Thank you for giving me an opportunity to respond to the concerns raised by the readers of my manuscript.
Excision of coronoids undoubtedly is the procedure of choice, which in most instances can be accomplished intraorally. When executed for long and broad coronoids, as in the case of TMJ ankylosis discussed, retrieval of the free segment may be sometimes difficult, as the same wedges rather firmly in the space between the arch and temporal bone. Instead of a simple coronoidotomy, resection of a wedge of osseous tissue from the coronoid base allows creation of sufficient gap to allow elimination of coronoid interference. Interposition of local soft tissue (in this case pedicled masseter muscle) is principally based on the concept of interposition arthroplasty using autogenous soft tissue to eliminate the dead space and provide a soft tissue barrier .
The risk for ectopic bone formation would have been high if the ostectomised gap was left unfilled as the resultant haematoma would have possibly provided the environment for recruitment of pleuripotential cells and the hypoxic environment of the scar allowing for cartilage and bone differentiation . The readers’ suggestion of a role for alloplastic interpostion to prevent this is not our preference for three reasons:
The incidence of heterotopic bone formation has been documented high when alloplastic reconstruction has been used for TMJ .
The use of alloplastic spacers whilst providing for good mobility has been in many situations associated with a variety of problems including foreign body reaction, erosion, infection and extrusion through skin .
Autogenous tissue interposition in the form of fat, muscle or full thickness skin, has shown fairly consistent result in preventing heterotopic ossification and TMJ reankylosis .
The technique presented needs further validation with a larger sample size. However, to resort to an extra oral approach for removal of contralteral coronoids in TMJ Ankylosis with the extensive dissection that it mandates, to us appears unjustified in the absence of a requirement for a concomitant joint exposure, as this carries a potential for facial nerve injury (albeit small). Endoscopic assisted removal presents an attractive alternative but has technical limitations owing to the question of universal availability.
Finally, open bite may develop post operatively when there has been shortening of the vertical ramus bilaterally, as in case of bilateral condylectomies or gap arthroplasties (with or without coronoidectomy). Our own experience with bilateral one stage coronoid release in unilateral TMJ ankylosis has been one of difficulty in complete closure in the initial post operative period, for which only guidance was required. Most long standing ankylosis patients due to coexisting malocclusion problems need subsequent orthodontics as well as orthognathic procedures or distraction osteogenesis for full rehabilitation.