When a broken bone heals in an abnormal position, it is called malunion. There are different abnormal positions in which a bone can heal. For example, the bone may be crooked, rotated, or shorter than it was before. A combination of these deformities may also be present. While some malunion do not impact a patient's daily activities and do not need treatment, those that occur in the lower limb often result in significant functional impairment. A malunion in this area can cause a limp, lead to pain and arthritis, and be cosmetically displeasing A slight amount of malunion occurs in large portion of fractures but in practice the term Malunion is reserved for cases resulting in disability that is of clinical significance.
There are four main factors that surgeons look for before completely treating a malunion fracture. They include:
Malunion caused by infection are among the most challenging to treat. The surgeon can perform blood tests to determine if there is any infection lingering. If necessary, a local biopsy may be performed, as this will provide a much more reliable answer. The infection must be eliminated before any reconstruction can occur. This is a multistep process involving a round of antibiotics, debridement of all affected bone and soft tissue; any needed wound closure and removal of external fixation. This may also include removing any and all hardware that a patient might have, to remove any bacteria that could be adhered to metal and protected from antibiotics.
After the infection is treated, reconstruction can begin. Surgeons take the extra mile in preventing additional infection by applying local antibiotics to the fracture site. Surgeons mix bone cement with antibiotics and create a necklace of antibiotic beads which is then placed in the site. This is done to further prevent a recurrence of infection. Once infection is cleared, reconstruction of the limb can be initiated using necessary orthopedic and orthoplastic techniques and technology.
Having an adequate blood supply helps in healing a fractured limb. If there is suspected inadequate blood supply in the bone, they will perform a CT scan or SPECT scan to confirm suspicion of dead bone. If this is the case, the dead bone must be removed to access healthy bone and bring the ends of the living bones together. Vascularized or non- vascularized bone grafts can also be used to bridge the gap. Depending on the amount of affected bone that must be removed, this may result in a disproportion in length. This difference in length can be addressed with advanced limb lengthening procedures.
Fractures complicate many things and impair movement. For fractures to heal properly, they need appropriate stability. Stability issues fall into two categories: hypertrophic and atrophic. Hypertrophic malunion or nonunion fractures are typically the result of inadequate fracture stability (either too little or too much support) but have strong healing potential. Atrophic malunion or nonunion fractures often have a more complicated, multifactor cause and require more complex treatment.surgeons evaluate musculoskeletal structure including alignment, healing, and the hardware used to identify type and how to address the stability issue which is dictated by location, which bone is affected, and what type of malunion has occurred.
A person's biology is also an important factor for healing. As part of diagnosing complex fractures, the medical staff will perform lab tests to check thyroid levels, vitamin D, calcium, magnesium, and phosphorus levels to name a few. Knowing these levels helps physicians and surgeons understand how capable the body is to facilitate healing on its own. If there are any hormonal imbalances, specialists such as an endocrinologist will treat you before reconstruction can occur.
Malunion is therefore preventable in most cases by keeping a close watch on position of the fracture during treatment. Sometimes, malunion is inevitable because of unchecked muscle pull (e.g., fracture of the clavicle), or excessive commination (e.g., Colles' fracture). Fractures at the ends of a bone always unite, but they often malunite e.g., supracondylar fracture of the humerus, Colles' fracture etc.
Consequences of malunion results in deformity, shortening of the limb, and limitation of movements. Each case is treated on its merit. A slight degree of malunion may not require any treatment, but a malunion producing significant disability, especially in adults, needs operative intervention. The following treatment possibilities can be considered:
Malunion may require treatment because of deformity (e.g., supracondylar fracture of the humerus), shortening (e.g., fracture of the shaft of the femur) or functional limitations (e.g. limitation of rotations in malunion of forearm fractures). Some of the methods for treating malunion are as follows:
Osteoclasis: It is used for correction of mild to moderate angular deformities in children. Under general an- aesthesia the fracture is recreated, the angulation corrected, and the limb immobilized in plaster.
Redoing the fracture surgically: This is the most commonly performed operation for malunion. The fracture site is exposed, the malunion corrected and the fracture fixed internally with suitable implants. Bone grafting is also performed, in addition, in most cases e.g., malunion of long bones.
Corrective osteotomy: In some cases, redoing the fracture, as discussed above may not be desirable due to a variety of reasons such as poor skin condition, poor vascularity of bone in that area etc. In such cases, the deformity is corrected by osteotomy at a site away from the fracture as the healing may be quicker at this new site.
Excision of the protruding bone: In a fracture of the clavicle, a bone spike protruding under the skin may be shaved off. Same may be required in a spikey malunion of fracture of the shaft of the tibia. Sometimes malunion may not need any treatment, either because it does not cause any disability, or because it is expected to correct by remodeling. Remodeling of a fracture depends on the following factors.Type of deformity: Sideways shifts are well corrected by remodeling. Five to ten degrees of angulation may also get corrected, but mal-rotation does not get corrected.Angulation in the plane of movement of the adjacent joint is remodeled better than that in other planes e.g., posterior angulation in a fracture of the tibia shaft remodels better.Location of fracture: Fractures near joints remodel better.