritis (Link) can lead to stress fractures and spondylolisthesis
- Genetics – some people are born with thinner pars regions than others
How do physios treat this condition?
The first part of treating this condition is an accurate diagnosis and treatment plan. A thorough clinical subjective and objective examination are required and in symptomatic adolescents <18 years old, further scans such as a bone scan, CT SPECT or MRI may be necessary. For adults scans are rarely necessary. Physiotherapy treatment is the cornerstone of treatment and the vast majority of cases will make a full recover with the right physiotherapy treatment alone
Physiotherapy treatment will be split into 3 phases after an accurate diagnosis is made. First up is a period of relative rest for 4-12 weeks depending on symptoms. Phase two is the rehabilitation phase, focusing on progressive strengthening and low impact aerobic exercise. The third phase is working on returning the patient to their chosen sport or activity. In total the whole timeframe for treatment is generally between 3-6 months
During the period of relative rest, the focus is on offloading the stress in your lower back at the pars area (from the anatomy before). This will mean no sports, running or exercise classes and avoiding end-of-range motion of your lumbar spine. During this phase we also begin core activation and bracing, and education about correct postures to maintain during everyday life. If the pain is still severe after 2-4 weeks, we may also consider using a brace to ensure that the fracture site is being offloaded and to help with stabilising your spine.
Once you have close to full lower back range of motion without pain, we can progress to the rehab phase. During the rehab phase we will progressively increase your core and postural strength by adding in exercises like planks, side planks, core exercises using a swiss ball and lower limb strengthening as well.
Next, we will start to integrate sports specific movements into your regime. This will mean more dynamic core exercises such as woodchops, multidirectional lunges, and a return to run program all with correct core control and alignment to minimise the pain. We will also look at sport specific activities. If you’re a fast bowler in cricket, the lower lumbar rotation can be a risk factor so we may need to take a look at your bowling action and training load, and come up with some ideas to unload the lower back.