膝内翻对膝骨关节炎股胫内外侧间室骨密度影响的QCT分析

QCT analysis of the effect of knee varus on bone mineral density of medial and lateral femoral tibial compartments in knee osteoarthritis

目的探讨力线正常与膝内翻的膝骨关节炎(KOA)患者在股骨侧与胫骨侧软骨下骨密度(BMD)方面的差异性。方法纳入明确诊断为KOA的450个膝关节的双下肢负重全长正位X线片和双下肢定量CT(QCT)扫描数据,其中力线正常组131个,膝内翻组319个。测量髋-膝-踝(HKA)角及股骨内髁、股骨外髁、胫骨内侧平台、胫骨外侧平台的BMD,同时计算胫骨内侧平台/胫骨外侧平台BMD比值及股骨内髁/股骨外髁BMD比值。比较2组在股胫内侧间室与外侧间室的BMD差异,并进行性别和年龄的亚组分析。Spearman相关分析膝内翻组中胫骨内、外侧平台BMD比值及股骨内、外髁BMD比值与内翻程度的相关性。结果膝内翻组的股骨内髁及胫骨内侧平台的BMD高于力线正常组;而股骨外髁及胫骨外侧平台的BMD则低于力线正常组。2组的胫骨内、外侧平台BMD比值均大于1,且膝内翻组的比值更大;而膝内翻组的股骨内、外髁BMD比值显著高于力线正常组。对于女性,上述结果更加明显且不受年龄影响。相关性分析显示,胫骨内、外侧平台BMD比值与HKA角呈负相关(r_(s)=-0.436,P<0.01),股骨内、外髁BMD比值与HKA角同样呈负相关(r_(s)=-0.394,P<0.01)。结论相比力线正常组,膝内翻组的股胫内侧间室BMD增加,而外侧间室BMD降低。

Objective To investigate the differences in subchondral bone mineral density(BMD)between the femoral and tibial sides in patients of knee osteoarthritis(KOA)with normal lines of force and varus.Methods The data of 450 knee joints with a definite diagnosis of KOA were included in this study including weight-bearing full-length X-ray films and quantitative computed tomography(QCT)scans of both lower limbs.Among them,131 were in the normal force line group and 319 were in the knee varus group.The hip-knee-ankle(HKA)angle and BMD of the femoral medial condyle,femoral lateral condyle,tibial medial plateau and tibial lateral plateau were measured.BMD ratio of tibial medial plateau to tibial lateral plateau and the BMD ratio of femoral medial condyle to femoral lateral condyle were calculated.BMD in medial and lateral compartments of the femur and tibia were compared between the two groups,followed by subgroup analyses based on gender and age.Spearman correlation was used to analyze the correlation between the BMD ratio of tibial medial plateau to tibial lateral plateau,the BMD ratio of femoral medial condyle to femoral lateral condyle and the degree of varus in the knee varus group.Results The BMD of the medial femoral condyles and medial tibial platforms were higher in the knee varus group than those in the normal force line group.The BMD of femoral lateral condyle and lateral tibial platform was lower in the knee varus group than that in the normal force line group.The BMD ratio of the medial to lateral tibial plateaus was greater than one in both groups,and the ratio of the knee varus group was greater.The BMD ratio of femoral medial to lateral condyle in the knee varus group was significantly higher than that in the normal force line group.For women,these findings were more pronounced and were independent of age.Correlation analysis showed that the BMD ratio of medial tibial plateau to lateral tibial plateau was negatively correlated with HKA angle(r_(s)=-0.436,P<0.01),and the BMD ratio of the medial femoral condyle to lateral femoral condyle was also negatively correlated with HKA angle(r_(s)=-0.394,P<0.01).Conclusion The BMD of medial femoral and tibial compartment is increased and the BMD of lateral compartment is decreased in the genu varus group compared with the normal force line group.