Unfortunately stress fractures are a common injury among runners. Although bone may appear to be a static tissue, it is actually very dynamic. Bone is constantly re-modeling itself in specific location based upon a variety of factors.
BASIC BONE PHYSIOLOGY BEHIND STRESS FRACTURES
Without going into the physiology of this in too much detail there are cells in your bones called osteoblasts that lay bone down and other cells called osteoclasts that reabsorb bone. Both of these cells interact in a complex network in our bony anatomy. Overall if they are in balance the bone density isn’t compromised.
However in response to load, or running these cells as well as others spring into action. If there is sufficient time between load or runs the bone adapts by laying down more bone in order to strengthen it for the action of running. However if there is insufficient recovery time, then initially a stress reaction can occur. If loading continues further microdamage can occur, eventually leading to a stress fracture. Simply put, stress fractures occur when we train too hard without adequate recovery.
A stress fracture is a microfracture in bone that results from repetitive physical loading. This can occur through 2 major ways.
1) The redistribution of impact forces resulting in increased stress at a focal point on the bone
2) The action of a muscle pull across a bone
Initially as seen in a stress reaction the body will seek to heal this overload through increasing the blood flow to the area and initiating inflammation. If through prolonged load, eventually the bony architecture (trabeculae) can become weak leading to the development of a microfracture(s) and potentially a complete fracture can occur if left untreated.
COMMON EXTRINSIC PREDISPOSING FACTORS LINKED TO STRESS FRACTURES
- Training type, excessive volume, excessive intensity, surfaces or changes in training play a big role
- A rapid change in any of the variables above
- Excessive fatigue with training/competition
- Faulty running technique
- Inadequate recovery
- Inadequate nutrition (Calcium, Vit D absorption etc)
- Poor footwear type, age of the shoe, use or lack of insole use
COMMON INTRISIC PREDISPOSING FACTORS LINKED TO STRESS FRACTURES
- Lower limb alignment and foot type (Flat foot vs high arch)
- Leg length discrepancies
- Muscle imbalances
- Muscle weakness
- Restricted range of motion e.g. Ankle stiffness
- Lack of flexibility
- Sex, size, body composition
- Genetic factors, hormonal factors
A runner with a stress fracture may experience only minimal symptoms early on. For example, one may feel a mild ache in the shins or on the top of the foot only after one’s long weekend run. As time goes on, however, the pain becomes more noticeable and occurs sooner. Pain is usually worst during or soon after a run. Rarely does pain associated with a stress fracture improve with running. One can usually identify a particular point which is most tender to touch. Since many stress fractures do not appear on xrays, a more sensitive test such as a bone scan or MRI may be needed to confirm the diagnosis.
COMMON RUNNING RELATED STRESS FRACTURES TREATMENT
- Pubic Ramus
- Femur – neck
- Femur – shaft
- Tibia (Plateau)
- Tibia shaft
- Medial Malleolus (Inside of the ankle)
- Metatarsal (Bone in the foot)
The time from diagnosis to full return to sport depends on a variety of factors such as, the length of the symptoms, the location of the stress fracture and the stage in the spectrum of bone stress. However most will heal anywhere from 4-8 weeks.
To keep it simple and without me writing a thesis here… physiotherapy management of a stress fractures involves the following:
- Pain management
- A non weight bearing to partial weight bearing period e.g. in a camboot/moonboot
- Muscle strengthening
- Maintaining your aerobic fitness e.g. water running, boxing, swimming
- Modification of individualised risk factors linked in with your specific injury (any one or combination of those listed above)
- Gradual reloading of the bone when sufficient healing is clinically present
- Return to sport (Stronger and wiser!)
I hope this gives you a brief insight into stress fracture… If you have any questions ask away!