翼外肌在创伤性颞下颌关节强直中的作用机制研究

The role of lateral pterygoid muscle in traumatic temporomandibular joint ankylosis

目的揭示翼外肌在创伤性颞下颌关节(temporomandibular joint,TMJ)强直发病中的作用机制。方法本研究纳入6个月大的雄性绵羊8只,双侧髁突均通过手术建立复合创伤继发TMJ强直动物模型,即手术造成双侧髁突矢状骨折、关节盘移位及关节窝损伤。此外,左侧切除部分翼外肌作为实验组,右侧保留翼外肌作为对照组。术后12周,通过用大体观察、螺旋CT扫描、Micro-CT扫描、组织学观察等方法对TMJ样本进行评估与分析。结果肉眼观察可见:对照组发生了TMJ骨性强直而实验组仅仅是纤维强直。螺旋CT和Micro-CT结果显示:与实验组相比,对照组关节面粗糙、有新骨形成并突入到关节腔内,且关节腔内有钙化的骨痂形成;对照组髁突的最大内外径和前后径均明显大于实验组(P<0.05);Micro-CT扫描结果还显示:对照组新生骨小梁的方向与翼外肌牵拉方向一致,而实验组无此特征。组织学结果也印证了对照组关节内发生了纤维-骨性强直,而实验组仅为纤维强直。结论在髁突矢状骨折的愈合过程中,翼外肌发挥了类牵张成骨的作用,从而参与创伤性TMJ强直的发生。

Objective To reveal the role of lateral pterygoid muscle in tramnatic temporomandibular joint （TMJ） ankylosis. Methods Bilateral TMJ complex trauma was performed in eight 6-month-old male sheep. Then, function of the right and left lateral pterygoid muscles was maintained （control group） or blocked （test group）, respectively. At the end of the 12th week after operation, all the animals were sacrificed and TMJ complex samples were evaluated by gross observation, spiral computed tomography （CT） scan- ning, Micro-CT scanning and histological examinations. Results Gross observation revealed bony ankylosis in the control group while fibrous adhesions in the test group. Results of spiral CT and Micro-CT demonstrated that the control group showed calcified callus for- mation in the joint space and roughened articular surfaces after new bone formation, which protruded into the joint space. The maximum anteroposterior and mediolateral condylar diameters were significantly larger in the control group than those in the test group. Micro-CT also showed that the primary growth orientation of new trabeculae was consistent with the direction of lateral pterygoid traction in the control group. Furthermore, histological examination showed fibro-osseous ankylosis in the control group. However, these characteristics were not found in the test group. Conclusion The lateral pterygoid muscle plays an important role, which is similar to distraction oste- ogenesis, in traumatic TMJ ankylosis.