膝关节软骨下局灶性骨髓病变的组织学特点

Histological features of focal subchondral bone marrow lesions of knee joint

目的探讨核磁共振（MRI）发现的膝关节软骨下局灶性骨髓病变（bone marrow lesions,BMLs）的组织学表现和特点。方法收集本院2013年9月至2015年2月因膝关节骨性关节炎行关节置换的40-70岁患者,术前完善患膝MRI,发现非负重区软骨下局灶性BMLs病灶（T1加权低信号区,T2加权及STIR脂肪抑制序列高信号区）者10例,其中男性3例,女性7例;术中获取病灶标本5例,其中男性2例,女性3例,年龄53-67（61±6）岁。标本切片均行HE染色及番红O/固绿染色,观察BMLs病灶区和相邻对照区组织学表现,Image Pro Plus 6.0图像分析软件测量各类病理组织所占面积比例和骨小梁体积分数（trabecular bone volume,BV/TV）。结果 5例局灶性BMLs病灶分别位于髌骨2例,股骨前髁2例,股骨后髁1例;术中见病灶部位表面软骨存在Ⅰ-Ⅳ度损伤,1例髌骨病灶截面为囊性变,其余为松质骨表现;术后病理学观察结果显示：除1例囊变外,其余4例病灶区以正常组织为主,占76.9%,异常组织占23.1%,BV/TV为26.7%,与对照区比较,骨髓坏死（t=-4.0,P=0.029）、异常骨小梁（t=-4.0,P=0.028）、BV/TV（t=6.4,P=0.008）差异有统计学意义。结论膝关节非负重区软骨下局灶性BMLs病灶表现出一些非特异性异常组织学表现和一定的共性,软骨损伤和骨小梁减少尤为明显。

Objective To explore the histological findings of the focal subchondral bone marrow lesions （BMLs） of the knee joint detected by MRI. Methods From September 2013 to February 2015, the knee osteoarthritis patients （ aged 40 - 70） referred for total knee arthroplasty were examined with sagittal short inversion time inversion-recovery （STIR） and T1- and T2-weighted turbo spin-echo MRI imaging before surgery. MRI detected the subchondral BMLs （hyperintense on STIR images and T2-weighted MR images, and hypointense on Tl-weighted MR images） at the non-weight-bearing area in 10 patients （3 males and 7 females）. Five specimens were obtained from 5 patients （2 males and 3 females） with the mean age of 61 ± 6.1 （ranged from 53 to 67） in the surgery. All the sections were stained with HE and Safranin O/fast green for observing the pathological features. The percentage of various tissue areas and the trabecular bone volume （BV/TV） were measured by Image Pro Plus 6.0 imaging system. Results Five BMLs included 2 cases involved in the patella, 2 in anterior femoral condyle and 1 in posterior femoral condyle. All the acetabular components were well fixed by the radiograph imaging. I - IV cartilage lesions were found at the BMLs. Cystic change was found in 1 case of patella and the others were cancellous bone. Histological appearance contained 1 case of bone cyst, and the rest 4 cases were consisted of normal tissues （76.9%） and several abnormalities （23.1%）. Trabecular bone volume （BV/TV） of the 4 cases was 26. 7%. Compared with the control regions, significant differences were found in the bone marrow necrosis （ t = - 4.0, P = 0. 029 ）, trabeculae abnormalities （t= -4.0, P =0.028） and BV/TV （t =6.4, P =0.008）. Conclusion Focal subchondral BMLs at the non-weight-bearing area of the knee joint represent a number of noncharacteristic histological abnormalities, and have some common features, especially the cartilage lesions and decrease of trabeculae.