A bone stress injury (BSI) is an overuse injury caused by repeated impact on a bone. It is important to point out here that bone is a living tissue just like muscles and tendons. Bones make up our skeletal system and are made of protein, collagen, minerals and calcium. BSI often occurs in weight-bearing bones, usually in the shin and foot. We commonly see runners, basketball players and football athletes presenting with BSI.
What are the symptoms of a bone stress injury?
You may feel a gradual increasing level of pain at the injured area over a few weeks, with the following symptoms:
local bone pain
tender to touch
some swelling around the bone region
worse when putting weight on the injured bone such as when running and jumping
better with rest.
As the BSI gets worse, you may start to feel the pain at night and at rest. However, it is important to remember not all BSI have these typical symptoms.
How long does it take for a BSI to heal?
Healing timeframe depends on the severity of your BSI at the time you were diagnosed. You doctor and physiotherapist will take your medical history and perform a comprehensive physical examination. You may also be required to take a simple X-ray in most clinical situations. However, sometimes MRI may be indicated if pain and swelling persist.
MRI classification system (Grade 1 to Grade 4) for bone stress injury help to correlate the extent of bone involvement with clinical symptoms, which leads to more accurate recommendations for rehab and return to sports activity. The Fredericson classification on MRI follows a progression related to the extent of injury. This begins with periosteal (outer bone layer) oedema (grade 1), followed by progressive marrow involvement (grades 2 and 3), and eventually cortical stress fracture (grades 4a and 4b). Stress fractures account for more than 10% of all sport-related injuries, and can be as high as 30% in sports that require running.
The estimated delay in returning to sport and impact activities based on the Fredericson classification is:
Grade 1: 2-3 weeks
Grades 2-4a: 4-8 weeks
Grade 4b: 9-12 weeks or more
The anatomical location of the BSI is an important factor too. These locations are classified into low, medium and high risk BSIs based on the biological healing process, blood supply and the direction of mechanical load to the bone in different areas of the body. There are also low, medium to high risk BSI locations within the same bone. Here are some examples of low versus high risk BSIs.
Low-risk BSI location:
Fibula / lateral malleolus
Calcaneus (heel bone)
Posteromedial tibia
Diaphysis of 2nd to 5th metatarsals
High-risk BSI location:
Medial malleolus
Talus (bone that makes up the lower part of the ankle joint)
Anterior cortex of tibia
Femoral neck
Low-risk BSI sites are prone to compressive (squashing) forces. Atheletes with low-risk BSI sites can normally weight bear early and heal well with activity modification. On the other hand, high-risk BSI sites, are vulnerable to tensile (elongating) forces and occur in areas with decreased blood flow. They are more at risk to advance to complete fractures and are susceptible to delayed union or nonunion.
In summary, low-grade BSIs at low-risk sites heal the fastest and have the shortest return time (2 to 3 weeks) to running and other sporting activites. High-grade BSIs at low-risk sites or low-grade BSIs at medium to high-risk sites will require more time (around 6 to 8 weeks) to return to sport as they take longer to recover. High-grade at high-risk BSI site sometimes can take up to 9 to 12 weeks or more returning to sport. Careful treatment with close guidance from your doctor and physiotherapist is required especially if you have higher grade BSIs at higher risk locations.
Breathe Physio and Pilates' Roadmap for Recovery provides a general guidance for bone stress injury (BSI) treatment and consists of 4 distinct stages.
Stage 1 - Pain Reduction
First and foremost, it is crucial to manage and settle down the pain and swelling around the BSI site. This is achieved by resting temporarily from pain-provoking activities i.e. running, hopping, jumping. Sometimes ice and using analgesic along with physiotherapy treatment (which may include joint mobilisations to joints above and below the bone) can be helpful. Nonsteroidal anti-inflammatory drugs should be avoided due to their potential negative effect on bone healing. For a Grade 2 to Grade 3 low-risk BSI site such as "shin splints" or medial tibial stress syndrome, the average healing time is between 4 to 8 weeks.
At the start of first two weeks, reducing and modifying your exercise volume, intensity and frequency remain the most effective approach during this stage for bone healing. Walking boot or crutches can be used for athletes who cannot walk without pain. Here you will be given gentle non-weight bearing exercises to maintain the flexibility of your affected joints close to the BSI site. It is worthwhile to note that getting enough calcium and vitamin D may reduce risk for BSIs.
In female athletes, menstrual irregularities should be investigated. It is important to note any hormonal use such as oral contraceptives and IUD which may affect the athlete's bone health. Previous history of fractures and family history of low bone mineral density should also be checked.
Criteria to advance to Stage 2:
No to minimal pain at the BSI site
Achieve a similar range of motion in the joints above and below the BSI site to your non-injured side
Stage 2 - Muscle Activation
Once you have fulfilled the criteria in Stage 1 - Pain Reduction, next stage focuses on activating the muscles surrounding your BSI area to provide more support to the bone. For Grade 2 to Grade 3 "shin splints" or medial tibial stress syndrome, we will start strengthening your ankle invertor, evertor and foot intrinsic muscles along with gastrocnemius and soleus muscles. Core (e.g. plank, side-plank, pall of press) and non to partial weight bearing gluteal muscles activation (e.g. clams, sidelying straight leg raise, fire hydrants) is also a crucial part of rehabilitation in this stage.
Strengthening ankle muscles
Strengthening core muscles
Some of you may want to still keep active while resting. In this case, choosing less impactful exercise such as swimming or cycling instead of continuing with your usual sport that requires running, sprinting and repetitive jumping will allow proper healing to occur in the bone stress site.
Criteria to advance to Stage 3:
Pain-free in your usual daily activities excluding sport
30-minute walk with minimal to no increase in pain
Stage 3 - Movement
The cornerstone of physiotherapy treatment involves understanding and correcting the underlying biomechanical factors that caused the bone stress injury in the first place.
Assessing and addressing the weaker link in your lower extremity kinetic chain from the lumbopelvic region to the feet and re-establish dynamic muscle control, balance, and proprioception remain a priority in Stage 3. In this stage you will commence weight-bearing double and single limb proximal stability exercises, which may include squat, single leg squat, lunge, step up, step down and lateral band walk. All of these exercises should be performed with good form. Here, some light plyometrics emphasising soft landing and hip strategy will also be introduced.
Pistol / single leg squats
Single leg glute and quad strengthening on the Pilates Reformer
Your progress and motor control pattern will be analysed by physiotherapists at Breathe. We will ask you to perform plyometrics tests such as countermovement jump, single leg jump and drop jump on VALD Forcedeck to ascertain your readiness for return to sport.
Criteria to advance to Stage 4:
Balance on one leg for 30 seconds
15-20 controlled single knee dips
20-30 single leg calf raises
Technique: Jump, bound and hop pain-free - land quietly, in a controlled manner
10 consecutive pain-free hops / 30 seconds of hopping pain free
100 up and 100 up “major” – this is a great introduction to impact and practicing running form. It’ll give you an idea of how your body will respond to running. If 100 up is painful, then it’s likely running will be.
Stage 4 - Return to Sport
In Stage 4 you should be cleared for a gradual return to training at a lighter intensity guided by pain level in your chosen sport. Closely monitoring your pain level during and up to 1 to 2 days after training will ensure you are loading the bone stress injury site appropriately. If you are experiencing more than 3-4 out of 10 pain (0 being no pain experienced and 10 being the worst pain you've felt), you are loading the BSI site too much and need to ease back.
On the other hand, if you've experienced minimal to less than 3-4 out of 10 pain with all training sessions, you can gradually increase training volume or intensity the following week. How much intensity to increase will hugely depend on the type of your BSI and the sport you play. It is crucial to have a sports physiotherapist or a sports physician to conduct a proper assessment before your first game after the injury especially if your sport requires a lot of sprinting, jumping, acceleration and deceleration, and change of direction.
The time it takes for a bone stress injury to heal depends on mainly two factors - the extent of the injury and the location of the injury site. A low-grade BSI at low-risk site generally takes 2-3 weeks, whereas a high-grade at high-risk BSI site sometimes can take up to 9 to 12 weeks or more returning to sport or running. Every individual heals differently even when they have exactly the same injury. If you want to ensure you can recover fast and safely, it is worthwhile to find a sports physiotherapist who you trust and work well together.
Author: Winnie Lu
Winnie is the principal physiotherapist and Director of Breathe Physio and Pilates. Winnie has extensive experience treating athletes who compete in cycling, running and soccer/football. Winnie also has many years of experience treating lower limb amputees, and eventually getting them back to playing sports. Winnie is an associate lecturer at the University of Queensland and mentors physiotherapy students during their clinical placements at Breathe. Winnie has a passion for optimising movement and helping clients become better athletes.
References:
Stress Fracture Rehabilitation Guidelines Sanford Health (2021). Stress Fracture Rehabilitation Guidelines.
Bone Stress Injuries in Runners 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), e38.
Fredericson MRI classification of medial tibial stress syndrome Skalski M (2023). Fredericson MRI classification of medial tibial stress syndrome. Case study, Radiopaedia.org.
Bone Stress Injuries and Stress Fractures Smith (2018). Bone Stress Injuries and Stress Fractures. Oxsport - Department of Sport and Exercise Medicine.