全膝关节置换术后下肢位置变化的影像学研究

Radiographic Analysis of the Alignment of Lower Extremity after Total Knee Arthroplusty

目的全膝关节置换术后的影像学参数对手术技术的判断和假体松动的早期发现都是十分重要的,但全膝关节置换术后的影像学参数会受到下肢位置变化的影响,本研究的目的在于探讨下肢位置变化与膝关节置换术后影像学参数的关系。方法对2014年9月到2015年5月我科收治的行全膝关节置换术的12名患者进行测量分析,从患者胫骨外旋20°到内旋25°每内旋5°摄一次前后位全长X线片,测量X线片中下肢力学轴线角度、下肢解剖轴线角度和胫骨解剖轴的角度的数据,获得下肢位置变化与膝关节置换术后影像学参数的关系。结果在内旋下肢的过程中,下肢力学轴线角度从胫骨外旋20°的内翻3°变成胫骨内旋20°的外翻2°,下肢解剖外翻角从胫骨外旋20°的外翻7.57°减小为胫骨内旋20°的外翻3.71°,胫骨解剖轴的角度从胫骨外旋20°的内翻1.6°减小到胫骨内旋20°的外翻1.4°。结论拍摄前后位X线平片时应该明确下肢的解剖标志的旋转位置,以避免下肢旋转而导致的测量误差。

Objective The radiologic parameter after total knee replacement is very important to estimate surgical techniques and to find early prosthetic loosening. However,the radiologic parameter will be influenced by lower limb position change. The aim of the study is to investigate the relationship of lower limb position and the radiologic parameter after total knee replacement. Methods There was retrospectively study of twelve patients after total knee replacement in our hospital from September 2014 to May 2015. The full-length radiographs were taken from external rotation 20° to internal rotation 25°.The lower limb mechanical axis angle,lower limb anatomical axis and tibia anatomical axis angle were measured to define the relationship of lower limb position and the radiologic parameter after total knee replacement. Results The lower limb mechanical axis angle varied from varus 3° to valgus 2° when tibia position changes from external rotation 20° to internal rotation 20°.The lower limb anatomical axis varied from valgus 7. 57° to valgus 3. 71°when tibia position changes from external rotation 20°to internal rotation 20° with leg full extended. Tibia anatomical axis angle varied from varus 1. 6° to valgus 1. 4°when tibia position changes from external rotation 20° to internal rotation 20°. Conclusion The rotation of anatomical landmarks on full length film should be carefully evaluated to avoid the mistakes caused by rotation of the lower extremities.