The goal of secondary reconstruction of the midface is to restore harmony with a primary focus of restoration of form and function.
An organized assessment of the facial structures is crucial to a successful outcome. These include the orbit, the nasal-ethmoid complex and the zygoma.
Within the orbit, secondary correction most often relates to malposition of the globe within the bony orbit.
When the naso-orbito-ethmoid complex is involved, proper positioning of the medial canthus is critical to avoid persistent telecanthus.
Virtual surgical planning, intraoperative navigation, and custom implants can be helpful for complex secondary reconstructions of the midface, especially in panfacial injuries.
Secondary deformities of the midface pose a significant challenge for even the most experienced of surgeons. Although the first operation provides the best opportunity for an ideal outcome, this not always is possible. There often is significant distortion in anatomy, inadequate bony foundation, and macerated soft tissue, especially in patients with avulsion injuries. Avulsion injuries result in a failure to achieve complete reduction and stabilization of fractures during the initial reconstruction.
The goal of secondary reconstruction is to restore harmony, with a primary focus of restoration of form and function. This is achieved in a manner similar to the approach taken during the primary reconstructive phase. In the assessment and treatment of secondary reconstruction patients, the main focus is to restore orbital volume and bizygomatic width and projection and to achieve proper occlusion. An organized assessment of the facial structures is crucial to a successful outcome. These include the orbit, the nasal-ethmoid complex, and the zygoma. Each of these anatomic subunits should be evaluated for functional deficits. Within the orbit, the deficits most often encountered are secondary to malposition of the globe within the bony orbit. These deficits include hypoglobus, dystopias, entropion or ectropion, and diplopia. Malpositioning of the zygomaticomaxillary complex (ZMC) also may lead to these deficits. Additionally, patients with secondary deformities of midface may present with malocclusion and limitations in opening and closing. When the naso-orbito-ethmoid (NOE) complex is involved, improper positioning of the medial canthus may lead to a persistent telecanthus. Furthermore, improper reduction of the nasal complex and lacrimal system results in impaired nasofrontal and lacrimal drainage and poor nasal projection. All these factors are compounded in panfacial fractures. The aim of this article is to review the approaches to the assessment and management of patients who present for the correction of secondary defects to the midface.
Secondary correction of enophthalmos
When present, postoperative enophthalmos may be observed at follow-up appointments after repair of many midface fractures, including the NOE, ZMC, and orbital complex. As the edema from the original injury and subsequent surgery subside, the globe settles into a depressed position relative to the contralateral side due to increased orbital cavity volume. This usually is due to inadequate reduction and loss/atrophy of intraorbital adipose tissue.
If not obtained in the immediate postoperative period, computed tomography (CT) imaging should be acquired in order to determine those areas of the orbital complex that are the most significant contributors to orbital volume expansion. Enophthalmos alone can be a subtle finding that is observed by the trained eye. The average layperson, however, notes an abnormal appearance with an enophthalmos of 3 mm to 4 mm. Binocular diplopia is the strongest indicator that secondary repair is required. Although a variety of approaches can be utilized, the favored approach is the transconjunctival approach because this technique is less prone to cause additional cosmetic defects, such as ectropion. Secondary repair of such a defect can be difficult after initial healing, because scar tissue often complicates the approach and limits the forward mobility of the globe. For this reason, thorough subperiosteal dissection along the orbital floor, medial wall, and lateral wall beyond the site of injury frequently is required. Historically, orbital volume was restored using autogenous bone grafts. More recently, orbital volume most often is reduced via placement of alloplastic implants composed of materials, such as titanium, porous polyethylene, or a combination of the 2. There also now is the option of using virtual surgical planning (VSP) to manufacture custom implants that can achieve a passive fit in situations where there is significant distortion of normal anatomy that is not amenable to reconstruction with stock materials. Although secondary repair can aid in globe position, if persistent diplopia is noted, then strabismus surgery or prism glasses may be required in order to restore the patient to their premorbid functional status.
Secondary correction of the zygomaticomaxillary complex
Secondary correction of ZMC injuries is indicated when inadequate reduction during the primary surgery produces a deficiency in malar projection. This usually is a result of inadequate restoration of proper contour of the zygomatic arch. Anatomically, the zygomatic arch is fairly straight. Failure to restore this arch form often leads to increased facial width and decreased projection.
Often the degree of ZMC displacement and/or lack of anatomic reduction dictates the amount of malar projection and contributes to the apparent flattening/widening of the face on the ipsilateral side. The characteristics of a patient’s skin and body habitus, however, also can affect this finding. Observing a patient from a cephalad position allows one to assess the patient’s malar projection bilaterally and palpation further assess the relative contributions from hard and soft tissues. Historically, such malar deficiencies were treated with local rearrangement of adipose tissue. This often has produced the undesirable result of lower eyelid shortening and hollowing and no longer is utilized. Once the deficiency has been identified, correction can be pursued with reosteotomy at the sites of improper reduction or more commonly with placement a malar implant via a vestibular approach. , The implant should be inserted in a subperiosteal plane and evaluated from frontal, profile, and cephalad views in order to best approximate symmetry with the contralateral side, trimming, and contouring the implant, as necessary, and eventually fixating the implant as needed. Although rarer, the possibility of a proper bony reduction in the setting of a purely soft tissue deficiency also should be considered, most often a result of malar fat pad atrophy and/or improper suspension of the soft tissue. Secondary correction of such soft tissue deficiencies can be compensated for by using adipose tissue grafting, dermal fillers, and/or rhytidectomy techniques.
Secondary correction of naso-orbito-ethmoid fractures
The NOE complex is a delicate 3-dimensional (3-D) anatomic structure. Damage to this region may result in severe facial dysfunction and malformation. NOE fractures involve the central upper midface. This consists of the confluence between the paired nasal bones that form the nasal sidewalls and medial orbital rims.
When secondary repair of NOE fractures is necessary, the repair should be planned methodically focusing on restoring facial function and form. Specific attention should be applied on the medial canthus and intercanthal relationship. The pivotal structure that is present in this region is the medial canthal tendon. This tendon supports the canthus and enables proper union between the eyelid and the globe. The canthal tendon serves to suspend the upper and lower tarsal plates across the eye and is critical in maintaining a sharp medial canthal angle. Therefore, in order to achieve a proper aesthetic result after NOE fracture repair, the medial canthal tendon must be fixated securely to the small bone fragments to which it has remained attached in Markowitz types I and II fractures or reattached to stable bone in Markowitz type III fractures.
Traumatic telecanthus and hypertelorism are the most frequent late complications from inadequate management of medial canthal tendons. The unaesthetic aspect of telecanthus is created not only by the increased intercanthal distance but also by the rounded palpebral fissure and the flattened nose. Therefore, in order to achieve proper and definitive correction, the entire nasal skeleton requires reshaping. This is accomplished by reosteotomy and medial repositioning of the bone fragment that anchors the displaced medial canthal attachment. This osteotomy should include the lacrimal crest and its associated attachment of the inner canthal ligament. If the ligamentous insertion is not violated, it should be preserved because the normal anatomic configuration is extremely difficult to reproduce operatively. Fixation of the mobilized nasal segments is performed using the same techniques as in primary repair. A transnasal wire secures the nasal bone fragment against outward rotation, even if a canthopexy is performed. In addition, if 1 canthus is superior to the other, the inferior canthus should be elevated to achieve symmetry. If the medial canthal tendon is detached completely during secondary surgery, the medial canthal tendon itself must be reduced with a separate transnasal canthopexy. The ligament is grasped with a 28-gauge wire at its origin, proximal to where the 3 limbs have not yet separated. This wire is passed transnasally and the point of insertion must be above and behind the nasolacrimal duel. If the bone in this area does not permit creation of an insertion point, a midface miniplate can be used as an alternative. Tightening of the transnasal canthopexy always should be the last step in secondary corrections because placement of bone grafts is facilitated by free canthal ligaments.
Unfortunately, there often is significant scar contracture and soft tissue thickening after NOE repairs, which can give the appearance of pseudotelecanthus. An oblique transnasal wiring technique with V-Y epicanthoplasty incision can minimize scar formation and contracture. In addition, maximal skeletal narrowing should be achieved in order to create a nearly normal intercanthal distance. Even with maximal narrowing, however, repair of telecanthus usually falls short of premorbid appearance. Irreparable telecanthus can be slightly masked by increasing the nasal profile with a dorsal nasal bone graft. Less invasively, favorable soft tissue adaptation has been described using a thermoplastic stent contoured and overextended in the naso-orbital region.
Considerations in panfacial fractures
Panfacial injuries provide a set of challenges for secondary reconstruction due to the extensive nature of these fractures. Initial repair also is complicated by can by significant facial injury and edema, thereby making access and intraoperative evaluation of facial projection difficult. Generally, this fracture pattern results in flattening and widening of the face due to depression of the midface and increased bigonial width secondary to mandible fractures involving the symphysis or parasymphysis. Primary reconstruction is aimed toward restoring facial projection by rebuilding the vertical and horizontal buttresses of the face. , Secondary reconstruction is necessitated weeks to months after the initial repair due to inadequate functional or cosmetic results. Sometimes, the facial injuries can go untreated due to the inexperience of surgery specialists at the primary care center. Additionally, incomplete or inadequate repair can be secondary to lack of resources at such institutions. These include VSP intraoperative CT and intraoperative navigation.
Regardless, panfacial fractures requiring secondary reconstruction usually feature common complications that can be addressed with a variety of surgical strategies, discussed previously. Malocclusion is the most commonly encountered complication. Cuddy and colleagues reviewed 33 patients with panfacial fractures that went untreated for 4 or more weeks, and malocclusion was present in 100% of the patients. Depending on the degree of severity, malocclusion can be treated by guiding elastics, orthodontics, or orthognathic surgery. In Cuddy and colleagues’ review, all patients had Le Fort I osteotomies done as the last step of reconstruction. Alternatively, other investigators have suggested establishing occlusion via Le Fort I osteotomy first, then reconstructing the remainder of the midface subunits with the techniques, discussed previously and reviewed later. This strategy can simplify an otherwise complex reconstruction.
Sequelae involving the midface include malar flattening, enopthalmos or hypoglobus, and telecanthus. Malar flattening typically is due to a depressed or posteriorly rotated ZMC fracture. Concomitant orbital floor fractures also may cause enophthalmos and hypoglobus secondary to the increase in orbital volume.
Minor malar deformities can be corrected using onlay grafting and recontouring or using custom implants. If a significant deficiency exists, projection can be restored by performing a ZMC osteotomy and then positioning/fixating the zygoma in a more ideal location. A bicoronal flap and maxillary vestibular and lower lid incisions typically are necessary for access. Complete subperiosteal dissection is important to fully mobilize the zygoma. Osteotomies are done using a combination of a sagittal saw and osteotomes. A saw cut typically is made first at the zygomaticofrontal suture, followed by osteotomy of the orbital floor with an osteotome. The saw then is used for osteotomies at the infraorbital rim, anterior maxilla, zygomaticomaxillary junction, and zygomatic arch. It is important to remember that mobilization and repositioning of the zygoma may create an orbital floor defect, which needs reconstruction with an orbital floor plate or calvarial bone graft to avoid subsequent enophthalmos. Similarly, gaps that are created at the osteotomy sites should be filled with bone graft after fixation is completed.
The NOE region can prove the most difficult to reconstruct due to lack of a sagittal buttress in the area. Common complications are telecanthus and dorsal nasal defects. Persistent telecanthus is due to the lateral displacement of the medial orbital bones where the medial canthal tendon attaches or inadequate canthopexy. Autogenous strut grafts can be used to restore projection of the nasal dorsum and at the same time can camouflage telecanthus.
The complexity of panfacial fractures makes using adjunctive tools essential. VSP from CT scans with fine cuts (<1 mm) allows for fabrication of custom plates, implants, or cutting guides. Intraoperative navigation also can be used to verify the positioning of bony segments prior to fixation. If the tooth-bearing skeleton is involved, dental impression and mounted casts can be invaluable in restoring proper occlusion. Typically, establishment of occlusion alone can restore the appropriate facial projection.
In cases of significant bone loss, either autogenous block graft or free flap reconstruction should be considered, particularly when implant-retained dental prostheses are desired. Residual soft tissue deficits can remain after bony reconstruction, and soft tissue augmentation can be achieved by a combination of soft tissue suspension and autogenous grafting.
Although it is ideal to avoid secondary reconstruction of panfacial fractures, the aforementioned circumstances necessitate at least some type of revision procedure. The advantage of secondary reconstruction is that it allows time for meticulous surgical planning and input from the patient that typically is not afforded during the primary repair.
Virtual surgical planning and custom implants in secondary reconstruction
VSP, intraoperative navigation, and custom implants can be helpful in secondary reconstructions of the midface. These technological advances have been shown to improve efficiency and precision for complex craniomaxillofacial surgical operations.
Combining multiplanar CT scans with 3-D reconstruction software permits the surgeon to visualize the complex anatomy of the midfacial region and can overcome the unintentional imprecisions associated with traditional intraoperative spatial repositioning. Prior to VSP, anatomic reduction relied on a surgeon’s capacity to mentally translate the 3-D movements. Unfortunately, bony repositioning in the midface is difficult to verify in real time to the naked eye. VSP allows the surgeon the ability to plan an accurate spatial bone correction, taking into account the many degrees and angles of movement. The advent of custom fixation plates has allowed for accurate fixation of the bony segments in their desired position.
Accuracy can be expanded on by using intraoperative simultaneous visualization of both the surgical field and the 3-D virtual planning superimposed on the CT images by means of tracked instruments. Interoperative navigation permits the ability the surgeon to verify in real time the precision of the repair. This is helpful particularly in the poorly visualized posterior-medial orbital wall reconstruction. Accurate reconstruction of this anatomy is critical in supporting and projecting the ocular globe and, thus, limiting chances of postoperative enophthalmos.
The advent of computer-aided design/computer-aided manufacturing technology has allowed surgeons to directly translate and integrate 3-D VSP without the need for navigation assistance. This process is achieved through patient-specific surgical cutting guides and patient-specific implants. Custom cutting guides are useful for midface deformities that require multispatial repositioning, as orbital hypertelorism or secondary correction of telecanthus. Patient-specific implants, most commonly made with poly-ether-ether-ketone implants or titanium, can be custom designed to a patient’s anatomy. This technology eliminates the often laborious and, at times, inaccurate method of hand manipulating stock implants intraoperatively. Furthermore, in unilateral defects, surgeons can use mirroring software to reproduce the unaffected facial side and reestablish facial symmetry.
VSP is a valuable instrument that may be used to help surgeons in the planning and intraoperative stages. VSP has been shown to increase the precision and accuracy of implant and hardware positioning. Moreover, the advent of patient-specific implants has transformed how surgeons manage complex 3-D defects and secondary reconstructions of the midface.