Joseph P. McCain¹ and Reem Hamdy Hossameldin²

¹Private Practice; Baptist Health Systems; and Oral and Maxillofacial Surgery, Herbert Wertheim College of Medicine, Florida International University Miami, Florida, USA; and Nova Southeastern School of Dental Medicine, Fort Lauderdale, Florida, USA

²Department of Oral and Maxillofacial Surgery, Faculty of Dental Medicine, Cairo University, Cairo, Egypt; and General Surgery Department, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, USA

A minimally invasive procedure used to diagnose and/or treat numerous joint pathologies.

Indications

1. Disabling joint conditions refractory to medical management and primary arthroscopy alone that require internal structural modifications of the temporomandibular joint (TMJ)
2. Wilkes stage II, stage III, and/or early stage IV of arthroscopic discopexy

Contraindications

1. Skin infection
2. Possible tumor seeding
3. Medical and other circumstances unique to patients

Anatomy

• Temporomandibular joint (TMJ): The TMJ is a diarthrodial joint separated into inferior and superior compartments by the articular disc. The inferior joint space contains approximately 0.9 mL of synovial fluid, whereas the superior joint space contains approximately 1.2 mL of synovial fluid. The inferior joint space is responsible for hinge opening or rotation (ginglymoid), and the superior joint space is responsible for gliding or translation motion (arthrodial), which is the second phase of opening. When the hinge opens, it permits the mandible to open approximately 2 to 3 cm as measured from the edges of the maxillary and mandibular incisor teeth. Translation allows increased opening to a maximum of 4 to 6 cm. The average vertical opening is approximately 45 mm. Anterior translation of the condyle terminates at the anterior peak of the articular eminence.
• Articular disk: The articular disk is composed of dense, collagenous connective tissue. The articular disk is biconcave in shape with a length of approximately 22 mm and a width of approximately 16 mm. The disk is firmly attached to the lateral and medial poles of the condyle. The anterior and anterior medial attachments are to the lateral head of the pterygoid muscle. The anterior lateral attachment is to the capsule only. The posterior attachment blends into the retrodiskal tissue, which attaches to the posterior wall of the glenoid fossa. The posterior retrodiskal tissue attachment consists of synovial cells, collagen fibers, nerves, blood vessels, and elastic fibers.
• Lateral pterygoid muscle: The most influential muscle involved in TMJ function is the lateral pterygoid muscle due to its attachment to both the disk and the condyle. The lateral pterygoid muscle has an inferior and superior belly. The origin of the inferior belly is the inferior two-thirds of the outer surface of the lateral pterygoid plate, the pyramidal process of the palatine bone, and the maxillary tuberosity. The insertion is into the anterior fovea of the condylar head. The vector of contraction is anterior and medial. The origin of the superior belly is the upper one-third of the lateral pterygoid plate and the infratemporal surface of the greater wing of the sphenoid. The insertion is into the superior aspect of the pterygoid fovea, the articular capsule, the medial aspect of the articular disk, and the condyle. During protrusion and opening, the pterygoid muscle pulls the condyle and disk anteriorly. If the muscle contracts on the right, it causes lateral excursion of the mandible to the left and vice versa.
• Glenoid fossa: The mean thickness of the glenoid fossa is 0.9 mm with a range of 0.5 to 1.5 mm. The dura and the temporal lobe are located superior to the glenoid fossa.

Arthroscopic Arthroplasty (Discopexy) Technique

1. The patient is placed supine on the operating room table and nasally intubated. An examination is performed under general anesthesia to evaluate the bilateral joints for joint mobility, condylar translation, and joint sounds (Figure 31.4 [all figures cited appear in Case Report 31.1]). The patient is prepped, draped, and positioned, allowing for visualization of the entire ear and lateral canthus of the eye. An ear wick impregnated in antibiotic solution or ointment is positioned within the external auditory canal for protection. A Quinn drape is placed (Figure 31.5) to allow for visualization of the ear, TMJ, and lateral canthus of the eye and to provide for a conduit to allow for manipulation of the jaw through the oral cavity without contamination of the extraoral incisions with oral microbes.

2. Standard landmarks are marked and include a line drawn from the lateral canthus of the eye and the tip of the tragus (Holmlund–Hellsing line) (Figure 31.5), the 10–2 point, and the 20–10 point (refer to Chapter 30).
3. The superior joint space is insufflated with 0.5 % Marcaine on a 22-gauge needle. Good plunger rebound confirms adequate insufflation of the space (Figure 31.6). Standard fossa portal entry is obtained with the 2.0 Dyonics operative system. The joint is examined with a 1.9 Dyonics video arthroscope attached to a Stryker camera system.
4. A patent irrigation system is established by placing a 22-gauge needle anterior to the fossa portal (Figure 31.7). Throughout the case, a patent irrigation system is maintained with irrigating fluid consisting of lactated Ringer’s and 1:300,000 epinephrine.
5. The superior joint cavity is explored and pertinent diagnostic arthroscopic findings are revealed (Figure 31.8). Operative maneuvers often follow diagnostic arthroscopy.
6. A second cannula is placed at 25 mm anterior to the first, utilizing the vector measuring system (Figure 31.9). For this portal to be most effective in diagnostic and operative arthroscopy, the arthroscope should illuminate the most anterolateral aspect of the anterior recess. Then, swiveling the arthroscope along the intermediate zone and advancing into the anterior recess, identifying the disc synovial crease, the scope is swiveled to the most lateral and anterior aspect of the disc–synovial crease. The second puncture site is placed exactly in the most anterior and lateral corner of the superior joint space to ensure maximum flexibility of the operative cannula. Variations in the second puncture site and technique are dictated by the anterior recess volume and condition of the joint.

7. A 2.0 cannula is inserted into the anterolateral corner of the superior joint space. This second cannula will become the operative cannula, the device channel. The surgeon identifies the disk synovial crease with a straight probe and performs an anterior release (pterygoid myotomy) (Figure 31.10) by splicing the synovial membrane from the most medial component of the disk synovial crease to the vascular hump in the mid-portion of the anterior recess. The synovial membrane and pterygoid muscle are detached from the disk. The disk is reduced with a straight probe while holding the jaw forward (Figure 31.11).

8. The retrodiscal tissue is contracted utilizing bipolar cautery. Occasionally, a superficial synovectomy (Figure 31.12) is performed, utilizing a stab incision within the posterior lateral gutter of the retrodiscal tissue using a banana blade, and then inserting the cautery into the deep retrodiscal tissues and contracting them.
9. Disk fixation can be accomplished by one of two methods. The first and more traditional method is the suture discopexy. A second method involves rigid fixation with either resorbable or titanium screws.

10. In suture discopexy, the disk is held in reduction, and a 20-gauge needle with a single out poly Dexon suture is inserted through the skin and subcuticular tissues, touching the condyle, into the inferior joint space, and then it angles superiorly to target the superior lateral aspect of the posterior band of the disc (Figure 31.13). The needle is advanced through the posterior band of the disk entering the superior joint space. It is important that the 20-gauge needle is inserted underneath the reduction cannula. A straight meniscus mender is inserted in the pre-auricular crease 5 to 7 mm below the fossa portal into the superior joint space. The snare of the meniscus mender is then inserted through the meniscus mender cannula, and the suture is passed through the 20-gauge needle into the superior joint space to be captured by the snare. Now, both free ends of the suture exit the skin (Figure 31.14). Small skin incisions are made at the exit points of the suture superiorly with a #11 blade. Straight hemostat is used to dissect down the suture tracing anteriorly to the capsule. The dissection is along the course of the facial nerve. Posteriorly, the dissection is carried down halfway to the capsule along the tragal cartilage.

11. A Mayo needle is used to thread the suture from anterior to posterior; both free ends of the suture now exit the skin posteriorly. While the disk is held in reduction, a tight surgeon’s knot is tied, plicating the disk to the capsule and to the subcutaneous tissue (Figure 31.15).
12. The joint is evaluated for function arthroscopically and by manual manipulation while the disk is reduced and the sutures are checked for suture tightness (Figure 31.16). After confirmation of no clicking noises and appropriate function or motion of the disk or condyle, the instruments are removed, and steps 15–17 are followed.
13. In rigid screw disk fixation, after the anterior release is accomplished and posterior scarification and disk reduction have been completed, the disk is ready for placement of a fixation screw. The disk is maintained in reduction, and the condyle is held forward. A third puncture site is placed using the vector measuring system. Ideally, the puncture is approximately 20 mm inferior to the fossa portal. The size of the cannula depends on the size of the screw used. Typically, the authors use a 2.0-mm cannula. The cannula at its distal end has a window so that the screw is visible as it is delivered into the joint and enfacing the disk. The angle of placement of this cannula and screw hole should be from posterior to anterior, superior to inferior, and medial to lateral. This placement avoids angling the drill superiorly toward the glenoid fossa and perforating it. Once the disk is held in reduction and the cannula has been inserted, the target area is the posterior-lateral corner of the disc–condyle assembly. Holding the cannula still, a drill is delivered through the cannula to the disk, and a monocortical screw placed through the condylar head itself. The drill bit is removed, and the screw attached to the screwdriver is delivered through the cannula. The screw is inserted through the disc and into the condyle, screwing it tightly so that the disk is now fastened to the condylar head itself. The window on the cannula enables the surgeon to watch the screw actually being turned into position. Once the screw is rigidly fixated, the cannula is pulled back, and the position of the screw is verified arthroscopically to ensure that it is fully engaged and that its position is ideal. Additionally, one can take a straight probe from the working cannula and wiggle the screw to make sure it is nonmobile and fully engaged.
14. Different types of screws can be applied to the joint. The authors have had success with the Osteomed cannulated screw (Osteomed, TX, USA), an Inion screw (Inion, Tampere, Finland), and a Smart nail (ConMed Linvatec, FL, USA). The ideal situation for rigid disc fixation is an average-sized joint space and a well-formed, nonperforated disc.

15. At the completion of the disk fixation procedure, the joint is lavaged, and one ampule of Healon (hyaluronic acid) is deposited (Figure 31.18) to act as an intra-articular Band-Aid to m/>

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