A stress fracture is a partial or complete bone fracture, resulting from repeated low grade stress. There has normally been an increase in the amount or intensity of activity just before the foot gets sore. The pain is worse with activity, and is usually in a specific area of the foot where the fracture is present. It may settle with rest, or continue at a low level.
The most common areas of the foot that present with stress fractures are the metatarsal shafts (2nd, 3rd and 4th), the navicular bone, and the sesamoid bones (little bones that sit under the big toe joint).
Diagnosis is usually made by feeling the sore area, description of pain and description of the amount of training and the surfaces that this training has been on. Sometimes an X-ray, MRI or CT scan are needed if the diagnosis is uncertain, or if an athlete wants to continue training and needs specific details of their injury.
Stress fractures can be caused by a number of factors:
Training errors:
A rapid increase in training loads or intensity (too much too soon)
Type of activity:
Navicular stress fractures are more common in sprinting and jumping sports
Training surfaces:
Hard surfaces such as concrete can increase the risk of stress fracture when combined with other factors
Foot biomechanics:
Depending on the location of the stress fracture, feet may either be over-pronated (rolled inwards, flattening of arch) or supinated (high arch, stiff foot type). Pronated feet often cause increased loading through the metatarsals and midfoot joints. Stiff ankles and high arched feet can have reduced shock absorption which can be a contributing factor.
Footwear:
Wearing the incorrect style of shoe for the activity, or footwear that does not have adequate support, can be a major contributing factor to the development of a stress fracture. The drop or gradient of the shoe (height at the back compared to the front) should be at 10mm for most activities.
Hormones:
Can be a factor in female athletes (‘the female triad’ – disordered eating, amenorrhea and osteoporosis).
Most stress fractures settle with rest.
Sometimes a cam walker needs to be worn for up to 8 weeks. Cross training is recommended, as long as there is no pain (swimming, pool running, cycling) to maintain fitness levels. Some stress fractures (particularly of the navicular and 5th metatarsal) need surgery.
A full biomechanical assessment will need to be undertaken by a Podiatrist.
This can detect a limb length discrepancy, over-pronation (rolling in of the ankle and flattening of the arch), muscle imbalance or weakness, and joint stiffness. Orthotics may need to be issued or the foot taped, to improve foot function. A footwear assessment also needs to be undertaken, and shoes updated if necessary. Sometimes, the patient may need to undertake gait retraining, which involves changing running technique through strengthening and repetition of improved technique.
Return to activity involves a graduated loading program.
This usually starts with a jog/walk program, which slowly increases the amount of jogging time. This progresses up to a 15 minute jog pain-free before any increases in intensity can be added or any agility, depending on the sport. The overall training program will then need to be reviewed, to monitor loads long term.
Diversity of training is the key to prevention of a stress fracture.
A training program should always include different surfaces, different intensities, and even different footwear. Cross-training is vital to any training program (swimming, pool running, cycling, rowing).
If you need any advice regarding treatment or prevention of a foot stress fracture, see Podiatrist Nicki Quigley at Bayside Sports Podiatry - 9589 3777.