Bone stress injuries are one of my special areas of interest in sports orthopaedics. Particularly in growing athletes, the balance between bone metabolism, growth, training load, and recovery is a key factor in both the development and treatment of the injury.
Bone is living and constantly regenerating tissue. Exercise strengthens bone, but at the same time, the bone must have time to recover from the strain.
A bone stress injury does not usually result from a single workout or a one-off event. Typically, it is caused by repetitive loading over the past few weeks.
Bone stress reaction, or an early-stage bone stress injury. It can be thought of as a precursor to a stress fracture: there is already a biological stress reaction in the bone, but an actual fracture line may not yet be present.
If the loading continues to exceed the bone's ability to recover, microdamage can accumulate and the injury can progress toward an actual stress fracture.
Bone stress reaction
early bone stress injury
more severe bone stress injury →
stress fracture
Not all stress injuries progress to a stress fracture. An injury detected at an early stage can often be healed by sufficiently modifying the load.
In bone metabolism, old bone damaged by mechanical stress is continuously removed and replaced with new bone.
Exercise is normally a good stimulus for bone. The problem arises if the repetitive load continues for so long that the the bone's remodelling and repair processes cannot keep pace with the load
This is when micro-damage begins to accumulate. On an MRI, this can be seen as a bone stress reaction and bone marrow edema. If the imbalance between loading and recovery continues, the process can progress to a stress fracture.
During growth, bone is not in the same biological state at all times.
Especially during the phase of rapid height growth, the growing skeleton must simultaneously adapt to both growth and the load caused by training.
If this is combined with a high volume of training, a rapid increase in workload, and insufficient recovery, the overall load can temporarily become too high.
GREEN
Workload and recovery are in balance.
The bone adapts and strengthens.
YELLOW
The load is approaching the bone's recovery capacity.
The risk of stress injury increases.
RED
The total load exceeds the bone's ability to recover.
Microdamage accumulates, and stress osteopathy can progress toward a stress fracture.
The goal of the treatment is to bring the total load back from the red to the green zone – without unnecessary total rest.
The lumbar spine is an important site for bone stress injuries in growing athletes.
The risk is particularly increased in sports involving repetitive rotational loading of the lumbar spine. Forceful extension can further increase the stress on the lower back, especially when rotation and extension are combined.
A typical symptom is lower back pain associated with exercise, which may initially be felt only during certain movements or after a workout.
A young athlete's prolonged lower back pain is not always muscular in origin. Particularly in sports involving repetitive rotational stress, one should also keep in mind bone stress injuries of the lumbar spine.
Magnetic resonance imaging (MRI) is a key examination in the diagnosis of bone stress injuries. It can detect an early bone stress reaction and assess the extent of the injury.
The patient is referred to a physiotherapist specializing in bone stress injuries and athlete rehabilitation.
The physiotherapist assesses:
• mobility
• muscle strength
• movement control
sport-specific loading
• the amount of training and its changes
• potential functional factors that increase the load on the injured area
Based on these, an individual exercise program is created with the goal of modifying the load placed on the injured area.
In most cases, the goal of treatment is not to stop all physical activity.
Particularly in children and adolescents, the aim is to maintain normal, pain-free daily physical activity as much as possible.
The overall load can be reduced, for example,by:
• pausing the training that causes the symptoms
• changing the content of the training
• reducing the amount of training
• using alternative safe forms of exercise
Bone needs loading to become stronger – but during an overuse injury, the load must remain within the bone's capacity to heal.
The physiotherapist and the doctor will work together to plan the progression to increase the load as recovery progresses.
The goal is to find a safe training zone at every stage, where the athlete can train without the bone load exceeding its current tolerance.
Pain-free daily activities →
light training →
increasing load →
running / jumping / sport-specific loading →
sport-specific training →
full return to sport
Healing is often assessed at around three months with a follow-up MRI, especially in lumbar spine stress injuries.
The goal is to ensure that the bone marrow edema has resolved or significantly subsided, and that any potential fracture is healing as planned.
The imaging result is always combined with symptoms and functional recovery.
Simply healing the injury is not always enough. At the same time, it is important to assess why the bone's tolerance limit was exceeded.
• a rapid increase in training volume or intensity
• growth phase
• previous bone stress injuries
• energy intake in relation to training
• nutrition
• Vitamin D and calcium
• hormonal factors
• illnesses or medications that affect bone health
• sport-specific loading
• biomechanical and functional factors
If necessary, the underlying secondary factors of the stress fracture will be investigated in more detail.
In the treatment of a bone stress injury, the goal is not solely the elimination of pain or achieving a normal MRI scan.
The goal is to understand:
Why did the bone become overloaded?
How can the load be changed?
How can an athlete be kept in the best possible condition during recovery?
How can a safe return to full training be achieved?
Growth, loading and recovery are key
A correct diagnosis, sufficient biological healing, and a controlled increase in load form the foundation for a safe return.