How does significant scar tissue complicate total joint replacement with double jaw surgery?

Complications of Scar Tissue in Total Joint Replacement with Double Jaw Surgery

Significant scar tissue severely complicates total joint replacement with double jaw surgery by increasing the risk of facial nerve injury, making anatomical identification difficult, and potentially compromising surgical outcomes. 1

Impact of Scar Tissue on Surgical Approach

Scar tissue presents several major challenges during temporomandibular joint (TMJ) replacement surgery:

Anatomical Complications

• Obscured visualization: Scar tissue significantly obscures normal anatomical landmarks, making identification of critical structures difficult 1
• Facial nerve risk: The risk of facial nerve injury increases dramatically, as scar tissue can obscure visualization of nerve branches, particularly in revision surgeries 1
• Surgical approach difficulties: The preauricular approach, while generally providing better access with reduced facial nerve injury risk, becomes more challenging with extensive scarring 1

Technical Challenges

• Extended operative time: Dissection through scar tissue is more time-consuming and technically demanding
• Increased bleeding risk: Scarred tissue often has altered vascularity, potentially leading to increased bleeding or unpredictable bleeding patterns
• Compromised vascular bed: Scarred tissue has reduced vascularity, which may compromise healing and increase infection risk 1

Specific Complications Related to Scar Tissue

Facial Nerve Injury

• Facial nerve weakness is the most common complication of TMJ replacement (7.8% paralysis rate) 1
• Risk factors significantly increased by scar tissue include:
  • Revision TMJ replacement
  • Multiple previous open TMJ procedures
  • Bilateral surgery 1

Infection Risk

• While surgical site infection rate is generally low (0.7%), scar tissue increases this risk 1
• Scarred tissue with reduced vascularity may:
  • Compromise antibiotic delivery to surgical site
  • Impair immune response
  • Create potential dead spaces where infection can develop 1

Prosthesis Positioning and Stability

• Accurate positioning of custom prosthetic components becomes more challenging
• Scar tissue may interfere with proper adaptation and fixation
• Risk of prosthesis dislocation increases, especially in the first six weeks post-operatively 2

Management Strategies for Scar Tissue

Preoperative Planning

• 3D CT scans and models: Essential for proper planning with scar tissue present 2
• Virtual surgical planning: Enables precise positioning of prosthetic components despite anatomical distortion 2
• Custom-designed prostheses: Provide better outcomes than stock devices when dealing with significant anatomical deviations caused by scarring 2

Intraoperative Techniques

• Routine identification of facial nerve branches: Critical in scarred fields to prevent nerve injury 1
• Careful dissection along fascial planes: Essential to prevent nerve injury in scarred tissue 1
• Extreme caution during nerve dissection: Particularly important in revision surgeries with scar tissue 1

Infection Prevention

• Prophylactic antibiotics: Administer 1st or 2nd-generation cephalosporins one hour prior to surgery 1, 2
• Extended antibiotic course: 7-10 day course of oral antibiotic prophylaxis post-operatively 1, 2
• Antimicrobial photo-disinfection therapy: Consider combining with chlorhexidine gluconate body wipes 2

Long-Term Outcomes and Expectations

Despite the complications of scar tissue, TMJ replacement with orthognathic surgery can still achieve positive outcomes:

• Pain reduction: Significant reduction in pain scores can be achieved despite scarring 3
• Functional improvements: Mean mouth opening typically improves from 22.4mm to 33.7mm 3
• Dietary improvements: Substantial improvements in ability to eat solid foods 3

However, patients with significant scarring should be counseled about:

• Potentially reduced anterior movement of the prosthetic condyle 4
• Restricted protrusion and lateral excursions compared to natural joints 4
• Higher risk of temporary facial nerve weakness 1, 3

Conclusion

While scar tissue significantly complicates total joint replacement with double jaw surgery, careful preoperative planning, meticulous surgical technique, and appropriate perioperative management can still lead to successful outcomes. The key is recognizing the specific challenges posed by scarring and implementing strategies to mitigate these risks.