EFFECT OF PARTIAL DISC-REMOVAL ON THE INTRA-ARTICULAR ARCHITECTURE OF THE SHEEPTMJ.

关节盘是TMJ复杂生物力学的重要组成部分，正常的TMJ功能是由其维持的。以往的研究报道，实验性椎间盘穿孔或手术引起的关节盘移位会影响TMJ的形状。临床上，关节盘位置的改变会导致髁突的形状和大小发生变化。然而，人们对这些变化知之甚少。间盘穿孔/缺失是否影响关节形态尚不明确。本研究的目的是探讨实验性关节盘部分摘除对绵羊TMJ关节内结构的影响。对绵羊TMJ进行以下两种手术：第一组：双侧TMJ摘除关节盘外侧半部分；第二组：双侧TMJ关节盘外侧半切成梳状。关节被“整块”取出，进行组织学处理和检查。术前采集滑液并进行手术。用高效液相色谱法测定滑液中硫酸软骨素的含量，形态、组织学和生化分析结果在第1组和第2组中基本一致。形态变化在髁突外侧明显，与盘状切除/梳状切口区相对应。外髁关节软骨随时间的延长而增殖，增厚。两组关节液中硫酸软骨素水平在术后2周和4周均有所升高，但与术前无明显差异。摘除关节盘后关节液中硫酸软骨素的变化与软骨增生性重塑一致，而不是骨性关节炎。髁突的形态改变归因于增生性重塑，可能是由于机械负荷增加所致。

The disc is an essential part of the complicated biomechanics of the TMJ.Normal TMJ function is maintained with the disc. Previous studies reported that experimental disc perforation or surgically induced disc displacement affects the shape of the TMJ.Altered disc position clinically leads to the condylar changes in shape and size. However, little information is known about the changes. Whether disc perforation/absence affects joint morphology is ambiguous. The purpose of this study is to investigate the effect of experimental partial disc-removal on the intra-articular architecture of the sheep TMJ.The following two procedures were carried out for the sheep TMJ.Group 1 : The lateral half of the disc was removed in the bilateral sheep TMJ.Group 2 : Lateral half of the disc was cut comb-like in the bilateral sheep TMJ.The animals were sacrificed at 2, 4, 12, and 24 weeks after the partial disc removal. The joint was removed 'en bloc', histologically processed and examined. The synovial fluid was collected before and do the procedure. Chondroitin-sulfate levels of the synovial fluid were measured by HPLC analysis.Morphologic, histologic, and biochemical analysis showed almost consistent results in the Group 1 and Group 2. The morphologic changes were notably observed at the lateral part of the condyle, corresponding to the area of disc-removal/comb-like cut. The lateral condylar articular cartilage proliferated and increased in its thickness with time. Synovial fluid chondroitin-sulfate levels increased at 2 and 4 postoperative weeks in the both groups, but were not significantly different to the pre-operative values.These changes after disc-removal were identical to cartilagenous proliferative remodeling rather than osteoarthritis. The condylar morphologic changes were attributed to proliferative remodeling and probably due to increased mechanical loading.