The Effects of Discectomy on The Osteoarthrotic Temporomandibular Joint in Sheep

双侧颞下颌关节（TMJ）骨关节病诱导4只羊，并在三个月的椎间盘切除术进行了一个关节，与其他被留下作为对照。在6个月时处死动物。对关节盘切除后的颞下颌关节标本和对照组骨关节炎标本进行X线片比较，关节盘切除后的颞下颌关节骨赘、糜烂、扁平、硬化等形态学改变明显大于对照组，双侧关节盘X线片未见皮质下囊肿形成。所有四个对照组的TMJ均表现出与骨关节病一致的病理变化，如关节盘穿孔、骨赘和髁突畸形。对照组髁突内广泛存在骨髓纤维化和皮质下囊肿形成，颞关节面较光滑。在盘状颞下颌关节，髁状突严重变形。然而，髁突骨髓大部分非纤维化和完整的直接关节下区以外。颞、髁关节面间纤维组织增生明显，关节间隙变窄。在一个关节中，关节间隙被松散的纤维组织完全闭塞。椎间盘切除术对骨关节炎性颞下颌关节的短期影响是重塑而不是退变。术后张口训练对预防纤维粘连具有重要的临床意义。

Bilateral temporomandibular joint (TMJ) osteoarthrosis was induced in four sheep and at three months a discectomy was performed on one joint, with the other being left as a control. The animals were sacrificed at six months. The specimens of the discectomized temporomandibular joint and control osteoarthrotic TMJ were radiologically compared.Morphological changes of osteophyte, erosion, flattening and sclerosis in the discectomized TMJ were greater than that in the control TMJ.Subcortical cyst formation was not observed in the radiograph on the both sides. The specimens were then histologically prepared and stained with H&E.All four control TMJ exhibited pathological changes consistent with osteoarthrosis, such as, disc perforation, osteophyte, and deformity ofthe condyle. The bone marrow fibrosis and subcortical cyst formation were extensive within the condyle in the control TMJ.The temporal articular surface was rather smooth. In the discectmized TMJ,the condyle was grossly deformed. However, the condylar bone marrow were mostly non-fibrotic and intact other than the immediate subarticular zone. Marked proliferation of the fibrous tissue was seen between the temporal and condylar articular surfaces, making the joint space narrow. In one joint, the joint space was completely obliterated by the loosely organized fibrous tissue. The short-term effects of discectomy on the osteoarthrotic TMJ were remodelling rather than degeneration. Postoperative mouth opening training is of clinical importance for prophylaxis of fibrous adhesion.