Few deformities of the maxillofacial region present with such a wide constellation of symptoms and clinical findings as ankylosis of the temporomandibular joint. Pain, swelling, disruption of diet and speech, airway complications, and the creation of cosmetic deformities all can result from this severe defect of the mandibular zygomatic complex. The basic surgical goals for correction of this deformity are threefold: to free up the ankylosis, to return the patient to function, and to prevent recurrence. The last 2 of these 3 goals are usually dependent on placement of an interpositional barrier following release of the fibrous or bony fusion that can be either prosthetic or tissue borne.
The most common causes of severe ankylosis of the temporomandibular joint are posttraumatic, but arthritis, infection, and scar tissue from previous surgery all are known etiologic factors. The 3 subtypes of ankyloses are classified depending on the extent of involvement: stage1, bony ankylosis limited to the condylar process; stage 2, ankylosis of bone reaching the sigmoid notch; and stage 3, ankylosis involving the coronoid process.
In the past, the surgical treatment of this problem has been regarded, even by the most experienced surgeons of our profession, as an undertaking that is fraught with complications such as bleeding and nerve damage, which can produce much anxiety for the surgeon with the possibility of potential morbidity for the patient. A portion of this anxiety is well founded in that the surgeon is operating in an area generously populated with major vessels that are difficult to access for control and blanketed by the 5 branches of the facial nerve where slight damage to any one of them could cause a significant cosmetic facial deformity.
The purpose of this article is to present a step-by-step approach to the correction of this deformity. While each deformity is different and may present a different set of anatomic findings, the theoretical approach remains the same: to always be in a position to deal with complications if they arise by having good visibility and access to the surgical field, through a careful and systematic approach.
Anesthesia considerations
While the airway is always the most essential factor in a successful anesthetic, it becomes more problematic in a patient with a limited opening due to an ankylosis deformity. The anesthesia team must be made aware that the mandible will be unable to be mobilized even with adequate muscle relaxation. Fiberoptic intubation or tracheostomy becomes the usual option to secure an adequate airway for this relatively prolonged procedure. All options need to be discussed and accepted by the patient, and adequate preparation for a surgical airway need to be in place in the event the endotracheal intubation is unsuccessful.
Hypotensive anesthesia is highly recommended for this procedure. The institution of an arterial line will allow the anesthesia team to safely maintain a mean arterial pressure in the range of 55 to 60 mm Hg and can be adjusted depending on the comfort of the anesthesia team relative to the medical condition of the patient. This technique is helpful in maintaining a dry surgical field, restricting blood loss in the event of a bleeding episode, and obtaining serial blood labs if necessary.
As with any procedure involving transcutaneous approaches to this area of the facial skeleton, the anesthesia team needs to know that the use of long-acting muscle relaxants is to be avoided until access to the mandible has been completed, to facilitate identification of the facial nerve branches.
Technique
Once the patient is intubated, before positioning, prepping, and draping, any intraoral procedure is completed such as placement of arch bars or fixation screws. The patient is then positioned with turning of the head or the table to provide maximum comfort and access for the operator followed by prepping and draping of the surgical field.
The skin incision for this procedure is similar to most involving the temporomandibular joint, through a preauricular approach. The usual precautions for protecting all branches of the facial nerve are taken but because of the wide exposure needed for this procedure and the use of anterior retraction, some temporary partial nerve trauma can almost always be anticipated. In an effort to avoid this complication some surgeons modify the initial incision by taking it down to temporal bone and bring the complete musculocutaneous flap forward. This technique is not always necessary, but does allow excellent exposure while protecting the facial nerve.
The first bony landmark to be identified is the zygomatic arch. Even in the most severe cases the arch can be identified as the most superior extent of the deformity. Subperiosteal dissection is then taken forward along the arch to identify the extent of the deformity. With obliteration of the joint space in the ankylotic joint, the next reliable bony landmark is the neck of the condyle. Once the neck is identified, subperiosteal dissection is taken down from the zygomatic arch to what can be identified as the posterior border of the neck or ramus of the residual defect. Once this is identified, the first Dunn retractor ( Fig. 1 ) is placed carefully around the back of the posterior border. Subperiosteal dissection now continues anteriorly to identify the anterior border of the deformity, which is usually the neck of the residual condyle. When this is identified, the second Dunn retractor is carefully placed in a subperiosteal position around to the medial surface of the neck ( Fig. 2 ). If the ankylosis only involves the condyle, these retractors are now ready to provide the operator with excellent exposure of the deformity and protection of the soft tissue anterior, posterior, and medially from any high-speed instruments used to incise the deformity. If the deformity is large and obliterates the entire sigmoid notch, further dissection needs to be taken along the zygomatic arch and medially to the anterior border of the ascending ramus. The Dunn retractor can then be placed around to the medial surface to expose the entire bony fusion before attempting the initial bone incision ( Fig. 3 ).
The goal of the first bone incision is to break the bony fusion at any level that is well exposed, protected by retractors, and requires a minimal amount of medial cutting; this is usually lower on the neck inferior to any medial bony deformities that may be a result of a previously fractured condyle. Initial testing of the completeness of the osteotomy can be tested with a small osteotome or a bone spreader. Once it is established that the osteotomy is complete, additional bone can be removed from the inferior or ramus side of the cut because this side has the more predictable anatomy. A reciprocating rasp, a small burr, or an oscillating saw can be used to create a larger gap between the two cut edges. Better access to the ramus for further bone removal can be obtained by having an assistant push up on the angle of the mandible, bringing the ramus stump into the already established gap ( Fig. 4 ).
Creating this initial gap between the two segments accomplishes two goals: providing direct access to the vital structures medial to the deformity, and establishing direct visualization and access to the sometimes malformed and medially displaced superior bony deformity. Now with judicious subperiosteal dissection, the bony deformity can be identified and removed with a reciprocating rasp and hand instruments ( Fig. 5 ). If any bleeding should occur, direct pressure as well as cautery can be applied with reasonable visualization.
At this point, the operator’s main objective is to continue to widen the gap between the two cut surfaces in preparation for whichever interpositional replacement, if any, is chosen. In most cases of severe ankylosis the operator chooses to remove the coronoid process with its temporalis attachment to assist in reestablishing a better opening capacity of the mandible. This goal is accomplished by extending the bony incision anteriorly along the base of the process to the ascending ramus. While clamping the cut base of the process in one hand, the operator can now strip the muscle attachment from all surfaces until the bone segment is completely free for removal.
If immediate replacement with either an autogenous or a prosthetic implant is anticipated, access to the ramus through a submandibular incision will be necessary. Performed early on in the procedure, this access can help in several ways in providing additional access to the ankylosed deformity. Stripping of the pterygomasseteric sling will help mobilize the mandible; clamping of the angle and moving the posterior ramus into the superior gap can improve access to further bone removal, and in some cases access for the coronoidectomy is better achieved through this approach.
If a staged procedure or simply a gap arthroplasty is planned, tissue grafts or sialastic spacers can be placed at this point, and the wound is closed. If immediate reconstruction with a prosthetic implant is planned, preparation of the fossa bed can be done through the superior incision followed by placement of the prosthesis. The patient is then put into intermaxillary fixation establishing the desired occlusion and vertical dimension. Through the lower incision the ramus can be prepared and the condylar prosthesis or autogenous graft can be placed.
In most cases, access to the oral cavity is necessary to either mobilize the mandible or to establish an occlusion with intermaxillary fixation for a short period of time. Careful attention needs to be paid to maintaining separate fields of surgery to prevent cross-contamination of bacteria from the unsterile oral cavity to the main surgical site. Separate “clean” and “dirty” instrument trays need to be designated, and members of the operating team must change gloves and sometimes gowns when transitioning between the two fields.
Postoperatively, in cases of gap arthroplasty and prosthetic total joint replacement, immediate physical therapy is the rule. For the first week, while the surgical wounds are healing and postoperative pain is still a factor, the patient can undertake passive therapy to a point of their own personal tolerance, which can be followed by a more regimented program of mechanical therapy provided by devices such as the Therabite Jaw Rehabilitation System (CranioMandibular Rehab, Denver, CO, USA). This aggressive therapy has been shown to be very important in preventing reoccurrence of the ankylosis and providing the best possible function of whichever interpositional implants are placed. In a staged procedure, when a postoperative computed tomography scan is needed for fabrication of a custom joint replacement, maxillomandibular fixation may be necessary for a short period of time. Also, in children and young adults receiving replacement rib grafts, it is recommended that the patient be kept in maxillomandibular fixation for 10 days followed by an aggressive program of jaw physiotherapy.
Immediately following surgery and during the initial jaw physiotherapy sessions, the patient may need intense pain control therapy. Oral pain control, however, should be tapered to nonsteroidal anti-inflammatory medication as soon as possible. In some cases of long-term facial pain arising from a variety of factors prior to surgery, it is best to have a pain specialist on board as part of the treatment team to help deal with pain issues immediately following the surgery and for the longer term if necessary.
During the initial jaw-opening therapy no other oral procedures should be performed other than routine hygiene and necessary caries control. Permanent reconstructive efforts such as dental implants, crown and bridge, and removable prosthodontics should be held off for at least 3 months until it is assured that the arch relationship and vertical dimension are stable. The use of prosthetic replacements will allow earlier intervention, due to the lack of remodeling and resorption in the reconstructed area.
Technique
Once the patient is intubated, before positioning, prepping, and draping, any intraoral procedure is completed such as placement of arch bars or fixation screws. The patient is then positioned with turning of the head or the table to provide maximum comfort and access for the operator followed by prepping and draping of the surgical field.
The skin incision for this procedure is similar to most involving the temporomandibular joint, through a preauricular approach. The usual precautions for protecting all branches of the facial nerve are taken but because of the wide exposure needed for this procedure and the use of anterior retraction, some temporary partial nerve trauma can almost always be anticipated. In an effort to avoid this complication some surgeons modify the initial incision by taking it down to temporal bone and bring the complete musculocutaneous flap forward. This technique is not always necessary, but does allow excellent exposure while protecting the facial nerve.
The first bony landmark to be identified is the zygomatic arch. Even in the most severe cases the arch can be identified as the most superior extent of the deformity. Subperiosteal dissection is then taken forward along the arch to identify the extent of the deformity. With obliteration of the joint space in the ankylotic joint, the next reliable bony landmark is the neck of the condyle. Once the neck is identified, subperiosteal dissection is taken down from the zygomatic arch to what can be identified as the posterior border of the neck or ramus of the residual defect. Once this is identified, the first Dunn retractor ( Fig. 1 ) is placed carefully around the back of the posterior border. Subperiosteal dissection now continues anteriorly to identify the anterior border of the deformity, which is usually the neck of the residual condyle. When this is identified, the second Dunn retractor is carefully placed in a subperiosteal position around to the medial surface of the neck ( Fig. 2 ). If the ankylosis only involves the condyle, these retractors are now ready to provide the operator with excellent exposure of the deformity and protection of the soft tissue anterior, posterior, and medially from any high-speed instruments used to incise the deformity. If the deformity is large and obliterates the entire sigmoid notch, further dissection needs to be taken along the zygomatic arch and medially to the anterior border of the ascending ramus. The Dunn retractor can then be placed around to the medial surface to expose the entire bony fusion before attempting the initial bone incision ( Fig. 3 ).
