Bone Stress Fractures

Posted on December 19, 2009
Filed Under back pain | Leave a Comment

Stress fractures are a common injury often seen in military personnel and in athletes or anyone who is subjecting their feet or lower body to overuse. It most commonly occurs in the legs but can occur in other parts of the body. Typical areas for this type of fracture are the leg bones of the metatarsals, the fibula and tibia, with areas higher up the legs much less commonly affected. Stress fractures are caused by repeated stresses to the bone which are not enough to fracture initially, leading to mechanical fatigue of the bone and eventually a fracture.

The affected area may be the source of increasing pain levels during exercise and activity, with the sufferer often reporting they have increased their training levels in intensity or frequency. Conservative treatment is usually straightforward with limitation of activity of the part and in some fractures immobilisation is required. Healing is often also straightforward although there is the danger of non-union in some fractures, with some needing internal fixation. Orthopaedic fixation and careful immobilisation will lead to healing in the vast majority of cases.

These types of fractures occur because bone has been loaded again and again and there is rarely any specific traumatic event responsible for the fracture. Bones remodel to reinforce themselves when they are subjected to loads involving tension or compression, with minor damage of the bone occurring due to the stresses. If the remodelling process gets behind as the microscopic bone damage occurs then a fracture can result. The most common occurrence is for the person to have significantly increased their activities recently.

Factors which increase the likelihood of a fracture occurring are reducing the bone area across which the stresses are acting, increasing the absolute levels of force and making the application of such stresses more frequent. The cross-sectional area of the bone is the factor determining the results of force applied, a smaller area meaning a higher order of force is suffered by the bone. Or the force could be increased in itself. Typical examples of risky activities are jumping or running, with other risks being changes in the exercise surface and techniques used.

Additional factors could be risk factors such as reduced bone density, dietary changes, weakness or other mechanical factors as the other factors are all mostly presumed to be the key ones. Scientific research has indicated being female, having a low body weight, poor diet and many other factors may be important. Female runners are particularly at risk, with reduced caloric intake, disturbances in menstrual cycle and lower bone density presenting in such athletes and others who require a low body weight such as ballet dancers.

Stress fractures present with unexpected onset whilst undergoing an activity, worse as the limb is loaded repetitively, without any traumatic occurrence. When the patient rests the pain will ease and be absent but will recur once the aggravating activity is restarted. The area around the fracture will be tender and perhaps swollen, with x-ray findings elusive initially, perhaps taking two to four weeks to become apparent. Bone scanning can be more sensitive to finding a stress fracture within three days of the initial event, but can be positive for other reasons.

The usual management of stress fractures is conservative care, with the simplest and often the most effective method being a reduction in the responsible activity for 4 to 6 weeks. If there is a significant degree of pain on weight bearing then they can be placed in a brace, a rigid walking boot or a below knee cast, with crutch use as required. Orthoses in the shoes have been studied and found to allow a reduction in fracture incidence of a certain amount, with shock absorbing insoles having less clear benefits but potential.

Most commonly these fractures heal well and without complications but there can be problems with non-union in some particular areas. The base areas of the second and the fifth foot metatarsals are areas which can suffer from poor healing and which should be followed up for more prolonged immobilisation or surgical intervention if they do not heal.

Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about Physiotherapist, back pain, orthopaedic conditions, neck pain, injury management and Physiotherapists in Coventry. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.

Comments

Leave a Reply