# TMJ Arthroscopy and Arthrocentesis

## Overview

Arthrocentesis and arthroscopy are minimally invasive surgical interventions for temporomandibular joint (TMJ) disorders. Both target the superior joint space where most pathologic changes occur. Arthrocentesis involves blind lysis and lavage without visualization, while arthroscopy provides lysis, lavage, and operative intervention under direct visualization. The primary indications are disc displacement without reduction (closed lock), synovitis, adhesions, and early degenerative changes that have failed conservative management.

## Arthrocentesis

### Indications

Arthrocentesis is indicated for acute or chronic disc displacement without reduction (closed lock), TMJ hypomobility due to adhesions, inflammatory arthritis of the TMJ, as an adjunct to intra-articular medication delivery (corticosteroids or hyaluronic acid), and after failure of 4-6 weeks of conservative management.

### Contraindications

Contraindications include overlying skin infection, bony ankylosis (where no joint space exists to lavage), advanced degenerative joint disease with significant osseous remodeling (where benefit is limited), and tumor involvement of the TMJ.

### Technique

#### Patient Preparation

Arthrocentesis can be performed under local anesthesia with or without IV sedation. An auriculotemporal nerve block and local infiltration over the joint are administered. The patient is positioned supine or semi-reclined with the head turned to the contralateral side, and a surgical skin prep of the preauricular area is performed.

#### Landmarks (Holmlund-Hellsing Technique)

The canthal-tragal line is drawn from the lateral canthus of the eye to the middle of the tragus. Entry point 1 (posterior) is located 10 mm anterior to the tragus and 2 mm inferior to the canthal-tragal line. Entry point 2 (anterior) is located 20 mm anterior to the tragus and 7 mm inferior to the canthal-tragal line. Alternatively, a single-puncture technique uses one needle for inflow and outflow.

#### Procedure

The patient opens maximally (or the jaw is manipulated open). An 18-gauge needle is inserted at the posterior point, directed slightly anteriorly and superiorly into the superior joint space. Two to three milliliters of lactated Ringer's solution are injected to distend the joint space, and a second needle is inserted at the anterior point for outflow. Lavage with 100-300 mL of lactated Ringer's solution is performed under pressure using a syringe or gravity drip. During lavage, the mandible is gently manipulated (opening, lateral excursion) to break adhesions. At completion, a corticosteroid (0.5-1 mL triamcinolone 40 mg/mL) or hyaluronic acid may be injected. The needles are removed and pressure is applied.

#### Single-Puncture Technique

The single-puncture technique uses one needle inserted into the superior joint space with alternating injection and aspiration through the same needle. It is simpler but provides less effective lavage than the dual-puncture technique and is suitable for medication delivery with limited lavage.

### Outcomes

Pain relief is reported by 70-85% of patients, with an average increase in maximum interincisal opening of 8-12 mm. Best results are achieved in acute closed lock of less than 6 months duration. Chronic closed lock exceeding 12 months has lower success rates of 50-65%. Repeat arthrocentesis can be performed if initial improvement is followed by recurrence.

<image>Illustration of the TMJ arthrocentesis technique showing the canthal-tragal line, the posterior (inflow) and anterior (outflow) needle entry points, the positions of the needles within the superior joint space, and the direction of lavage flow through the joint</image>

## Arthroscopy

### Indications

Arthroscopy is indicated after failed arthrocentesis or conservative management, for diagnostic evaluation when MRI findings do not correlate with clinical presentation, and for operative intervention including disc repositioning, adhesion lysis, synovectomy, and posterior attachment cauterization. Additional indications include disc displacement without reduction (closed lock), chronic inflammatory synovitis, adhesive capsulitis, and early to moderate degenerative joint disease.

### Equipment

The arthroscope is a 1.9 mm or 2.4 mm instrument (Hopkins rod-lens system) connected to a light source and camera system. The instrumentation includes a trocar and cannula system (sharp and blunt), irrigation system (gravity or pump), operative instruments (probes, graspers, scissors, and cautery via laser or radiofrequency), and an outflow needle or separate working cannula.

### Surgical Anatomy of the Superior Joint Space

The superior joint space is divided into the anterior recess, central zone, and posterior recess. Key landmarks viewed arthroscopically include the articular eminence (anterior slope), the posterior slope of the eminence, the disc surface (assessed for fibrillation or perforation), the retrodiscal tissue (vascularized, often inflamed), the synovial membrane (evaluated for chondromalacia, hyperemia, or villous hypertrophy), and the pterygoid shadow (anterior attachment of the disc, which serves as a guide to the anterior recess).

### Technique

#### Setup

General anesthesia or deep IV sedation is most commonly used, with nasotracheal intubation to allow jaw manipulation. The patient is positioned supine with the head turned contralaterally, and the preauricular area is prepped and draped.

#### Port Placement

The posterolateral approach is the standard for diagnostic and operative access. The puncture site is the same as the posterior arthrocentesis entry point (Holmlund-Hellsing). A needle is placed into the superior joint space, the joint is distended with 2-3 mL saline, and the trocar and cannula are advanced into the joint. The trocar is then replaced with the arthroscope. The anterolateral approach serves as the working port for operative arthroscopy. It is placed under direct visualization using the arthroscope in the posterior port, and working instruments are introduced through the anterior cannula. The endaural approach is an alternative posterior entry through the external auditory canal margin.

#### Diagnostic Arthroscopy

A systematic examination of the superior joint space assesses the synovial membrane, disc surface, articular surfaces, adhesions, and effusion. Chondromalacia is graded from Grade I (softening) through Grade II (fibrillation), Grade III (fissuring), to Grade IV (full-thickness erosion with bare bone). Findings are documented with video and photography.

#### Operative Arthroscopy

Lysis and lavage break down adhesions with a blunt trocar or probe and use high-volume lavage. Anterior release involves sweeping the anterior disc attachment to improve disc mobility. Disc repositioning sutures the disc to the posterior attachment or lateral capsule, though outcomes are difficult and variable. Posterior attachment cauterization uses radiofrequency or laser cautery of the bilaminar zone to create scarring and tighten the posterior attachment, promoting disc stability. Synovectomy removes inflamed, hypertrophied synovium with mechanical shavers or cautery. Debridement removes loose bodies and debrides chondromalacic surfaces. Lateral capsule tightening (plication) sutures the lateral capsule to reduce joint laxity.

<image>Arthroscopic views of the TMJ superior joint space showing normal anatomy (smooth articular eminence and disc surface), pathologic findings including synovial hyperemia, fibrous adhesions bridging the disc to the fossa, and Grade III chondromalacia with disc surface fibrillation and fissuring</image>

### Outcomes

Pain relief is achieved in 80-90% of patients, with significant improvement in maximum interincisal opening. Arthroscopy produces better outcomes than arthrocentesis for chronic closed lock and adhesive conditions. Disc repositioning via arthroscopy yields variable long-term disc position but good symptomatic outcomes. The complication rate is 1-5%, and most patients do not require subsequent open surgery.

## Complications

### Arthrocentesis Complications

Complications of arthrocentesis include extravasation of fluid into surrounding tissues causing temporary swelling, hematoma, nerve injury (auriculotemporal nerve, rare and usually neuropraxia), injury to superficial temporal vessels, needle breakage (exceedingly rare), preauricular fistula (rare), and middle ear injury if the needle is directed too posteriorly.

### Arthroscopy Complications

Arthroscopy carries all arthrocentesis complications plus additional risks including scuffing of articular surfaces (iatrogenic chondromalacia), instrument breakage within the joint, facial nerve injury (temporal or zygomatic branch, typically neuropraxia), perforation into the middle cranial fossa (extremely rare but reported), otologic injury (external auditory canal perforation), infection (rare, less than 1%), and excessive joint fluid extravasation causing airway concern (rare).

## Arthrocentesis vs. Arthroscopy: Comparative Evidence

### Systematic Review Findings

| Parameter | Arthrocentesis | Arthroscopy |
|---|---|---|
| Pain relief | 70-85% | 80-90% |
| Duration | 15-30 min | 45-90 min |
| Anesthesia | Local +/- sedation | General or deep sedation |
| Visualization | None (blind) | Direct |
| Operative capability | Lavage only | Lysis, cautery, repositioning, synovectomy |
| Cost | Low | High (equipment, training) |
| Acute closed lock outcomes | Excellent | Excellent (comparable) |
| Chronic closed lock outcomes | Moderate (50-65%) | Better (visualization advantage) |
| Complication rate | <1% | 1-5% |

For acute closed lock, arthrocentesis and arthroscopy show comparable outcomes for pain and function. For chronic closed lock, arthroscopy may have a slight advantage due to the ability to address adhesions under visualization. Arthrocentesis is significantly less expensive and shorter in duration (15-30 minutes versus 45-90 minutes). Arthroscopy requires significant training and equipment investment. The current consensus is that arthrocentesis is a reasonable first-line surgical intervention, with arthroscopy reserved for arthrocentesis failures or when operative intervention is planned.

## Clinical Pearls

Arthrocentesis should be attempted before arthroscopy in most cases because it is simpler, cheaper, and has comparable outcomes for many conditions. The key therapeutic mechanism of both procedures is lavage -- removal of inflammatory mediators, adhesion breakdown, and restoration of joint lubrication. For acute closed lock of less than 3 months duration, early arthrocentesis gives the best results, and clinicians should not delay for prolonged conservative care if symptoms are severe. When performing arthrocentesis, the first needle must be properly positioned in the superior joint space before inserting the second -- passive backflow of fluid confirms correct placement. Intra-articular corticosteroid after lavage provides additional anti-inflammatory benefit but should not be repeated frequently. Hyaluronic acid viscosupplementation may provide longer-lasting lubrication than corticosteroid, though evidence is mixed. Post-procedure jaw exercises are critical, and patients should be instructed to begin gentle opening exercises the same day. Arthroscopy requires dedicated training through cadaver courses and fellowship, as the learning curve is steep and the joint space is small with nearby vital structures.

<image>Comparison diagram of arthrocentesis versus arthroscopy showing the equipment required, port placement, visualization capabilities, operative interventions possible, and a summary table of success rates, costs, and complication rates for each procedure</image>

## References
- Nitzan DW, Dolwick MF, Martinez GA. Temporomandibular joint arthrocentesis: a simplified treatment for severe limited mouth opening. J Oral Maxillofac Surg. 1991.
- Holmlund AB, Hellsing G. Arthroscopy of the temporomandibular joint: an autopsy study. Int J Oral Surg. 1985.
- Al-Moraissi EA, et al. Arthroscopy versus arthrocentesis in the management of internal derangement of the TMJ: a systematic review and meta-analysis. Int J Oral Maxillofac Surg. 2015.
- Murakami K, et al. Four-year follow-up study of temporomandibular joint arthroscopic surgery. J Oral Maxillofac Surg. 1996.
- Laskin DM, Greene CS, Hylander WL. TMDs: An Evidence-Based Approach to Diagnosis and Treatment. Quintessence. 2006.
- Monje-Gil F, et al. TMJ arthroscopy: a state-of-the-art review. Med Oral Patol Oral Cir Bucal. 2012.