Because of the altered shape of a limb in the presence of a deformity, the function of that limb is greatly affected. A bent or twisted femur (thigh bone) or tibia (shin bone), for example, will probably result in abnormal loading of the knee and ankle joints. This will cause pain and gradual ligament loosening and joint instability. Eventually, arthritis will incur. Because of the disuse of the limb, the muscles may atrophy and become weak. The walking ability of the patient is greatly affected. This means that there is pain and/or increased energy demands for the usual daily activities.
Bone deformities may occur in many shapes and directions. They may be acutely angulated or smoothly curved, twisted and combined with translation or shortening. They may be near the joint or in the middle (diaphysis)of a long bone.
The correction of bone deformities is done by carefully cutting the bone (osteotomy) at certain point or points and then turning them back into the correct alignment. Small deformities can be corrected acutely during the operation and the bone is fixed with internal fixation devices like nails or plates.
More complex or bigger deformities are corrected gradually with the use of special external fixators which allow the slow correction of the alignment. This is done because the nerves, vessels, tendons and muscles cannot be stretched too much too quickly.
Before the operation the surgeon reviews special xrays and CT scan in order to make decisions about the number and exact point of osteotomies, the fixation device and the rate of correction of the deformity. The correction of limb deformities is a prolonged process which requires expertise and dedication to succeed.