9.14\ Eminectomy and Meniscal

Plication

9.14.1\ Discussion

Eminectomy with or without meniscal plication is a treatment option of chronic, recurrent temporomandibular joint dislocation. The recurrent dislocations often result in pterygoid spasm and severe pain. Eminectomy consists of resecting

the articular eminence of the glenoid (Fig. 9.34). For plication, the lateral pterygoid is detached from the meniscus, which is then rotated such that the disc from the posterior portion overlies the condylar head as a cap upon the condyle. Anchors can be placed to ensure stability of the construct. On MRI, the absence of the eminence and a thickened disc are apparent. In addition, MRI can show increased rotation and translation of the condylar head.

Fig. 9.34  Eminectomy. Both patients have a history of chronic left temporomandibular joint dislocation treated via eminectomy, temporomandibular joint meniscus plication, and lateral pterygoid myotomy. Sagittal CT (a) image shows reduction and flattening of the articular emi-

nence with anterior translation of the condyle to remain in the appropriate range of motion. Sagittal proton density MRI in another patient (b) shows thickening of the folded disc (arrow) and flattening of the articular eminence

9.15\ Temporomandibular Joint

Discectomy

9.15.1\ Discussion

Discectomy without disc replacement has been used as a treatment for painful temporomandibular joint internal derangement. Following tem-

a

poromandibular joint discectomy, a narrow soft tissue interface normally forms between the mandibular condyle and the glenoid fossa, which effectively functions as a substitute for the resected disc. On MRI, this soft tissue has intermediate to high signal intensity (Fig. 9.35). The soft tissue normally mineralizes over time, resulting in a shallower glenoid fossa.

b

Fig. 9.35  Discectomy. The patient has a history of temporomandibular joint cyst treated via discectomy. Postoperative sagittal proton density MRI (a) shows the absence of the low-signal disc and an area of intermediate

to high signal in the joint space. The contralateral sagittal proton density MRI (b) shows the normal disc (arrow) for comparison

9.16\ Temporomandibular Joint

Costochondral Graft

Reconstruction

9.16.1\ Discussion

The morphology and tissue components make rib costochondral grafts well suited for temporomandibular joint reconstruction, particularly in the pediatric population due to the graft’s growth potential. The procedure generally consists of

resecting the mandibular condyle, trimming the cartilaginous portion of the graft to match the normal contour of the articular surface, and affixing the osseous portion of the graft to the mandibular ramus (Fig. 9.36). This type of reconstruction provides satisfactory function in the majority of cases. However, complications include fracture, continued ankylosis, differential growth of the graft with respect to the contralateral side, degenerative disease (Fig. 9.37), and graft resorption (Fig. 9.38).

b

Fig. 9.38  Rib graft resorption. Coronal CT image demonstrates small inferior remnants of the bilateral rib grafts resulting in superior migration of the mandible and erosion of the fixation hardware into the zygomatic processes

9.17\ Temporomandibular Joint

Disc Replacement Implants

9.17.1\ Discussion

Two main types of alloplastic temporomandibular joint disc implants have been used: Proplast-­ Teflon and silicone rubber (Silastic). Proplast

implants were intended to be permanent, but have been banned by the FDA. Silicone implants can be used either on a temporary or a permanent basis. Both types of implants appear as uniformly low-signal, linear structures on both T1-weighted and T2-weighted MRI sequences. On CT, both types of prostheses are hyperattenuating (Fig. 9.39).