What is the likely cause and initial management for a unilateral jaw locking with limited opening?

Unilateral Jaw Locking with Limited Movement

This presentation most likely represents TMJ disc displacement without reduction (closed lock), and you should immediately initiate conservative management with jaw rest, soft diet, NSAIDs, heat/cold therapy, and early supervised physical therapy—avoiding any invasive procedures for at least 8-12 weeks. 1, 2

Most Likely Diagnosis

The sensation of a single jaw joint being "stuck" with limited movement strongly suggests TMJ anterior disc displacement without reduction (ADDwoR), commonly called a "closed lock." 3, 4 This occurs when:

• The articular disc loses its capacity to reduce (slide back into position) during mouth opening 5
• The displaced disc acts as a mechanical obstruction, limiting mandibular translation 6
• Patients experience acute onset of restricted mouth opening, typically unilateral 7, 3

Key diagnostic features to confirm:

• Sudden onset of limited mouth opening (typically <30mm interincisal distance) 3
• Unilateral restriction with deviation toward the affected side on opening 7
• History of prior clicking that suddenly stopped (the click represented disc reduction, now absent) 5, 8
• Pain may or may not be present—surprisingly, many closed locks are relatively painless 5
• Palpation reveals tenderness over the affected TMJ and muscles of mastication 7

Critical Prognostic Information

The natural history of this condition is remarkably favorable—most patients experience spontaneous improvement in pain and mouth opening within weeks to months, even without disc recapture. 5, 8 This favorable prognosis fundamentally shapes the treatment approach, which prioritizes conservative management and avoids irreversible interventions.

Immediate First-Line Management (Start Today)

Conservative therapy should begin immediately and continue for at least 4-6 weeks before considering any escalation: 2

• Jaw rest and activity modification: Avoid wide mouth opening, hard/chewy foods, and prolonged talking 9, 2
• Soft diet: Minimize mechanical loading on the TMJ during the acute phase 9, 2
• NSAIDs: First-line pharmacotherapy for pain relief and inflammation reduction 1, 2
• Heat and/or cold therapy: Apply to reduce pain and inflammation 1, 9, 2
• Intermaxillary elastics: If this represents an acute dislocation rather than disc displacement, apply elastics to stabilize the joint for at least one week 9

Early Supervised Physical Therapy (Within First Week)

Physical therapy should be initiated early and provides the largest treatment effect for TMJ disorders: 1, 2

• Jaw exercises and stretching: Provide approximately 1.5 times the minimally important difference in pain reduction and should be started early 2
• Manual jaw mobilization: Delivers substantial pain reduction and improves joint mobility 1, 2
• Trigger point therapy: Provides one of the largest reductions in pain severity by releasing tension in masticatory muscles 1, 2
• Postural exercises: Improve head and neck alignment, reducing compensatory muscle tension 1, 2

Special consideration for acute presentations (<2 months): Manual therapy may actually reposition the disc in early cases, followed by splint and movement therapy to maintain the disc-condyle relationship 3. However, even if anatomical repositioning fails, functional improvement remains the primary goal 3.

Second-Line Interventions (If Inadequate Response at 2-4 Weeks)

1, 2

• Occlusal splints: May be beneficial for persistent symptoms, particularly if bruxism is contributing 2
• Acupuncture: Shows moderate certainty evidence for TMJ pain relief 1, 2
• Augmented cognitive behavioral therapy: Provides the largest reduction in chronic pain severity when combined with relaxation therapy or biofeedback 1, 2
• Combined approaches: Jaw exercise with mobilization, or manipulation with postural exercise 1

Minimally Invasive Procedures (Only After 8-12 Weeks of Failed Conservative Management)

2

• Arthrocentesis (joint lavage): May provide symptomatic relief in refractory cases 1, 9, 2
• Intra-articular glucocorticoid injections: Reserved for refractory and symptomatic TMJ dysfunction in skeletally mature patients only 2
• Arthroscopy: Minimally invasive procedure for internal joint assessment and treatment 1

Critical Pitfalls to Avoid

Do not rush to invasive procedures before exhausting conservative options—this is the single most important management principle: 1, 9, 2

• Avoid discectomy: Surgical disc removal is strongly contraindicated 1
• Avoid irreversible oral splints: Permanent alterations to dentition cause serious harms including permanent changes in range of motion 1, 2
• Avoid NSAIDs combined with opioids: This combination increases risks without clear additional benefits 1, 2
• Do not neglect patient education: Patients must understand the favorable natural history and importance of self-management strategies 1

Differential Considerations

While disc displacement without reduction is most likely, also consider:

• TMJ dislocation: The condyle is displaced anterior to the articular eminence and cannot return—requires manual reduction followed by intermaxillary elastics 9
• TMJ ankylosis: Bony or fibrous fusion of the joint—would show more chronic, progressive restriction rather than acute onset 7
• Coronoid process impingement: Enlarged coronoid interfering with zygomatic arch 7
• Maxillary sinusitis: Can cause unilateral facial pain but wouldn't cause true jaw locking 7

Follow-Up Timeline

• Reassess at 2-4 weeks: Add second-line interventions if no improvement 2
• Reassess at 8-12 weeks: Consider minimally invasive procedures only if conservative management has completely failed 2
• Use standardized outcome measures: Track pain levels, maximal interincisal opening, and quality of life at each visit 1