膝内外翻畸形时髋臼负重顶区的生物力学变化

Biomechanical changes in the acetabular dome region to knee joint varus and valgus

背景:膝内、外翻畸形改变了膝关节的形态,除影响膝关节的功能外,还可能改变相邻关节髋关节的生物力学行为,也就是髋臼与股骨头之间的力学传导。目的:评价不同程度膝内、外翻畸形对髋臼负重顶区的生物力学影响。方法:取成年男性鲜尸体下肢标本3个,剔除附着的肌肉组织,保留骨膜、韧带及关节囊,通过胫骨高位截骨模拟不同程度的膝内外翻畸形。标本分为中立位组、膝内翻10°组、膝内翻20°组、膝外翻10°组和膝外翻20°组。实验中骨盆的位置选择单足站立中立位。标本通过生物力学试验机加载至50kg,采用压敏片技术测量髋臼顶负重区的负重面积、平均应力及峰值应力。结果与结论:髋臼顶区中立位时股胫关节面负重面积为(6.33±0.12)cm2,平均应力(3.62±0.33)MPa,峰值应力为(4.58±0.20)MPa。当膝内、外翻达10°时,髋臼顶区负重面积减少,平均应力及峰值应力有明显的增加,但差异无显著性意义(P>0.05);当膝内、外翻达20°时髋臼负重面积显著减少,平均应力峰值及应力显著增加,差异有非常显著性意义(P<0.01)。结果提示:随膝内、外翻畸形程度的不同,髋臼负重顶区的负重面积、峰值应力及平均应力也发生变化,当膝内、外翻达20°时,负重面积显著减少,平均应力峰值及应力显著增加,这可能是膝内外翻畸形造成髋骨关节炎的病因之一。因此临床上应重视对膝骨关节炎内、外翻畸形患者的早期干预。

BACKGROUND：Knee joint varus and valgus can change the morphology of the knee joint, influence the function of the knee joint and can change the biomechanical behavior of adjacent articular hip which is the mechanics conduction between the acetabulum and femoral head. OBJECTIVE：To investigate the effect of different varus and valgus angle on the biomechanics of acetabular dome region. METHODS：Three lower limb specimens were col ected from adult male fresh cadaver. Al muscles and connective tissues were dissected while hip and knee periosteum, joint capsules and ligaments were preserved. The high tibial osteotomy was operated to simulate different degrees of knee varus and valgus. The specimens were divided into neutral position group, knee varus 10° group, knee varus 20° group, knee valgus 20° group and knee valgus 10° group. During the experiment, the pelves were in the single-leg standing neutral position. The specimens were loaded with 50 kg by biomechanical testing machine. The loading area, mean stress, and the peak stress in the acetabular dome region were measured with pressure sensitive film system. RESULTS AND CONCLUSION：The loading area of tibiofemoral articular surface in the acetabular dome region under the neutral position was （6.33±0.12） cm2, the mean stress was （3.62±0.33） MPa and the peak stress was （4.58±0.20） MPa. When the knee joint varus and valgus for 10°, the loading area in the acetabular dome region was decreased, while the mean stress and peak stress were significantly increased, but the difference between varus and valgus 10° was no significant （P〉0.05）;when the knee joint varus and valgus for 20°, loading area in the acetabular dome region was significantly decreased, while the mean stress and peak stress were significantly increased, and there was significant difference between varus and valgus 20° （P〈0.01）. The loading area, mean stress and the peak stress distribution in hip dome region were changed with the tendency of knee varus and valgus increasing. When the knee joint varus and valgus for 20°, the loading area in the acetabular dome region was significantly decreased, while the mean stress and peak stress were significantly increased, this may be one of the factors of hip osteoarthritis caused by knee varus and valgus. Therefore, we should pay attention on the early intervention to the patients with knee osteoarthritis varus and valgus deformity in clinic.