[Animal experiment on the histological changes and associated factors of autotransplanted costochondral graft in arthroplasty of TMJ].
OBJECTIVE
To explore the histological changes and associated factors of autotransplanted costochondral graft in arthroplasty of the temporomandibular joint(TMJ).


METHODS
Twenty two New Zealand rabbits of 3 months were randomly divided into 4 groups. Each of A, B, C groups had 6 animals. The left discs, condyloid processes and upper parts of the mandibular rami were removed; 1 cm of rami in A, B groups and 2 cm of rami in C group were resected. The lengths of the grafts were all 2 cm. Arthroplasty with autotransplanted costochondral graft was modeled in A, B groups but the lengths of the chondral parts were different, with 4 mm in group A and 1 mm in group B. In group C the lengths of chondral parts were also 4 mm but the grafts were fixed in deep soft tissue where the rami had been taken off. Group D comprised 4 animals as normal control. The rabbits were sacrificed in batches at weeks 4 and 6 after operation. Cephalometrical and histological examinations were conducted.


RESULTS
X-ray films showed the heights of the left mandibles were shorter than those of the right side in groups A, B and C, but significant difference was observed only between groups B and C. Histological examination showed that bony connections had been formed between the bony part of the grafts and the rami in groups A and B, with proliferative layer of the cartilage approaching to articular surface and on which parallel dense collagenous fibers could be found. Group B had less cartilaginous proliferation and regeneration than Group A. The chondral part of group C displayed hypertrophy, surounded by newly formed cartilage. But the growth centers in the costochondral junctions of the grafts still kept intrinsic structural characteristics.


CONCLUSIONS
Remodeling of the costochondral grafts appeared in groups A, B and C. Nevertheless adaptable remodeling only developed in the group with the grafts firmly fixed to the mandibular rami. The shorter the length of chondral parts, the less the ability of cartilaginous proliferation and regeneration.
Xu
Baohua
B
Department of Maxillofacial Surgery, West China Stomatological Hospital, Sichuan University, Chengdu 610041, China.
Shi
Zongdao
Z
Zeng
Zulong
Z
Guo
Chunlan
C
D000818:Animals; D001178:Arthroplasty / Q000379:methods*; D016723:Bone Remodeling; D002356:Cartilage / Q000637:transplantation*; D011817:Rabbits; D011897:Random Allocation; D012272:Ribs / Q000637:transplantation*; D013704:Temporomandibular Joint / Q000293:injuries / Q000601:surgery*; D014182:Transplantation, Autologous