What is the role of autologous (autogous) fat grafting in total Temporomandibular Joint (TMJ) replacement?

Role of Autologous Fat Grafting in Total TMJ Replacement

Autologous fat grafting is highly recommended as an adjunctive procedure during total temporomandibular joint replacement (TMJR) to prevent heterotopic bone formation and excessive fibrosis around the prosthesis, thereby improving postoperative range of motion and reducing the risk of reankylosis. 1, 2

Mechanism and Benefits of Autologous Fat Grafting

• Autologous fat harvested from the abdomen is packed around the articulating portion of the TMJ prosthesis after the fossa and mandibular components are stabilized 2
• Fat grafting serves as a biological barrier that minimizes heterotopic calcification and excessive joint fibrosis, which are common complications following TMJ reconstruction 3
• Studies have demonstrated that patients receiving fat grafts during TMJR show significantly better outcomes in terms of maximal incisal opening (MIO) compared to those without fat grafts 3

Evidence Supporting Fat Grafting in TMJR

• A landmark study by Wolford (1997) found statistically significant differences in postoperative mobility between patients who received autologous fat grafts and those who did not, with the fat graft group achieving greater maximal incisal opening (38.7 mm vs 33.1 mm) 3
• Long-term follow-up studies have shown that patients with fat grafting maintain better jaw function and range of motion, with no radiographic or clinical evidence of heterotopic calcifications 2
• In a study of 115 patients (203 joints) undergoing TMJR with simultaneous fat grafting, significant improvements were observed in maximal incisal opening and jaw function without evidence of heterotopic bone formation 2

Clinical Applications and Technique

• The procedure involves harvesting autologous fat from the abdomen and carefully packing it around the articulating portion of the joint prosthesis 1
• Fat grafting is particularly valuable in cases of TMJ reankylosis, where the risk of recurrent heterotopic bone formation is high 1, 4
• A 2021 study demonstrated that stock TMJ replacement with fat grafting provided adequate mouth opening without signs of reankylosis in adult TMJ ankylosis patients, suggesting it can be considered a definitive treatment modality 4

Potential Complications and Considerations

• Donor site complications may occur, including abdominal cysts (1.8%) and seroma formation (6.9%) requiring intervention 2
• The most common long-term complication of TMJ replacement surgery is facial nerve weakness, with manifestations ranging from paresis to paralysis (7.8%) 5
• Other significant complications of TMJR include implant instability, loosening of screws, and potential metal hypersensitivity affecting approximately 10-15% of patients 5

Clinical Decision-Making Algorithm

1. For patients requiring total TMJ replacement, particularly those with:

   • History of TMJ ankylosis or reankylosis 1, 4
   • Previous failed TMJ surgeries 1
   • Risk factors for heterotopic bone formation 2

2. Consider autologous fat grafting as an adjunctive procedure during TMJR to:

   • Prevent heterotopic bone formation 2, 3
   • Minimize excessive joint fibrosis 2
   • Improve postoperative range of motion 3

3. Technique considerations:

   • Harvest fat from the abdomen 2
   • Pack fat around the articulating portion of the prosthesis after components are stabilized 2
   • Ensure adequate volume of fat to completely surround the prosthetic joint 3

Conclusion for Clinical Practice

• While the current evidence supports the use of autologous fat grafting in TMJR, some researchers suggest that a prospective multicenter randomized controlled trial would be beneficial before justifying common application due to the added morbidity 6
• Nevertheless, the available evidence strongly indicates that autologous fat grafting is a valuable adjunct to TMJR that can significantly improve outcomes by preventing heterotopic bone formation and maintaining better postoperative joint mobility 2, 3, 4