In the orthopedic experience, various pharmacologic agents, most notably indo- methacin and etidronate, have been used with varying success in preventing heterotopic bone in hip and knee TJP reconstruction [49, 50]. Pharmacologic therapy has been suggested for use after TMJ TJP reconstruction, but no data exists regarding its effectiveness. Radiation treatment of the operated area within 4 days of prosthetic hip reconstruction is now a common practice and appears to offer an effective means of preventing heterotopic bone formation in orthopedics. However, local radiation of the TMJ raises concerns regarding potential adverse effects on adjacent vital structures. The use of postoperative radiation (10Gy) following CCG, gap arthroplasty, or debridement of heterotopic bone has been shown to still result in heterotopic bone in 33-50% of cases [51, 52].
Gap Arthroplasty and Grafts
Various techniques have been used to treat TMJ ankylosis including gap arthroplasty with or without tissue grafts and flaps. The long-term functional results after gap arthroplasty and interpositional grafting have been shown to be comparable to those obtained through use of other treatments . However, the incidence of re-ankylosis with gap arthroplasty does appear to be higher than with CCG . An additional problem with gap arthroplasty either with or without an interposing tissue is the vertical stability of the mandible and the occlusion.
Topazian compared gap arthroplasty with interpositional arthroplasty in TMJ ankylosis surgery and found interpositional arthroplasty to provide more favorable results . The use of temporalis myofascial flaps and dermal grafts also appear to produce satisfactory results . Similar results have been reported with the use of dermis-fat grafts [57-59]. The pedicled vascularized temporalis myofascial flap continues to be a relatively predictable and stable interpositional graft following gap arthroplasty. The ability of this flap to prevent heterotopic bone is less clear in part due to the lack of a critical-sized defect with this flap.
Concomitant use of CCG and the temporalis myofascial flap has also been reported to be successful in maintaining the occlusion with good functional outcomes and decreased pain [60-62]. The disadvantages of CCG are the poor quality of medullary and cortical bone, the possibility of resorption or infection, bone flexibility, elasticity that may cause the graft to be deformed, possible separation of the cartilage from the bone, and occasional fractures. Furthermore, the inherent growth potential of CCG can result in unpredictable growth.