Ogawa Takeshi, Takao Masaki, Hamada Hidetoshi, Sakai Takashi, Sugano Nobuhiko
Department of Orthopaedic Medical Engineering, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, Japan.
Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, Japan.
Int Orthop. 2018 Sep;42(9):2059-2065. doi: 10.1007/s00264-018-3908-9. Epub 2018 Mar 27.
The aim was to compare patients who suffered recurrent dislocation following total hip arthroplasty (THA) with those who did not to clarify the degree of soft tissue tension in dislocation patients.
The subjects were 18 hips with recurrent dislocation (unstable THA group) and 37 hips without dislocation (stable THA group). To evaluate soft tissue tension, radiographs were taken while applying distal traction at traction forces of 40, 30, and 20% of the body weight (BW) and femoral head displacement was measured. Acetabular offset, femoral offset, limb offset, and leg length discrepancy were measured in patients with a normal contralateral hip joint.
The mean femoral head displacement in the unstable THA group was 5.6 mm at 40% of the BW, 4.6 mm at 30% of the BW, and 3.5 mm at 20% of the BW. In the stable THA group, the mean femoral head displacement was 1.4 mm at 40% of the BW, 1.1 mm at 30% of the BW, and 0.9 mm at 20% of the BW. Significant differences were seen between the groups at all traction forces. Furthermore, on comparing the unstable and stable THA groups, femoral offset was found to significantly be smaller in the affected side than in the healthy side in the unstable THA group.
We found that soft tissue tension is approximately fourfold lower in patients exhibiting recurrent dislocations following THA than in patients exhibiting no dislocations and that femoral offset was related to decreased soft tissue tension.
比较全髋关节置换术(THA)后复发性脱位患者与未脱位患者,以明确脱位患者的软组织张力程度。
研究对象为18例复发性脱位的髋关节(不稳定THA组)和37例未脱位的髋关节(稳定THA组)。为评估软组织张力,在施加相当于体重40%、30%和20%的远端牵引力时拍摄X线片,并测量股骨头移位情况。对健侧髋关节正常的患者测量髋臼偏移、股骨偏移、肢体偏移和腿长差异。
不稳定THA组在体重40%牵引力时股骨头平均移位5.6毫米,30%牵引力时为4.6毫米,20%牵引力时为3.5毫米。稳定THA组在体重40%牵引力时股骨头平均移位1.4毫米,30%牵引力时为1.1毫米,20%牵引力时为0.9毫米。在所有牵引力下两组间均存在显著差异。此外,比较不稳定和稳定THA组时发现,不稳定THA组患侧的股骨偏移明显小于健侧。
我们发现,THA后复发性脱位患者的软组织张力比未脱位患者低约四倍,且股骨偏移与软组织张力降低有关。