Frontal sinus fractures

Frontal recess fractures result in disruption of the only frontal sinus outflow tract. Regardless of anterior or posterior table injuries, frontal recess fractures that result in sinus outflow obstruction will require frontal sinus obliteration. However, one recent article has described some success with expectant observation of frontal sinus fractures, after open reduction and internal fixation of anterior table frontal sinus and naso-orbito-ethmoid fractures. They reported spontaneous ventilation of the sinus in five of seven patients. Two patients had persistent obstruction requiring an endoscopic frontal sinusotomy. At the time of publication, these two patients had adequate sinus ventilation (at 21 and 25 months), and no patients had recurrent infection or mucocele formation (mean follow-up, 17 months). However, endoscopic frontal sinusotomy following frontal recess trauma is technically challenging. This approach should only be considered in reliable patients and should be reserved for surgeons with extensive experience in both endoscopic sinus surgery as well as open approaches to frontal sinus fractures.

Nondisplaced (1-2 mm) anterior table fractures can be observed with little risk of long-term morbidity. Fractures with greater displacement (2-6 mm) present little risk of mucocele formation; however, the risk of an esthetic deformity increases. Although a surgical repair may be necessary, a traditional coronal approach may result in an iatrogenic deformity (alopecia) more severe than the injury itself. This author and others have studied endoscopic fracture reduction in the acute setting. It is very challenging because of the extreme ranges of interfragmentary resistance between bone fragments. If the interfragmentary resistance is too high, the fracture cannot be reduced; if it is too low, the fragments will not stay in place without the application of hardware. Therefore, the author currently prefers to observe these patients and perform an endoscopic camouflage of the fracture if an esthetic deformity develops.^,  This avoids the need for a coronal incision and also allows the patient to assess the degree of deformity after all of the facial edema has resolved. The patient can then make an educated decision as to whether he/she desires surgical intervention. In the author's experience, a significant number of these patients will have minimal or no deformity and will require no surgical intervention. More complex anterior table fractures with marked depression may require open reduction or, on rare occasions, obliteration.

The treatment algorithm for posterior table fractures is complex due to the risk of CSF leak, meningitis, and mucocele formation.^,  If the posterior table is minimally displaced (less than one table width) and no CSF leak is present, the patient may be observed. If a CSF leak is present, 1 week of observation is indicated; approximately 50% will resolve spontaneously. If the leak is persistent, open reduction, repair of the leak, and sinus obliteration is indicated. Fractures with significant posterior table displacement (greater than 1 table width), no CSF leak, and mild comminution should be treated with sinus obliteration. The most severe injuries are those with a frank CSF leak and moderate to severe comminution. In these instances, sinus obliteration is indicated. If the injury results in disruption of more than 25% to 30% of the posterior table, sinus cranialization should be considered.

Trephination and endoscopic evaluation of the frontal sinus can be useful to assess the frontal recess and extent of any posterior table injury. Appropriate consent is obtained for the procedure, including the risks of bleeding, infection, paresthesias, and poor esthetic result. After infiltration of local anesthesia, a 1.0- to 1.5-cm skin incision is placed midway between the medial canthus and the glabella, approximately 1 cm inferior to the brow (Figure 2). The incision is best hidden by placing it inferior and deep to the curve of the forehead. A small “V”-shaped relaxing incision can be added to reduce the risk of scar contracture and webbing. The supratrochlear neurovascular pedicle is located deep to the medial aspect of the brow and should be protected while the dissection is carried through the periosteum. The incision should not be placed within the eyebrow itself. This increases the risk to the supratrochlear neurovascular pedicle and may result in injury of the hair follicles leading to an obvious deformity. Sharp dissection can be used to expose the bone; however, the author prefers to use a guarded micropoint monopolar electrocautery on a low setting to reduce bleeding. The location of the frontal sinus is confirmed on the CT scan (or with navigation), and a small cutting burr is used to open a 4- to 5-mm frontal sinusotomy approximately 1 cm medial and inferior to the medial brow (Figure 2, inset). The mucosa is incised sharply, and the sinus can be suctioned free of any blood or mucous. The posterior table and nasofrontal recess can be examined with a 0° and/or 30° endoscope for any evidence of mucosal laceration or hematoma. A valsalva maneuver can assist with the diagnosis of a CSF leak. On rare occasions, the author has used a flexible pediatric bronchoscope to visualize the lateral aspects of the frontal sinus. Other authors have described instillation of methylene blue or fluorescein into the frontal recess to assess patency into the nasal cavity. Unfortunately this does not rule out the presence of a fracture or assess the long-term risk of frontal recess stenosis. The author is aware of no studies to confirm efficacy of this technique. Once the examination has been completed, the skin and soft tissue are closed meticulously in layers.

This technique is limited to isolated anterior table frontal sinus fractures. The repair is generally performed 2 to 4 months after the injury, when all forehead swelling has resolved and an accurate assessment of any esthetic deformity can be made. Not all anterior table fractures are appropriate for this technique. Injuries with severe comminution and marked mucosal injury may require open reduction or even obliteration. Fractures that extend inferiorly over the orbital rim can be difficult to visualize endoscopically, and may also require an open repair.

If the patient is seen acutely, the reasoning and indications for a delayed repair must be explained (i.e., observation to confirm that an esthetic deformity is present and the fact that an endoscopic repair can avoid a coronal incision). It should be articulated to the patient that a traditional open reduction cannot be performed secondarily. Although the risk of mucocele is very low, this should also be discussed. Appropriate consent is obtained for the procedure including the risks of bleeding, infection, paresthesias, alopecia, poor esthetic result, and possible need for open approach if an endoscopic repair cannot be performed.

The surgical technique is similar to a brow lift. A 3- to 5-cm parasagittal “working” incision should be placed above the fracture, 3 cm behind the hairline, and carried through the periosteum onto bone (Figure 3). Care should be taken to avoid excessive trauma to the hair follicles. Local vasoconstriction agents should be used, and electrocautery should be avoided if possible. The incision length should be kept to a minimum, but this will vary depending on the size of the fracture and implant to be inserted. A 1- to 2-cm subperiosteal “endoscope” incision is then placed at the same height, 4 to 6 cm medial to the working incision. In patients with a prominent forehead or receding hairline, the incisions may need to be closer to the hairline to allow visualization around the forehead curvature.

Using endoscopic brow lift instrumentation and external palpation, a directed subperiosteal dissection is performed down to the level of the fracture. A 4.0-mm, 30-degree endoscope (with rigid endosheath and camera) is inserted through the endoscope incision to visualize the optical cavity. A large endosheath guard is recommended to maintain a generous optical cavity. Under direct visualization, the periosteum is then carefully elevated over the defect using an endoscopic brow lift elevator (Figure 4). The supraorbital and supratrochlear neurovascular pedicles may be visible at the orbital rim. Caution should be used to avoid excessive traction, which can result in postoperative paresthesias. The dissection is generally easy, and there is little risk of entry into the sinus because the fracture has healed. Once the limits of the fracture have been visualized, a 0.85-mm-thick porous polyethylene sheet is trimmed to approximate the defect. The superior edge is then marked with a pen to maintain orientation endoscopically during insertion. The implant is inserted through the working incision and manipulated both internally (with instruments) and externally (with fingers) above the defect (Figure 5A). Once the implant is in place over the fracture, the size and shape are evaluated and it is removed to be trimmed and refined. The process is repeated until the diameter of the implant is approximately 2.0 to 3.0 mm larger than the defect. At times, the author has sutured two to three layers of polyethylene sheeting together in an inverted pyramid shape to more accurately fill deeper defects. Once the implant is appropriately fashioned, a 25-gauge needle is passed through the skin over the fracture and endoscopically visualized to determine the best site for a percutaneous incision and screw placement. Optimal incision placement will allow for screws to be placed on either side of the implant through a single incision. Larger implants may require two stab incisions. Once the appropriate site has been determined, a #11 blade is used to make a 2-mm, through-and-through stab incision. A 1.7-mm, self-drilling screw (length 4-7 mm) is passed through the stab incision, through the edge of the implant, and into stable bone peripheral to the fracture edge (Figure 5B). The screw must be securely attached to the screwdriver to avoid dislodging the screw as it passes through the soft tissue. The screw must be placed at least 1.0 mm away from the implant edge or it may tear. If the implant remains unstable after the first screw, a second screw is placed on the contralateral side. The scalp incisions are then closed in layers, and a pressure dressing is applied.

Anterior table fractures that cannot be observed or managed endoscopically may require open reduction and internal fixation. The patient is consented for the procedure, including the risks of bleeding, infection, paresthesias, headache, CSF leak, orbital injury, diplopia, meningitis, external deformity, and late mucocele formation. In patients with longer hair (at least 3-4 cm), the author prefers a zig-zag incision placed 4 to 6 cm behind the hairline (Figure 6A). The zig-zag pattern allows gravity to pull the hair down and cover the transverse arms of the incision. The hair need not be shaved but can be banded instead. The application of a water-based lubricant to the hair facilitates separating the hair and rapid application of the rubber bands (Figure 6B). If the patient wears very short hair, the zig-zag pattern only lengthens and accentuates the incision. In these patients the traditional straight line, coronal incision works equally well and is easier to perform (Figure 7). If a straight-line incision is used, some type of marker should be placed along the incision to assist with symmetric closure of the scalp. Some options include small methylene blue tattoos placed on opposite sides of the incision with a 21-guage needle or placement of a small “widow's peak” in the midline (Figure 7). In patients with male pattern baldness, the incision can be moved posteriorly to camouflage it within the hair. This may necessitate a slightly more extensive longer lateral dissection to allow forward rotation of the scalp flap. Mid-forehead, brow, and “gull wing” incisions should be avoided due to the prominent scar and associated forehead anesthesia. Whichever incision is chosen, the technique should be described to the patient in detail; particularly to those with male pattern baldness.

In the operating room, the bed is turned 180° away from anesthesia, and corneal shields or temporary tarsoraphies are placed. Towels are stapled to the scalp just behind the incision line. An adherent plastic suction pouch is applied at the leading edge of the towel to collect blood and minimize spillage onto the surgeons. If large lacerations are present on the forehead, they should be explored and used to assist with fracture repair. Significant extension of forehead lacerations should be avoided. The greatest blood loss occurs with the initial incision and wound closure. When possible, generous amounts of a vasoconstrictor agent should be injected in a subgaleal plane before surgery. The scalp is then incised from one temporal line to the other. The incision passes through the skin and subcutaneous tissues. Two double-prong skin hooks are used to retract the skin away from the skull. This elevation will protect the underlying pericranium from inadvertent injury. A scalpel is used to incise the galea. Once the galea is violated, air will rapidly enter into the subgaleal plane, and there will be an obvious separation between the galea and the pericranium. The skin hooks are then moved medial and lateral as the skin incision is completed. Bleeding from larger vessels should be tied off individually. Electrocautery should be used sparingly as it may injure hair follicles. Rainey clips can be used for hemostasis. Finger dissection can then be used to elevate 2 to 3 cm on either sides of the incision, taking care to maintain the integrity of the pericranium.

The lateral dissection demands a thorough understanding of temporal anatomy. The initial incision is extended below the temporal line and behind the helix on one side (Figures 6A and 7). The incision should be carried through the temporoparietal fascia (superficial temporal fascia) and onto the temporalis muscle fascia (deep temporal fascia). This incision traverses the temporal artery and vein, which should be controlled by using a suture ligature or Rainey clips. The appropriate depth can be confirmed by placing a small (1-2 mm) nick in the temporalis muscle fascia and confirming the presence of dark red temporalis muscle beneath. The flap is then elevated anteriorly using blunt finger dissection or gauze, with intermittent use of the scalpel. The integrity of the temporoparietal fascia must be maintained, as it contains the frontal branch of the facial nerve (Figure 8). As the temporal flap is elevated, it is joined with the central dissection (medial to the temporal line) by sharply incising the fibers along the temporal line. Once again, special attention must be used to avoid injury to the temporal nerve. If necessary to help ease tension on the flap and gain lateral exposure, sharp dissection can be performed over the posterior aspect of the frontozygomatic suture line toward the zygomatic arch. Finally, the temporal dissection is completed on the contralateral side.

The scalp is then rotated forward, and blunt or sharp dissection can be used to elevate the subgaleal flap to a level 3 to 4 cm above the orbital rims. Care is taken to avoid injury to the supraorbital and supratrochlear neurovascular pedicles. The frontal bone can then be exposed by incising the periosteum directly above the fracture. However, it is generally wise to maintain the integrity of the vascularized pericranial flap, as it can be used for frontal recontouring, dural repair, or obliteration of the sinus. The pericranial flap can be elevated by placing an incision through the periosteum, parallel and 2 cm behind the initial scalp incision. This is then joined with lateral incisions 2 cm cephalad to the temporal line (Figure 9). Although periosteal lacerations may exist at the fracture site, a careful dissection will usually maintain an intact vascular supply and provide a lengthy flap for reconstruction (Figure 10). More extensive inferior dissection exposing the orbital rims and roof necessitates release of the supraorbital neurovascular pedicle. Release of the neurovascular pedicle from the supraorbital “notch” requires a methodical subperiosteal dissection to avoid nerve injury or exposure of orbital fat. If a true foramina is present, it is necessary to use an osteotome to release the pedicle. A 2- to 3-mm osteotome is placed laterally in the foramina and angled toward the lateral orbital wall. A malleable retractor protects the orbit, and mallet is used to fracture out the notch (Figure 11, inset). This is repeated on the medial side of the foramina. A careful subperisteal dissection across the orbital roof will allow release of the neurovascular pedicle.

After complete exposure of the frontal bone, attention should be turned to fracture reduction. Reduction of noncomminuted, compressed fractures can be extremely challenging. When the convex surface of the frontal bone is fractured, it goes through a compression phase before it becomes concave (Figure 12A). Fracture reduction will require enough force to pull the bone fragments back through the compression phase (Figure 12B). It may be necessary to remove a bone fragment, release the tension, and make room for reduction. If comminution exists or bone segments overlap at the fracture site, a small bone hook can be insinuated between the fragments to assist with fracture elevation. Another technique is to place a 1.5- to 2.0-mm screw in the depressed segment, grasp the screw with a heavy hemostat, and pull upward to reduce the segment. Every attempt should be made to keep the majority of the fragments in place, as this will allow for a more accurate repair.

Once the bone fragments are mobilized, the sinus mucosa should be evaluated. A 30° endoscope can be helpful to visualize the sinus and the nasofrontal recess through a limited bone defect. Mucosa involved in a fracture line should be removed to avoid entrapment. The fragments are then reduced and plated with 1.0- to 1.3-mm microplates. Missing bone is uncommon; however, high-velocity injuries may result in small, comminuted fragments, which cannot be reapproximated. Small gaps (4-10 mm) can be reconstructed with titanium mesh. Although hydroxyappatite bone cement has been recommended to fill bone defects, the author believes this should be avoided due to an unacceptably high risk of infection and extrusion. However, bone pate, burred from intact calvarium, can be used in combination with a pericranial flap to smooth surface irregularities.

After the bony reconstruction, it is important to resuspend the temporal soft tissues to avoid long-term ptosis of the forehead and upper midface. Two, 2-0 monofilament sutures are passed through the temporoparietal fascia and suspended up to the temporalis muscle fascia. The stitch is placed as an “air” knot, and a needle driver is used to maintain the first throw, while the second throw is applied (Figure 13). To reduce blood loss during the closure, the Rainey clips are removed in thirds and a tight galeal closure is performed with interrupted 3-0 “pop-off” sutures. Electrocautery is kept to a minimum, reducing the risk of postop alopecia. Bilateral ¼-inch Penrose drains are placed beneath the scalp, exiting the coronal incision above each ear, and sutured to the skin. Staples are used to close the skin. A pressure dressing is applied. Care should be taken to assure that the ears are not rolled forward under the pressure dressing. The Penrose drains are removed at 24 hours, the pressure dressing at 3 days, and the skin staples at 10 days.

More severe injuries may require frontal sinus obliteration. This involves exposure of the entire sinus, fastidious removal of all sinus mucosa, and obliteration of the cavity with autologous materials. Many different materials have been used for sinus obliteration, including abdominal fat, cancellous bone, muscle, pericranium, and spontaneous osteoneogenesis with “auto-obliteration.” The author prefers abdominal fat. As previously mentioned, hydroxyappatite cement should be avoided due to the unacceptably high risk of infection and extrusion.

The patient is given informed consent, including the risks of bleeding, infection, paresthesias, brain injury, CSF leak, meningitis, diplopia, visual loss, external deformity, and late mucocele formation. A coronal flap is used to expose the fracture as previously described. The full pericranial flap should be maintained to repair any CSF leak, dural defect, or obliterate the sinus (Figure 10). After complete exposure, all anterior table bone fragments should be removed and kept moist. Placing the fragments atop a drawing of the fracture will help maintain the anatomic orientation of each segment before the repair. With isolated fractures, it is often necessary to perform a frontal sinusotomy or remove the remainder of the anterior table. Localization of the sinusotomy cuts can be performed in several ways. Historically a “6 foot penny Caldwell” x-ray was used (i.e., anterior–posterior Caldwell x-ray with the patient placed 6 feet from the x-ray tube). However, current digital radiograph technology has made this x-ray very difficult to obtain. Intraoperative navigation is accurate but requires a specialized scan and navigation hardware. Alternatively, one tine of a bipolar cautery can be placed on each side of the anterior table. The internal tine is then used to “walk” around the periphery of the sinus, while the outer tine is used to mark an outline the sinus using a bovie electrocautery (Figure 14). A third technique involves application of a light source into a fracture line; this transilluminates the periphery of the sinus.

After the limits of the sinus have been drawn out, two microplates (1.0-1.3 mm) are applied on opposite sides of sinus. Each plate is “preapplied” with 3- to 4-mm screws, spanning the proposed osteotomy site. This allows the surgeon to accurately reapproximate the bone fragments despite the fact that a bone defect (or kerf) will be formed with the osteotomy. One screw is left in place on the upper border of each plate, and they are rotated superiorly out of the surgical field (Figure 15). Although a sagittal saw can be used to perform the sinusotomy, the author prefers a Midas Rex drill (Medtronic, Fort Worth, TX) with a B-1 bit, which has both drilling and side-cutting capabilities. The surgeon should initially use the bit to drill “postage stamp” perforations around the periphery of the sinus (Figure 16A). The drill must be angled toward the sinus cavity to avoid intracranial penetration and injury (Figure 16B). The side-cutting capability of the bit can then be used to join the perforations and complete the osteotomy (Figure 16A). Care should be taken to avoid obliteration of the predrilled miniplate holes while performing the osteotomy. Particular attention should be paid to osteotomize the lateral orbital rims and the glabella without injury to the supraorbital/supratrochlear neurovascular pedicles. These osteotomies can be performed with a B-1 bit or a 2- to 4-mm osteotome. A curved 4-mm osteotome is then inserted obliquely through the frontal osteotomy and used to break down any intersinus septations. Finally, the anterior table is out-fractured and hinged anteriorly.

After complete exposure of the sinus, the posterior table integrity is evaluated. If it is stable and free of large defects, sinus obliteration is acceptable. However, all sinus mucosa must be meticulously removed from both the posterior and anterior tables. The author prefers to start with a large (4-6 mm) cutting burr and move to small diamond burrs for deeper in the sinus. Access to the deepest portions of the sinus can be extremely challenging in patients with pronounced pnuematization. Special attention must be paid to the deepest areas at the periphery of the sinus to assure complete mucosal removal (Figure 17). After complete removal of the sinus mucosa, attention is turned to the frontal recess. The mucosa of the frontal sinus infundibulum is elevated and inverted into the frontal recess. A small temporalis muscle plug is then placed into the frontal recess to obliterate the ostea. Finally, a 5-mm osteotome is used to obtain two 5 × 5-mm bone chips from the calvarium (Figure 18A). These are inserted to seal off the frontal sinus infundibulum (Figure 18B).

A fat graft is obtained through a left lower quadrant (or periumbilical) incision using a separate, sterile instrument set. An attempt should be made to harvest the fat graft in a single piece, with minimal trauma and avoiding electrocautery when possible. The fat graft is then inserted into the sinus cavity, and the anterior table fragments are replaced. The fat should meet but not extrude into the saw kerf. Anterior table stabilization is achieved by rotating the preapplied microplates inferiorly and reapplication of the screws. Mesh and/or bone paté can be used to camouflage surface irregularities, if necessary.

The most severe injuries with disruption of the posterior table will require frontal sinus cranialization. Consultation with a neurosurgical colleague is recommended. The surgical approach is identical to that described under “frontal sinus obliteration”; however, maintaining the integrity of the pericranial flap becomes more critical for dural repair and control of CSF leaks. All free bone fragments from the anterior and posterior table are removed and drilled free of mucosa. Once the sinus is fully exposed, the dura should be carefully dissected from the posterior table remnant with Penfield elevators. The brain should be gently retracted and any remaining portion of the posterior table removed using straight and angled rongeurs. A drill is then used to smooth the posterior table edge flush with the anterior sinus walls, floor, and anterior cranial fossa. The frontal recess is occluded as previously described in “frontal sinus obliteration.” Simple lacerations of the dura can be repaired with interrupted 5-0 nylon sutures and tissue glue. More complex injuries may require neurosurgical debridement and closure with a pericranial flap. When a pericranial flap is used, a small bony defect must be fashioned just above the orbital rims. This allows the flap to pass intracranially without cutting off the blood supply. The anterior table is then reconstructed using 1.0- to 1.3-mm microplates and mesh. The bony disruption may be so severe that posterior table fragments are required to reconstruction the anterior table. The incision is closed as described under “anterior table fractures.”