Bone stress injuries are common injuries seen in sports and can have a significant impact on sporting participation. Bone stress injuries are a continuum pathology characterised by repeated microdamage with inadequate recovery. This initially leads to bone stress reactions and can progress to a stress fracture without appropriate intervention. The location depends widely on the sport you play. They are commonly seen in the lower limb in runners, with the tibia making up 23.6%, the fibula (23%) and in the feet (33% across the metatarsals and navicular). Other areas of the lower limb that may develop bone stress include, the pelvis, femur and sacrum. Bone stress injuries can also be seen in gymnasts, cricket bowlers and other impact sports, and can occur in the upper limb, spine or ribs.
Bone stress injuries develop over time, noticed by a gradual increase in pain which is usually quite localised. Unlike soft tissue injuries which commonly have a warm up phenomenon during training or sports (meaning they tend to improve and feel better once the body has warmed up), bone stress injuries get worse during training and will improve with rest. On physical examination, pain can usually be reproduced through impact activity and sometimes palpation, depending on location. If a bone stress injury is suspected, an MRI is usually warranted to confirm or rule out the diagnosis.
What is a bone stress injury?
When we load a bone we cause microdamage which stimulates bone cells (osteoblasts, osteoclasts and osteocytes) to help strengthen and remodel the bone, thereby increasing the bones tolerance to stress. If the microdamage takes place with inadequate recovery and time between sessions for bone cells to appropriately repair your bones, the microdamage never completes recovers and can lead to microcracks in your bone, this is called a bone stress reaction. If this is not appropriately managed through adequate rest, these microcracks will further escalate by expanding through the entire width of the bone, resulting in a fracture.
Risk factors for bone stress injuries
Bone stress injuries are multifactorial. While it is highly unlikely for a bone stress injury to occur without some form of training stress, training stress is not the only thing to consider when preventing and managing bone stress injuries. Risk factors include:
- Rapid change in training stimulus: volume, intensity and surfaces
- Inadequate recovery between sessions
- Relative Energy Deficiency in Sport (RED-S): chronic insufficient energy levels required to meet the demands of your sport, which is essential for healthy bone turnover
- Bone health: calcium intake and vitamin D considerations
- Biomechanics resulting in increased bone loading at specific points
- Female: increased risk of bone stress injuries in females compared to males
Treatment and return to sport
Due to the multifaceted nature of bone stress injuries, it is highly encouraged to have your injury assessed by a Sports Physician or Doctor who will be able to refer you to other appropriate health professionals which may include but is not limited to, Endocrinologists, Physiotherapists, Podiatrists and Dietitians.
A period of rest is essential to eliminate any further loading and stress to the bone. How much rest is needed is very individual depending on the severity of the injury. It may include a period of non-weight bearing using crutches or a moon boot until walking is symptom free. Throughout this period, your usual sport may be supplemented with low impact activities including cross training (e.g. swimming) or resistance training other areas of the body, that is not going to be stressing the injury further. Your Doctor or Specialist will advise when you are able to begin returning to your sport and again. The return to sport process is going to be highly individualised and there are no recipes that can be followed. It is essential that all loading remains completely pain free and training is reintroduced gradually with ample rest between sessions. This is often going to look like a slowly progressive walk run program, keeping running intensity very low initially.
Bone stress injuries can be slow, unpredictable and complex injuries. If you at all suspect you may have a bone stress injury, we will be able to assist through a thorough assessment and well supported rehabilitation process.