Fracture Frontal Bone
Introduction: Fractures involving the frontal bone are very uncommon injury. The incidence ranging from 5 - 15% of all facial injuries. This injury is potentially fatal because of its close proximity to the frontal lobe of brain.
Anatomy: The frontal sinus is a pyramidal air filled cavity within the frontal bone. Its size and shape are highly variable. In fact it is usually asymmetrical. It has two walls: the anterior and posterior tables. The anterior table is very strong when compared to the posterior table. The posterior table is in close proximity to the frontal lobe of the brain. The floor of the frontal sinus is very weak and is formed by membranous bone.
Fractures involving the frontal sinus must be considered as head injuries and should be managed thus because of the close proximity of the brain.
Causes of frontal sinus injuries:
1. Road traffic accident
3. Industrial accidents
4. Recreational accidents
Assessment of patient with injury to frontal sinus:
1. All suspected patients should undergo a complete ophthalmic examination to rule out injury to the eye.
2. All these patients must undergo CT scan of brain and skull for compete evaluation
3. The patient's consiousness should be monitored carefully to rule out intracranial complications
4. Other associated injuries must be looked for because the force necessary to cause fracture of frontal bone is enormous.
Goals of treatment of fracture frontal sinus are:
1. Removing the factors if any predisposing to infection
2. Restoration of normal sinus function
3. To treat cosmetic defect
Classification of frontal sinus fracture:
1. Depressed anterior wall fractures
2. Posterior wall fractures
3. Through and through injury involving both tables of frontal sinus
4. Fractures involving the fronto nasal duct
Anterior Wall fracture of frontal sinus: Linear fractures that has not displaced the fractured fragments may be managed conservatively. Depressed fractures involving the anterior wall must be elevated, frontal sinus inspected and fixed. Compound anterior wall fractures should always be explored, foreign bodies if any must be removed.
In the case of large comminuted fractures of anterior wall with missing fragments of bone, frontal sinus obliteration should be resorted to using abdominal fat and reconstruction under taken with free iliac / rib graft. If the bone gap is less than 1.5 cms then bone grafting need not be resorted to.
Posterior wall fracture of frontal sinus: Linear fractures involving the posterior wall should always be explored. The frontal sinus should be obliterated if there is entrapment or displaced of mucosa. All cases of depressed fractures of posterior table should be considered for frontal sinus obliteration. If the posterior wall fracture is extensively comminuted, then cranialization of the frontal sinus should be resorted to. CSF leaks if any should be sealed by a meticulous dural repair. Since the posterior table is thin, even minor deflections of bony fragments is sufficient to cause ingrowth of sinus mucosa into the anterior cranial fossa leading onto the formation of mucopyocele. This is one of the reason why some authors advocate routine obliteration of frontal sinus in all cases of fractures involving the posterior table.
Nasofrontal duct injuries: These injuries are very difficult to diagnose even with a CT scan. The presence of unresolving fluid inside the frontal sinus for a period of more than 4 weeks should lead to the suspicion. A diagnostic trephening should be done in these patients and the fluid if any should be evacuated. The patency of the duct can be tested by instilling methylene blue or flourescein dye and looking for it discharge from the nose. Exploration is indicated if there is no efflux of the dye introduced. Fractures involving the anterior table with involvement of naso ethmoidal complex should always be explored because involvement of naso frontal duct is common in these patients. It is always easy to treat unilateral injuries because a simple removal of the intersinus septum will cause the drainage to occur via the opposite side. Bilateral involvement is a problem, and in these patients the duct must be reconstructed either by stenting or mucosal flaps. A high degree of failure is common in these cases.
Through and through fractures involving the frontal sinus tables is highly dangerous associated with more than 50% mortality. Exploration is a must in these patients, cranialisation of the sinus should be resorted to. CSF leaks if any should be meticulously closed. In extreme cases frontal lobotomy need to be performed.
Complications of fractures of frontal sinus:
3. Cosmetic defect
4. Injury to naso frontal duct
5. Injury to the frontal lobe of brain
This 38 year old male patient presented with h/o injury 15 days duration. He had irregular sutured wound over the left frontal area. There was a depression seen over the anterior wall of left frontal sinus.
CT scan taken showed depressed fracture of anterior table of frontal sinus. The posterior table was found intact. The frontal sinus was fould filled with fluid.
Clinical photograph of a patient with fracture frontal bone
Image showing fractured anterior table of frontal sinus being elevated