Unlike some other tissues in the body, the human bone has the ability to fully regenerate after a fracture. Between the ends of the fracture segments, callus (fresh bone material) is formed, which gradually becomes harder and more stable. The time it takes until the bone is completely healed depends on the affected bone, the affected area, and the age of the patient.
Fractures in children almost always heal well. Most often, a cast or splint is used to fix the bone. Sometimes surgical stabilization with elastic nails or plates is necessary. In some cases, especially with casting, the position and alignment of the fracture cannot be completely corrected. Mild malalignment and/or shortening or even over-length might persist. In young children and in cases of metaphysis (fractures that are close to the end of the bone), those malalignments can correct spontaneously with growth.
Malalignment in older children, malalignment occurring after fractures more in the middle of the bone, and torsional (rotational) malalignment correct less well and often persist. In those cases, surgical correction can be warranted.
If a fracture involves the growth plate, deformity and malalignment can develop or increase during further growth.
Premature closure of a growth plate after a fracture leads to limb-length discrepancy with more or less severe shortening of the bone, depending on the age of the patient at the time of the trauma. If the physis (growth plate) is only partially closed, and especially if the bone bridge closing the physis is on the side of the bone, a deformity will occur in addition to the shortening.
If the bone bridge crossing the physis is small, surgical removal of the bridge can be attempted.
Rarely, a limb can be longer after fracture. This occurs more with fractures in the diaphysis (middle) of the bone. However, the resulting limb-length discrepancy is usually small and can reduce spontaneously during further growth.
If a fracture is malunited (has healed in an incorrect position), it is possible to correct it surgically. The bone ends are usually osteotomized (cut), anatomically aligned, and fixed with plates, screws, or nails. Sometimes external fixation is used to achieve the best result.
Generally, we see three different patterns: malalignment, shortening, or a combination of both. Another important parameter is the status of the growth plate (whether it is injured or healthy). If it is healthy, it can be used to guide or control growth.
In the presence of malalignment and/or shortening with a healthy growth plate and enough growth remaining, guided growth is an option. Guided growth can be achieved by performing hemi-epiphysiodesis (blocking the growth plate on one side) using a small plate and two screws. Additionally, it can be achieved by performing epiphysiodesis (blocking the growth plate completely) to stop growth of the longer limb and correct limb-length discrepancy.
Although hemi-epiphysiodesis using a small pate and two screws is an exact procedure that is commonly applied, stopping the growth to correct limb-length discrepancy is more difficult. The timing of surgery is essential, because the growth plate of the long bone must be stopped at exactly the right time so that both bones end up the same length. Although various mathematical models and parameters for this calculation are available, the result in an individual patient can vary and fall out of the prediction. Nevertheless, stopping the growth is an elegant way to correct limb-length discrepancy in bones that end up longer after fracture.
Malalignment without shortening can easily be corrected acutely using internal fixation (nail, screws, plates) in most cases. If the deformity is severe or overly complex (more than one plane and additional rotation), gradual correction using external fixation might be preferable.
For posttraumatic shortening with or without malalignment, six-axis external fixation or implantable lengthening nails are available.