Stress Fracture

How Physical Therapy Treatment Works With Bone Injury

Stress fractures, a common injury among sportspeople, were first reported in military recruits in the 19th century. A stress fracture is a microfracture in bone that results from repetitive physical loading below the single cycle failure threshold. Overload stress can be applied to bone through two mechanisms:

  1. The redistribution of impact forces resulting in increased stress at local points in bone.
  2. The action of muscle pull across bone.

Histological changes resulting from bone stress occur along a continuum beginning with vascular congestion and thrombosis. This is followed by osteoclastic and osteoblastic activity leading to rarefactio , weakened trabeculae and microfracture and ending in complete fracture. This sequence of events can be interrupted at any point in the continuum if the process is recognized.

Similarly ,the process of bony remodeling and stress fracture in athletes is recognized as occurring along a clinical continuum with pain or radiographic changes presenting identificable markers along the continuum. Since radioisotopic imaging and MRI can detect changes in bone at the phase of accelerated remodeling, these investigations can show stress-induced bony changes in the continuum.

Stress fractures may occur in virtually any bone in the body. The most commonly affected bones are the tibia, metatarsals, fibula, tarsal navicular, femur and pelvis. A list of sites of stress fractures and the likely associated sports or activities . The diagnostic features of a stress fracture.

It is important to note that a, bone scan although a routine investigation for stress fractures, is non-specific, and other bony abnormalities such as tumors and osteomyelitis may cause similar pictures. It may also be difficult to localize the site of the area of increased uptake precisely, especially in an area such as the foot where numerous small bones are in close proximity.

Diagnostic Features

  1. Localized pain and tenderness over the fracture site.
  2. A history of a recent change in training or taking up a new activity.
  3. X-ray appearance is often normal or there may be a periosteal reaction.
  4. Abnormal appearance on radioistopic bone scan (scintigraphy), CT scan or MRI.

MRI is being increasingly advocated as the investigation of choice for stress fractures. Even though MRI does not image fractures as clearly as do computed tomography (CT) scans, it is of comparable sensitivity to radioisotopic bone scans in assessing bony damage. The typical MRI appearance of a stress fracture show speriosteal and marrow edema plus or minus the actual fracture line.

The treatment of stress fractures generally requires avoidance of the precipitating activity. The majority of stress fractures heal within six weeks of beginning relative rest. Healing is assessed clinically by the absence of local tenderness and functionally by the ability to perform the precipitating activity without pain. It is not useful to attempt to monitor healing with X-ray or radioistopic bone scan. CT scan appearances of healing stress fractures can be deceptive as in some cases the fracture is still visible well after clinical healing has occurred.

The return to spot after clinical healing of a stress fracture should be a gradual process to enable the bone to adapt to an increased load. An essential component of the management of an over use injury is identification and modification of risk factors. There are, however, a number of sites of stress fractures in which delayed union or non-union of the fracture commonly occurs. These fractures need to be treated more aggressively. The sites of these fractures and the recommended treatment.

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