The condyle of the mandible or jaw bone is the part that forms the temporomandibular joint or jaw joint. Just below that is the subcondylar region. Together they form 26 to 40 percent of all fractures of the mandible. These fractures can be very painful and they can cause deformity of the face and an inability to open and close the jaw. They are associated with injuries to the cervical spine, facial nerve injuries and displacement of the condyle into the middle cranial fossa (into the brain). There can be damage to the ear canal and blockage of the main artery that leads to the brain.
The mandible bone itself is a curved bone that extends from one condyle to the other. When one condyle is fractured, there is the possibility of fracture of the other condyle and fractures to other areas of the mandible. The cartilage within the temporomandibular joint can become damaged, leading to arthritis of the TMJ in the future. The joint can also become more likely to dislocate in the future.
Research tells us that fractures on one side of face occur about three times more frequently than fractures occurring on both sides (both condyles). Either way, there is often significant disruption in the ability to chew or to open one’s mouth.
The cause of condylar fractures depends on locality. For example, in the Netherlands where biking is common, cycling accidents are the main cause of condylar or subcondylar fractures. Motor vehicle accidents and assaults are common causes of these kinds of fractures in the urban areas. All terrain vehicles cause condylar fractures in more rural areas. Playground falls and bicycle accidents are more common causes of these injuries among children.
Anytime there is a fall to the side of the face, fractures of the condyle on either side must be suspected. Because other mandibular fractures can occur along with condylar fractures, the pain may be diffuse or may be localized to the other mandibular fracture so that you can miss the condylar fracture. This is especially true with subcondylar fractures. There can be bruising of the side of the face and the teeth may be set wrong. X-rays can show displacement of the condyle compared to the rest of the mandible and can show dislocation of the condyle in the temporomandibular joint. The doctor can also sometimes see paralysis of the facial nerve because the fracture fragments have somehow damaged the nerve in the area of the temporomandibular joint. There can be blood behind the tympanic membrane (ear drum) or bleeding from the ear.
One study looked at 382 patients who had sustained a total of 443 condylar fractures, some having sustained fractures of both condyles. These represented 52 percent of all mandibular fractures, most of them having been associated with assaults, while the rest were from falls or motor vehicle injuries. In the most severe of cases, the condyle was pushed completely out of the glenoid fossa (the TMJ joint). This seemed to happen from falls and automobile accidents than from personal violence. Fractures caused by personal violence were more likely to be unilateral, located in the subcondylar region and nondisplaced. Many patients needed open surgery to correct their fractures and to maintain alignment.