A stress fracture is a break in a bone that is caused by repetitive stress. It may occur in any bone, but is quite common in the metatarsal bones of the foot. A stress fracture usually starts as a small crack in the outer shell (the cortex) of the bone. Without proper treatment, this may progress to fracture all the way through the bone. If you suspect that you have a stress fracture, call our office right away and tell the receptionist that you think you may have a fracture. The receptionist will try to get you an appointment right away.
Metatarsal Stress Fracture Symptoms
Metatarsal stress fractures often appear initially as simply pain over the top of the foot, sometimes – but not always – with swelling. It is usually worse after activity or during activities that require bending of the foot. They are most common in the second and third metatarsal bones. It is very common for patients to state that they have no memory of any injury.
Stress Fracture in Foot, Examination and Treatment
Once we examine your feet, if we feel that you may have a stress fracture we will likely take an x-ray. It should be noted that metatarsal stress fracture may not become apparent on x-rays until a few weeks after the injury. Stress fractures of the third and fifth metatarsals seen in the xrays below.
If it turns out that you do likely have a stress fracture, we will immobilize your foot with a special shoe or boot. In addition we will likely use some sort of arch support to help spread weight over a larger portion of the foot. These treatments usually protect your foot so it can heal while allowing you to still bear weight on the foot. Crutches are usually not necessary except for metatarsal base fractures. A Jones fracture is the term used for a fracture approximately 1.5 cm from the base of the 5th metatarsal, Figure 2, these fractures are very difficult to heal and require a long period of non weight bearing or surgery. Bone stimulators are often suggested for a Jone’s fractures.
What Causes Stress Fractures?
There are a number of causes, but common ones include:
- Decreased density of the bones (e.g.. osteoporosis)
- Unusual stress on a metatarsal due to mal-position or another forefoot deformity (e.g.. bunion)
- Abnormal foot structure or mechanics (e.g.. flatfoot)
- Increased levels of activity, especially without proper conditioning
- Unstable shoes
- Excessive stress (such as running a marathon)
Metatarsal Stress Reactions – The Stress Fracture That Never Shows on X-ray
Sometimes a patient will have all the symptoms of a stress fracture including pain right on a metatarsal bone and swelling on top of the foot but no fracture ever shows up on x-ray. This is often due to a condition called a stress reaction. Stress reactions are simply the precursor to an stress fracture where there is weakening of the inside of the bone but it never quite breaks through. Stress reactions will not show up on x-ray but do show up on MRI or bone scans. Diagnosis of stress reactions is very straightforward, however, and these tests are rarely necessary.
Which Metatarsals Tend to Have the Most Stress Fractures?
The most common stress fractures are of the 2nd. This is for several reasons:
1. It is next to the first metatarsal which is biggest of the metatarsals and the one that should take up the most force. But in some foot types the first metatarsal is allowed to move out of the way when force is applied to the bottom of it. That leaves the much thinner and weaker 2nd metatarsal to take up that extra weight resulting in more potential for fracture.
2. The 2nd is the longest of the metatarsal bones. This causes it to have more force applied to it.
3. At it’s base, the 2nd metatarsal is locked into place preventing it from moving when force is applied to it from the bottom. Again this increases force on this bone and makes it more susceptible to injury.
After the 2nd, the 3rd and 4th are the most common metatarsal bones to have stress fractures. The 1st and 5th metatarsals are thicker and more robust and less likely to be injured.
How are Stress Fractures Prevented?
Since stress fractures are usually caused by too much pressure on the metatarsal bone, we want to reduce pressure on that bone to prevent the stress fracture from occurring again. We can do this best with the use of custom orthotics that are prescribed specifically to reduce pressure on the injured portion of the foot. We prescribe the orthotics in a manner that acts to transfer the force off of the at-risk metatarsal and redistribute that force to other parts of the foot. Wearing the proper shoes is also critical and we will help you in finding the correct shoes for your feet.
How Should Orthotics Be Made to Prevent Stress Fractures?
Orthotics in this situation have one primary goal and that is to reduce force through the metatarsal bone that is at risk of stress fracture or has previously had a stress fracture. How we make this orthotic will depend on your foot type and the underlying cause of the excessive force in the metatarsal bone. For example, if your foot is rolling in excessively and that is causing the first metatarsal bone to be pushed up, we need to design the orthotic to prevent this so that the first metatarsal bone continues to bear weight in order to reduce pressure on the 2nd. In addition the orthotics should contour very close to the arch of the foot so that it can transfer pressure off of the ball of the foot (the metatarsal heads) and onto the arch of the foot.
Sometimes a prefabricated orthotic can accomplish this and sometimes a custom orthotic is necessary. Our favorite prefabricated orthotic to prevent stress fractures is the P3 Full-length Orthotic because it has a higher than average arch for a prefabricated device and thus does a good job of transferring force off of the metatarsal heads.
Custom orthotics tend to work even better at preventing stress fractures because they take even more pressure off of the metatarsal heads.
If you think you may have a stress fracture, or you have previously had one and want to prevent recurrence, contact us for an appointment in our convenient Seattle office.