膝关节自发性骨坏死与内侧半月板突出相关性的MRI观察

Association between spontaneous osteonecrosis of the knee and medial meniscus extrusion:a MRI observation

[目的]分析内侧半月板突出与膝关节自发性骨坏死的相关性,同时探讨内侧半月板后角根部撕裂（MMRT）对内侧半月板突出长度、骨坏死体积的影响。[方法]选取本院2011年1月~2014年12月诊断膝关节自发性骨坏死的17例患者,根据MRI上所测量的内侧半月板突出长度分为两组,突出长度≥3 mm者为半脱位组,〈3mm则为对照组,对比两组间骨坏死体积;同时分析突出长度与骨坏死体积之间的相关性;根据MRI上是否存在内侧半月板后角根部撕裂,将患者分为撕裂组（MMRT组）和对照组,对比两组间内侧半月板突出长度以及骨坏死体积。[结果]17例患者中有16例（94.1%）存在不同程度的内侧半月板突出,其中9例（52.9%）为内侧半月板半脱位,半脱位组的骨坏死体积显著大于对照组（P=0.004）,且内侧半月板突出长度与骨坏死体积之间呈正相关（r=0.845,P=0.000）。同时发现有7例（42.1%）患者伴有内侧半月板后角根部撕裂,撕裂组（MMRT组）的内侧半月板突出长度和骨坏死体积均大于对照组,但差异无统计学意义（P值分别为0.315、0.088）。[结论]内侧半月板突出和半脱位在膝关节自发性骨坏死患者中发生率高,而且突出长度与骨坏死体积呈正相关,这一现象支持膝关节自发性骨坏死病因学中的应力源性理论。导致严重内侧半月板突出的因素可能是多方面的,不仅仅是内侧半月板后角根部撕裂。

[Objective] To investigate the relationship between spontaneous osteonecrosis of the knee（ SONK） and medial meniscus extrusion,and to evaluate the effects of posterior medial meniscus root tears on the distance of medial meniscus extrusion and the size of osteonecrotic lesions. [Methods] A total of 17 patients diagnosed as SONK between January 2011 and December 2014 were enrolled in this study. These patients were divided into two groups,ie,subluxation group（ extrusion distance≥3 mm） and control group（ the extrusion distance 3 mm）. The size of osteonecrotic lesions was compared between two groups. And the correlation between the extrusion distances and the size of osteonecrotic lesions were analyzed. According to the performance on MRI,patients were divided into two groups,ie,the posterior medial meniscus root tears group（ MMRT group）and control group. We accessed the difference of each group by comparing the distance of medial meniscus extrusion and size of osteonecrotic lesions. [Results] Sixteen patients had medial meniscus extrusion,the incidence rate was 94. 1%. Nine cases were meniscal subluxation,the incidence rate was 52. 9%. The mean size of osteonecrotic lesions in subluxation group was significantly larger than that in control group（ P = 0. 004）. There was a significant correlation between the distance of medial meniscus extrusion and size of osteonecrotic lesions（ r = 0. 845,P = 0. 000）. The mean distance of medial meniscus extrusion and size of osteonecrotic lesions were larger in MMRT group,but there were no statistical difference compared with that in control group（ P = 0. 315,P = 0. 088,respectively）. [Conclusion] The incidence of medial meniscus extrusion and subluxation are high in SONK patients,and the size of osteonecrotic lesions is associated with the distance of medial meniscus extrusion.These results could support the stress theory in etiology of SONK. Severe meniscus extrusion may be related to multiple factors,not just posterior medial meniscus root tears.