What Are Bone Stress Injuries?
Bone stress injuries are damage to the bone ranging from swelling, stress reactions, and finally to a stress fracture. They are common in middle and long distance runners. If bone stress injuries are diagnosed early they can usually be managed very effectively with physio and load management (i.e. reducing weight-bearing activity through the injured bone). Sometimes immobilisation in a boot is required, and occasionally crutches are needed, however the earlier the injury is picked up the less likely these restrictions will be necessary.
Early diagnosis and management is critical to avoid requiring extended times away from running. It is also essential to avoid potentially more serious interventions like time not being able to weight-bear at all through the area, or in extreme cases, surgery to fixate a fracture with a pin or plate.
Why Do Bone Stress Injuries Occur?
Bone stress injuries occur when the bone is unable to the recover from the current loading demands. In simple terms, this is when the rate of bone breakdown (due to loading during running) is greater than the rate of bone repair (between runs), so over time the bone weakens and undergoes structural fatigue.
For runners the bone damage typically occurs due to repeated submaximal loads which causes the bone to break down faster than it can rebuild. Theses types of injuries are quite common in runners. They account for 30% of all distance running injuries, with an annual incidence of 20%.
Most Common Sites For Bone Stress Injuries In Runners
Approximately 50% of bone stress injuries occur in the tibia bone in the shin, with other common sites being the femur (thigh bone), calcaneus (heel bone), metatarsals (the long foot bones), and fibula (the other shin bone). By far the most common site is the shin, and these shin injuries make up part of the group of injuries known as “shin splints“.
Running technique can play a role in determining where bone stress injuries occur. In rearfoot strikers, bone stress injuries typically occur in the tibia and femur, whereas in forefoot strikers bone stress injuries typically occur in the foot.
Risk Factors for Bone Stress Injuries
Risk factors can be broken up in to two main factors: biological and biomechanical.
Biological
– Being female
– Genetics
– Low bone mineral density
– Medications, in particular steroid use
– Relative energy deficiency
– Low calcium and vitamin D intakes
Biomechanical
– Training load which is primarily dictated by training intensity, volume, and frequency
– Anatomical, which includes lean body mass, foot type (pronation/ supination) and calf muscle bulk
It should also be noted that research shows that psychosocial factors can be also involved with injury risk such as work stress, smoking, alcohol consumption and poor sleep. These factors may reduce our body’s ability to recover and repair the bone damage caused by loading during running. This means that even if your body is used to running a certain distance across an average week, if these other psychological factors increase (eg a stressful deadline at work), your rate of bone recovery between runs can reduce, leading to bone stress reaction injuries even though you have not increased your average running volume.
Signs Of Bone Stress Injury
Bone stress injuries typically have a gradual onset of pain and no clear one-off mechanism. There will be local bony tenderness, and pain during single leg hopping. In “shin splints”, because a lot of the bone (tibia or fibula) is just under the skin, you can often find a well-localised area of soreness to feel or push on. You may also feel some fluid or thickening of the area. If you do these tests on yourself and they are positive then you should see your physio to get things checked before you continue to run. As outlined above, early diagnosis and management usually means a really good outcome without the need for more intensive management or time out from running.
If the injury is in the femur (thigh bone), there will usually be a positive fulcrum test, and even bruising and local swelling in extreme cases. In femoral stress reactions or fracture it may be harder to localise the pain because the bone is really deep underneath the skin. It may feel like it aches and is sore deep within your mid-upper thigh or hip, and you may not be able to find a well localised spot that is sore to feel or push on. If this sound like you, then it is important to see a physio to get a professional diagnosis because if not managed well early, femoral stress fractures may need more intensive treatment such as complete non-weight bearing or surgery.
Diagnosis Of Bone Stress Reaction Injuries
Diagnosis is often able to be made clinically by your physio – i.e. through taking a thorough history and going through a physical examination. Your physio may also want to confirm the diagnosis with an MRI. An MRI is the gold standard investigation and also doesn’t expose the person to radiation, so it is normally chosen over an x-ray or CT.
Treatment For Shin Pain In Runners
Shin pain, often called “shin splints”, is common in middle-long distance runners. It can be due to a variety of causes, some of which are soft tissue (eg tendinopathy and muscle pain). These can be managed well with physio including load management, muscle strengthening, mobility/stretching when required, and addressing other factors such as running technique and running training progressions.
A primary goal of assessing, diagnosing and treating shin pain early in runners is to avoid the injury progressing from soft tissue to a bone stress injury. And if the bone is already involved, the priority is to effectively manage loading as early as possible so that the bone is able to recover and then re-loading can occur.
If the injury is allowed to progress from a stress reaction (i.e. signs that the bone has a level of trauma but there is no definite fracture line) to a stress fracture (i.e. where a defined fracture line is present), then the treatment required may be much more intense, the time taken to heal is far longer, the client needs more time out of running, and the risk of progressing to needing medical treatment such as surgery is much greater.
For these reasons, we strongly encourage runners to see a running physio early if they start experiencing shin pain. Early diagnosis and management is very effective, plus you can be guided on how to perform cross-training to maintain your cardio fitness and strength in other areas of your body while your shin heals. This significantly reduces your risk of sustaining another injury when you are able to return to running after your shin pain resolves.
Recovery From Bone Stress Injuries
Phase 1
Low Risk Bone Stress Injuries
– Cessation of running
– Weight bearing as tolerated
– Complete low-impact exercise within set symptom restrictions
– Maintaining strength and endurance in the non-injured side
High Risk Bone Stress Injuries
– Immobilisation, usually by wearing a Cam boot or similar
– Non-weightbearing, followed by gradual re-introduction of weightbearing within symptom restrictions
– Surgery in some cases, using pins or plates to stabilise the stress fracture and allow bone healing
Phase 2
– Begins after 10-14 days of being pain free on palpation and able to single leg hop
– Resume running around 50% of preinjury speed and distance
– For the first 2 weeks running should only be completed every second day
– Gradually increasing running loads over following 3-6 weeks
How To Reduce Your Risk Of Bone Stress Injury
– Managing training loads appropriately – avoid big spikes or increases in running volume
– Participating in regular strength and plyometric training
– Ensuring recovery through adequate energy intake, 7-10 hours of sleep and scheduled rest days
– Sufficient consumption of calcium and vitamin D
– Addressing lifestyle factors such as excessive alcohol consumption and smoking
References
1. Bennell, K. L., Malcolm, S. A., Thomas, S. A., Wark, J. D., & Brukner, P. D. (1996). The incidence and distribution of stress fractures in competitive track and field athletes: a twelve-month prospective study. The American journal of sports medicine, 24(2), 211-217.
2. Duplanty, A. A., Levitt, D. E., Hill, D. W., McFarlin, B. K., DiMarco, N. M., & Vingren, J. L. (2018). Resistance training is associated with higher bone mineral density among young adult male distance runners independent of physiological factors. The Journal of Strength & Conditioning Research, 32(6), 1594-1600.
3. Song, S. H., & Koo, J. H. (2020). Bone stress injuries in runners: A review for raising interest in stress fractures in Korea. Journal of Korean Medical Science, 35(8).
4. Warden, S. J., Davis, I. S., & Fredericson, M. (2014). Management and prevention of bone stress injuries in long-distance runners. Journal of orthopaedic & sports physical therapy, 44(10), 749-765.
