What is the most common long-term complication after Temporomandibular Joint (TMJ) total joint replacement?

Most Common Long-Term Complication After TMJ Total Joint Replacement

Facial nerve weakness is the most common long-term complication associated with temporomandibular joint (TMJ) total joint replacement, with manifestations ranging from paresis and paralysis (7.8%) to sensory alterations (1.8%). 1

Understanding Facial Nerve Complications

Facial nerve complications after TMJ replacement occur due to several factors:

• The proximity of the surgical site to vital structures and prolonged tissue retraction during surgery can stretch and temporarily impact nerve function 1
• Transient weakness of the temporal, buccal, and marginal mandibular branches of the facial nerve is commonly observed immediately post-operatively 1
• Most cases resolve within six months, though a minority of patients experience persistent paralysis of the temporal branch requiring unilateral brow lift 1
• TMJ replacement operations account for 40% of facial nerve injuries in oral and maxillofacial surgeries 1

Risk Factors for Facial Nerve Injury

Several factors increase the risk of temporary facial nerve injury:

• Revision TMJ replacement procedures 1
• Bilateral surgery 1
• Multiple previous open TMJ procedures 1
• Risk factors for permanent injury are less predictable but likely similar 1

Prevention and Management of Facial Nerve Injury

To minimize the risk of facial nerve complications:

• Routine identification of facial nerve branches in the operative field is essential 1
• Careful dissection along fascial planes helps prevent nerve injury 1
• Extreme caution during nerve dissection, particularly in revision surgeries where scar tissue may obscure visualization 1
• The preauricular approach provides better access with reduced risk of facial nerve injury 1
• Low-intensity laser therapy, particularly when augmented with vitamin complex medication, has shown efficacy in mitigating nerve injury effects 1

Other Significant Long-Term Complications

While facial nerve weakness is the most common, other important long-term complications include:

• Implant instability and loosening of screws 1
• Relapse of TMJ ankylosis 1
• Unresolved functional deficits 1
• Infection (though relatively low incidence at 0.7%) 1
• Metal hypersensitivity (affecting approximately 10-15% of patients with implants) 1

Outcomes and Success Rates

Despite these complications, TMJ replacement generally shows positive long-term outcomes:

• Significant improvements in maximum interincisal opening (MIO) and mandibular function 1, 2
• Pain reduction from mean scores of 7.4 to 1.7 on a 10-point scale over 10 years 2
• Increase in maximum mouth opening from 21.0 mm to 34.7 mm over 10 years 2
• Improvement in dietary scores from 4.1 to 9.5 on a 10-point scale over 10 years 2
• Low revision rates (3%) and replacement rates (4.9%) 3

Clinical Implications

When performing TMJ total joint replacement:

• Patients should be counseled about the risk of facial nerve weakness as the most common long-term complication 1
• Regular long-term follow-up is essential to monitor for complications, as some may develop years after surgery 1
• Particular attention should be paid to patients with risk factors such as multiple previous surgeries 1
• Custom TMJR devices are recommended as the standard of care in cases with significant anatomical deviations or substantial changes in mandibular position 1