Pathologic fractures are fractures that occur in weakened bone. Osteoporosis is the most common cause of weakening of the bone but other conditions such as: cancer, infection, inherited bone disorders or bone cysts can also cause the bone to be weak. A fragility fracture is one caused by a relatively minor trauma such as a fall from a standing height. Normally one can fall from a standing height without causing a fracture of a bone. These fractures are associated/caused by osteoporosis. All bones are susceptible to a fragility fracture. Three common examples of a fragility fracture include: vertebral fractures, fractures of the neck of the femur, and Colles fractures of the wrist.
Bone is a living tissue that is constantly being formed and resorbed. Osteoporosis refers to a condition in which the bone density is decreased. This condition is caused by an imbalance between the formation and breakdown of bone. We all lose bone as we become older. By our mid-thirties there is approximately 0.5% loss of our bone per year. When one has osteoporosis, there is greater loss than formation of bone. Patients with osteoporosis have lost approximately 30-40% of their bone density. Understandably this can lead to a higher risk of fracture. One study has shown that 40% of 50 year old females will have an osteoporotic fracture during their lifetime. Osteoporosis is more common in woman than men. The risk of hip fracture after age 50 is 15-18% in woman and 6% in men.
Some fractures require surgery and one of the mainstays of Orthopaedic fracture care is plate and screws. The AO group in Switzerland developed the modern plating systems that we use to treat many fractures. The dynamic compression plate allowed stability of fractures for healing and the ability to move the joints near the fracture allowing good return of function. Traditional plates rely on friction between the plate and bone to hold the fracture stable. The plate is attached to the bone by the screws. If the bone quality is poor (as in osteoporosis) the screws may not hold causing less than ideal stability. When doing surgery on a patient with osteoporosis the surgeon often gets the feeling that there is no bite or stability to the screws (feels like you are placing a screw in Styrofoam). This does not provide confidence that the plate and screws will provide the stability needed to hold the bones in position until the fracture heals. Making matters worse, elderly patients often do not have the strength to avoid weight-bearing on the fractured extremity. This places the fracture and plate/screws under more stress than would be seen in younger patients.
In the past there was not a great solution for treatment of certain fractures in the elderly patient with osteoporosis. Different strategies have been proposed including injecting bone cement in the bone before placing screws in order to allow more 'bite' of the screws. Other patients were treated with different devices such as external fixators (for wrist fractures) or rods (for certain fractures of the femur or tibia). These advances were helpful but did not allow us to stabilize every fracture.
In the 1990s the AO group developed a new concept of plating called locked plating. The screws in these systems lock into the plate and therefore do not rely on the density/strength of the bone. The screw and plate create a fixed angle construct that is less prone to loosening or toggling. They have been found to have a positive role in stabilization of osteoporotic fractures (Cordey & Perren, Injury 2000). In addition locked plates have been found to be helpful in treating unstable or more difficult fracture patterns (for example allowing use of one plate for tibial plateau fractures that traditionally required use of 2 plates). They have also allowed stabilization of certain fractures in the elderly osteoporotic patients such as: the wrist/Colles fracture, and proximal humerus fractures. Before locked plating these fractures were with treated with casts or benign neglect often leading to stiff/minimally functioning joints.
Recently, many of these locked plates have been pre-contoured to fit a specific part of the bone. For instance there are locking plates designed for the distal aspect of the femur or for the fibula in the ankle. This can make surgery easier and quicker (no more timely bending of plates). Use of these pre-contoured plates has also allowed more effective stabilization of difficult fractures and also at times allowed plates to be placed in a percutaneous manner (without a large incision) which may be beneficial in certain patients such as the elderly. The locked plates also have many novel uses including stabilization of fractures near a total knee implant that previously had no good solution. Overall these new plates have allowed orthopaedists to treat many more difficult fractures in the elderly osteoporotic patients.