Also known as or related to:
Stress reaction, bone reaction, bone oedema, osseous oedema, metatarsal stress reaction, tibial stress fracture, shin splints fracture, mid foot stress fracture, heel stress fracture, fibular stress fracture.
Bone Fracture vs Stress Fracture
A proper bone fracture will show as an actual break on an x-ray where the bone itself has been cracked. There will almost always be a fall or sudden event involved that cracks the bone.
A stress fracture involves an increase in force or load through the bone that it can't handle. Extra blood flows into the bone to try and heal this damaged area of bone. There won't be a visible fracture on x-ray and these can be difficult to diagnose.
The terminology of these irritated areas of bone has changed over the years. Traditionally they were referred to as stress fractures, however this was confusing as there is no actual fracture line visible on x-ray. Terminology has recently changed to practitioners using the term Bone Stress Reactions which is a better description of the extra blood flow travelling into the area of irritated bone. Other terms include Bone Oedema (osseous oedema) which means 'bone and extra blood flow'.
Difficult to Diagnose
Stress reactions can often go undiagnosed for months or even many years. There is no fracture line to be seen on an x-ray and the very subtle indicators of a stress reaction only show on x-ray 50% of the time and after 8 weeks of injury.
In the clinic, a stress reaction can be difficult to isolate. A thorough history is critical and suspicion of a stress reaction is achieved by a process of eliminating all other lower limb injuries.
When a stress reaction is suspected, medical imaging becomes very important to be certain of the diagnosis of a stress reaction. Bone Scans were used for diagnosis in the past, however the radiation required is unacceptably high now that MRI has become cheaper and more accessible. MRI is 100% sensitive for stress reactions. If the MRI doesn't show any extra blood flow into the bones, then we can be certain that a stress reaction isn't present. MRI is critical for a definitive diagnosis of stress reactions.
Risk Factors for Stress Reactions
Too much load
The biggest risk factor for a stress reaction is a sudden change in training load. We have always known that a sudden increase in training such as three big sessions in a row or a sudden increase in a single training will put a patient at risk of a stress reaction.
Too much rest
It has been discovered more recently that a sudden stop in training is also a big risk factor. Patients who stop for more than 3 weeks will be able to resume training at full intensity, however their bones and tendons would have lost some strength and will be prone to stress fractures and injury. It is important to build back gradually.
Increase impact and load through a bone is commonly a result of poor lower limb mechanics. Foot function, shoe set-up, run technique and muscle imbalances can all contribute to increased load through a particular bone and a resultant stress reaction.
Certain medical conditions or medications can affect bone density and the ability of certain bones to withstand the forces being applied with running.
Common Areas for Stress Reactions
Stress reactions can happen in any bone in the body if repetitive load is applied above what the bone can handle. There are some specific bones in the lower limb that are notoriously prone to stress reactions.
2nd Metatarsal Stress Reaction
For most people, the second toe is the last point to leave the ground at toe off and it absorbs a lot of energy with running. The neck of the second metatarsal is the end of the long bone where this force is applied and is the most common bone in the body for a stress reaction.
Tibial Stress Reaction
Shin splints is an extremely common lower limb complaint and over 90% of splint splints cases will be from the muscle that runs along the shin being over worked. This muscle attaches to the shin bone and the lining of the bone can become irritated and feel very much like a stress reaction even though it is not a stress reaction. More information on treating this can be found on our shin splints page by clicking here. Sometimes the pulling on the lining of the bone can progress to a tibial stress reaction and other times the force through the tibia with running results in a stress reaction proper. There are many things that we can do to reduce load through the shin bone when running. Footwear, run technique and foot function are critical.
Mid Foot Stress Reactions
The small bones in the middle of the foot are square, strong bones designed to withstand a lot of force with gait. It is rare, but sometimes these bones can have stress reactions that can be difficult to diagnose.
Stress Reaction Treatments
Treating Stress Reactions involves reducing the load through the injured bone to a level that allows healing. Often this might involve using a removable air cast or even crutches. The extent of immobilization and the duration depends on the bone that is suffering from the stress reaction. Some bones only require 2 weeks of immobilization while others can require 12 weeks.
Some clinicians simply immobilize patients for a fixed period of time and send them on their way. It is very important to gradually return the load through the injured bone as well as the rest of the body. Immobilization results in the rest of the bones and tendons of the body weakening and makes them prone to injury if a return to running isn't structured correctly.
New innovations such as Zero Gravity Treadmills are excellent for return to run (see our blog article on Zero Gravity Treadmills here) as they enable a gradual increase in load through the bones to allow rapid bone strengthening.
It is also important to identify risk factors that caused the stress fracture in the first place so that changes can be made to prevent recurrence. Reviewing training loads, techniques to return from periods of rest, lower limb mechanics overloading the bone, run technique issues, footwear set-up and underlying medical conditions all need to be assessed and addressed.
If you need help with a suspected stress fracture or help with managing and preventing stress fractures, book an appointment with one of our sports podiatrists here.