TMJ Osteoarthritis

Temporomandibular joint osteoarthritis is a degenerative joint disease with breakdown of articular cartilage, subchondral bone remodelling and osteophyte formation. It is a cause of joint pain, crepitus and limited movement.

Radiographic changes are found in about 8 to 16% of adults, and more in the elderly and in women, but many are asymptomatic. Primary disease is age related, and secondary disease follows trauma, disc displacement, inflammatory arthritis and overload from bruxism.

Pathophysiology. Overload and repeated mechanical stress, with oxidative and inflammatory mediators (IL-1 beta, TNF-alpha, matrix metalloproteinases), degrade cartilage and bone.

Disc displacement and perforation, hypermobility and parafunction increase loading. The condyle flattens, erodes and forms osteophytes, with fibrosis of the joint space in late disease.

Pre-auricular pain on chewing and jaw movement, stiffness, reduced mouth opening, coarse crepitus (grating noise), deviation of the jaw to the affected side, and sometimes locking. Pain is usually worse later in the day, and tenderness is present over the joint.

Check for inflammatory arthritis (morning stiffness over 30 minutes, other joints, rheumatoid or psoriatic features), trauma, bruxism and other orofacial pain. Rapid onset of swelling, fever or an open bite warrants evaluation for septic arthritis or fracture.

• Clinical examination: maximum unassisted opening (normal 40 mm or more), deviation, crepitus, joint tenderness and muscle tenderness, and occlusion.
• Cone beam CT: the best imaging for bone change, showing flattening, erosions, subchondral cysts, osteophytes and sclerosis. Panoramic films are less sensitive.
• MRI for disc position, joint effusion and bone marrow oedema, when internal derangement or inflammatory disease is suspected.
• Bloods when inflammatory arthritis is suspected: C-reactive protein, ESR, rheumatoid factor, anti-CCP antibodies and antinuclear antibody, with HLA-B27 when relevant.
• Joint aspiration, with culture and crystals, for effusion with fever.

Differential diagnosis.

• Rheumatoid, psoriatic and juvenile idiopathic arthritis
• Internal derangement of the joint
• Myofascial pain of the masticatory muscles
• Septic arthritis
• Gout and pseudogout
• Condylar fracture or resorption
• Giant cell arteritis and trigeminal neuralgia

• Education and self-care: soft diet, avoiding wide opening and hard chewing, heat for 15 to 20 minutes, jaw exercises and physiotherapy, and behavioural treatment of bruxism and stress.
• Oral analgesia: naproxen 250 to 500 mg twice daily with food for 2 to 4 weeks (maximum 1000 mg daily for short courses), with a proton pump inhibitor in people with risk of ulcer, or ibuprofen 400 mg three times daily with food. Avoid NSAIDs in renal impairment, peptic ulcer, heart failure and anticoagulation. Paracetamol 1 g every 6 hours (maximum 4 g daily) as an adjunct. Topical diclofenac 1% gel over the joint three to four times daily.
• Stabilisation splint worn at night for 3 to 6 months, with review of occlusal contacts.
• Arthrocentesis, with lavage of 100 to 300 mL of sterile saline or lactated Ringer solution, for pain and limited opening not responding to conservative measures. Add an intra-articular injection of hyaluronic acid 1 mL, repeated weekly for 3 to 5 injections, or a corticosteroid (triamcinolone acetonide 10 mg/mL, 0.5 to 1 mL), limited to 1 or 2 injections a year because repeated steroid damages cartilage and bone.
• Arthroscopy for adhesions and persistent pain, and open surgery (disc repair, condylar shaving, arthroplasty or total joint replacement) for end stage disease with severe pain, limited function or ankylosis.
• Inflammatory arthritis: rheumatology treatment of the underlying disease, with methotrexate and biologics as appropriate.

Special groups. Children and adolescents need assessment for juvenile idiopathic arthritis, with intra-articular steroid by a specialist, and long term follow up for growth disturbance. Older adults need renal and gastric protection when using NSAIDs.

Monitoring. Review at 4 to 6 weeks to assess pain, mouth opening and function, and at 3 and 6 months. Repeat imaging for progression or a change in symptoms.

Referral and escalation. Refer to oral and maxillofacial surgery or an orofacial pain clinic for failed conservative care, severe limitation or locking. Refer to rheumatology for suspected inflammatory arthritis, and urgently for suspected septic arthritis or fracture.